Comtech EF Data CDM-840 - Manual (Page 234)

CDM-840 Remote Router Revision 2
Appendix G MN-CDM840
G–2
In the cellular network, the RAN connects cell-site nodes with central-site nodes:
• For Global System for Mobile Communications (GSM) / 2G, the Base Transceiver Stations
(BTS) connect to the Base Station Controllers (BSC) via the Abis interface. Voice, data and
signaling are transported over one or more E1s.
• For Universal Mobile Telecommunications Systems (UMTS) / 3G, the NodeB connects to
the Radio Network Controller (RNC) via the “lub” interface. Voice, data and signaling are
transported over one or more E1s using Asynchronous Transfer Mode (ATM).
G.1.2 RAN Inefficiency
The 2G/3G RAN design is not efficient for satellite backhaul. For example, in the GSM Abis
interface shown in Figure G-2, the resource allocation is on a fixed basis (one or more E1s per
BTS), irrespective of the actual traffic. Within the E1, the Time Slots (TS) are dedicated to
signaling, voice and data per Transceiver (TRX).
Figure G-2. Typical Abis Map