Adaptive modulation in ad hoc DS/CDMA packet radio networks

This paper investigates the benefit of adaptive modulation based on channel state information (CSI) in direct-sequence/ code-division multiple-access (DS/CDMA) multihop packet radio networks. By exploiting varying channel conditions, adaptive modulation can be used in ad hoc networks to provide uppe...

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Bibliographic Details
Published in:IEEE transactions on communications 2006-04, Vol.54 (4), p.714-725
Main Authors: Souryal, M.R., Vojcic, R., Pickholtz, L.
Format: Article
Language:English
Subjects:
Ad hoc networks
Adaptive modulation
Applied sciences
Attenuation
Channel state information
Channels
cochannel interference
Code division multiple access
code-division multiaccess
Detection, estimation, filtering, equalization, prediction
Exact sciences and technology
Fading
Information, signal and communications theory
Interference
Modulation
Modulation coding
Modulation, demodulation
Multiaccess communication
Multilevel
Networks
packet radio
Packet radio networks
Radio
Radio networks
Relays
Signal and communications theory
Signal, noise
Spread spectrum communication
Systems, networks and services of telecommunications
Telecommunications
Telecommunications and information theory
Teletraffic
Transmission and modulation (techniques and equipments)
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Summary:This paper investigates the benefit of adaptive modulation based on channel state information (CSI) in direct-sequence/ code-division multiple-access (DS/CDMA) multihop packet radio networks. By exploiting varying channel conditions, adaptive modulation can be used in ad hoc networks to provide upper layers with higher capacity links over which to relay traffic. Using the /spl alpha/-stable interference model, the distribution of the signal-to-interference ratio (SIR) is obtained for a slotted system of randomly, uniformly distributed nodes using multilevel coherent modulation schemes. Performance is evaluated in terms of the information efficiency, which is a new progress-related measure for multihop networks. Three types of adaptivity are analyzed, differing in the level of CSI available: 1) full knowledge of the SIR at the receiver; 2) knowledge of only the signal attenuation due to fading; and 3) knowledge of only the slow fading component of the signal attenuation. The effect of imperfect channel information is also investigated. Sample results are given for interference-limited networks experiencing fourth-power path loss with distance, Ricean fading, and lognormal shadowing.
ISSN:0090-6778
1558-0857
DOI:10.1109/TCOMM.2006.873092