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.nr LL 40.5P
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.rs
\v | 5i'
.sp 1P
.ce 1000
\v'3P'
SECTION\ 2
.ce 0
.sp 1P
.ce 1000
\fBDESCRIPTION\ OF\ ISDNs\fR 
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ I.120\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBINTEGRATED\ SERVICES\ DIGITAL\ NETWORKS\ (ISDNs)\fR 
.EF '%	Fascicle\ III.7\ \(em\ Rec.\ I.120''
.OF '''Fascicle\ III.7\ \(em\ Rec.\ I.120	%'
.ce 0
.sp 1P
.ce 1000
\fR \fI(Malaga\(hyTorremolinos, 1984)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBPrinciples of ISDN\fR 
.sp 1P
.RT
.PP
1.1
The main feature of the ISDN concept is the support of a wide range of 
voice and non\(hyvoice applications in the same network. A key element 
of service integration for an ISDN is the provision of a range of services 
(see 
Part\ II of the I\(hySeries in this Fascicle) using a limited set of connection
types and multipurpose user\(hynetwork interface arrangements (see Parts\ III
and\ IV of the I\(hySeries in Fascicle\ III.8).
.sp 9p
.RT
.PP
1.2
ISDNs support a variety of applications including both switched
and non\(hyswitched connections. Switched connections in an ISDN include both
circuit\(hyswitched and packet\(hyswitched connections and their
concatenations.
.PP
1.3
As far as practicable, new services introduced into an ISDN
should be arranged to be compatible with 64\ kbit/s switched digital
connections.
.PP
1.4
An ISDN will contain intelligence for the purpose of providing
service features, maintenance and network management functions. This
intelligence may not be sufficient for some new services and may have to be
supplemented by either additional intelligence within the network, or possibly 
compatible intelligence in the user terminals. 
.PP
1.5
A layered protocol structure should be used for the specification of the 
access to an ISDN. Access from a user to ISDN resources may vary 
depending upon the service required and upon the status of implementation of
national ISDNs.
.PP
1.6
It is recognized that ISDNs may be implemented in a variety of
configurations according to specific national situations.
.sp 2P
.LP
\fB2\fR 	\fBEvolution of ISDNs\fR 
.sp 1P
.RT
.PP
2.1
ISDNs will be based on the concepts developed for telephone
IDNs and may evolve by progressively incorporating additional functions and
network features including those of any other dedicated networks such as
circuit\(hyswitching and packet\(hyswitching for data so as to provide 
for existing and new services. 
.sp 9p
.RT
.PP
2.2
The transition from an existing network to a comprehensive ISDN
may require a period of time extending over one or more decades. During this
period arrangements must be developed for the interworking of services 
on ISDNs and services on other networks (see Part\ V). 
.PP
2.3
In the evolution towards an ISDN, digital end\(hyto\(hyend connectivity 
will be obtained via plant and equipment used in existing networks, such 
as 
digital transmission, time\(hydivision multiplex switching and/or space\(hydivision 
multiplex switching. Existing relevant Recommendations for these constituent 
elements of an ISDN are contained in the appropriate series of Recommendations 
of CCITT and of CCIR. 
.bp
.PP
2.4
In the early stages of the evolution of ISDNs, some interim
user\(hynetwork arrangements may need to be adopted in certain countries to
facilitate early penetration of digital service capabilities. Arrangements
corresponding to national variants may comply partly or wholly with I\(hySeries
Recommendations. However, the intention is that they not be specifically
included in the I\(hySeries.
.PP
2.5
An evolving ISDN may also include at later stages switched
connections at bit rates higher and lower than 64\ kbit/s.
\v'1P'
.sp 2P
.LP
\fBRecommendation\ I.121\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBBROADBAND\ ASPECTS\ OF\ ISDN\fR 
.EF '%	Fascicle\ III.7\ \(em\ Rec.\ I.121''
.OF '''Fascicle\ III.7\ \(em\ Rec.\ I.121	%'
.ce 0
.sp 1P
.ce 1000
\fI(Melbourne, 1988)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.LP
	\fBForeword\fR 
.sp 1P
.RT
.PP
This Recommendation should be interpreted as a guideline to the
objective of providing more detailed Recommendations on all broadband aspects 
of ISDN\ (B\(hyISDN) during the next Study Period\ (1989\(hy1992). 
.PP
The Recommendation was elaborated taking into account the
following:
.RT
.LP
	\(em
	the emerging demand for broadband services;
.LP
	\(em
	the availability of high speed transmission, switching and
signal processing technologies;
.LP
	\(em
	the need for covering broadband aspects of ISDN, in CCITT
Recommendations,
.LP
	\(em
	the need to integrate both interactive and distribution
services;
.LP
	\(em
	 the need to integrate both circuit and packet transfer modes into one 
universal broadband network; 
.LP
	\(em
	the need to provide flexibility to both user and
operator.
.sp 2P
.LP
\fB1\fR 	\fBPrinciples and concept\fR 
.sp 1P
.RT
.sp 1P
.LP
1.1
	\fIPrinciples of\fR \fI B\(hyISDN\fR 
.sp 9p
.RT
.PP
The main feature of the ISDN concept is the support of a wide range of 
audio, video and data applications in the same network. A key element of 
service integration for an ISDN is the provision of a range of services 
using a limited set of connection types and multipurpose user\(hynetwork 
interfaces. 
.PP
In the context of this Recommendation, the term B\(hyISDN is used for
convenience in order to refer to and emphasize the broadband aspects of 
ISDN. The intent, however, is that there be one comprehensive notion of 
an ISDN which provides broadband and other ISDN services. 
.PP
B\(hyISDNs support both switched and non\(hyswitched connections.
Connections in a B\(hyISDN support both circuit\(hymode and packet\(hymode 
services. 
.PP
A B\(hyISDN will contain intelligence for the purpose of providing
service features, maintenance and network management functions. This
intelligence may not be sufficient for some new services and may have to be
supplemented by either additional intelligence within the network, or possibly 
compatible intelligence in user terminals. 
.PP
A layered structure should be used for the specification of the access 
protocol to a B\(hyISDN. 
.PP
It is recognized that ISDNs may be implemented in a variety of
configurations according to specific national situations.
.bp
.RT
.sp 2P
.LP
1.2
	\fIEvolution of B\(hyISDN\fR 
.sp 1P
.RT
.sp 1P
.LP
1.2.1 
	\fITarget transfer mode\fR 
.sp 9p
.RT
.PP
Asynchronous transfer mode (ATM) is the target transfer mode
solution for implementing a B\(hyISDN. It will influence the standardization of
digital hierarchies and multiplexing structures, switching and interfaces 
for broadband signals. 
.PP
ATM as used in this Recommendation concerns a specific packet\(hyoriented 
transfer mode using the 
asynchronous time division multiplexing
technique: the multiplexed information flow is organized in fixed size 
blocks, called cells. A 
cell
consists of a user information field and a header; the primary role of the 
header
is to identify cells belonging to the
same 
virtual channel
on an asynchronous time division multiplex. Cells are assigned on demand, 
depending on the source activity and the available 
resources. Cell sequence integrity on a virtual channel is preserved by the
ATM layer
.
.PP
ATM is a connection\(hyoriented technique. Header values are assigned to 
each section of a connection when required and released when no longer 
needed. The connections identified by the headers remain unchanged during 
the lifetime of a call. Signalling and user information are carried on 
separate virtual 
channels.
.PP
ATM will offer a flexible transfer capability common to all services, including 
connectionless services. 
.RT
.sp 1P
.LP
1.2.2 
	\fIEvolution steps\fR 
.sp 9p
.RT
.PP
B\(hyISDN will be based on the concepts developed for ISDN and may
evolve by progressively incorporating additional functions and services
(e.g.\ high quality video applications).
.PP
The deployment of B\(hyISDN may require a period of time extending over 
one or more decades. Thus, arrangements must be developed for the interworking 
of services on B\(hyISDN and services on other networks. 
.PP
In the evolution towards a B\(hyISDN, digital end\(hyto\(hyend connectivity
will be obtained in part via plant and equipment used in existing and planned 
networks, such as digital transmission and switching. Relevant Recommendations 
for these constituent elements of a B\(hyISDN are contained in the appropriate 
series of Recommendations of CCITT and of CCIR.
.PP
In the early stages of the evolution of B\(hyISDN, some interim
user\(hynetwork arrangements [e.g.\ combinations of synchronous transfer
mode\ (STM) and ATM\ techniques] may need to be adopted in certain countries 
to facilitate early penetration of digital service capabilities. 
.RT
.sp 2P
.LP
\fB2\fR 	\fBService aspects of B\(hyISDN\fR 
.sp 1P
.RT
.sp 1P
.LP
2.1
	\fIGeneral\fR 
.sp 9p
.RT
.PP
The principles of services supported by an ISDN are described in
the\ I.200\(hySeries Recommendations. The description of B\(hyISDN services 
is based on the principles of the existing\ I\(hySeries Recommendations. 
.PP
This section describes the classification of broadband services, the definition 
of those service classes, and gives examples of services in each 
service class proposed to be supported by the ISDN.
.PP
This classification does not take into account the location of the
implementation of the functions either in the network or in the terminals. 
This classification is primarily from the point of view of the network 
and not from the user point of view. 
.PP
Depending on their communication functions and applications, the
services to be supported by the B\(hyISDN may be internationally standardized 
and offered by the Administration as bearer services or teleservices. 
.RT
.sp 1P
.LP
2.2
	\fIService classes\fR 
.sp 9p
.RT
.PP
Depending on the different forms of the broadband communication and their 
applications, two main service categories have been identified: 
interactive services and distribution services. The interactive services are
subdivided into three classes of services, viz., the conversational services, 
the messaging services, and the retrieval services. The distribution services 
are represented by the class of distribution services without user individual 
presentation control and the class of distribution services with user 
individual presentation control (see Figure\ 1/I.121).
.bp
.RT
.LP
.rs
.sp 20P
.ad r
\fBFigure 1/I.121, (N), p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
2.3
	\fIDefinition of service classes\fR 
.sp 1P
.RT
.sp 1P
.LP
2.3.1
	\fBConversational services\fR 
.sp 9p
.RT
.PP
Conversational services in general provide the means for
bidirectional dialogue communication with real\(hytime (no store\(hyand\(hyforward) 
end\(hyto\(hyend information transfer from user to user or between user 
and host 
(e.g.\ for data processing). The flow of the user information may be
bidirectional symmetric, bidirectional asymmetric and in some specific cases
(e.g.\ such as video surveillance), the flow of information may be
unidirectional. The information is generated by the sending user or users, 
and is dedicated to one or more individual communication partners at the 
receiving site. 
.PP
Examples of broadband conversational services are videotelephony,
video conference and high speed data transmission.
.RT
.sp 1P
.LP
2.3.2
	\fBMessaging services\fR 
.sp 9p
.RT
.PP
Messaging services offer user\(hyto\(hyuser communication between
individual users via storage units with store\(hyand\(hyforward, mailbox and/or
message handling (e.g.\ information editing, processing and conversion)
functions.
.PP
Examples of broadband messaging services are message handling services 
and mail services for moving pictures (films), high resolution images and 
audio information. 
.RT
.sp 1P
.LP
2.3.3
	\fBRetrieval services\fR 
.sp 9p
.RT
.PP
The user of retrieval services can retrieve information stored in information 
centres and in general provided for public use. This information 
will be sent to the user on his demand only. The information can be retrieved 
on an individual basis. Moreover, the time at which an information sequence 
is to start is under the control of the user. 
.PP
Examples are broadband retrieval services for film, high resolution
image, audio information, and archive information.
.bp
.RT
.sp 1P
.LP
2.3.4 
	\fBDistribution services without user individual presentation
control\fR 
.sp 9p
.RT
.PP
These services include broadcast services. They provide a
continuous flow of information which is distributed from a central source 
to an unlimited number of authorized receivers connected to the network. 
The user can access this flow of information \fIwithout\fR the ability 
to determine at which 
instant the distribution of a string of information will be started. The 
user cannot control the start and order of the presentation of the broadcast 
information. Depending on the point of time of the user's access, the
information will not be presented from its beginning.
.PP
Examples are broadcast services for television and
audio\(hyprogrammes.
.RT
.sp 1P
.LP
2.3.5 
	\fBDistribution services with user individual presentation
control\fR 
.sp 9p
.RT
.PP
Services of this class also distribute information from a central source 
to a large number of users. However, the information is provided as a 
sequence of information entities (e.g.\ frames) with cyclical repetition. So,
the user has the ability of individual access to the cyclical distributed
information and can control the start and order of presentation. Due to the
cyclical repetition, the information entities selected by the user will 
always be presented from its beginning. 
.PP
One example of such a service is full channel broadcast
videography.
.RT
.sp 1P
.LP
2.4
	\fIExamples of\fR 
\fIbroadband services\fR 
.sp 9p
.RT
.PP
Table\ A\(hy1/I.121 contains examples of possible services, their
applications and some possible attribute values describing the main
characteristics of the services.
.PP
Guideline prose definitions, service attributes and attribute values for 
describing a number of possible broadband services are presented in 
Annex\ B. Services described include:
.RT
.LP
	\(em
	broadband unrestricted bearer services;
.LP
	\(em
	high quality broadband video telephony:
.LP
	\(em
	high quality broadband video conference;
.LP
	\(em
	existing quality and high definition TV distribution;
.LP
	\(em
	broadband Videotex.
.sp 2P
.LP
2.5
	\fIUser\(hynetwork interface\fR \fIfrom the service point of view\fR 
.sp 1P
.RT
.sp 1P
.LP
2.5.1
	\fINeed for simultaneous services\fR 
.sp 9p
.RT
.PP
The user\(hynetwork interface will be required to support a varying
mixture of services to broadband network users. The simultaneous services
required at the interface will vary between customers, e.g.\ the requirements
for residential customers may differ from those business customers. The
capacity of the interface, the mix of simultaneous services, and the bit 
rate required for each service are all interrelated. 
.PP
The user\(hynetwork interface must be able to accommodate at least
an \d4\uuser rate (see\ Note), (or an equivalent mix of services whose
aggregate bit rate may be up to that of an H\d4\uuser rate), plus some
additional narrow\(hyband services and signalling. Moreover, there may 
be a need to carry a greater volume of services and to provide the capability 
of 
supporting services whose rates exceed the H\d4\uuser rate.
.PP
The study of simultaneous service requirements is important and will impact 
broadband aspects of ISDN such as bit rates, user interfaces, protocol 
processing,\ etc. 
.PP
\fINote\fR \ \(em\ The term H\d4\uuser rate is used here to give an indication 
of the range of bit rates available to the user (see\ \(sc\ 5). No implications 
for channel provision are intended. 
.RT
.sp 1P
.LP
2.5.2
	\fIFlexibility of the user\(hynetwork interface\fR 
.sp 9p
.RT
.PP
Not only will ISDNs in different environments need to support a
large variety of customer requirements for different services, but also the
access requirements of a given customer may often change from time to
time.
.PP
For these reasons, it is necessary that the user network interface be flexible 
and capable of offering dynamic allocation of resources to 
services.
.bp
.RT
.sp 2P
.LP
\fB3\fR 	\fBArchitecture models\fR 
.sp 1P
.RT
.sp 1P
.LP
3.1
	\fIFunctional architecture\fR 
.sp 9p
.RT
.PP
The general 
architecture of the ISDN
from the functional
point of view is described in Recommendation\ I.324.
.RT
.sp 1P
.LP
3.2
	\fIBasic architectural model\fR 
.sp 9p
.RT
.PP
Figure\ 2/I.121 shows the main information transfer and signalling functional 
components of ISDN including broadband aspects: 
.RT
.LP
	\(em
	local functional capabilities (LFC), i.e.\ local exchange
functions and possibly including remote switching
cross\(hyconnect muldexes,\ etc.;
.LP
	\(em
	inter\(hyexchange signalling functional entities;
.LP
	\(em
	64\ kbit/s based functional entities;
.LP
	\(em
	broadband functional entities.
.PP
These components need not be provided by distinct networks but may be combined 
as appropriate for a particular implementation. 
.LP
.rs
.sp 25P
.ad r
\fBFigure 2/I.121, (N), p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
3.3
	\fIReference configurations\fR 
.sp 1P
.RT
.sp 1P
.LP
3.3.1
	\fIReference configuration for the user\(hynetwork interface\fR 
.sp 9p
.RT
.PP
The reference configuration defined in Figure\ 1/I.411 and shown
here as Figure\ 3/I.121 is considered sufficiently general to be applicable 
not only for a basic access and a primary rate access but also to a broadband 
access. Both 
reference points\ S and\ T
are valid for broadband
accesses.
.PP
The functions of the NT1 are, in principle, identical for\ 64\ kbit/s
based ISDN and B\(hyISDN. The same applies to the NT2.
.bp
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure 3/I.121, (N), p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.3.2 
	\fIPhysical realization of reference configurations and\fR 
\fIuser\(hynetwork interfaces\fR 
.sp 9p
.RT
.PP
In order to clearly illustrate the broadband aspects, the notations for 
reference points and for functional groupings with broadband capabilities 
are appended with the letter\ B (e.g.\ B\(hyNT1, T\dB\u). 
.PP
Interfaces at reference points S\dB\uand T\dB\uwill be standardized. These 
interfaces will support all ISDN services. 
.PP
Figure 4/I.121 gives examples of physical configurations illustrating combinations 
of physical interfaces at various reference points. The examples cover 
configurations that could possibly the supported by standardized 
interfaces and reference points\ S\dB\uand T\dB\u. Other configurations 
may also be supported. 
.PP
Configurations \fIj)\fR  | and \fIk\fR  | in Figure\ 4/I.121 require that the
interface specifications for S\dB\uand for T\dB\uhave a high degree of
commonality. Such commonality is highly desirable. The feasibility of achieving 
the needed commonality requires further study. 
.PP
One objective in designing interfaces is to support multiple terminals 
simultaneously via simplified\ B\(hyNT2 (e.g.\ a\ B\(hyNT2 consisting solely 
of physical connections). 
.RT
.sp 1P
.LP
3.4
	\fIB\(hyISDN protocol model for ATM\fR 
.sp 9p
.RT
.PP
The B\(hyISDN protocol model for ATM is shown in Figure\ 5/I.121. Two specific 
layers related to the ATM functions are: 
.RT
.LP
	\(em
	 an ATM layer that is common to all services and provides cell transfer 
capabilities; and 
.LP
	\(em
	an adaptation layer that is service dependent.
.sp 1P
.LP
3.4.1
	\fIATM layer\fR 
.sp 9p
.RT
.PP
The boundary between the ATM layer and the service adaptation layer corresponds 
to the boundary between functions devoted to the header and 
functions devoted to the information field.
.RT
.sp 1P
.LP
3.4.2
	\fIAdaptation layer\fR 
.sp 9p
.RT
.PP
The adaptation layer supports higher layer functions of the user
and control planes and supports connections between ATM and non\(hyATM 
interfaces. Information is mapped by the adaptation layer into ATM cells. 
At the 
transmitting end, information units (e.g.\ LAPD frames) are segmented or
information units (e.g.\ PCM voice samples) are collected to be inserted
into\ ATM cells. At the receiving end the information units are reassembled
(e.g.\ LAPD frames) or read\(hyout (e.g.\ PCM voice samples) from ATM cells. 
Any 
adaptation layer specific information (e.g.\ data field length, time stamps,
sequence number) that must be passed between peer adaptation layers is
contained in the information field of the ATM cell.
.PP
The adaptation layer could be terminated in a Network
Termination\ (NT), Network Adapter\ (NA), Terminal Adapters\ (TA), Terminal 
Equipment\ (TE) and Exchange Termination\ (ET) (see Figure\ 6/I.121). Network 
adapter functions include those adaptation functions that are necessary 
between ATM and non\(hyATM parts of ISDN. 
.bp
.RT
.LP
.rs
.sp 47P
.ad r
\fBFigure 4/I.121, (N), p. 4\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 14P
.ad r
\fBFigure 5/I.121, (N), p. 5\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 23P
.ad r
\fBFigure 6/I.121, (N), p. 6\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.4.3
	\fIAdaptation layer functions\fR 
.sp 9p
.RT
.PP
Examples of adaptation functions include Continuous Bit Stream
Oriented\ (CBO) services adaptation functions, existing packet mode services
adaptation functions and connectionless services adaptation
functions:
.RT
.LP
	\(em
	CBO adaptation functions
.LP
	CBO oriented services are those which involve an
uninterrupted flow of digital information; for example; 64\ kbit/s PCM voice.
The CBO adaptation functions support these services over an ATM network. 
Within the adaptation layer the following functions may be performed: 
.LP
	1)
	cell assembly and disassembly;
.LP
	2)
	compensation for the variable delay of the ATM
network;
.LP
	3)
	handling of lost cell conditions;
.LP
	4)
	clock recovery. Some alternatives are to synchronize
the output bit stream to the network clock or to the
source bit stream;
.LP
	5)
	mapping of the control signal (e.g.\ V.35) into the ATM
cell stream.
.LP
	\(em
	Existing packet mode services adaptation functions
.LP
	Existing packet mode services (e.g.\ LAPD) can be supported
by the CBO adaptation functions. This does not take advantage of the idle
periods between data transmission. The packet mode adaptation layer provides
bandwidth savings by taking advantage of the bursty nature of packet services. 
Operations that may be carried out by the packet mode adaptation functions 
include:
.LP
	1)
	detection of information blocks from the higher
layer;
.LP
	2)
	dividing information blocks into ATM cells;
.LP
	3)
	handling of partially filled cells;
.LP
	4)
	reassembling information blocks from received ATM
cells;
.LP
	5)
	sending information blocks to the higher layer;
.LP
	6)
	rate adaptation;
.LP
	7)
	action on loss of cells.
.LP
	\(em
	Adaptation functions may be defined for connectionless
services.
.sp 2P
.LP
\fB4\fR 	\fBAsynchronous transfer mode\fR \fBcharacteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
4.1
	\fIGeneral considerations\fR 
.sp 9p
.RT
.PP
The information field is transported transparently by the ATM
layer; no processing (e.g.\ error control) is performed on the information 
field at the ATM layer. 
.PP
The header and the information field each consist of a fixed integer number 
of octets at a given reference point. The information field length is 
the same for all connections at all reference points where the ATM technique 
is applied. 
.RT
.sp 1P
.LP
4.2
	\fIHeader functions\fR 
.sp 9p
.RT
.PP
The 
header
contains just the information required to
transfer the information field through the ATM network. Application\(hyoriented 
or service\(hyoriented information does not appear inside the header. 
.PP
The three following functions are mandatory:
.RT
.LP
	\(em
	virtual channel identification (VCI);
.LP
	\(em
	error detection on the header;
.LP
	\(em
	unassigned cell indication.
.PP
The need for additional functions supported by the header is for further 
study. The following candidates have been identified: 
.LP
	\(em
	error correction on the header;
.LP
	\(em
	Quality of Service identification (e.g.\ delay or loss
priority);
.LP
	\(em
	payload type (e.g.\ virtual circuit test cells);
.LP
	\(em
	cell loss detection;
.LP
	\(em
	access control at the user\(hynetwork interface\ (UNI);
.bp
.LP
	\(em
	cell sequence numbering;
.LP
	\(em
	terminal identifier;
.LP
	\(em
	virtual path identification;
.LP
	\(em
	line equipment identification.
.sp 1P
.LP
4.3
	\fIHeader format\fR 
.sp 9p
.RT
.PP
VCI and error control are supported by explicit fields. Whether
identified functions are explicitly (by fields) or implicitly (by\ VCI)
supported is for further study.
.RT
.sp 1P
.LP
4.4
	\fIHeader size\fR 
.sp 9p
.RT
.PP
The size of the header should be chosen in the range of\ 3
to\ 8\ octets. To determine the appropriate size, urgent study on the header
functions mentioned in\ \(sc\ 4.2 and on the capacity for future and additional 
uses is recommended. As an objective, the header size should be the same 
at all 
reference points. The feasibility of this is for further study.
.RT
.sp 1P
.LP
4.5
	\fIInformation field size\fR 
.sp 9p
.RT
.PP
The size of the information field should be chosen in the range
of\ 32 to\ 120\ octets. To determine the appropriate size, the two following 
items need urgent study: 
.RT
.LP
	\(em
	 end\(hyto\(hyend Quality of Service covering acceptable end\(hyto\(hyend 
delay and loss of information; 
.LP
	\(em
	 transmission efficiency: the information field size\(hyto\(hyheader size 
ratio should allow all existing and envisaged services to be efficiently 
supported on the transmission media. 
.sp 2P
.LP
\fB5\fR 	\fBBroadband channel rates\fR 
.sp 1P
.RT
.PP
In this section channels refer to virtual channels with appropriate transmission 
channel bit rates. In addition to\ B, H\do\uand H\d1\uchannels, 
B\(hyISDN will support broadband channels H\d2\uand H\d4\uhaving the following 
bit rates: 
.RT
.LP
	1)
	H\d2\\d1\ubroadband channel
: 32 | 68\ kbit/s;
.LP
	2)
	H\d2\\d2\ubroadband channel
:
.LP
	\(em
	in the approximate range of 43 to 45\ Mbit/s;
.LP
	\(em
	an integer multiple of 64\ kbit/s;
.LP
	\(em
	not greater than the payload of existing third level
asynchronous transmission systems of the 1.5\ Mbit/s
based hierarchy.
.LP
	Consistent with these three requirements, one objective is
to maximize the bit rate of the H\d2\\d2\ubroadband
channel.
.LP
	3)
	H\d4\ubroadband channel
:
.LP
	\(em
	in the range of\ 132 to 138.240\ Mbit/s;
.LP
	\(em
	an integer multiple of 64\ kbit/s.
.LP
	When subsequently defining the exact bit rate, the following
factors will be taken into account:
.LP
	\(em
	the ATM basis of the 150\ Mbit/s user network
interface;
.LP
	\(em
	the possible need, during an interim period, to use STM
techniques to carry the bit stream of this channel in
transmission systems based on the existing and the new
digital hierarchy;
.LP
	\(em
	the possible need to support a television signal
multiplex as specified by the CMTT.
.PP
The final specification of H\d2\\d2\uand H\d4\ubroadband channel rates 
should be such that: 
\v'6p'
.ce 1000
4\ x\ H\d2\\d1\urate \(=\ H\d4\urate
.ce 0
.sp 1P
.ce 1000
3\ x\ H\d2\\d2\urate \(=\ H\d4\urate
.ce 0
.sp 1P
.PP
.sp 1
Additional broadband channels may be defined if necessary.
.bp
.sp 2P
.LP
\fB6\fR 	\fBUser\(hynetwork interface (UNI)\fR 
.sp 1P
.RT
.sp 1P
.LP
6.1
	\fIGeneral\fR 
.sp 9p
.RT
.PP
This section defines some structural, physical and functional
characteristics of 
broadband user\(hynetwork interfaces
. The
characteristics discussed apply to interfaces at the T\dB\uand at the S\dB\ureference 
points. The commonality between the interface of T\dB\uand at 
S\dB\ureference points is a matter of further study.
.PP
B\(hyISDN user\(hynetwork interfaces will be standardized at two bit rates. 
One of these will be at approximately 150\ Mbit/s and the other will be 
at 
approximately 600\ Mbit/s. The broadband UNI need not be symmetrical. Each of
these interfaces must be capable of supporting broadband services as well as
64\ kbit/s based ISDN services.
.PP
As an objective, the target solution for both B\(hyISDN user\(hynetwork
interfaces is based on ATM.
.PP
Other interface capabilities such as maintenance are not considered in 
this section. 
.RT
.sp 1P
.LP
6.2
	\fIStructure of 150 Mbit/s UNI\fR 
.sp 9p
.RT
.PP
The structure of 150 Mbit/s UNI will be unique and will be based on one 
of the following alternatives: 
.RT
.LP
	1)
	ATM
.LP
	This structure shown in case \fIa)\fR  | and case \fIb)\fR  | of
Figure\ 7/I.121 uses only 
labelled multiplexing with cell
interleaving
. This category has two possible
alternatives:
.LP
	a)
	no frame structure is imposed on this interface;
.LP
	b)
	all cells are aligned in a frame structure constructed
by periodically located synchronization cells.
.LP
	2)
	ATM within a non\(hyATM frame
.LP
	This structure, shown in case \fIc)\fR  | of Figure\ 7/I.121,
places ATM cells in the payload of a frame constructed by using
overhead not based on ATM cells.
.PP
\fINote\fR \ \(em\ In the evolution to B\(hyISDN, a frame structure similar 
to case\ \fIe)\fR  | of Figure\ 8/I.121 may also be considered as one alternative. 
.LP
.rs
.sp 22P
.ad r
\fBFigure 7/I.121, (N), p. 7\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 30P
.ad r
\fBFigure 8/I.121, (N), p. 8\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
6.3
	\fIStructure of 600 Mbit/s UNI\fR 
.sp 9p
.RT
.PP
Five candidate structures as shown in Figure\ 8/I.121 have been
identified for the 600\ Mbit/s UNI. Structures shown in cases\ \fIa)\fR 
, \fIb)\fR 
and\ \fIc)\fR of Figure\ 8/I.121 are identical to cases\ \fIa)\fR , \fIb)\fR 
and\ \fIc)\fR of 
Figure\ 7/I.121. Structures shown in cases \fId)\fR and\ \fIe)\fR of Figure\ 
8/I.121 
have the 
payload
partitioned into 
payload modules
, where
case\ \fIe)\fR shows some of these in STM, for possible use in an interim 
period. 
.PP
The 600 Mbit/s UNI may be constructed as if derived by (bit, byte,
cell) interleaving of four\ 150\ Mbit/s structures and in this case, the gross
bit rate of the 600\ Mbit/s UNI will be four times the gross bit rate of the
150\ Mbit/s UNI.
.PP
The structure of the 600\ Mbit/s interface may need to provide for the 
capability of supporting services whose rates exceed the rate of the H\d4\ubroadband 
channel. This item requires further study. 
.RT
.sp 2P
.LP
6.4
	\fIPhysical and functional characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
6.4.1
	\fIPhysical characteristics\fR 
.sp 9p
.RT
.PP
Layer 1 of the broadband UNI requires electrical or optical
transmission capable of supporting the requisite rate.
.PP
As an objective, the interfaces should allow for the support of
point\(hyto\(hymultipoint configurations.
.bp
.RT
.sp 1P
.LP
6.4.2
	\fIFunctional characteristics\fR 
.sp 9p
.RT
.PP
The channel mix need not be the same in both directions of
transmission.
.RT
.sp 1P
.LP
6.4.3
	\fITiming characteristics\fR 
.sp 9p
.RT
.PP
The NT1 will derive bit timing information from the aggregate bit stream 
received from the network. 
.PP
In case \fIa)\fR  | of Figure\ 7/I.121 and of Figure\ 8/I.121, no frame 
timing is provided. Only cell delineation is provided using randomly located 
synchronization cells.
.PP
In case \fIb)\fR  | of Figure\ 7/I.121 and of Figure\ 8/I.121, frame timing 
is provided using periodically located synchronization cells. 
.PP
In case \fIc)\fR  | of Figure\ 7/I.121 and cases \fIc)\fR , \fId)\fR  | 
and \fIe)\fR  | of 
Figure\ 8/I.121, frame timing is provided from the 
overhead information
. The ATM stream within the payload or a payload module may be self delineated, 
i.e.\ cells are delineated by inserting synchronization cells randomly 
or 
periodically. Alternatively, cell delineation can be achieved by using the
periodic structure of the payload.
.PP
In all cases the exact method for cell delineation is for further
study.
.RT
.sp 2P
.LP
\fB7\fR 	\fBNetwork aspects\fR 
.sp 1P
.RT
.sp 1P
.LP
7.1
	\fIGeneralities\fR 
.sp 9p
.RT
.PP
UNI will be defined according to user needs. Maximum commonality
between UNI and the network node interfaces is aimed for.
.RT
.sp 1P
.LP
7.2
	\fITransmission of ATM\fR 
.sp 9p
.RT
.PP
ATM can be supported by any digital transmission hierarchy or
system (e.g. existing hierarchies of Rec.\ G.702, the proposed synchronous
hierarchy of Rec.\ G.707, G.708, G.709 and any future hierarchy that may be
defined). The transfer of information by means of a stream of cells is the
basic concept of ATM. It is desirable to be able to perform this process 
at the highest practical bit rate. Standardization of a broadband digital 
transmission hierarchy has to accommodate these principles. 
.RT
.sp 1P
.LP
7.3
	\fISynchronization\fR 
.sp 9p
.RT
.PP
The need for synchronization in the ATM network requires further
study.
.RT
.sp 1P
.LP
7.4
	\fISignalling\fR 
.sp 9p
.RT
.PP
In B\(hyISDN, signalling and user information are carried on separate
ATM virtual channels
. A user may have multiple signalling entities
connected to the network connection control management via separate ATM 
virtual channels. Enhanced or extended\ I.441 and\ I.451 access protocols 
will be used in B\(hyISDN to accommodate the additional B\(hyISDN capabilities. 
.RT
.sp 2P
.LP
7.5
	\fITraffic management and usage monitoring\fR 
.sp 1P
.RT
.sp 1P
.LP
7.5.1
	\fISource characterization\fR 
.sp 9p
.RT
.PP
Two types of service sources can be classified according to the
traffic patterns they produce:
.RT
.LP
	\(em
	constant traffic sources
. Constant traffic sources
produce a fixed rate of information, e.g.\ PCM encoded
speech;
.LP
	\(em
	variable traffic sources
. Variable traffic sources
produce a variable rate of information, e.g.\ bursty data
sources.
.bp
.sp 1P
.LP
7.5.2
	\fISource indication at call establishment\fR 
.sp 9p
.RT
.PP
The signalling messages sent by a user to establish a call may
include the following type of information:
.RT
.LP
	\(em
	source traffic characteristics, e.g.\ burstiness;
.LP
	\(em
	required network transport capabilities, e.g.\ Quality of
Service parameters.
.sp 1P
.LP
7.5.3
	\fINetwork resource management at call establishment\fR 
.sp 9p
.RT
.PP
In response to the source indication the network may manage
resources in several ways, such as:
.RT
.LP
	\(em
	dedicate resources to a given connection;
.LP
	\(em
	share resources among multiple connections;
.LP
	\(em
	share resources among a class of connections
(e.g.\ connections supporting bursty data
sources).
.PP
For each of the above\(hymentioned alternatives, networks may manage resources 
according to the following examples: 
.LP
	\(em
	\fICase A\fR 
.LP
	 In this case sufficient resources are provided to accommodate the expected 
maximum source bit rate. It could be used for continuous bit 
stream oriented services, as well as other services.
.LP
	\(em
	\fICase B\fR 
.LP
	In this case resources are provided at a level somewhere
between the expected peak and average source bit rate. This strategy could 
be applied to bursty sources. 
.PP
Other ways of managing resources may also be envisaged.
.sp 1P
.LP
7.5.4
	\fIUsage monitoring\fR 
.sp 9p
.RT
.PP
In ATM a user could attempt to send traffic exceeding the
characteristic negotiated at call establishment. ATM networks will provide
usage monitoring to detect such situations. When the negotiated capacity is
being exceeded, appropriate action is taken by the network to protect the
Quality of Service provided to other network users.
.RT
.sp 1P
.LP
7.5.5
	\fIFlow control\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 1P
.LP
7.5.6
	\fICongestion handling\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 2P
.LP
\fB8\fR 	\fBAdaptation between ATM and non\(hyATM parts of the ISDN\fR 
.sp 1P
.RT
.PP
Interworking is envisaged between ATM based and 64\ kbit/s based
networks and terminals. For that purpose, network adaptations and terminal
adaptations will be defined, for example:
.RT
.LP
	\(em
	to connect a terminal according to standardized interfaces
(I\(hySeries Recommendations) to the ATM network;
.LP
	\(em
	to provide internetworking between ATM and 64\ kbit/s based
parts of the ISDN.
.PP
This item requires further study.
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation I.121)
.sp 9p
.RT
.ce 0
.ce 1000
\fBExamples of broadband services\fR 
.sp 1P
.RT
.ce 0
.PP
Table\ A\(hy1/I.121 contains examples of possible services, their
applications and some possible attribute values describing the main
characteristics of the services.
.bp
.sp 1P
.RT
.ce
\fBH.T. [1T1.121]\fR 
.ce
TABLE\ A\(hy1/I.121
.ce
\fBPossible broadband services in ISDN\fR 
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | cw(36p) | cw(60p) | cw(60p) .
Service   classes  	Type of  information  	 {
Examples of
broadband
services
 }	Applications  	 {
Some possible attribute
values | ug\d\u)\d\u,\d \uh\d\u)\d
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
Conversational services	 {
Moving pictures (video) and sound
 }	 {
Broadband | ub\d\u)\d\u,\d \uc\d\u)\d
video\(hytelephony
 }	 {
Communication for the transfer of voice (sound), moving
pictures, and video scanned still images and documents between two
locations (person\(hyto\(hyperson) | uc\d\u)\d
\(em\ 
Tele\(hyeducation
\(em\ 
Tele\(hyshopping
\(em\ 
Tele\(hyadvertising
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
\(em
(Value for information transfer rate is under
study)
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
Broadband | ub\d\u)\d\u,\d \uc\d\u)\d
videoconference
 }	 {
Multipoint communication for the transfer of voice (sound),
moving pictures, and video scanned still images and documents between two
or more locations (personne\(hyto\(hygroup, group\(hyto\(hygroup | uc\d\u)\d
\(em\ 
Tele\(hyeducation
\(em\ 
Tele\(hyshopping
\(em\ 
Tele\(hyadvertising
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		Video\(hysurveillance	 {
\(em
Building security
\(em
Traffic monitoring
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
Video/audio information transmission service
 }	 {
\(em
TV signal transfer
\(em
Video/audio dialogue
\(em
Contribution of information
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Sound	 {
Multiple sound\(hy programme signals
 }	 {
\(em
Multilingual commentary channels
\(em
Multiple programme transfers
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Data	 {
High speed unrestricted digital information transmission
service
 }	 {
\(em
High speed data transfer
\(em
LAN (local area network) interconnection
\(em
Computer\(hycomputer interconnection
\(em
Transfer of video and other information types
\(em
Still image transfer
\(em
Multi\(hysite interactive CAD/CAM
 }	 {
\(em
Demand/reserved/per
ma
nent
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
High volume file transfer service
 }	\(em Data file transfer	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau A\(hy1/I.121, [1T1.121], p. 9\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T1.121]\fR 
.ce
TABLE\ A\(hy1/I.121 \fI(continued)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | cw(36p) | cw(60p) | cw(60p) .
Service   classes  	Type of  information  	 {
Examples of
broadband
services
 }	Applications  	 {
Some possible attribute
values | ug\d\u)\d\u,\d \uh\d\u)\d
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
 {
Conversational services \fI(continued)\fR
 }	Data \fI(continued)\fR	High speed teleaction	 {
\(em
Realtime control
\(em
Telemetry
\(em
Alarms
 }	
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Document	High speed Telefax	 {
User\(hyto\(hyuser transfer of text, images, drawings,\ etc.
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
High resolution image communication service
 }	 {
\(em
Professional images
\(em
Medical images
\(em
Remote games and game networks
 }	
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
Document communication service
 }	 {
User\(hyto\(hyuser transfer of mixed documents | ud\d\u)\d
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/bidirectional asymmetric
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
Messaging services	 {
Moving pictures (video) and sound
 }	Video mail service	 {
Electronic mailbox service for the transfer of moving pictures
and accompanying sound
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/uni
directional (for further
study)
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Document	Document mail service	 {
Electronic mailbox service for mixed documents | ud\d\u)\d
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint
\(em
Bidirectional symmetric/uni
directional (for further
study)
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
Retrieval services	 {
Text, data, graphics, sound, still images, moving pictures
 }	Broadband videotex	 {
\(em
Videotex including moving pictures
\(em
Remote education and train
ing
\(em
Telesoftware
\(em
Tele\(hyshopping
\(em
Tele\(hyadvertising
\(em
News retrieval
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint
\(em
Bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		Video retrieval service	 {
\(em
Entertainment purposes
\(em
Remote education and train
ing
 }	 {
\(em
Demand/reserved
\(em
Point\(hyto\(hypoint/multipoint | uf\d
\u)\d
\(em
Bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
High resolution image retrieval service
 }	 {
\(em
Entertainment purposes
\(em
Remote education and train\(hy
ing
\(em
Professional image communications
\(em
Medical image communications
 }	 {
\(em
Demand/reserved
\(em
Point\(hyto\(hypoint/multipoint | uf\d
\u)\d
\(em
Bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		Document retrieval service	 {
\*QMixed documents\*U retrieval from information centres,
archives,\ etc. | ud\d\u)\d\u,\d \ue\d\u)\d
 }	 {
\(em
Demand
\(em
Point\(hyto\(hypoint/multipoint | uf\d
\u)\d
\(em
Bidirectional asymmetric
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		Data retrieval service	Telesoftware	
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau A\(hy1/I.121, [2T1.121], p. 10\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [3T1.121]\fR 
.ce
TABLE\ A\(hy1/I.121 \fI(continued)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | cw(36p) | cw(60p) | cw(60p) .
Service   classes  	Type of  information  	 {
Examples of
broadband
services
 }	Applications  	 {
Some possible attribute
values | ug\d\u)\d\u,\d \uh\d\u)\d
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
 {
Distribution services without user individual presentation control
 }	Video	 {
Existing quality TV distribution service (PAL, SECAM, NTSC)
 }	TV programme distribution	 {
\(em
Demand (selection)/per
ma
nent
\(em
Broadcast
\(em
Bidirectional asymmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
Extended quality TV distribution service
\(em
Enchanced definition TV distribution service
\(em
High quality TV
 }	TV programme distribution	 {
\(em
Demand (selection)/per
ma
nent
\(em
Broadcast
\(em
Bidirectional asymmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
High definition TV distribution service
 }	TV programme distribution	 {
\(em
Demand (selection)/per
ma
nent
\(em
Broadcast
\(em
Bidirectional asymmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
		 {
Pay\(hyTV (pay\(hyper\(hyview, pay\(hyper\(hychannel)
 }	TV programme distribution	 {
\(em
Demand (selection)/per
ma
nent
\(em
Broadcast/multipoint
\(em
Bidirectional asymmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Text, graphics, still images	Document distribution service	 {
\(em
Electronic newspaper
\(em
Electronic publishing
 }	 {
\(em
Demand (selection/per
ma
nent
\(em
Broadcast/multipoint | uf\d
\u)\d
\(em
Bidirectional asymmetric/unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Data	 {
High speed unrestricted digital information distribution
service
 }	 {
\(em
Distribution of unrestricted data
 }	 {
\(em
Permanent
\(em
Broadcast
\(em
Unidirectional
 }
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
				
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
	Moving pictures and sound	 {
Video information distribution service
 }	 {
\(em
Distribution of video/audio signals
 }	 {
\(em
Permanent
\(em
Broadcast
\(em
Unidirectional
 }
_
.T&
lw(36p) | lw(36p) | lw(36p) | lw(60p) | lw(60p) .
 {
Distribution services with user individual presentation control
 }	 {
Text, graphics, sound, still images
 }	 {
Full channel broadcast videography
 }	 {
\(em
Remote education and train
ing
\(em
Tele\(hyadvertising
\(em
News retrieval
\(em
Telesoftware
 }	 {
\(em
Permanent
\(em
Broadcast
\(em
Unidirectional
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau A\(hy1/I.121, [3T1.121], p. 11\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.sp 1
.bp
.ce
\fBH.T. [4T1.121]\fR 
.ce
\fINotes to Table  A\(hy1/I.121:\fR 
.LP
\ua\d\u)\d
In this table only those broadband services are considered which may require 
higher transfer capacity than that of the H 
1 capacity.
Services for sound retrieval, main sound applications and visual services
with reduced or highly reduced resolutions are not listed.
.LP
\ub\d\u)\d
This terminology indicates that a re\(hydefinition regarding existing terms 
has taken place. The new terms may or may not exist for a transition 
period.
.LP
\uc\d\u)\d
The realization of the different applications may require the
definition of different quality classes.
.LP
\ud\d\u)\d
\*QMixed document\*U means that a document may contain text, graphic, still 
and moving picture information as well as voice annotation. 
.LP
\ue\d\u)\d
Special high layer functions are necessary if post\(hyprocessing
after retrieval is required.
.LP
\uf\d
\u)\d
Further study is required to indicate whether the
point\(hyto\(hymultipoint connection represents in this case a main application. 
.LP
\ug\d\u)\d
At present, the packet mode is dedicated to non\(hyrealtime
applications. Depending on the final definition of the packet transfer 
mode, further applications may appear. The application of this attribute 
value 
requires further study.
.LP
\uh\d\u)\d
For the moment this column merely highlights some possible
attribute values to give a general indication of the characteristics of
these services. The full specification of these services will require a 
listing of all values which will be defined for broadband services in Recommendations 
of the I.200\(hySeries. 
.ce
\fBH.T. [1T2.121]\fR 
.ce
TABLE\ B\(hy1/I.121
.ce
\fBBroadband unrestricted bearer services\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
\fIInformation transfer attributes\fR
 }		
			
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
1.
Information transfer mode | ua\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | ub\d\u)\d
Statistical | ub\d\u)\d
 }	
			
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.
Information transfer rate (Mbit/s) 
 }	 {
H
2
1, H
2
2 or H
4 channel bit\(hyrate
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.1
Peak bit rate (throughput)
 }		 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }	 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.2
Average bit rate | uc\d\u)\d
 }		As peak bit rate	Under study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
3.
Information transfer capability
 }	Unrestricted	Unrestricted
_
.T&
lw(72p) | lw(72p) | lw(84p) .
4. Structure	 {
Unstructured or 8 kHz integrity | ud\d\u)\d
 }	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
5.
Etablishment of communication
 }	Demand/reserved/permanent	Demand/reserved/permanent
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
6.
Communication configuration
 }	 {
Point\(hyto\(hypoint/multipoint/broadcast
 }	 {
Point\(hyto\(hypoint/multipoint/broadcast
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
7. Symmetry	 {
Bidirectional symmetric/bidirectional asymmetric/unidirectional
 }	 {
Bidirectional symmetric/bidirectional asymmetric/unidirectional
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
\fIAccess attributes\fR		
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
8.
Access channel and rate (kbit/s)
8.1 User information 
 }	 {
H
2
1, H
2
2 or
H
4 for user information
 }	 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rates
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
8.2 Signalling/selecting	 {
Signalling channel for signalling and
OAM | ue\d\u)\d \(em under study
 }	 {
Signalling channel for signalling and
OAM | ue\d\u)\d \(em under study
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
9. Access protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
Signalling access Protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.1 Layer 1	To be defined	To be defined 
.T&
lw(72p) | lw(72p) | lw(84p) .
I.440/441
I.450/451
Need additions for broadband communication
 }	 {
I.440/441
I.450/451
Need additions for broadband communication
 }
.T&
lw(72p) | lw(72p) | lw(84p) .
Information access protocols	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
9.4 Layer 1  		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.5 Layer 2	\(em \uf\d \u)\d	\(em \uf\d \u)\d
.T&
lw(72p) | lw(72p) | lw(84p) .
9.6 Layer 3	\(em \uf\d \u)\d	\(em \uf\d \u)\d    
_
.T&
lw(72p) | lw(72p) | lw(84p) .
\fIGeneral attributes\fR		
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
10.
Supplementary services provided
 }	For further study	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
11.
Quality of service
\(em
End\(hyto\(hyend transfer delay
\(em
Delay jitter
(cell jitter)
\(em
Error characteristics
\(em
Information loss probability
 }	For further study	For further study
_
.TE
.nr PS 9
.RT
.ad r
\fBNotes du Tableau A\(hy1/I.121, [4T1.121], p. 12\fR 
.sp 1P
.RT
.ad b
.RT
.ce 1000
ANNEX B
.ce 0
.ce 1000
(to Recommendation I.121)
.sp 9p
.RT
.ce 0
.ce 1000
\fBDefinitions of possible broadband service\fR 
.sp 1P
.RT
.ce 0
.ce 1000
\fBfamilies and their attribute values\fR 
.ce 0
.LP
B.1
	\fBbroadband unrestricted bearer services\fR 
.sp 1P
.RT
.sp 1P
.LP
B.1.1
	\fIDefinition\fR 
.sp 9p
.RT
.PP
Bearer services which provide unrestricted end\(hyto\(hyend transfer of 
digital information without alteration between S\dB\u/T\dB\ureference points 
and require broadband channel rates. User information is transferred over 
standardized broadband channels for STM (circuit) services or a virtual 
channel of defined capacity for ATM based services; signalling is provided 
over a 
signalling channel.
.RT
.sp 1P
.LP
B.1.2
	\fIAttribute description\fR 
.sp 9p
.RT
.PP
See Table B\(hy1/I.121.
.RT
.sp 2P
.LP
B.2
	\fBhigh quality broadband videotelephony services\fR 
.sp 1P
.RT
.sp 1P
.LP
B.2.1
	\fIDefinition\fR 
.sp 9p
.RT
.PP
High quality broadband videotelephony services are symmetrical
real\(hytime, bi\(hydirectional audio\(hyvisual services which provide 
person\(hyto\(hyperson communication for the transfer of high quality voice 
(sound), moving pictures, and optionally video\(hyscanned still images 
between two locations. 
.RT
.sp 1P
.LP
B.2.2
	\fIAttribute description\fR 
.sp 9p
.RT
.PP
See Table B\(hy2/I.121.
.bp
.RT
.ce
\fBH.T. [1T2.121]\fR 
.ce
TABLE\ B\(hy1/I.121
.ce
\fBBroadband unrestricted bearer services\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
\fIInformation transfer attributes\fR
 }		
			
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
1.
Information transfer mode | ua\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | ub\d\u)\d
Statistical | ub\d\u)\d
 }	
			
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.
Information transfer rate (Mbit/s) 
 }	 {
H
2
1, H
2
2 or H
4 channel bit\(hyrate
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.1
Peak bit rate (throughput)
 }		 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }	 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.2
Average bit rate | uc\d\u)\d
 }		As peak bit rate	Under study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
3.
Information transfer capability
 }	Unrestricted	Unrestricted
_
.T&
lw(72p) | lw(72p) | lw(84p) .
4. Structure	 {
Unstructured or 8 kHz integrity | ud\d\u)\d
 }	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
5.
Etablishment of communication
 }	Demand/reserved/permanent	Demand/reserved/permanent
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
6.
Communication configuration
 }	 {
Point\(hyto\(hypoint/multipoint/broadcast
 }	 {
Point\(hyto\(hypoint/multipoint/broadcast
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
7. Symmetry	 {
Bidirectional symmetric/bidirectional asymmetric/unidirectional
 }	 {
Bidirectional symmetric/bidirectional asymmetric/unidirectional
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
\fIAccess attributes\fR		
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
8.
Access channel and rate (kbit/s)
8.1
User information 
 }	 {
H
2
1, H
2
2 or
H
4 for user information
 }	 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rates
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
8.2 Signalling/selecting	 {
Signalling channel for signalling and
OAM | ue\d\u)\d \(em under study
 }	 {
Signalling channel for signalling and
OAM | ue\d\u)\d \(em under study
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
9. Access protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
Signalling access Protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.1 Layer 1	To be defined	To be defined 
.T&
lw(72p) | lw(72p) | lw(84p) .
I.440/441
I.450/451
Need additions for broadband communication
 }	 {
I.440/441
I.450/451
Need additions for broadband communication
 }
.T&
lw(72p) | lw(72p) | lw(84p) .
Information access protocols	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
9.4 Layer 1  		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.5 Layer 2	\(em \uf\d \u)\d	\(em \uf\d \u)\d
.T&
lw(72p) | lw(72p) | lw(84p) .
9.6 Layer 3	\(em \uf\d \u)\d	\(em \uf\d \u)\d    
_
.T&
lw(72p) | lw(72p) | lw(84p) .
\fIGeneral attributes\fR		
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
10.
Supplementary services provided
 }	For further study	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
11.
Quality of service
\(em
End\(hyto\(hyend transfer delay
\(em
Delay jitter
(cell jitter)
\(em
Error characteristics
\(em
Information loss probability
 }	For further study	For further study
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy1/I.121, [1T2.121], p. 13\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T2.121]\fR 
.ce
TABLE\ B\(hy1/I.121\fI(continued)\fR 
.ce

.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
12.
Interworking possibilities
 }	For further study 	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
13.
Operational and commercial
 }	 {
For further study. This study should include maintenance
facilities.
 }	 {
For further study. This study should include maintenance
facilities.
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy1/I.121, [2T2.121], p. 14\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 30P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [1T3.121]\fR 
.ce
TABLE\ B\(hy2/I.121
.ce
\fBHigh quality broadband videotelephony services\fR 
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
\fIInformation transfer attributes\fR
 }		
			
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
1.
Information transfer mode | ub\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | uc\d\u)\d
Statistical | uc\d\u)\d
 }	
			
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.
Information transfer rate | ud\d\u)\d (Mbit/s)
 }	 {
H
2
1, H
2
2 or H
4 channel bit\(hyrate
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.1
Peak bit rate (throughput)
 }		 {
H
2
1, H
2
2 or H
4
channel or other bit rate
 }	 {
H
2
1, H
2
2 or H
4
channel or other bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.2
Average bit rate | ue\d\u)\d
 }		As peak bit rate	Under study  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
3.
Information transfer capability
 }	 {
High quality video + 15 kHz
audio + user\(hyto\(hyuser messages
 }	 {
High quality video + 15 kHz audio + User\(hyto\(hyuser
messages
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
4. Structure	Unstructured	For further study
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
5.
Establishment of communication
 }	Demand/reserved/permanent	Demand/reserved/permanent
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
6.
Communication configuration
 }	 {
Point\(hyto\(hypoint/multipoint
 }	 {
Point\(hyto\(hypoint/multipoint
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
7. Symmetry	Bidirectional symmetric	Bidirectional symmetric  
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
\fIAccess attributes\fR  			
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
8. Access channel and rate	 {
H
2 or H
4 (bit rates under study) for user
information
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
8.1 User information		 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rate
 }	 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
8.2 Signalling	 {
Signalling channel for signalling and OAM\(hyunder
study
 }	 {
Signalling channel under study
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
9. Access protocols  		
.T&
lw(72p) | lw(72p) | lw(84p) .
Signalling access protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.1 Layer 1	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
I.440/441
I.450/451
Need additions for broadband
communication
 }	 {
I.440/441
I.450/451
Need additions for broadband
communication
 }
.T&
lw(72p) | lw(72p) | lw(84p) .
Information access protocols	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
9.4
Layer 1
9.5
Layer 2
9.6
Layer 3
 }	Under study	Under study
_
.T&
lw(72p) | lw(156p) .
 {
\fIHigh layer attributes\fR
 }	
.T&
lw(72p) | cw(156p) .
10. Type of user information	 {
Moving pictures + sound + user\(hyto\(hyuser messages
 }
_
.T&
lw(72p) | lw(156p) .
 {
11.
Transport (layer 4) functions/protocol
 }	Under study  
_
.T&
lw(72p) | lw(156p) .
 {
12.
Session (layer 5) functions/protocol
 }	Under study    
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy2/I.121, [1T3.121], p. 15\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T3.121]\fR 
.ce
TABLE\ B\(hy2/I.121 \fI(continued)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(156p) .
 {
13.
Presentation (layer 6) functions/protocol
 }	
.T&
lw(72p) | lw(156p) .
 {
13.1
Video
13.2
Audio
13.3
Auxiliary
13.4
User\(hyto\(hyuser messages
 }	 {
Under study. This study should include video, sound, auxiliary
information such as text, facsimile, etc., and user\(hyto\(hyuser control
messages
 }
_
.T&
lw(72p) | lw(156p) .
 {
14.
Application (layer 7) function/protocol
 }	
.T&
lw(72p) | lw(156p) .
 {
14.1
Video
14.2
Audio
14.3
Auxiliary
14.4
User\(hyto\(hyuser messages
 }	Under study  
_
.T&
lw(72p) | lw(156p) .
\fIGeneral attributes\fR	
.T&
lw(72p) | lw(156p) .
 {
15.
Supplementary services provided
 }	 {
As for telephony; others under study 
 }
_
.T&
lw(72p) | lw(156p) .
16. Quality of service	
.T&
lw(72p) | lw(156p) .
16.1 Video	 {
Equal to or higher than existing TV
 }
_
.T&
lw(72p) | lw(156p) .
16.2 Audio	15 kHz stereo | uf\d \u)\d  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
\(em
End\(hyto\(hyend transfer delay
\(em
Delay jitter
(call jitter)
\(em
Error characteristics
\(em
Information loss probability
 }	Under study 	Under study   
_
.T&
lw(72p) | lw(156p) .
 {
17.
Interworking possibilities
 }	 {
With other videotelephone, telephone, and video\(hyconference
services
 }
_
.T&
lw(72p) | lw(156p) .
 {
18.
Operational and commercial
 }	 {
For further study. This study should include maintenance
facilities
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy2/I.121, [2T3.121], p. 16\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
B.3
	\fBhigh quality broadband videoconference services\fR 
.sp 1P
.RT
.sp 1P
.LP
B.3.1
	\fIDefinition\fR 
.sp 9p
.RT
.PP
High Quality Broadband Videoconference services provide
person\(hyto\(hyperson or group\(hyto\(hygroup capability for the transfer 
of different 
high quality information types primarily including voice (sound), full 
motion video, moving pictures, and, optionally, video\(hyscanned still 
images, documents and other video information, to support conferencing 
between two or more 
locations.
.RT
.sp 1P
.LP
B.3.2
	\fIAttribute description\fR 
.sp 9p
.RT
.PP
See Table B\(hy3/I.121.
.RT
.sp 2P
.LP
B.4
	\fBhigh definition TV and existing quality TV distribution
services\fR 
.sp 1P
.RT
.sp 1P
.LP
B.4.1
	\fIDefinition\fR 
.sp 9p
.RT
.PP
High definition TV (HDTV)/existing quality TV distribution
services provide the capability of distributing TV programmes with the 
quality of HDTV/existing quality TV as appropriate. 
.RT
.sp 1P
.LP
B.4.2 
	\fIAttribute description\fR 
.sp 9p
.RT
.PP
See Table B\(hy4/I.121.
.RT
.sp 2P
.LP
B.5
	\fBbroadband videotex services\fR 
.sp 1P
.RT
.sp 1P
.LP
B.5.1
	\fIDefinition\fR 
.sp 9p
.RT
.PP
Broadband Videotex services are interactive services which
provide, through appropriate access by standardized procedures, for users of
broadband videotex terminals to communicate with data bases via
telecommunications networks.
.RT
.LP
.rs
.sp 21P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [1T4.121]\fR 
.ce
TABLE\ B\(hy3/I.121
.ce
\fBHigh quality broadband videoconference
.ce
services\fR 
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
\fIInformation transfer attributes\fR
 }		
			
.T&
lw(72p) | lw(72p) | lw(42p) sw(42p) , ^  | ^  | l | l.
 {
1.
Information transfer mode | ub\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | uc\d\u)\d
Statistical | uc\d\u)\d
 }	
			
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.
Information transfer rate | ud\d\u)\d
(Mbit/s)
 }	 {
H
2
1, H
2
2 or H
4 channel bit\(hyrate
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.1
Peak bit rate (throughput)
 }		 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }	 {
H
2
1, H
2
2 or H
4 channel or
other bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
 {
2.2
average bit rate | ue\d\u)\d
 }		As peak bit rate	Under study  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
3.
Information transfer capability
 }	 {
High quality video + 15 kHz audio + user\(hyto\(hyuser
messages
 }	 {
High quality video + 15 kHz audio stereo + user\(hyto\(hyuser
messages
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
4. Structure	Unstructured	For further study  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
5.
Establishment of communication
 }	Demand/reserved/permanent	Demand/reserved/permanent  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
6.
Communication configuration
 }	 {
Multipoint/point\(hyto\(hypoint
 }	 {
Multipoint/point\(hyto\(hypoint
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
7. Symmetry	 {
Bidirectional symmetric/bidirectional asymmetric/others
for further study
 }	 {
Bidirectional symmetric/bidirectional asymmetric/others
for further study
 }
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
\fIAccess attributes\fR  			
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
8. Access channel and rate	 {
H
2 or H
4 for user information (multipoint
communication)
 }		
_
.T&
lw(72p) | lw(72p) | lw(42p) | lw(42p) .
8.1 User information		 {
Virtual channel with
H
2 or H
4 channel bit rate
 }	 {
Virtual channel with H
4 channel bit rate
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
8.2 Signalling	 {
Signalling channel for signalling and OAM \(em under
study
 }	 {
Signalling channel under study
 }
_
.T&
lw(72p) | lw(72p) | lw(84p) .
9. Access protocols  		
.T&
lw(72p) | lw(72p) | lw(84p) .
Signalling access protocols		
.T&
lw(72p) | lw(72p) | lw(84p) .
9.1 Layer 1	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
I.440/441
I.450/451
Need supplements for broadband
communication 
 }	 {
I.440/441
I.450/451
Need supplements for broadband
communication
 }
.T&
lw(72p) | lw(72p) | lw(84p) .
Information access protocols	To be defined	To be defined
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
9.4
Layer 1
9.5
Layer 2
9.6
Layer 3
 }	Under study	Under study
_
.T&
lw(72p) | lw(156p) .
 {
\fIHigh layer attributes\fR
 }	
.T&
lw(72p) | cw(156p) .
10. Type of user information	 {
Moving pictures + sound + user\(hyto\(hyuser messages
 }
_
.T&
lw(72p) | lw(156p) .
 {
11.
Transport (layer 4) functions/protocol
 }	Under study  
_
.T&
lw(72p) | lw(156p) .
 {
12.
Session (layer 5) functions/protocol
\fR
 }	Under study    
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy3/I.121, [1T4.121], p. 17\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T4.121]\fR 
.ce
TABLE\ B\(hy3/I.121 \fI(continued)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(156p) .
Attributes	Values
_
.T&
lw(72p) | lw(156p) .
 {
13.
Presentation (layer 6) functions/protocol
 }	
.T&
lw(72p) | lw(156p) .
 {
13.1
Video
13.2
Audio
13.3
Auxiliary
13.4
User\(hyto\(hyuser messages
 }	 {
Under study. This study should include video, sound auxiliary
information such as text, facsimile, etc., and user\(hyto\(hyuser
control messages 
 }
_
.T&
lw(72p) | lw(156p) .
 {
14.
Application (layer 7) function/protocol
 }	
.T&
lw(72p) | lw(156p) .
 {
14.1
Video
14.2
Audio
14.3
Auxiliary
14.4
User\(hyto\(hyuser messages
 }	Under study  
_
.T&
lw(72p) | lw(156p) .
\fIGeneral attributes\fR	
.T&
lw(72p) | lw(156p) .
 {
15.
Supplementary services provided
 }	 {
As for telephony; others under study
 }
_
.T&
lw(72p) | lw(156p) .
16. Quality of service	
.T&
lw(72p) | lw(156p) .
16.1 Video	 {
Equal to or higher than existing TV
 }
_
.T&
lw(72p) | lw(156p) .
16.2 Audio	15 kHz stereo | uf\d \u)\d  
_
.T&
lw(72p) | lw(72p) | lw(84p) .
 {
\(em
End\(hyto\(hyend transfer delay
\(em
Delay jitter (cell
jitter)
\(em
Error characteristics
\(em
Information loss probability
 }	Under study 	Under study  
_
.T&
lw(72p) | lw(156p) .
 {
17.
Interworking possibilities
 }	 {
With other videoconference, videotelephone, and telephone
services
 }
_
.T&
lw(72p) | lw(156p) .
 {
18.
Operational and commercial
 }	 {
For further study. This study should include maintenance
facilities
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy3/I.121, [2T4.121], p. 18\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [1T5.121]\fR 
.ce

.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ B\(hy4/I.121
.T&
cw(342p) .
 {
\fBHigh definition TV (HDTV) distribution services and existing quality \fR
\fBTV distribution services\fR
 }
.T&
cw(72p) | cw(138p) | cw(132p) , ^  | c | c.
Attributes	 {
Existing quality TV distribution
service | ua\d\u)\d | ub\d\u)\d
 }	HDTV distribution service
	Values	Values
_
.TE
.TS
center box ;
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
\fIInformation transfer attributes\fR
 }				
.T&
lw(72p) | lw(66p) | lw(36p) sw(36p) | lw(66p) | lw(66p) , ^  | ^  | l | l ^  | | l.
 {
1.
Information transfer mode | uc\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | ud\d\u)\d
Statistical | ud\d\u)\d
 }	 {
STM (circuit)
ATM 
Deterministic | ud\d\u)\d
 }		
				
_
.T&
lw(72p) | lw(66p) | lw(36p) | lw(36p) | lw(66p) | lw(66p) .
 {
2.
Information transfer rate (Mbit/s)
 }	 {
H
2
1, H
2
2 or H
4\(hychannel bit\(hyrate
 }			 {
H
4\(hychannel bit rate or greater 
 }	
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
2.1
Peak bit rate (throughput)
 }		 {
H
2
1, H
2
2 or H
4 channel or other bit
rate
 }	n/a  	 {
H
4\(hychannel bit rate or greater
 }
_
.T&
lw(72p) | lw(66p) | lw(36p) | lw(36p) | lw(66p) | lw(66p) .
 {
2.2
Average bit rate | ue\d\u)\d
 }		As peak bit rate	Under study	n/a	As peak bit rate  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
 {
3.
Information transfer capability 
 }	 {
High quality video + 15\ kHz audio stereo
 }	 {
High quality video + 15\ kHz audio stereo
 }	 {
HDTV quality video + 15\ kHz audio
stereo
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
4. Structure	Unstructured	Service data unit integrity	Unstructured	For further study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
5.
Establishment of communication
 }	Demand/reserved	Demand/reserved	Demand/reserved	Demand/reserved  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
6.
Communication configuration 
 }	 {
Broadcast (other values for further study)
 }	 {
Broadcast (other values for further study)
 }	 {
Broadcast (other values for further study)
 }	 {
Broadcast (other values for further study)
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
7. Symmetry	Unidirectional	Unidirectional	Unidirectional	Unidirectional  
_
.T&
lw(72p) | lw(66p) | lw(36p) | lw(36p) | lw(132p) .
\fIAccess attributes\fR  				
.T&
lw(72p) | lw(66p) | lw(36p) | lw(36p) | lw(132p) .
 {
8.
Access channel and rate
8.1
User information
 }	 {
H
2 or H
4 (bits rates under study) for user information
 }	 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rate
 }	 {
Virtual channel with H
2
1, H
2
2 or H
4
channel or other bit rate
 }	 {
Virtual channel dependent on the necessary information
transfer rate
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
8.2 Signalling/selecting	 {
D channel or a special channel for distribution service signalling
 }	 {
D channel or special channel (under study)
 }		 {
D channel or special channel (under study)
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy4/I.121, [1T5.121], p. 19\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T5.121]\fR 
.ce

.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
 {
TABLE\ B\(hy4/I.121 \fI(continued)\fR
 }
.T&
cw(72p) | cw(138p) | cw(132p) , ^  | c | c.
Attributes	 {
Existing quality TV distribution
service | ua\d\u)\d | ub\d\u)\d
 }	HDTV distribution service
	Values	Values
_
.TE
.TS
center box;
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
9. Access protocols				
Signalling access protocols				
9.1 Layer 1	To be defined	To be defined	To be defined	To be defined 
I.440/441
I.450/451
Need supplements for broadband
communication
 }	 {
I.440/441
I.450/451
Need supplements for broadband
communication
 }	 {
I.440/441
I.450/451
Need supplements for broadband
communication
 }	
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
Information access protocols	To be defined	To be defined	To be defined	To be defined 
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
9.4
Layer 1
9.5
Layer 2
9.6
Layer 3
 }	Under study	Under study	Under study	Under study
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
 {
\fIHigh layer attributes\fR
 }			
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
10. Type of user information	Moving picture + sound + data	Moving picture + sound + data	 {
Moving picture + sound + data
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
 {
11.
Transfer (layer 4) function/protocol
 }	For further study	For further study	For further study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
 {
12.
Session (layer 5) function/protocol
 }	For further study	For further study	For further study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
 {
13.
Presentation (layer 6) function/protocol
 }			
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
 {
13.1
Video
13.2
Audio
13.3
Auxiliary
13.4
User\(hyto\(hyuser messages
 }	 {
For further study, awaiting suitable coding
schemes
 }	 {
For further study, awaiting suitable coding
schemes
 }	 {
For further study, awaiting suitable coding
schemes
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
 {
14.
Application (layer 7) function/protocol
 }			
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
 {
14.1
Video
14.2
Audio
14.3
Auxiliary
14.4
User\(hyto\(hyuser messages
 }	For further study	For further study	For further study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
\fIGeneral attributes\fR			
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
 {
15.
Supplementary services provided
 }	For further study	For further study	For further study    
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau B\(hy4/I.121, [2T5.121], p. 20\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [3T5.121]\fR 
.ce

.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
 {
TABLE\ B\(hy4/I.121 \fI(continued)\fR
 }
.T&
cw(72p) | cw(138p) | cw(132p) , ^  | c | c.
Attributes	 {
Existing quality TV distribution
service | ua\d\u)\d | ub\d\u)\d
 }	HDTV distribution service
	Values	Values
_
.TE
.TS
center box;
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
16. Quality of service			
.T&
lw(72p) | lw(66p) | lw(72p) | cw(132p) .
16.1 Video	Equal to existing TV	 {
Equal to existing TV (or better)
 }	HDTV quality  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(132p) .
16.2 Audio	 {
Equal to existing high fidelity stereo standards
(or better)
 }	 {
Equal to existing high fidelity stereo standards
(or better)
 }	 {
Equal to existing high fidelity stereo standards
(or better)
 }
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
\(em
End\(hyto\(hyend transfer delay
\(em
Delay jitter (cell
jitter)
\(em
Error characteristics 
\(em
Information loss probability 
 }	Under study	Under study	Under study	Under study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
17.
Interworking possibilities
 }	For further study	For further study	For further study	For further study  
_
.T&
lw(72p) | lw(66p) | lw(72p) | lw(66p) | lw(66p) .
 {
18.
Operational and commercial
 }	For further study	For further study	For further study	 {
For further study
 }
.TE
.LP
\ua\d\u)\d
The attribute values characterize a TV distribution service
providing high video quality equal to, or higher than, existing TV standards. Until now only coding mechanisms for those video qualities have been available which require transfer bit rates equal to, or higher than, the
H
2
1\(hychannel bit rate. Due to future development in research of coding
algorithms and techniques, the transfer bit rates necessary for those video
qualities may decrease.
.LP
\ub\d\u)\d
Preliminary name.
.LP
\uc\d\u)\d
The values for the information transfer mode attribute need
further study. For example, the distinction between the STM (circuit) and the ATM (deterministic) values needs to be investigated.
.LP
\ud\d\u)\d
In the ATM deterministic mode a transfer capacity of the peak bit rate will be provided to the user all the time (average bit rate\ =\ peak bit
rate). In the ATM statistical mode a transfer capacity of only the average
gross bit rate (i.e. the average net bit rate plus cell headers) will be
provided to the user (depending on the throughput class).
.LP
\ue\d\u)\d
Average over, for example, 100 ms.
.nr PS 9
.RT
.ad r
\fBTableau B\(hy4/I.121, [3T5.121], p. 21\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp