Pulse or digital communications – Repeaters – Testing
Reexamination Certificate
1999-11-30
2003-01-21
Chin, Stephen (Department: 2734)
Pulse or digital communications
Repeaters
Testing
C375S227000, C375S228000, C375S285000, C375S296000, C455S059000, C455S059000, C455S067700, C455S069000, C455S226100, C370S252000, C370S280000, C370S317000, C370S321000, C370S337000, C370S347000, C370S442000
Reexamination Certificate
active
06510174
ABSTRACT:
The present invention relates generally to a manner by which to facilitate improved communication quality of a communication signal transmitted upon a communication link in a communication system, such as a cellular radio communication system. More particularly, the present invention relates to apparatus, and an associated method, by which to select a link parameter of a communication signal transmitted by a sending station upon the communication link. In one implementation, uplink sounding bursts are transmitted by a mobile station and utilized to determine the link parameters to be exhibited by subsequently-generated communication signals.
BACKGROUND OF THE INVENTION
Communication through the use of wireless communication systems has achieved wide popularity in recent years. Multi-user, wireless communication systems of improved capabilities have been implemented as a result of advancements in communication technologies. Communication pursuant to such multi-user, wireless communication systems can be affordably made, further increasing the popularity of usage of such systems.
In a wireless communication system, a communication channel formed between a sending station and a receiving station is a radio channel defined upon a portion of the electromagnetic spectrum. Because a radio channel forms a communication link, a wireline connection is not required to be formed between the sending and receiving stations to permit the communication of information between the stations. Communication by way of a wireless communication system is thereby permitted at, and between, locations at which the formation of a wireline connection would not be practical. Also, because a communication channel is formed of a radio channel, a radio communication system can be more economically installed as the infrastructure costs associated with a wireline communication system are significantly reduced.
A cellular communication system is exemplary of a wireless, multi-user radio communication system which has been made possible due to advancements in communication technologies and which has achieved wide levels of usage. A cellular communication system efficiently utilizes the portion of the electromagnetic spectrum allocated thereto. A plurality of fixed-site base stations are installed throughout a geographical area. By transmitting relatively low-power signals, the same frequencies can be reused at different locations throughout the geographical area. Thereby, communications can be effectuated between more than one set of sending and receiving stations concurrently at separate locations throughout the area encompassed by the cellular communication system.
Cellular standards have been promulgated relating to various types of cellular communication systems, and various types of cellular communication systems have been constructed corresponding to such standards. Several of such standards pertaining to a cellular communication system utilize TDMA (time-division, multiple-access) communication techniques. In a TDMA communication system, a carrier is divided into time slots in which a carrier—time slot combination defines a channel. Groups of adjacently-positioned time slots sometimes are together defined to form a frame, and group of frames are sometimes together defined as superframes or hyperframes.
In a particular communication session, one or more time slots per frame is allocated to a sending-receiving station pair to effectuate the communication of data therebetween. Because a single frequency bandwidth can be utilized to effectuate more than one communication session, improved communication capacity of the communication system is possible.
In an ideal communication system, a communication signal, when received at a receiving station, is substantially identical to the corresponding communication signal when transmitted by a sending station but delayed in time. However, in a non ideal communication system in which the communication signal must be transmitted upon a non ideal communication channel, the signal, when received at the receiving station is dissimilar to the corresponding communication signal when sent by the sending station. Distortion of the communication signal caused by transmission of the communication signal upon the communication channel causes such dissimilarities to result. If the distortion is significant, the informational content of the signal cannot be recovered at the receiving station.
In the aforementioned, TDMA cellular communication system, the communication channel, formed of a radio link, might be of characteristics which distort the values of the data bits of which a communication signal is formed. Fading, such as that caused by multi-path transmission or Rayleigh fading, alters values of the data bits of the communication signal during its transmission. Such distortion, if not corrected, reduces the communication quality levels of communications in a communication session formed between a mobile station and another station. Problems are sometimes most problematical when a mobile station is positioned at a cell-edge during a communication session. An increased path length between the mobile station and a base station resulting from position of the mobile station increases the possibility of increased levels of multi-path distortion as well as reducing the power level of a signal, when received at a receiving station. Also, co-channel, and other, interference with communications in other cells is more likely to be significant when the mobile station is positioned at a cell-edge.
Various techniques are utilized to overcome distortion introduced upon a communication signal as a result of transmission upon a non ideal communication channel. Channel encoding of the communication signal, prior to its transmission, for instance, increases the redundancy of the transmitted signal. By increasing the redundancy, the likelihood that the informational content of the signal can be recovered, once received at the receiving station, is increased. Alteration of the modulation format by which a communication signal is formed is sometimes also utilized to increase the likelihood that the informational content of the transmitted signal can be recovered. In a communication system which utilizes feedback acknowledgments of transmitted signal portions, power control schemes utilizing power control step size increments or decrements are utilized to increase, or decrease, the power levels of a transmitted signal, dependent upon channel characteristics. Selection of the number of times in which a signal portion is retransmitted or a selection of a timing of retransmission of a signal portion in the absence of positive acknowledgments also are utilized in some communication systems to overcome problems associated with non ideal channel conditions.
In some communication systems, communication signals are transmitted in bursts. Communication of GPRS (general packet radio service) messages proposed for the GSM (global system for mobile communications) family of standards is exemplary of communications which are effectuated in discrete bursts. Because of the bursty nature of the GPRS communications, additional difficulties in selecting the link parameters to communicate the messages is made more difficult. That is to say, GPRS messages are transmitted at intermittent intervals. The channel characteristics at the successive intervals during which the GPRS signals are transmitted might well differ significantly from one another. As a result, link parameters most appropriate to facilitate a good quality level of communications during one burst might be inappropriate to maximize communication quality levels at a subsequent interval.
If a manner could be provided by which to facilitate the selection of link parameters to communicate communication signals at improved communication quality levels, improved communication system performance would result.
It is in light of this background information related to radio communications that the significant improvements of the present invention have evolved.
SUMM
Lappetelainen Antti
Sexton Thomas A.
Chin Stephen
Fraccaroli Federico
Ha Dac V.
Nokia Corporation
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