Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2000-12-28
2004-05-11
Trost, William (Department: 2683)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S517000, C455S068000, C455S069000
Reexamination Certificate
active
06735449
ABSTRACT:
The present invention relates generally to a manner by which to effectuate power control of the power level at which a communication signal is communicated in a two-way communication system, such as a cellular communication system in which both a pilot channel signal and a traffic channel signal are transmitted. More particularly, the present invention relates to apparatus, and an associated method, by which to make power control decisions by which to power control the traffic channel signal responsive to calculation of time rates of change of values associated with signal indicia, such as the SIR (Signal to Interference Ratio), of the pilot channel communication signal. Earlier power-control decisions are made, in contrast to conventional closed-loop, power-control techniques, to facilitate operation of an embodiment of the present invention.
BACKGROUND OF THE INVENTION
A communication system is formed, at a minimum, of a sending station and a receiving station which are interconnected theretogether by way of a communication channel. Information to be communicated by the sending station is communicated upon the communication channel to the receiving station. A wide variety of different types of communication systems have been developed and are regularly utilized to effectuate communication of information between the sending and receiving stations.
New types of communication systems have been made possible as a result of communication technologies. A radio communication system is exemplary of a type of communication system which has benefited from advancements in communication technologies. A communication channel formed between the sending and receiving stations of a radio communication system is defined upon a radio link. Because a radio link is utilized to form the communication channel, the conventional need to utilize wire-line connections between the sending and the receiving stations is obviated. Increased communication mobility is, as a result, inherent in a radio communication system in contrast to a conventional wire-line system. Because a wire-line connection is not required to be formed between the sending and receiving stations to permit the communication of information therebetween, communications are permitted at, and between, locations at which the formation of a wire-line connection would not be possible. Also, because a communication channel is formed of a radio channel, a radio communication system can generally be more economically installed, as the infrastructure costs which would otherwise be required to install a wire-line communication system are significantly reduced in a radio communication system.
A cellular communication system is exemplary of a radio communication system which has been made possible due to advancements in communication technologies. A cellular communication system advantageously provides for radio communications with mobile stations to permit telephonic communication therewith. A cellular communication system also makes relatively efficient utilization of the portion of the electromagnetic spectrum allocated thereto and upon which radio channels are defined. The relatively efficient utilization of the allocated electromagnetic spectrum is provided through the installation of a plurality spaced-apart, fixed-site transceivers installed throughout a geographical area to be encompassed by the cellular communication system. Because of the spaced-apart positioning of the fixed-site transceivers, referred to base transceiver stations (BTSs), only relatively low-power signals need to be communicated between a base transceiver station and a mobile station. That is to say, because of the positioning of the base transceiver stations, a mobile station shall be positioned in proximity to at least one of the base transceiver stations, necessitating only low-power signals to be generated to communicate a signal to, or from, a base transceiver station. And, the same communication channel can be reused at different locations throughout the cellular communication system as the low power levels of the signals permit the reuse of the same channel according to a cell re-use scheme.
Various standards have been promulgated relating to various types of cellular, as well as other, communication systems. And, various types of cellular, as well as other, communication systems have been constructed, corresponding to such standards. The IS-95 and IS-98 interim standards, promulgated by the EIA/TIA, are exemplary of standards which pertain to a cellular communication system, utilizing CDMA (code division multiple access) communication techniques. An IS2000 standard has been proposed which also utilizes CDMA communication techniques. In a CDMA communication system, a plurality of concurrently-generated communication signals are generated upon a common bandwidth. Channel differentiation is defined by the coding by which the data which is to be communicated between sending and receiving stations is encoded.
Power control of communication signals in almost any communication system is important to minimize the possibility that a communication signal might interfere with another concurrently-generated communication signal. In a CDMA communication system in which coding provides channel differentiation between concurrently-communicated signals generated upon a common bandwidth, power control is particularly important to ensure that a communication signal is not of such a great power level to prevent the detection of other concurrently-generated signals.
CDMA communication systems, such as the aforementioned IS-95, IS-98, and the proposed IS-2000 standards, set forth, amongst other things, requirements for closed-loop power control to control the power levels at which communication signals generated in such systems are communicated. And more, more generally, because of the need to control power levels of signals generated during operation of a CDMA communication system, closed-loop power control schemes are also advantageously implemented in other types of CDMA communication systems.
Generally, in a closed-loop power control scheme, a receiving station detects signals communicated thereto by a sending station. Measurements are made at the receiving station of indicia associated with the signal detected thereat. Responsive to the measurement of the indicia, a determination is made at the receiving station as to whether subsequently-generated communication signals to be communicated to the receiving station by the sending station should be increased, or decreased, in power. Indications of such determination are returned to the sending station and the power level of subsequently-generated communication signals are altered as appropriate.
In one power control scheme set forth for the IS-2000 system, forward link power control is effectuated by measuring, at the mobile station, signal indicia associated with forward-link traffic channel signals. Namely, measurements are made of frame error rates of the frames of the forward-link traffic channel signals. The frame error rate of the traffic channel signal is associated with the SIR (signal to interference ratio) of the traffic channel signal. Responsive to the measurements, a decision is made either to request an increase or to request a decrease in the power levels of the forward-link traffic channel signals. Estimation of the SIR levels of the forward-link traffic channel signals based upon these measurements, however, are susceptible to bias and variance.
Because any delay in the alteration in the power levels at which a communication signal is communicated might adversely affect communications of other communication signals, it is important effectuate power control quickly. Measurement, and subsequent determination, of communication signal indicia at a receiving stations results in some delay in the effectuation of power control in a closed-loop power control scheme.
Any manner by which to permit earlier determination of whether to alter the power levels of the communication signals to be transmitted to a receiving stati
Le Danh C
Nokia Corporation
Trost William
LandOfFree
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