Code Division Multiple Access (CDMA) phần 8 potx

P1: IML/FFX P2: IML

MOBK023-04 MOBK023-Buehrer.cls September 28, 2006 15:55

SPREAD SPECTRUM PACKET RADIO NETWORKS 125

0 50 100 150 200 250 300 350 400

0

0.05

0.1

0.15

0.2

0.25

Average loading (users)

Normalized throughput

Synchronous, fixed rate

Synchronous, variable rate

Asynchronous, fixed rate

Asynchronous, variable rate

FIGURE 4.7: System throughput for FHMA system with no side information (N = 128, perfect codes).

wish to exploit the benefits of spread spectrum. Such networks can be based on either direct

sequence or frequency hopping. In such networks, a primary consideration is the assignment of

spreading waveforms, and we discussed the primary methods of code assignment. Due to the

potential for severe near-far situations in ad hoc networks, frequency-hopped approaches are

typically more appropriate. Thus, we focused on the network throughput for FHMA systems.

P1: IML/FFX P2: IML

MOBK023-04 MOBK023-Buehrer.cls September 28, 2006 15:55

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