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Power control for an asynchronous multirate decorrelator
- Source :
- IEEE Transactions on Communications. 48:804-812
- Publication Year :
- 2000
- Publisher :
- Institute of Electrical and Electronics Engineers (IEEE), 2000.
-
Abstract
- For code-division multiple-access (CDMA) wireless systems employing multiuser detection, the varied bit-error rate (BER) requirements of multimedia traffic dictate the use of transmitted power control. Using a decorrelator in an asynchronous multirate direct-sequence CDMA system, it may be necessary for different users to combat the noise enhancement and the propagation losses to varying degrees depending on individual requirements. In this context, we propose a power control algorithm for a multirate decorrelator that is suitable for a class of BER-based link quality objectives. If the uplink channel gain of the desired user is known, then it is straightforward for each user to choose the transmitted power needed to meet its target BER objective. In practice, however, the uplink channel gain is often difficult to measure. To avoid this measurement, we employ stochastic approximation methods to develop a simple iterative power control algorithm. In this algorithm, each mobile uses the output of its own decorrelator to update its transmitted power in order to achieve its BER objective. We show that when a user's bits have nonzero asymptotic efficiencies, the power control algorithm converges quickly in the mean square sense to the minimum power at which a user achieves its quality-of-service objective.
- Subjects :
- Computer science
Code division multiple access
Iterative method
Context (language use)
Data_CODINGANDINFORMATIONTHEORY
Stochastic approximation
Multiuser detection
Spread spectrum
Asynchronous communication
Computer Science::Networking and Internet Architecture
Electronic engineering
Electrical and Electronic Engineering
Decorrelation
Computer Science::Information Theory
Power control
Subjects
Details
- ISSN :
- 00906778
- Volume :
- 48
- Database :
- OpenAIRE
- Journal :
- IEEE Transactions on Communications
- Accession number :
- edsair.doi...........41f0630468907e230fc02cbe12d2c6b6