Specifications

Reference Guide

2-39

Applications Frame Relay Access and Concentration Server

2.8.4 Grooming and Concentration in Cellular Networks

Figure 2-25 shows how a remote cell site uses an IAD, trademarked “CellDAX” for all cellular

environment, to transport cellular voice and data traffic to the Mobile Switch Center (MSC).

At the MSC, a DCS directs the CDPD traffic (typically, a single DS0) from each of the 96 cell

sites to the IAD at same MCS. Because CDPD uses HDLC framing the traffic from the 96

DS0s can be encapsulated by the two Frame Relay server cards located in the IAD. Each

Frame Relay server can take in 64 DS0s directly into ports. Typically the CDPD traffic is

bursty and often less than one full DS0 and so can be groomed and concentrated by the Frame

Relay server down to 48 or 24 DS0s depending upon the level of concentration needed. This

results in a net savings of two or three T1/E1 spans across the regional MSCs respectively. The

MD-IS (Mobile Data Intermediate System) then processes the traffic and routes it to the

appropriate destinations.

Figure 2-25. Cellular Network Frame Relay Application

Cell

Site

# 96

Mobile

Base Station

56/64Kbps

CellDAX

DS1

Mobile Switch Office

MDIS

Frame Switch

4 Channelized

DS1s = 96 DS0s

2 Frame Relay DS1s

IAD