Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2001-01-02
2004-08-17
Maung, Nay (Department: 2684)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S069000
Reexamination Certificate
active
06778839
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of signal transmission in a wireless telecommunications network, and more particularly to power control.
BACKGROUND ART
In an open loop power control system, transmission power is selected without benefit of immediate feedback, and thus without exact knowledge of the power level necessary to insure faultless signal reception at the other end of the transmission. Consequently, a typical transmitting device in an open loop power control system necessarily makes power estimates based upon incomplete information. If a power estimate is too low, then the signal will not be received at the other end of the transmission; but if the power estimate is too high, then the signal interferes needlessly with other users. Both the problem of low power estimation and the problem of high power estimation occur in the prior art, due to inadequate estimation methods. See, for example, 3
rd
Generation Partnership Project; Technical Specification Group GERAN; Digital Cellular Telecommunications System, Phase 2t; Radio Subsystem Link Control (3GPP TS 05.08 V8.6.0, September 2000, Annex B, pages 85-88). This is a problem in the downlink from a base station to a mobile device, and in the uplink direction as well.
A further problem with prior art is the problem of fixed bit rate. When bit rate is fixed and constant, then transmission power is correspondingly limited. If the fixed bit rate is high, then high transmission power is required, which may induce excessive interference. However, if the fixed bit rate is low, then the transmission is slower (i.e., large transport time) and the transmission channel is occupied longer at the expense of other users. It is therefore evident that a fixed bit rate makes it difficult or impossible to adjust transmission power so as to minimize both transport time and induced interference. This is a major problem in prior art, wherein the bit rate is typically a constant, possibly chosen based upon traffic estimation.
Even when the prior art employs a fixed bit rate, the limited flexibility of the transmission power is often not exploited. For example, in the downlink, power transmission in prior art may be a constant that is chosen by radio network planning. In the uplink, power transmission may be adjustable, but only according to the uplink pathloss (i.e., signal attenuation) presumed equal to the measured downlink pathloss. The uplink transmission power may also be adjusted depending upon what sector the mobile transmitter is located in; a sector-specific constant offset may be broadcast in each sector. The rudimentary nature of all of these prior art techniques results in transmission power that induces excessive interference, and results in bit rates that produce excessive transport delays.
DISCLOSURE OF THE INVENTION
The central idea of the present invention is to select bit rate and transmission power so as to minimize the induced interference problem and the transport delay problem. According to the present invention, neither bit rate nor transmission power is constant. In comparison to methods with fixed bit rate or transmission power, the present method makes better use of the available radio resource in diverse load conditions, and the result is higher throughput with lower system interference.
The method and device of the present invention provide a wireless transmission signal having appropriate transmission power and bit rate. To accomplish this, a set of input parameters are used to calculate bit rate and transmission power that minimize a cost function representing induced interference and transport delay. A command signal indicates the calculated bit rate and calculated transmission power in response to the input parameters which were provided by an input parameter signal. The invention then provides the transmission signal having the bit rate and transmission power dictated by the command signal.
The command signal is provided by a computing module in response to the input parameter signal. The command signal is received by a transmitter module, which provides the transmission signal having the bit rate and transmission power determined by the computing module.
This invention can operate in either the uplink direction (i.e. from a mobile device to a base station) or the downlink direction (i.e. from a base station to a mobile device), or both, in a wireless telecommunications system. This invention is especially designed for a system employing open loop power control.
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patent: 6167031 (2000-12-01), Olofsson et al.
patent: 6473467 (2002-10-01), Wallace et al.
patent: 6546252 (2003-04-01), Jetzek et al.
patent: 6571089 (2003-05-01), Richards et al.
patent: 2002/0080765 (2002-06-01), Zeira et al.
patent: 2002/0085502 (2002-07-01), Chheda et al.
patent: 2002/0093926 (2002-07-01), Kilfoyle
patent: 0942541 (1999-09-01), None
patent: 0986282 (2000-03-01), None
Technical Specification 3GPP TS 05.08, Version 8.6.0 (Sep. 2000):3rd Generation Partnership Project; Technical Specification Group GERAN; Digital cellular telecommunications system(Phase 2+);Radio subsystem link control(Release 1999), Global System for Mobile Communications, 3GPP, Annex B: Power Control Procedures, pp. 85-88.
Maung Nay
Nguyen Tu X
Nokia Corporation
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