5i' SECTION 4 DETERMINATION OF THE NUMBER OF CIRCUITS IN AUTOMATIC AND SEMIAUTOMATIC OPERATION Recommendation E.520 NUMBER OF CIRCUITS TO BE PROVIDED IN AUTOMATIC AND/OR SEMIAUTOMATIC OPERATION, WITHOUT OVERFLOW FACILITIES This Recommendation refers to groups of circuits used: - in automatic operation; - in semiautomatic operation; - in both automatic and semiautomatic operations on the same group of circuits. 1 General method 1.1 The CCITT recommends that the number of circuits needed for a group should be read from tables or curves based on the clas- sical Erlang B formula (see Supplements Nos. 1 and 2 at the end of this fascicle which refers to full availability groups). Recom- mended methods for traffic determination are indicated in Recommendation E.500. For semi-automatic operation the loss probability p should be based on 3% during the mean busy hour. For automatic operation the loss probability p should be based on 1% during the mean busy hour. Semiautomatic traffic using the same circuits as automatic traffic is to be added to the automatic traffic and the same param- eter value of p = 1% should be used for the total traffic. The values of 3% and 1% quoted above refer to the Erlang B formula and derived tables and curves. The 3% value should not be considered as determining a grade of service because with semiau- tomatic operation there will be some smoothing of the traffic peaks; it is quoted here only to determine the value of the parameter p (loss probability) to use in the Erlang B tables and curves. 1.2 In order to provide a satisfactory grade of service both for the mean busy-hour traffic and for the traffic on exceptionally busy days, it is recommended that the proposed number of circuits should, if necessary, be increased to ensure that the loss proba- bility shall not exceed 7% during the mean busy hour for the aver- age traffic estimated for the five busiest days as specified in Recommendation E.500. 1.3 For small groups of long intercontinental circuits with automatic operation some relaxation could be made in respect to loss probability. It is envisaged that such circuits would be operated on a both-way basis and that a reasonable minimum for automatic service would be a group of six circuits. A table provid- ing relaxation in Annex A is based on a loss probability of 3% for six circuits, with a smooth progression to 1% for 20 circuits. The general provision for exceptional days remains unchanged. For exceptional circumstances in which very small groups (less than six intercontinental circuits) are used for automatic opera- tion, dimensioning of the group should be based on the loss proba- bility of 3%. 2 Time differences Time differences at the two terminations of intercontinental circuits are likely to be much more pronounced than those on con- tinental circuits. In order to allow for differences on groups con- taining both-way circuits it will be desirable to acquire informa- tion in respect to traffic flow both during the mean busy hour for both directions and during the mean busy hour for each direction. It is possible that in some cases overflow traffic can be accepted without any necessity to increase the number of circuits, in spite of the fact that this overflow traffic is of a peaky nature. Such circumstances may arise if there is no traffic over- flowing from high-usage groups during the mean busy hour of the final group. 3 Both-way circuits 3.1 With the use of both-way circuits there is a danger of simultaneous seizure at both ends; this is particularly the case on circuits with a long propagation time. It is advisable to arrange the sequence of selection at the two ends so that such double seizure can only occur when a single circuit remains free. When all the circuits of a group are operated on a both-way basis, time differences in the directional mean busy hours may result in a total mean busy-hour traffic flow for the group which is not the sum of the mean busy-hour traffic loads in each direc- tion. Furthermore, such differences in directional mean busy hour may vary with seasons of the year. However, the available methods of traffic measurement can determine the traffic flow during mean busy hour for this total traffic. 3.2 Some intercontinental groups may include one-way as well as both-way operated circuits. It is recommended that in all cases the one-way circuits should be used, when free, in preference to the both-way circuits. The number of circuits to be provided will depend upon the one-way and total traffic. The total traffic will need to be determined for: a) each direction of traffic; b) both-way traffic. This determination is to be made for the busy hour or the busy hours corresponding to the two cases a) and b) above. In the cases where the number of one-way circuits is approxi- mately equal for each direction, no special procedure is necessary, and the calculation can be treated as for a simple two-group grad- ing [1]. If the number of one-way circuits is quite different for the two directions, some correction may be needed for the difference in randomness of the flow of calls from the two one-way circuit groups to the both-way circuit group. The general techniques for handling cases of this type are quoted in Recommendation E.521. ANNEX A (to Recommendation E.520) Table A-1/E.520 may be applied to small groups of long inter- continental circuits. The values in column 2 are suitable for a random offered traffic with full availability access. The table is based on 1% loss probability for 20 circuits and increases progressively to a loss probability of 2% at 9 circuits and 3% at 6 circuits (loss probabilities for these three values being based on the Erlang loss formula: see Supplement No. 1). The traffic flow values obtained from a smoothing curve coincide very nearly with those determined by equal marginal utility theory, i.e. an improvement factor of 0.05 Erlang for an additional cir- cuit. For groups requiring more than 20 circuits the table for loss probability of 1%, mentioned in Supplement No. 1, should be used. H.T. [T1.520] TABLE A-1/E.520 ___________________________________________________________________ Traffic flow (in erlangs) Number of circuits Offered Carried Encountering congestion ___________________________________________________________________ (1) (2) (3) (4) ___________________________________________________________________ 6 2.54 2.47 0.08 7 3.13 3.05 0.09 8 3.73 3.65 0.09 9 4.35 4.26 0.09 10 4.99 4.90 0.09 11 5.64 5.55 0.10 12 6.31 6.21 0.10 13 6.99 6.88 0.10 14 7.67 7.57 0.10 15 8.37 8.27 0.11 16 9.08 8.96 0.11 17 9.81 9.69 0.11 18 10.54 10.42 0.11 19 11.28 11.16 0.12 20 12.03 11.91 0.12 ___________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table A-1/E.520 [T1.520] p.1 Reference [1] TANGE (I.): Optimal use of both-way circuits in cases of unlimited availability, TELE , English Edition, No. 1, 1956. Recommendation E.521 CALCULATION OF THE NUMBER OF CIRCUITS IN A GROUP CARRYING OVERFLOW TRAFFIC A calculation of the number of circuits in a group carrying overflow traffic should be based on this Recommendation and on Recommendation E.522 dealing with high-usage groups. The objective grade of service used is that the average block- ing during the busy-hour of the 30 busiest days of the year will not exceed 1%. To determine the number of circuits in a group carrying over- flow traffic , three traffic parameters are required: the average traffic offered to the group, the weighted peakedness factor , and the level of day-to-day traffic variations. The level of day-to-day traffic variations indicates the degree to which the daily busy-hour traffic deviates from the overall mean traffic, and is determined by the sample variance of the 30 busy-hour traffic. The peakedness factor indicates the degree to which the varia- bility of the traffic deviates from pure chance traffic within a single hour, and in statistical terms is the variance-to-mean ratio of the distribution of simultaneous overflow traffic. 1 Determination of the level of day-to-day traffic varia- tions Let M1, M2, . | | , M3\d0denote the 30 busy-hour loads of the traffic offered to the final group. Determine the mean traffic M of the daily traffic by M = [Formula Deleted] j =1 ~ 0 M j .bp Determine the sample variance Vdof the daily traffic by V d = [Formula Deleted] j =1 ~ 0 (M j - M ) 2 Determine the point (M , Vd) on Figure 1/E.521; M on the hor- izontal axis, and Vdon the vertical axis. i) If the point (M , Vd) is below the bottom curve, the level of variation is Null . ii) If the point is between the lower two curves, the level of variation is Low . iii) If the point is between the upper two curves, the level of variation is Medium . iv) If the point is above the highest curve, the level of variation is High . Default procedures: if the data are not available to compute the variance Vduse the following guidelines: a) If no more than 25 per cent of the traffic offered to the final group is overflow from other groups, assume the level of day-to-day variation is Low. b) Otherwise, assume a Medium level of variation. Figure 1/E.521, p.2 (Recup.) 2 Determination of peakedness factor z Peakedness factors depend principally upon the number of high-usage circuits over which random traffic has access. When the number of such high-usage circuits does not exceed 30, the actual peakedness of the traffic overflowing from a high-usage group will be only slightly below the maximum peakedness values , | Table 1/E.521. H.T. [T1.521] TABLE 1/E.521 Maximum peakedness factor z i _________________________ Tables giving: - the exact mean of the overflow traffic, and - the difference between variance and mean of the overflow have been computed and are set out in [1]. Curves giving the exact mean and variance of overflow traffic are given in [2]. See also a more detailed description of the method in [3] and [4]. _____________________________________________________ | { { _____________________________________________________ 1 1.17 16 2.44 2 1.31 17 2.49 3 1.43 18 2.55 4 1.54 19 2.61 5 1.64 20 2.66 6 1.73 21 2.71 7 1.82 22 2.76 8 1.90 23 2.81 9 1.98 24 2.86 10 2.05 25 2.91 11 2.12 26 2.96 12 2.19 27 3.00 13 2.26 28 3.05 14 2.32 29 3.09 15 2.38 30 3.14 _____________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 1/E.521 [T1.521] (Recup. + Corr.) p.3 For more than 30 circuits, the peakedness of the traffic over- flowing from a high-usage group i of nicircuits is given by zi= 1 - |i+ fInfIi+ 1 + |fIi(em AfIi _________________________ where Ai is the mean (random) traffic offered to the nicircuits and |i is the traffic overflowing. The overflow traffic |iis found by employing the standard Erlang loss formula E 1, ni (Ai): |i= A i E 1, ni (Ai). The weighted mean peakedness factor z , is then calculated from: z = i =1 ~ fIh |fIi i =1 ~ fIh |fIi _________ for the h parcels of traffic being offered to the final group. Note that for the traffic directly offered to the final group, the peakedness factor is zi = 1. 3 Determination of the mean traffic offered to the final group and the number of circuits required 3.1 For planning future network requirements, the traffic overflowing to a final group should be determined theoretically from forecasts of traffics offered to the high-usage groups. The mean traffic overflowing to the final group from a high-usage group is determined in two steps: i) the "single-hour" overflow traffic |ioverflowing from nicircuits is given as above by |i= A i E i, ni (Ai), when Aiis the forecast of traffic offered to the i th high-usage group; ii) the average overflow traffic | i overflowing from the nicircuits is then determined by adjusting the single-hour traffic |ifor the effect of day-to-day traffic variations. | i= ri|i The adjustment factor riis given in Table 2/E.521; it is a function of: - the offered traffic Ai, - the traffic A i E i, n -1 (Ai) - |icarried by the last trunk i , and - the level of day-to-day variations of the traffic offered to the high-usage group. This level can be determined using the method described in S 1 above, but applying it to measurements of traffic offered to the high-usage group. If such measurements are not available a medium level can be used. The mean traffic offered to the final group is then the sum of all | iover the h parcels of traffic: M = i =1 ~ fIh | i It can be assumed that the level of day-to-day traffic varia- tions on the final group remains constant over the forecast time period. Using the level of day-to-day traffic variation as determined in S 1 above on the final group and the peakedness factor of S 2 above, the appropriate table of Tables 3/E.521 to 6/E.521 is used to derive the number of circuits required. Note 1 - This method of calculation of the mean traffic offered to the final group is valid only if the overflow traffic due to blocking encountered in the exchange in the attempts to con- nect to a high-usage, is negligible. Note 2 - Table 3/E.521 differs slightly from the previous tables published by CCITT, although in Table 3.1/E.521 there is no allowance for day-to-day variations. The new table takes into account a systematic bias in the measurement procedure that is based on a finite period of time (1 hour), instead of an infinite period as was assumed in the previous table [5]. Note 3 - Tables 4/E.521, 5/E.521 and 6/E.521 are based on the calculation of the average blocking from the formula: | = B (m ) f (m )dm , where B (m ) is the single-hour expected blocking and f (m ) is the density distribution of day-to-day traffic (m ), assuming a Pearson Type III distribution: 336.nr 15 408 | |f(m)=/ (M 2/V fId ) M /V)(____fRfIm [(M 2/V fId )- 1] e -M mfR /V fId | | M and Vdare the mean and day-to-day variance of the traffic as cal- culated [5] in S 1 above. H.T. [T2.521] TABLE 2/E.521 Overflow adjustment for high-usage trunk groups Factor r i __________________________________________________________________________________________________________________________________________________________ Last trunk traffic { Low daily variation Medium daily variation High daily variation 0.25 0.3 0.4 0.5 0.6 0.25 0.3 0.4 0.5 0.6 0.25 0.3 __________________________________________________________________________________________________________________________________________________________ 3 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 5 1.0 1.0 1.0 1.0 1.0 1.1 1.1 1.1 1.0 1.0 1.2 1.2 1.1 1.1 1.0 7 1.0 1.0 1.0 1.0 1.0 1.2 1.2 1.1 1.1 1.0 1.4 1.3 1.2 1.1 1.1 10 1.1 1.1 1.1 1.0 1.0 1.3 1.2 1.2 1.1 1.1 1.5 1.4 1.3 1.2 1.1 15 1.2 1.1 1.1 1.1 1.0 1.5 1.4 1.2 1.2 1.1 1.8 1.6 1.4 1.3 1.1 20 1.2 1.2 1.1 1.1 1.0 1.6 1.5 1.3 1.2 1.1 2.0 1.8 1.5 1.3 1.2 25 1.3 1.2 1.2 1.1 1.1 1.8 1.6 1.4 1.3 1.1 2.3 2.0 1.7 1.4 1.2 30 1.3 1.3 1.2 1.1 1.1 1.8 1.7 1.4 1.3 1.2 2.4 2.1 1.7 1.5 1.3 __________________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 2/E.521 (Recup. + Corr.) [T2.521], p.4 Blanc H.T. [T3.521] TABLE 3/E.521 Single-hour capacity, in Erlangs, as a function of the number of trunks and of the peakedness factor ___________________________________________________________________________ Parameters: - | lockage 0.01; { - | fINo allowance for day-to-day variation; } { - | eighted mean peakedness factor. } ___________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | _______________________________________________________________________________________________________________________________________________________ Number of trunks required 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.4 3.8 4.0 1 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.53 0.33 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0.94 0.69 0.50 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5 1.42 1.14 0.89 0.67 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6 1.97 1.64 1.36 1.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 2.56 2.19 1.86 1.58 1.31 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 3.19 2.81 2.44 2.11 1.81 1.53 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 3.83 3.42 3.03 2.67 2.36 2.03 1.75 1.50 0.0 0.0 0.0 0.0 0.0 0.0 10 4.53 4.08 3.67 3.28 2.92 2.58 2.28 2.00 1.75 0.0 0.0 0.0 0.0 0.0 11 5.22 4.75 4.31 3.89 3.53 3.17 2.83 2.53 2.25 1.97 0.0 0.0 0.0 0.0 12 5.94 5.44 4.97 4.56 4.14 3.78 3.42 3.08 2.78 2.47 2.22 0.0 0.0 0.0 13 6.67 6.14 5.64 5.19 4.81 4.39 4.03 3.67 3.33 3.03 2.72 0.0 0.0 0.0 14 7.42 6.86 6.36 5.89 5.44 5.03 4.67 4.28 3.94 3.61 3.28 2.69 0.0 0.0 15 8.17 7.58 7.06 6.58 6.11 5.69 5.31 4.92 4.56 4.19 3.86 3.22 0.0 0.0 16 8.94 8.33 7.78 7.28 6.81 6.36 5.94 5.56 5.17 4.81 4.44 3.81 3.19 0.0 17 9.72 9.08 8.50 8.00 7.50 7.06 6.61 6.19 5.81 5.42 5.06 4.39 3.75 3.44 18 10.50 9.83 9.25 8.72 8.22 7.75 7.31 6.86 6.44 6.06 5.69 4.97 4.31 4.00 19 11.31 10.61 10.00 9.44 8.92 8.44 7.97 7.53 7.11 6.72 6.33 5.58 4.89 4.58 20 12.08 11.39 10.78 10.19 9.67 9.14 8.67 8.22 7.81 7.39 6.97 6.22 5.50 5.17 21 12.89 12.19 11.53 10.94 10.39 9.86 9.39 8.92 8.47 8.06 7.64 6.86 6.11 5.78 22 13.72 13.00 12.31 11.69 11.14 10.61 10.08 9.61 9.17 8.72 8.31 7.50 6.75 6.39 23 14.53 13.78 13.08 12.47 11.89 11.36 10.81 10.33 9.86 9.42 8.97 8.17 7.39 7.00 24 15.36 14.58 13.89 13.22 12.64 12.08 11.56 11.03 10.56 10.11 9.67 8.83 8.03 7.64 25 16.19 15.39 14.67 14.00 13.39 12.83 12.28 11.78 11.28 10.81 10.36 9.50 8.69 8.31 26 17.03 16.22 15.47 14.81 14.17 13.58 13.03 12.50 12.00 11.53 11.06 10.19 9.36 8.94 27 17.86 17.03 16.28 15.58 14.94 14.33 13.78 13.22 12.72 12.22 11.75 10.86 10.03 9.61 28 18.69 17.86 17.08 16.36 15.72 15.11 14.53 13.97 13.44 12.94 12.47 11.56 10.69 10.28 29 19.56 18.69 17.89 17.17 16.50 15.86 15.28 14.72 14.19 13.67 13.19 12.28 11.39 10.94 30 20.39 19.53 18.72 17.97 17.28 16.64 16.06 15.47 14.92 14.42 13.92 12.97 12.08 11.64 31 21.25 20.36 19.53 18.78 18.08 17.42 16.81 16.22 15.67 15.14 14.64 13.69 12.78 12.33 32 22.11 21.19 20.36 19.58 18.89 18.22 17.58 17.00 16.42 15.89 15.36 14.39 13.47 13.03 33 22.97 22.06 21.19 20.39 19.67 19.00 18.36 17.75 17.19 16.64 16.11 15.11 14.17 13.72 34 23.83 22.89 22.00 21.22 20.47 19.81 19.14 18.53 17.94 17.39 16.86 15.86 14.89 14.42 35 24.69 23.75 22.83 22.03 21.28 20.58 19.92 19.31 18.69 18.14 17.61 16.58 15.61 15.14 36 25.58 24.58 23.69 22.86 22.11 21.39 20.72 20.08 19.47 18.89 18.36 17.31 16.31 15.83 37 26.44 25.44 24.53 23.69 22.92 22.19 21.50 20.86 20.25 19.67 19.11 18.06 17.06 16.56 38 27.31 26.31 25.36 24.53 23.72 23.00 22.31 21.64 21.03 20.44 19.86 18.81 17.78 17.28 39 28.19 27.17 26.22 25.36 24.56 23.81 23.11 22.44 21.81 21.19 20.64 19.53 18.50 18.00 40 29.08 28.03 27.06 26.19 25.39 24.61 23.89 23.22 22.58 21.97 21.39 20.28 19.25 18.72 41 29.94 28.89 27.92 27.03 26.19 25.44 24.69 24.03 23.36 22.75 22.17 21.06 19.97 19.47 42 30.83 29.75 28.78 27.86 27.03 26.25 25.53 24.81 24.17 23.53 22.94 21.81 20.72 20.19 43 31.72 30.64 29.61 28.72 27.86 27.08 26.33 25.61 24.94 24.31 23.69 22.56 21.47 20.94 44 32.61 31.50 30.47 29.56 28.69 27.89 27.14 26.42 25.75 25.11 24.50 23.33 22.22 21.69 45 33.50 32.39 31.33 30.42 29.53 28.72 27.94 27.22 26.56 25.89 25.28 24.08 22.97 22.42 46 34.39 33.25 32.19 31.25 30.39 29.56 28.78 28.03 27.33 26.69 26.06 24.86 23.72 23.17 47 35.28 34.14 33.08 32.11 31.22 30.39 29.58 28.86 28.14 27.47 26.83 25.64 24.47 23.92 48 36.17 35.00 33.94 32.97 32.06 31.22 30.42 29.67 28.94 28.28 27.64 26.42 25.25 24.69 49 37.06 35.89 34.81 33.81 32.92 32.06 31.25 30.47 29.75 29.08 28.42 27.19 26.00 25.44 50 37.97 36.78 35.67 34.67 33.75 32.89 32.08 31.31 30.58 29.89 29.22 27.97 26.78 26.19 _______________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 3/E.521 (Recup.) [T3.521], p.5 H.T. [T4.521] TABLE 4/E.521 Single-hour capacity, in Erlangs, as a function of the number of trunks and of the peakedness factor ___________________________________________________________________________ Parameters: - | lockage 0.01; { - | fILow day-to-day variation allowance; } { - | eighted mean peakedness factor. } ___________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | _______________________________________________________________________________________________________________________________________________________ Number of trunks required 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.4 3.8 4.0 1 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.53 0.33 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0.94 0.69 0.50 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5 1.39 1.14 0.89 0.67 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6 1.89 1.64 1.36 1.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 2.44 2.14 1.86 1.58 1.31 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 3.03 2.69 2.42 2.11 1.81 1.53 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 3.64 3.28 2.97 2.67 2.36 2.03 1.75 1.50 0.0 0.0 0.0 0.0 0.0 0.0 10 4.25 3.89 3.56 3.22 2.92 2.58 2.28 2.00 1.75 0.0 0.0 0.0 0.0 0.0 11 4.92 4.53 4.17 3.83 3.50 3.17 2.83 2.53 2.25 1.97 0.0 0.0 0.0 0.0 12 5.58 5.17 4.78 4.44 4.08 3.78 3.42 3.08 2.78 2.47 2.22 0.0 0.0 0.0 13 6.25 5.81 5.42 5.06 4.69 4.36 4.03 3.67 3.33 3.03 2.72 0.0 0.0 0.0 14 6.94 6.50 6.08 5.69 5.33 4.97 4.64 4.28 3.94 3.61 3.28 2.69 0.0 0.0 15 7.64 7.17 6.75 6.33 5.97 5.61 5.25 4.92 4.56 4.19 3.86 3.22 0.0 0.0 16 8.33 7.86 7.42 7.00 6.61 6.25 5.89 5.53 5.17 4.81 4.44 3.81 3.19 0.0 17 9.06 8.56 8.11 7.67 7.28 6.89 6.53 6.17 5.81 5.42 5.06 4.39 3.75 3.44 18 9.81 9.28 8.81 8.36 7.94 7.56 7.17 6.81 6.44 6.06 5.69 4.97 4.31 4.00 19 10.53 10.00 9.50 9.06 8.61 8.22 7.83 7.44 7.08 6.72 6.33 5.58 4.89 4.58 20 11.28 10.72 10.22 9.75 9.31 8.89 8.50 8.11 7.72 7.36 6.97 6.22 5.50 5.17 21 12.03 11.44 10.94 10.44 10.00 9.56 9.17 8.78 8.39 8.03 7.64 6.86 6.11 5.78 22 12.78 12.19 11.67 11.17 10.69 10.25 9.83 9.44 9.06 8.67 8.31 7.56 6.75 6.39 23 13.53 12.94 12.39 11.89 11.42 10.94 10.53 10.11 9.72 9.33 8.94 8.19 7.39 7.00 24 14.31 13.69 13.14 12.61 12.11 11.67 11.22 10.81 10.39 10.00 9.61 8.86 8.03 7.64 25 15.08 14.44 13.86 13.33 12.83 12.36 11.92 11.50 11.08 10.67 10.28 9.50 8.67 8.31 26 15.86 15.22 14.61 14.08 13.56 13.08 12.61 12.19 11.75 11.36 10.94 10.17 9.33 8.94 27 16.64 15.97 15.36 14.81 14.28 13.81 13.33 12.89 12.44 12.03 11.64 10.83 10.00 9.61 28 17.42 16.75 16.14 15.56 15.03 14.53 14.06 13.58 13.14 12.72 12.31 11.50 10.67 10.28 29 18.22 17.53 16.89 16.31 15.78 15.25 14.78 14.31 13.86 13.42 13.00 12.19 11.36 10.94 30 19.00 18.31 17.67 17.06 16.50 16.00 15.50 15.03 14.56 14.11 13.69 12.86 12.06 11.64 31 19.81 19.08 18.44 17.83 17.25 16.72 16.22 15.72 15.28 14.83 14.39 13.56 12.75 12.33 32 20.61 19.89 19.19 18.58 18.00 17.47 16.94 16.47 16.00 15.53 15.11 14.25 13.44 13.03 33 21.39 20.67 19.97 19.36 18.78 18.22 17.69 17.19 16.72 16.25 15.81 14.94 14.14 13.72 34 22.22 21.47 20.75 20.11 19.53 18.97 18.42 17.92 17.44 16.97 16.53 15.67 14.83 14.42 35 23.03 22.25 21.56 20.89 20.28 19.72 19.17 18.67 18.17 17.69 17.22 16.36 15.56 15.11 36 23.83 23.06 22.33 21.67 21.06 20.47 19.92 19.39 18.89 18.42 17.94 17.08 16.25 15.81 37 24.64 23.86 23.14 22.44 21.83 21.25 20.67 20.14 19.64 19.14 18.67 17.78 16.94 16.50 38 25.47 24.67 23.92 23.25 22.61 22.00 21.44 20.89 20.36 19.89 19.42 18.50 17.64 17.19 39 26.28 25.47 24.72 24.03 23.39 22.78 22.19 21.64 21.11 20.61 20.14 19.22 18.33 17.89 40 27.11 26.28 25.53 24.81 24.17 23.53 22.94 22.39 21.86 21.36 20.86 19.94 19.06 18.61 41 27.92 27.08 26.31 25.61 24.94 24.31 23.72 23.14 22.61 22.11 21.61 20.67 19.78 19.31 42 28.75 27.92 27.11 26.39 25.72 25.08 24.47 23.92 23.36 22.83 22.33 21.39 20.47 20.03 43 29.58 28.72 27.92 27.19 26.50 25.86 25.25 24.67 24.11 23.58 23.08 22.11 21.19 20.75 44 30.42 29.56 28.75 28.00 27.31 26.64 26.03 25.44 24.89 24.33 23.83 22.86 21.92 21.44 45 31.25 30.36 29.56 28.81 28.08 27.44 26.81 26.22 25.64 25.11 24.58 23.58 22.64 22.17 46 32.08 31.19 30.36 29.61 28.89 28.22 27.58 26.97 26.42 25.86 25.33 24.33 23.36 22.89 47 32.92 32.03 31.17 30.42 29.69 29.00 28.36 27.75 27.17 26.61 26.08 25.06 24.11 23.64 48 33.75 32.83 32.00 31.22 30.47 29.81 29.14 28.53 27.94 27.39 26.83 25.81 24.83 24.36 49 34.58 33.67 32.81 32.03 31.28 30.58 29.94 29.31 28.72 28.14 27.58 26.56 25.56 25.08 50 35.44 34.50 33.64 32.83 32.08 31.39 30.72 30.08 29.50 28.92 28.36 27.31 26.31 25.83 _______________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 4/E.521 (Recup.) [T4.521], p.6 H.T. [T5.521] TABLE 5/E.521 Single-hour capacity, in Erlangs, as a function of the number of trunks and of the peakedness factor ___________________________________________________________________________ Parameters: - | lockage 0.01; { - | fIMedium day-to-day variation allowance; } { - | eighted mean peakedness factor. } ___________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | _______________________________________________________________________________________________________________________________________________________ Number of trunks required 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.4 3.8 4.0 1 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.53 0.33 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0.94 0.69 0.50 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5 1.39 1.14 0.89 0.67 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6 1.86 1.61 1.36 1.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 2.39 2.11 1.83 1.58 1.31 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 2.94 2.64 2.36 2.08 1.81 1.53 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 3.53 3.19 2.89 2.61 2.33 2.03 1.75 1.50 0.0 0.0 0.0 0.0 0.0 0.0 10 4.11 3.78 3.47 3.17 2.86 2.58 2.28 2.00 1.75 0.0 0.0 0.0 0.0 0.0 11 4.72 4.39 4.03 3.72 3.42 3.14 2.83 2.53 2.25 1.97 0.0 0.0 0.0 0.0 12 5.36 4.97 4.64 4.31 4.00 3.69 3.39 3.08 2.78 2.47 2.22 0.0 0.0 0.0 13 6.00 5.61 5.25 4.89 4.56 4.25 3.94 3.67 3.33 3.03 2.72 0.0 0.0 0.0 14 6.64 6.22 5.86 5.50 5.17 4.83 4.53 4.22 3.92 3.61 3.28 2.69 0.0 0.0 15 7.31 6.89 6.47 6.11 5.78 5.42 5.11 4.78 4.47 4.19 3.86 3.22 0.0 0.0 16 7.97 7.53 7.11 6.75 6.39 6.03 5.69 5.39 5.06 4.75 4.44 3.81 3.19 0.0 17 8.64 8.19 7.78 7.36 7.00 6.64 6.31 5.97 5.64 5.33 5.03 4.39 3.75 3.44 18 9.33 8.86 8.42 8.03 7.64 7.28 6.92 6.58 6.25 5.92 5.61 4.97 4.31 4.00 19 10.03 9.53 9.08 8.67 8.28 7.89 7.53 7.19 6.86 6.53 6.19 5.58 4.89 4.58 20 10.69 10.19 9.75 9.33 8.92 8.53 8.17 7.81 7.47 7.14 6.81 6.17 5.50 5.17 21 11.42 10.89 10.42 9.97 9.56 9.17 8.81 8.44 8.08 7.75 7.42 6.75 6.11 5.78 22 12.11 11.58 11.11 10.64 10.22 9.83 9.44 9.06 8.69 8.36 8.03 7.36 6.72 6.39 23 12.83 12.28 11.78 11.33 10.89 10.47 10.08 9.69 9.33 8.97 8.64 7.97 7.33 7.00 24 13.53 13.00 12.47 12.00 11.56 11.14 10.72 10.36 9.97 9.61 9.25 8.58 7.94 7.61 25 14.25 13.69 13.17 12.69 12.25 11.81 11.39 11.00 10.61 10.25 9.89 9.19 8.56 9.19 26 14.97 14.42 13.86 13.39 12.92 12.47 12.06 11.64 11.28 10.89 10.53 9.83 9.17 8.81 27 15.69 15.11 14.58 14.08 13.61 13.14 12.72 12.31 11.92 11.53 11.17 10.44 9.78 9.42 28 16.44 15.83 15.28 14.78 14.28 13.83 13.39 12.97 12.58 12.19 11.81 11.08 10.39 10.06 29 17.17 16.56 16.00 15.47 14.97 14.53 14.08 13.64 13.25 12.83 12.47 11.72 11.03 10.67 30 17.92 17.28 16.72 16.17 15.67 15.19 14.75 14.31 13.92 13.50 13.11 12.36 11.64 11.31 31 18.64 18.03 17.42 16.89 16.39 15.89 15.44 15.00 14.58 14.17 13.78 13.03 12.28 11.94 32 19.39 18.75 18.14 17.58 17.08 16.58 16.11 15.67 15.25 14.83 14.44 13.67 12.92 12.56 33 20.14 19.47 18.86 18.31 17.78 17.28 16.81 16.36 15.92 15.50 15.11 14.33 13.58 13.19 34 20.89 20.22 19.61 19.03 18.50 18.00 17.50 17.06 16.61 16.17 15.78 14.97 14.22 13.86 35 21.64 20.97 20.33 19.75 19.22 18.69 18.19 17.75 17.28 16.86 16.44 15.64 14.86 14.50 36 22.39 21.69 21.06 20.47 19.92 19.42 18.92 18.44 17.97 17.53 17.11 16.31 15.53 15.14 37 23.14 22.44 21.81 21.19 20.64 20.11 19.61 19.14 18.67 18.22 17.81 16.97 16.19 15.81 38 23.89 23.19 22.53 21.94 21.36 20.83 20.31 19.83 19.36 18.92 18.47 17.64 16.86 16.47 39 24.64 23.94 23.28 22.67 22.08 21.56 21.03 20.53 20.06 19.61 19.17 18.33 17.53 17.11 40 25.42 24.69 24.03 23.39 22.81 22.25 21.75 21.25 20.75 20.31 19.86 19.00 18.19 17.78 41 26.17 25.44 24.78 24.14 23.56 22.97 22.44 21.94 21.47 21.00 20.56 19.69 18.86 18.44 42 26.94 26.19 25.50 24.86 24.28 23.72 23.17 22.67 22.17 21.69 21.25 20.36 19.53 19.11 43 27.72 26.97 26.25 25.61 25.00 24.44 23.89 23.36 22.86 22.39 21.94 21.06 20.19 19.81 44 28.47 27.72 27.00 26.36 25.75 25.17 24.61 24.08 23.58 23.08 22.64 21.75 20.89 20.47 45 29.25 28.47 27.78 27.11 26.47 25.89 25.33 24.81 24.31 23.81 23.33 22.44 21.56 21.14 46 30.03 29.25 28.53 27.86 27.22 26.64 26.06 25.53 25.00 24.50 24.03 23.14 22.25 21.83 47 30.81 30.00 29.28 28.61 27.97 27.36 26.78 26.25 25.72 25.22 24.75 23.83 22.94 22.50 48 31.58 30.78 30.03 29.36 28.72 28.11 27.53 26.97 26.44 25.94 25.44 24.53 23.64 23.19 49 32.36 31.56 30.81 30.11 29.44 28.83 28.25 27.69 27.17 26.64 26.17 25.22 24.33 23.89 50 33.14 32.31 31.56 30.86 30.19 29.58 29.00 28.42 27.89 27.36 26.86 25.92 25.03 24.58 _______________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 5/E.521 (Recup.) [T5.521], p.7 H.T. [T6.521] TABLE 6/E.521 Single-hour capacity, in Erlangs, as a function of the number of trunks and of the peakedness factor ___________________________________________________________________________ Parameters: - | lockage 0.01; { - | fIHigh day-to-day variation allowance; } { - | eighted mean peakedness factor. } ___________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | _______________________________________________________________________________________________________________________________________________________ Number of trunks required 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.4 3.8 4.0 1 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.53 0.33 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0.94 0.69 0.50 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5 1.36 1.14 0.89 0.67 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6 1.86 1.61 1.36 1.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 2.36 2.08 1.83 1.58 1.31 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 2.89 2.61 2.33 2.06 1.81 1.53 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 3.44 3.14 2.86 2.58 2.31 2.03 1.75 1.50 0.0 0.0 0.0 0.0 0.0 0.0 10 4.03 3.69 3.39 3.11 2.83 2.56 2.28 2.00 1.75 0.0 0.0 0.0 0.0 0.0 11 4.61 4.25 3.94 3.64 3.36 3.08 2.81 2.53 2.25 1.97 0.0 0.0 0.0 0.0 12 5.19 4.83 4.50 4.19 3.89 3.61 3.33 3.06 2.78 2.47 2.22 0.0 0.0 0.0 13 5.81 5.42 5.08 4.78 4.44 4.17 3.86 3.58 3.31 3.03 2.72 0.0 0.0 0.0 14 6.42 6.03 5.67 5.33 5.03 4.72 4.42 4.14 3.83 3.58 3.28 2.69 0.0 0.0 15 7.03 6.64 6.28 5.92 5.61 5.28 4.97 4.69 4.39 4.11 3.83 3.22 0.0 0.0 16 7.67 7.25 6.86 6.53 6.19 5.86 5.56 5.25 4.94 4.67 4.36 3.81 3.19 0.0 17 8.31 7.86 7.47 7.11 6.78 6.44 6.11 5.81 5.50 5.22 4.92 4.36 3.75 3.44 18 8.94 8.50 8.11 7.72 7.36 7.03 6.69 6.39 6.08 5.78 5.47 4.89 4.31 4.00 19 9.58 9.14 8.72 8.33 7.97 7.64 7.31 6.97 6.64 6.33 6.03 5.44 4.89 4.58 20 10.22 9.78 9.36 8.94 8.58 8.22 7.89 7.56 7.22 6.92 6.61 6.00 5.44 5.14 21 10.89 10.42 9.97 9.58 9.19 8.83 8.50 8.14 7.83 7.50 7.19 6.58 6.00 5.69 22 11.53 11.06 10.61 10.22 9.83 9.44 9.08 8.75 8.42 8.08 7.78 7.17 6.56 6.25 23 12.19 11.72 11.28 10.83 10.44 10.06 9.69 9.36 9.00 8.67 8.36 7.72 7.14 6.83 24 12.86 12.36 11.92 11.47 11.08 10.69 10.31 9.94 9.61 9.28 8.94 8.31 7.69 7.39 25 13.53 13.03 12.56 12.11 11.69 11.31 10.94 10.56 10.22 9.89 9.56 8.92 8.28 7.97 26 14.19 13.69 13.22 12.75 12.33 11.94 11.56 11.19 10.83 10.47 10.14 9.50 8.86 8.56 27 14.89 14.36 13.86 13.42 12.97 12.58 12.19 11.81 11.44 11.08 10.75 10.08 9.44 9.14 28 15.56 15.03 14.53 14.06 13.64 13.22 12.81 12.42 12.06 11.69 11.36 10.69 10.03 9.72 29 16.25 15.69 15.19 14.72 14.28 13.86 13.44 13.06 12.69 12.33 11.97 11.31 10.64 10.31 30 16.92 16.36 15.86 15.36 14.92 14.50 14.08 13.69 13.31 12.94 12.58 11.89 11.22 10.92 31 17.61 17.06 16.53 16.03 15.58 15.14 14.72 14.33 13.94 13.56 13.19 12.50 11.83 11.50 32 18.31 17.72 17.19 16.69 16.22 15.78 15.36 14.94 14.56 14.19 13.83 13.11 12.44 12.11 33 18.97 18.42 17.86 17.36 16.89 16.44 16.00 15.58 15.19 14.81 14.44 13.72 13.06 12.69 34 19.67 19.08 18.53 18.03 17.56 17.08 16.67 16.25 15.83 15.44 15.08 14.36 13.67 13.31 35 20.36 19.78 19.22 18.69 18.22 17.75 17.31 16.89 16.47 16.08 15.69 14.97 14.28 13.92 36 21.06 20.47 19.89 19.36 18.89 18.42 17.97 17.53 17.11 16.72 16.33 15.61 14.89 14.53 37 21.75 21.14 20.58 20.06 19.56 19.08 18.61 18.19 17.78 17.36 16.97 16.22 15.50 15.14 38 22.44 21.83 21.25 20.72 20.22 19.72 19.28 18.83 18.42 18.00 17.61 16.86 16.14 15.78 39 23.17 22.53 21.94 21.39 20.89 20.39 19.94 19.50 19.06 18.64 18.25 17.50 16.75 16.39 40 23.86 23.22 22.64 22.08 21.56 21.06 20.58 20.14 19.72 19.31 18.89 18.11 17.39 17.00 41 24.56 23.92 23.33 22.75 22.22 21.75 21.25 20.81 20.36 19.94 19.53 18.75 18.00 17.64 42 25.28 24.61 24.00 23.44 22.92 22.42 21.92 21.47 21.03 20.58 20.19 19.39 18.64 18.29 43 25.97 25.31 24.69 24.14 23.58 23.08 22.58 22.14 21.67 21.25 20.83 20.03 19.28 18.89 44 26.67 26.03 25.39 24.81 24.28 23.75 23.25 22.78 22.33 21.92 21.47 20.67 19.89 19.53 45 27.39 26.72 26.08 25.50 24.94 24.44 23.94 23.44 23.00 22.56 22.14 21.33 20.53 20.17 46 28.08 27.42 26.78 26.19 25.64 25.11 24.61 24.14 23.67 23.22 22.78 21.97 21.17 20.81 47 28.81 28.14 27.47 26.89 26.33 25.81 25.28 24.81 24.33 23.89 23.44 22.61 21.81 21.44 48 29.53 28.83 28.19 27.58 27.00 26.47 25.97 25.47 25.00 24.56 24.11 23.28 22.47 22.08 49 30.22 29.53 28.89 28.28 27.69 27.17 26.64 26.14 25.67 25.19 24.75 23.92 23.11 22.72 50 30.94 30.25 29.58 28.97 28.39 27.83 27.31 26.81 26.33 25.86 25.42 24.58 23.75 23.36 _______________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 6/E.521 (Recup.) [T6.521], p.8 3.2 Computer implementation When computer facilities are available, it is possible to automate the use of Tables 3/E.521 to 6/E.521. For that purpose, numerical algorithms have been developed and are described in [5]. 4 Example 4.1 Level of day-to-day traffic variations If the traffics offered to a final group over the 30 busiest days are given (M1 to M3\d0) and if the mean load and variance are calculated to be 10 and 20 respectively, then applying Figure 1/E.521, a high level of day-to-day traffic variations should be used. 4.2 Future traffic offered to the final group and peaked- ness factor If the forecast of future traffics indicates that three par- cels of traffic will be offered to the final group: - the overflow from 6 circuits offered 7.8 Erlangs, - the overflow from 12 circuits offered 10 Erlangs, - 7 Erlangs offered directly, then Table 7/E.521 can be developed. Table 7/E.521 (Recup. + Corr.) T7.521 p.9 Note that the values of riare derived from Table 2/E.521 for medium level of day-to-day traffic variations; if the 30 busiest day traffics for each of the high-usage groups were available, a more appropriate level could be used for each group. Now all the information required is available: using the capa- city Table 6/E.521 for high level of day-to-day traffic variations, the average traffic offered to the final group M = 11.39 and a peakedness factor z = 1.3 (from interpolating between z = 1.2 and z = 1.4), it is calculated that 23 circuits are required. Note that if the measurements used in S 4.1 above were not available, then to determine the level of day-to-day traffic varia- tions it would have been necessary to use the default procedure of S 1 above. Overflow traffic offered to the final group = 4.15 Erlangs. Total traffic offered to the final group = 11.15 Erlangs. The ratio 4.15/11.15 = 0.37 is higher than 0.25 and hence a medium level of day-to-day traffic variations would have been used. References [1] Tabellen fur die Planung von Fernsprecheinrichtungen , Siemens u. Halske, Munchen, 1961. [2] WILKINSON (R. | .): Theories for toll traffic engineer- ing in the USA (Figures 12 and 13), Bell System Technical Journal , Vol. 35, March 1956. [3] WILKINSON (R. | .): Simplified engineering of single stage alternate routing systems, Fourth International Teletraffic Congress , London, 1964. [4] WILKINSON (R. | .): Non-random traffic curves and tables, Bell Telephone Laboratories , 1970. [5] HILL (D. | .) and NEAL (S. | .): The traffic capacity of a probability-engineered trunk group, Bell System Technical Journal , September 1976. Recommendation E.522 NUMBER OF CIRCUITS IN A HIGH-USAGE GROUP 1 Introduction For the economic planning of an alternate routing network the number of circuits in a high-usage group should be determined so that the annual charges for the whole network arrangement are at a minimum. This is done under the constraint that given requirements for the grade of service are fulfilled. In the optimum arrangement, the cost per erlang of carrying a marginal amount of traffic over the high-usage route or over the alternative route is the same. Figure 1/E.522 p.10 The optimum number of high-usage circuits, n , from one exchange (1) to another exchange (2) is therefore obtained from the following expression when the overflow traffic is routed over a transit exchange T (route 1-T-2, see Figure 1/E.522). F n (A ) = A { fIE 1, n (A ) - E 1, (n + 1) (A } = M x nnual charge(1-T-2) ___________________ A is the traffic flow offered, for the relation "1-2", in the Erlang loss formula for a full availability group Fn(A ) gives the marginal occupancy (improvement function) for the high-usage group, if one more circuit were added. M is the marginal utilization factor for the final route "1-T-2" (which has nothing to do with cost ratio), if one addi- tional circuit were provided. The annual charges are marginal charges for adding one additional circuit to route "1-2" and like- wise to route "1-T-2". Planning of an alternate routing network is described in the technical literature (see [1] to [10]). Annual charge as used in this Recommendation refers to invest- ment costs. 2 Recommended practical method 2.1 Field of application It must be recognized that the conditions applying to alterna- tive routing will vary widely between the continental network and the intercontinental network. Significant differences between the two cases apply to the length and cost of circuits, the traffic flow and the different times at which the busy hours occur. The method described attempts to take account of these factors in so far as it is practicable to do so in any simplified procedure. 2.2 Traffic statistics The importance of reliable traffic estimates should be emphasized. Traffic estimates are required for each of the _________________________ Marginal occupancy is often called LTC (last trunk capacity). Marginal utilization factor is often called ATC (addi- tional trunk capacity). relations in question, for both the busy hour of the relation and for the busy hour of each link of the routes to which the traffic overflows. Since this may be affected by the high-usage arrangements finally adopted, it will be necessary to have traffic estimates for each relation covering most of the significant hours of the day. This applies particularly to the intercontinental network where the final routes carry traffic com- ponents with widely differing busy hours. 2.3 Basis of the recommended method The method is based on a simplification of the economic dimen- sioning equations described under 1. Introduction. The simplifying assumptions are: i) the ratios of the alternative high-usage annual charges are grouped in classes and a single ratio selected as representative for each class. This is acceptable because total network costs are known to be relatively insensitive to changes in the annual charges ratio; ii) the marginal utilization factor M applicable to the overflow routes is regarded as constant within a range of cir- cuit group sizes; H.T. [T1.522] ___________________________________ { Size of group (number of circuits) } Value of M ___________________________________ For less than 10 0.6 For 10 or more 0.8 ___________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 1/E.522 (Recup.) [T1.522], p.11 iii) each high-usage group will be dimensioned against the cheapest alternative route to which traffic overflows. (That is, the effect of parallel alternative routes is ignored.) Where greater precision is required in either network or indi- vidual route dimensioning, more sophisticated methods may be employed (see [5] and [7]). 2.4 Determination of cost ratio In continental and intercontinental working, the number of circuits to be provided in high-usage circuit groups depends upon the ratio of the annual charges estimated by the Administrations involved. The annual charge ratio (see Table 1/E.522) is defined as: R = nnual charge of one additional circuit on the high-usage route _______________________________________________________________ The "annual charge of one additional circuit on the alterna- tive route" is calculated by summing: - the annual charge per circuit of each link comprising the alternative route, and - the annual charge of switching one circuit at each intermediate switching centre. When a third Administration is involved, it may be necessary to calculate the annual charge for switching at the intermediate centre from the transit switching charge per holding minute Annual charges for switching = M x 60 x F x 26 x 12 x transit switching charge per holding minute. In the calculation of the conversion factor F from busy hour to day, its dependence on the traffic offered to the high usage route, the overflow probability and the time difference should be taken into account. As a guideline, Table 1/E.522, which is calcu- lated using the standard traffic profiles of Table 1/E.523, may be used. H.T. [T2.522] TABLE 1/E.522 _________________________ It may be necessary to calculate transit switching charge per holding minute from charge per conversation minute (efficiency factor is described in Recommendation E.506). ____________________________________________________________________________________________________________________________________ Time difference Offered traffic (erlangs) Overflow probability (%) 0 1 2 3 4 5 6 7 8 9 10 11 12 ____________________________________________________________________________________________________________________________________ 1 2.6 3.2 3.7 3.8 2.7 2.3 2.3 1.7 3.2 2.4 2.2 2.0 2.7 10 3.7 4.5 4.8 4.7 3.5 3.1 3.0 2.5 4.1 3.2 2.9 2.8 3.6 20 4.5 5.2 5.4 5.3 4.0 3.7 3.5 3.1 4.7 3.8 3.4 3.4 4.2 5 30 5.1 5.8 6.0 5.8 4.6 4.2 4.0 3.7 5.1 4.3 3.9 4.0 4.8 40 5.7 6.4 6.5 6.3 5.1 4.7 4.5 4.2 5.6 4.8 4.4 4.6 5.3 50 6.3 6.9 7.0 6.8 5.6 5.2 5.0 4.7 6.0 5.3 5.0 5.1 5.8 ____________________________________________________________________________________________________________________________________ 1 2.1 2.6 3.3 3.5 2.5 2.1 2.1 1.4 2.8 2.0 2.0 1.8 2.4 10 3.2 4.0 4.4 4.3 3.1 2.7 2.6 2.1 3.8 2.8 2.6 2.4 3.2 20 4.0 4.8 5.1 4.9 3.6 3.3 3.1 2.7 4.3 3.4 3.0 3.0 3.8 10 30 4.7 5.4 5.6 5.4 4.2 3.8 3.6 3.3 4.8 3.9 3.4 3.6 4.4 40 5.3 6.0 6.1 5.9 4.7 4.4 4.2 3.8 5.3 4.4 4.0 4.2 4.9 50 5.9 6.6 6.7 6.4 5.3 4.9 4.7 4.4 5.7 5.0 4.6 4.8 5.5 ____________________________________________________________________________________________________________________________________ 1 1.6 2.0 2.8 3.1 2.2 1.8 2.0 1.2 2.4 1.7 1.8 1.6 2.1 10 2.7 3.3 3.9 3.9 2.7 2.4 2.3 1.7 3.3 2.4 2.3 2.0 2.7 20 3.5 4.2 4.6 4.4 3.2 2.8 2.7 2.2 3.9 3.0 2.6 2.5 3.3 25 30 4.2 5.0 5.2 5.0 3.7 3.4 3.2 2.8 4.4 3.5 3.0 3.1 3.9 40 4.8 5.6 5.8 5.5 4.3 3.9 3.8 3.4 4.9 4.0 3.5 3.7 4.5 50 5.5 6.2 6.3 6.1 4.9 4.5 4.3 4.0 5.4 4.6 4.1 4.4 5.1 ____________________________________________________________________________________________________________________________________ 1 1.3 1.7 2.4 2.9 2.1 1.6 2.0 1.1 2.1 1.5 1.6 1.4 2.0 10 2.3 2.8 3.5 3.6 2.5 2.2 2.1 1.4 3.1 2.2 2.2 1.8 2.4 20 3.1 3.9 4.3 4.2 3.0 2.6 2.4 1.9 3.7 2.7 2.5 2.2 3.0 50 30 3.9 4.7 5.0 4.8 3.4 3.1 2.9 2.5 4.2 3.3 2.8 2.8 3.6 40 4.6 5.4 5.6 5.3 4.0 3.7 3.5 3.2 4.7 3.8 3.2 3.5 4.3 50 5.3 6.0 6.1 5.9 4.7 4.3 4.2 3.8 5.2 4.3 3.8 4.2 4.9 ____________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note - Linear interpolation may be used to obtain intermediate results. Table 1/E.522 [T2.522], p.12 The value determined for R should then be employed to select in Table 2/E.522 the precise (or next higher) value of annual charges ratio for use in traffic tables. The value of annual charges ratios may be grouped in the following general sets: a) Within a single continent or other smaller closely connected land mass involving distances up to 1000 miles, high traffic and frequently one-way operation: These values are tentative. Ranges and representative values of annual charges ratio require further study. Annual charges ratio: R = 1.5; 2.0 ; 3.0; 4.0; 5.0; 6.0 and 7.0 b) Intercontinental working involving long dis- tances, small traffic and usually two-way operation: Annual charges ratio: R = 1.1; 1.3 ; 1.5; 2.0; 3.0; 4.0 and 5.0. 2.5 Use of method High-usage circuit groups carrying random traffic can be dimensioned from Table 2/E.522. Step 1 - Estimate the annual charges ratio R as described under 2.4 above. (There is little difference between adjacent ratios.) If this ratio is difficult to estimate, the values under- lined in a) and b) of S 2.4 above, should be used. Step 2 - Consult Table 2/E.522 to determine the number of high-usage circuits N . Note - When two values of N are given the right-hand figure applies to alternative routes of more than 10 circuits, the left-hand figure applies to smaller groups. The left-hand figure is omitted when it is no longer possible for the alternative route to be small. 3 24-hour traffic profiles The traffic value used in the method in S 2 should be the value of traffic offered to the high-usage route during the busy hour of the final route. In the case that some of the busy hours of the circuit groups or links forming an alternative route do not coincide with the busy hour of the relation, the ensuing method should be fol- lowed to take 24-hour traffic profiles into account (see [6], [8] and [9]). The method consists of the following three basic steps: i) prepare hourly traffic demands for which dimen- sioning is to be done; ii) size all circuit groups, high usage and final, for one hourly traffic demand; iii) iterate the process in step ii) for each addi- tional hourly matrix. 3.1 Preparation of hourly traffic demands Each Administration gathers historical traffic data on an hourly basis in accordance with Recommendations E.500 and E.523. Using historical data and information contained in Recommendation E.506, hourly traffic demand forecasts are made, resulting in a series of hourly demands for each exchange to every other exchange. 3.2 Sizing circuit groups for one-hourly traffic demand Using the methods in S 2 and Recommendation E.521, trunk group sizes are prepared for the first hourly traffic demand disregarding other hourly traffic demands. H.T. [T3.522] _____________________________________________________ TABLE 2/E.522 { Number of high-usage circuits for different values of offered traffic, annual charges ratios and sizes of overflow groups } _____________________________________________________ | | | | | | | | | | | | | | __________________________________________________________________________________________________________________________________________________ | | | | | | | | | | Annual charges ratios | | | | | | | | | { 1.1 1.3 { 0.545/0.727 0.46/0.615 { { __________________________________________________________________________________________________________________________________________________ 1.5 1/0 1/0 2/1 2/2 3/2 3/3 4/3 4/3 4/4 6 1.75 1/0 2/1 2/1 3/2 3/3 4/3 4/4 4/4 4/4 6 2.0 1/0 2/1 2/2 3/2 4/3 4/4 4/4 5/4 5/5 7 2.25 2/0 2/1 3/2 3/3 4/4 5/4 5/4 5/5 5/5 7 2.5 2/0 3/1 3/2 4/3 5/4 5/5 5/5 6/5 6/5 7 2.75 2/1 3/2 3/2 4/3 5/4 5/5 6/5 6/6 6/6 8 3.0 3/1 3/2 4/3 4/4 5/5 6/5 6/6 6/6 7/6 8 3.5 3/1 4/2 4/3 5/4 6/5 7/6 7/6 7/7 7/7 9 4.0 4/2 4/3 5/4 6/5 7/6 7/7 8/7 8/7 8/8 10 4.5 4/2 5/3 6/4 6/6 7/7 8/7 8/8 9/8 9/8 10 5.0 5/3 6/4 6/5 7/6 8/7 9/8 9/9 9/9 10/9 11 5.5 5/3 6/5 7/5 8/7 9/8 9/9 10/9 10/10 10/10 12 6.0 6/3 7/5 7/6 8/7 9/9 10/9 11/10 11/10 11/11 13 7.0 7/4 8/6 8/7 10/8 11/10 11/11 12/11 12/12 13/12 14 8.0 8/5 9/7 10/8 11/10 12/11 13/12 13/13 14/13 14/13 15 9.0 /6 /8 /9 /11 /12 /13 /14 /14 /15 17 10.0 /7 /9 /10 /12 /14 /15 /15 /16 /16 18 12.0 /9 /11 /12 /14 /16 /17 /18 /18 /19 20 15.0 /12 /14 /16 /18 /20 /21 /21 /22 /22 24 20.0 /16 /19 /21 /23 /25 /27 /28 /28 /29 30 25.0 /21 /24 /26 /29 /31 /33 /33 /34 /35 36 30.0 /26 /29 /31 /34 /37 /38 /39 /40 /41 42 40.0 /36 /39 /42 /45 /48 /50 /51 /52 /52 53 50.0 /45 /49 /52 /55 /59 /61 /62 /63 64 60.0 /55 /60 /62 /66 /70 /72 /73 75 80.0 /74 /80 /83 /87 /92 /94 /95 96 100.0 /94 /100 /103 /108 /113 /116 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 117 120.0 /113 /120 /124 /129 /134 /137 { Direct final circuit groups are } 138 150.0 /143 /150 /154 /160 /166 /169 economical within this area. 170 200.0 /192 /200 /205 /212 /219 221 250.0 /241 /250 /256 /263 /271 273 300.0 /290 /300 /306 /315 /323 324 __________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | Table 2/E.522 (Recup. + Corr.) [T3.522], p.13 MONTAGE a l'italienne, reprendre des originaux 3.3 Iterating for each additional hourly traffic matrix In sizing the circuit groups for the second hourly traffic demand, the method is provided with the circuit quantities result- ing from the previous step, and is constrained solely to increasing circuit group sizes; i.e., if the circuit group sizes for the first hourly traffic demand were greater than for the second hourly demand, then the circuit group sizes for the first hourly traffic demand would be retained. All additional hourly traffic demands are processed in the same iterative manner. The resulting circuit group sizes then satisfy the traffic demands for all hours being considered (see Annex A for a computational example). 3.4 Processing sequence Processing may start with the first hour of traffic demand, however, experiments have indicated that efficiencies of the network can be improved if processing starts with the hour with the smallest total traffic demand. It should be noted that this method gives us suboptimal networks, which may be improved by manual refinements. 4 Minimum outlay alternate routing networks The method below allows Administrations to adjust alternate routing networks to take into account existing revenue accounting divisions. The method consists of the following steps: i) Obtain 24-hour traffic profiles in accordance with Recommendations E.500 and E.523; ii) Compute circuit quantities and costs for a no-overflow network in accordance with Recommendation E.520; iii) Compute monthly overflow minutes (holding time) at varying percentages of busy-hour overflow. This is done by applying three conversion factors to the busy hour overflow erlangs: - Ratio of holding minutes to erlangs: a fixed value of 60. - Daily overflow to busy-hour overflow ratio: a value that depends on the 24-hour traffic profile and the degree of overflow. - Monthly overflow to daily overflow ratio (Recommendation E.506): a value that depends on the day-to-day pat- tern within a month and the degree of overflow. iv) Starting with the network calculated in step ii): - reduce the high usage circuits by one circuit, - calculate overflow to final circuit groups, - dimension final circuit groups in accordance with Recommendation E.521, - calculate circuit costs and transit charges; v) Iterate step iv) until the minimum outlay (cir- cuit costs plus transit charges) for terminal administrations is reached (see Annex B for computational example). 5 Service considerations On intercontinental circuits, where both-way operation is employed, a minimum of two circuits may be economical. Service con- siderations may also favour an increase in the number of direct circuits provided, particularly where the annual charges ratio approaches unity. Although the dimensioning of high-usage groups is normally determined by traffic flows and annual charges ratios, it is recognized that such groups form part of a network having service requirements relative to the subscriber. The ability to handle the offered traffic with acceptable traffic efficiency should be tempered by the overall network considerations on quality of service. The quality of service feature, which is of primary importance in a system of high-usage and final circuit groups, is the advan- tage derived from direct circuits versus multi-link connections. A liberal use of direct high-usage circuit groups, taking into account the economic factors, favours a high quality of service to the subscriber. It is recommended that new high-usage groups should be provided whenever the traffic flow and cost ratios are not con- clusive. This practice may result in direct high-usage groups of two circuits or more. The introduction of high-usage groups improves the overall grade of service and provides better opportunities of handling traffic during surges and breakdown conditions. When high-usage links bypass the main final routes the introduction of high-usage routes can assist in avoiding expenses which might otherwise be incurred in keeping below the maximum number of long-distance links in series. In the future, more measurements of traffic flows may be necessary for international accounting purposes and high-usage cir- cuits should make this easier. ANNEX A (to Recommendation E.522) Example of network dimensioning taking into account 24-hour traffic profiles A.1 Assumptions (see also Figure A-1/E.522) Calculations are performed under the following conditions: 1) Time difference: A is 9 hours west of B C is 5 hours west of A B is 10 hours west of C 2) Traffic profiles: 24-hour traffic profiles as per Table 1/E.523 are used. 3) Busy hour traffic: A-B 50 erlangs A-C 100 erlangs C-B 70 erlangs 4) Cost ratio: R = 1.3 Figure A-1/E.522 p.14 A.2 Numerical results 24 hourly traffic demands are processed. The order of process- ing are from the hour with the smallest total traffic demand to the hour with the largest total traffic demand. Computational results are given in Table A-1/E.522. H.T. [T4.522] TABLE A-1/E.522 Numerical results _______________________________________________________________________________________________________________ Hour Hourly traffic demand { Number of circuits obtained by single hour dimensioning (disregarding lower bounds imposed by the previous iterative stage) } { Number of circuits obtained considering lower bounds imposed by the previous iterative stage } { Number of circuits required to meet multiple hourly traffic demands } _______________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___________________________________________________________________________________ A-B A-C C-B A-B A-C C-B A-B A-C C-B A-B A-C C-B ___________________________________________________________________________________ 6 17.50 5.00 3.50 17 19 17 17 19 17 17 19 17 7 20.00 5.00 3.50 19 20 18 19 20 18 19 20 18 5 2.50 5.00 28.00 1 14 41 19 11 39 19 20 39 4 2.50 5.00 35.00 1 14 49 19 11 47 19 20 47 8 37.50 5.00 3.50 37 23 22 19 38 37 19 38 47 9 40.00 5.00 3.50 39 24 23 19 41 40 19 41 47 3 2.50 5.00 45.50 1 14 61 19 11 59 19 41 59 18 2.50 50.00 3.50 1 66 12 19 64 9 19 64 59 10 50.00 5.00 3.50 49 26 25 9 61 59 19 64 59 19 2.50 60.00 3.50 1 77 12 19 75 9 19 75 59 20 2.50 60.00 3.50 1 77 12 19 75 9 19 75 59 22 12.50 30.00 24.50 12 45 39 12 45 39 19 75 59 2 2.50 5.00 63.00 1 14 80 19 11 78 19 75 78 17 2.50 70.00 3.50 1 87 12 19 85 9 19 85 78 1 2.50 5.00 70.00 1 14 87 19 11 85 19 85 85 23 20.00 20.00 42.00 19 36 60 19 36 60 19 85 85 11 47.50 25.00 17.50 47 46 38 3 85 77 19 85 85 21 12.50 55.00 24.50 12 73 39 12 73 39 19 85 85 12 42.50 30.00 21.00 42 50 41 3 85 76 19 85 85 16 2.50 90.00 3.50 1 109 12 19 107 9 19 107 85 0 20.00 20.00 66.50 19 36 87 19 36 87 19 107 87 13 30.00 65.00 35.00 29 86 54 5 107 76 19 107 87 15 17.50 100.00 28.00 17 121 44 19 120 43 19 120 87 14 27.50 95.00 38.50 27 117 57 19 124 64 19 124 87 ___________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |