Product Info

WipLL Radio Technology - Physical Layer System Description
2-32 Airspan Networks Inc. 25030311-08
Since voice and data services differ by their packet size and their sensitivity to delay,
their protocol efficiency can be substantially different. Therefore, when calculating
bandwidth for different applications, the gross bandwidth should be used, which
takes into account the protocol efficiency.
2.6.5.2. VoIP Bandwidth and Simultaneous Calls
The VoIP bandwidth and the number of supported simultaneous calls are a function
of the selected codec and the sample interval. Assuming a 4 Mbps gross rate, the
following numbers can be used:
Table 2-11: VoIP bandwidth (Kbps) for 4 Mbps gross rate
Codec Sample Interval
(msec)
Simultaneous Calls
20 10
G.711 (64 Kbps)
40 15
20 14
G.729 (8 Kbps)
40 28
30 22
G.723.1 (5.3 Kbps)
60 42
If silence suppression is used, a factor of 65% should be applied on the call
bandwidth.
Note: The selection of the appropriate codec should be based on a balance
between the occupied bandwidth and the voice quality.
2.6.5.3. Data Bandwidth
It is assumed that packet size for data applications is relatively large (about 1,500
bytes), resulting in a protocol efficiency of 80%. Taking this into account, the sum
of all data bandwidth should be divided by 80% to obtain the bandwidth over the air.