Consider the following:
# of BTS: 30
Erlangs per BTS: 5
Blocking Rate: 1%
If the network is supported using SCPC technology, operator will have to provision:
30 SCPC links, each link will need to support 11 trunks
Total trunk lines in network = 30*11=330
Bandwidth per line (Assumes optimization feature added) = 10 kbps
Total full duplex bandwidth = 330*10=3.3 Mbps
If the network is supported using TDM/TDMA technology, operator will have to provision:
1 TDM outbound carrier, 1 TDMA inbound carrier
To support aggregate 30*5=150 Erlangs on a single carrier in each direction,
Total trunk lines required = 170 lines (benefit of a single carrier)
Optimized bandwidth per line = 10 kbps
Total full duplex bandwidth required = 1.7 Mbps
Benefits of the Hughes TDMA Solution:
The Hughes solution results in significant space segment savings over the SCPC solution
Savings calculated above excludes potential savings due to busy hour differences across BTS.
A Hughes solution also provides central management, resulting in additional operational cost savings.
Mobile operators must note that even though SCPC vendors may claim their solutions offer much higher order modulation than TDM/TDMA solutions, since Erlang calculations are still done on an individual link level in an SCPC architecture, modulation efficiency is offset by the higher number of trunks required to support the same amount of traffic in an SCPC network.
As is evident from the above calculation, a TDM/TDMA solution is more efficient due to its ability to statistically multiplex the cellular traffic across the entire network instead of over a specific point-to-point link. However, mobile operators must ensure that the chosen TDM/TDMA solution has the ability to provide high-quality, low-jitter bandwidth to support their cellular traffic.
The Hughes HX and HN systems support guaranteed high-quality jitter-free bandwidth that is perfectly suited for cellular backhaul. In addition, Hughes solutions include certified third-party A.bis optimizers that provide further optimization of the A.bis links.