CDMAPerformance Analysis and Dynamic Resource
Allocation 
Performance Analysis and Dynamic Resource Allocation in Multi-Service DS-CDMA Networks
Primary Investigator
Vadimir Marbukh: email: marbukh@nist.gov;
Telephone: (301) 975-2235
The main force driving evolution of wired networking technology is the need to handle multimedia traffic with widely varying statistical characteristics and with specific requirements for Quality of Service (QoS). While this trend will continue, future network infrastructures will be a mixture of both wired and wireless networks. In fact, wireless access to the Internet will probably become much more common than wired access. To prevent waste of resources in the wired backbone, the wireless access network must have the same or comparable capabilities to handle multimedia traffic. Today, wireless technology lags far behind wired technology in its ability to serve multimedia traffic. The effectiveness of wireless technology is restricted by wireless channel impairments and by severe limitations on wireless bandwidth and on transmission power by mobiles. To overcome these restrictions, system designers have a finite but complex set of techniques to employ. Such techniques include error-correction and error-detection coding, source coding, medium access protocols, smart antennas, power control algorithms, and retransmissions.
Recently, Direct-Sequence Code Division Multiple Access (DS-CDMA) has emerged as a technology for 3G wireless communication systems. DS-CDMA allocates the wireless bandwidth on demand: all users share the same wireless bandwidth and simultaneous transmissions affect each other through an increase in the random noise. However, in DS-CDMA a user bit-service rate is a complex non-linear function of various intrinsic parameters, such as transmission power and processing gain, as well as various extrinsic parameters, such as interference from other users and conditions on the wireless channel. To provide guaranteed QoS for multimedia traffic DS-CDMA requires fast, closed-loop control of system parameters based on real-time information about the intrinsic and extrinsic parameters, and about the performance of the system. For a closed-loop system to operate successfully, accurate and timely measures of appropriate parameters must be fed into the control algorithm. Our work includes identifying the system parameters, besides transmission power, having the greatest effect on the provision and maintenance of the QoS for multimedia traffic, developing control algorithms based on the parameters identified, and comparison of the performance of the proposed algorithms against the theoretical limits.
This work is supported by NIST ATP.
Publications
V. Marbukh, "On Ability of a Communication Channel to
accommodate Multimedia Traffic," Proc. Globecom, Rio de Janeiro,
Brazil, 1999. 
V. Marbukh and N. Moayeri, "A Framework for Throughput and
Stability Analysis of a DS-CDMA Network," Proc. IEEE VTC,
Houston, US, 1999.
V. Marbukh and N. Moayeri, "A Queueing Model of a Spread
Spectrum Multiple Access," Proc. 4th ACTS Mobile Communications
Summit, Sorrento, Italy, 1999.
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Last modified: Wed May 23 12:00:06 EST 2001 |
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