Subject: [NEXTEL-1] Power Control by Interference Prediction for Broadband Wireless Packet Networks*

From: Marcel <[email-masked]>
Date: Mon, 17 Mar 2003 15:51:01 -0500

Who said Nexhell can't reduce the Interference on its own?
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Power Control by Interference Prediction for Broadband Wireless Packet Networks*

Kin K. Leung
AT&T Labs, Room 5A-1D35
200 South Laurel Ave
Middletown, NJ 07748
Phone: +1 732-420-9041
Email: [email-masked]
September 22, 1999
January 8, 2001 (Revised)

Abstract

A Kalman-filter method for power control is proposed for broadband, packet-switched
TDMA wireless networks. By exploiting the temporal correlation of co-channel interference,
a
Kalman filter is used to predict future interference power. Based on the predicted
interference and
estimated path gain between the transmitter and receiver, transmission power is determined
to
achieve a desired signal-to-interference-plus-noise ratio (SINR). A condition to ensure
power
stability in the packet-switched environment is established and proven for a special case
of the
Kalman-filter method. The condition generalizes the existing one for a fixed path-gain
matrix, as
for circuit-switched networks.

Performance results reveal that the Kalman-filter method for power control provides a
significant performance improvement. Specifically, when messages consist of 10 packets on
average, the 90th and 95th percentile of the SINR by the new method are 3.79 and 5.46 dB
above
those when no power control is in use, and lie just 0.96 and 1.14 dB below the upper-bound

performance of the optimal power control, respectively, in a system with 4-sector cells
and an
interleaved frequency assignment of a reuse factor of 2/8. In addition, the new method
performs
noticeably better than the delta-modulation method and a simple scheme that uses the last
measurement as predicted interference power. In an example of 8-PSK modulation and average

message length of 20 packets, the SINR performance gain by the new method improves the
network throughput by about 150% and 70%, relative to no power control and the simple
scheme,
respectively.

http://www.bell-labs.com/user/kin/papers/kalman.journal.pdf
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