Abstract: The invention provides improved suppression of co-channel interference (CCI) in a wireless cellular communications system where at least two base stations use the same transmit frequency. The method according to the invention uses the difference in synchronization times between the home signal and the CCI signal to suppress the CCI signal. The method uses a modified known method of estimating time of arrival (TOA) to estimate sync positions for the CCI signal. This enables the use of interference cancelling methods in communications systems using un-synchronized base stations. Receiver performance is improved, which in turn improves data throughput and received speech quality, since interfering signals from base stations using the same frequency can be suppressed.

Abstract: A mobile station adapted to be used in a radio communications system includes a receiver apparatus adapted to receive blocks of distorted information bits at a first rate from a transmitter via a communications link, and a first detecting apparatus adapted to detect information bits from the distorted information bits. The mobile station also includes a second detecting apparatus adapted, when the quality of the received blocks of information bits is above a given level, to detect information bits from the distorted information bits using fewer computation resources than the first detecting apparatus.

Abstract: A digital communication receiver communicates with a digital communication transmitter across a communication channel and has: a channel estimator, which provide a channel estimate of the communication channel based on a received signal; an equalizer, which estimates a sequence of transmitted symbols and provides a sequence of decided symbols based on the received signal and the channel estimate; and a channel tracker, which produces an updated channel estimate based on the received signal and the decided symbols, and which supplies the updated channel estimate to the equalizer. The digital communication receiver has a controller, which receives channel quality indicative data associated with an output from the equalizer, determines whether these data fail to meet a predetermined criterion, and, if so, supplies an enabling control signal to the channel tracker.

Abstract: The invention relates to: A method for estimating residual noise in the frequency range (271) of a desired part (240) of a signal to a corresponding apparatus and to a mobile telephone utilizing the method. The object of the present invention is to generate a measure for the residual noise in a signal. The problem is solved in that the amplitude of the signal (114) comprising the noise is modified, and the signal (114) is combined with the modified signal (115) to create a noise estimation measure (116). The invention may e.g. be used in digital radio communications systems to contribute to the monitoring of link quality and therefore to improve payload throughput. One of the advantages of the invention is that an indication of link quality at an early stage in the receiver is provided.

Abstract: A method and apparatus for processing a received signal containing a desired burst and a co-channel interferer burst are disclosed. The invention includes receiving the received signal from a front end receiver. A time offset between the desired burst and the co-channel interferer burst is detected. A detection procedure is then selected based on the time offset between the desired burst and the co-channel interferer burst. Preferably, one of three detection procedures is selected based on the time offset detected and optionally the signal strength of the co-channel interferer burst. If a first or second time offset is detected, then a joint detection or an iterative detection procedure is selected and performed, respectively. Finally, if a third time offset is detected or if the co-channel interferer has a low signal strength, then a conventional detection procedure is selected and performed.

Abstract: The invention provides improved suppression of co-channel interference (CCI) in a wireless cellular communications system where at least two base stations use the same transmit frequency. The method according to the invention uses the difference in synchronisation times between the home signal and the CCI signal to suppress the CCI signal. The method uses a modified known method of estimating time of arrival (TOA) to estimate sync positions for the CCI signal. This enables the use of interference cancelling methods in communications systems using un-synchronised base stations. Receiver performance is improved, which in turn improves data throughput and received speech quality, since interfering signals from base stations using the same frequency can be suppressed.

Abstract: Methods of receiving communications signals can include generating a received analog signal including energy corresponding to communications transmitted from a remote transmitter, and performing an analog-to-digital conversion of the received analog signal to provide a received digital signal. The received digital signal can be digitally filtered using a first digital filter having a first bandwidth to provide a first filtered digital signal, and the first filtered digital signal can be processed to provide an estimate of the communications transmitted from the remote transmitter. The received digital signal can be digitally filtered using a second digital filter having a second bandwidth to provide a second filtered digital signal wherein the second bandwidth is greater than the first bandwidth, and a signal characteristic of the second filtered digital signal can be measured. Related receivers are also discussed.

Abstract: A direct conversion receiver is disclosed, in which a DC offset is estimated in two stages. A coarse DC estimation is performed, and the estimate is removed from the received sequence. Then, a coarse synchronization is performed in order to estimate the synchronization position within the burst. Subsequently, a coarse channel estimation and a finer DC estimation are performed simultaneously, and the refined DC estimate is removed. Finally, a refined synchronization and channel estimation are performed, and the refined estimate of the channel is fed to an equaliser, which acts on the received signal, after removal of the refined estimate of the DC component.

Abstract: Methods of receiving communications signals can include generating a received analog signal including energy corresponding to communications transmitted from a remote transmitter, and performing an analog-to-digital conversion of the received analog signal to provide a received digital signal. The received digital signal can be digitally filtered using a first digital filter having a first bandwidth to provide a first filtered digital signal, and the first filtered digital signal can be processed to provide an estimate of the communications transmitted from the remote transmitter. The received digital signal can be digitally filtered using a second digital filter having a second bandwidth to provide a second filtered digital signal wherein the second bandwidth is greater than the first bandwidth, and a signal characteristic of the second filtered digital signal can be measured. Related receivers are also discussed.

Abstract: A homodyne radio receiver apparatus receives radio frequency signal bursts containing a number of symbols and generates digital samples of at least a complex base band signal (I and Q) of each signal burst. A DC compensator comprises an average calculator (8,8′), which determines an average DC-level of said samples, and a signed square sum calculator (9,9′), which calculates a signed square sum of a plurality of said samples and weights the square sum by a compensation factor. Correction means (10,10′) subtracts the square sum from an output of said average calculator means for forming the DC-level estimate.

Abstract: Link quality control information is generated by receiving a received signal from a front end receiver. Time dispersion information is then estimated during a synchronization of the received signal. Then, link quality control information is generated using the time dispersion information. The link quality control information includes information pertaining to an optimal transmission parameter. The link quality control information can be transmitted back to a unit that transmitted the received signal so that the appropriate transmission parameters may be adjusted.

Abstract: A method and apparatus for processing a received signal containing a desired burst and a co-channel interferer burst are disclosed. The invention includes receiving the received signal from a front end receiver. A time offset between the desired burst and the co-channel interferer burst is detected. A detection procedure is then selected based on the time offset between the desired burst and the co-channel interferer burst. Preferably, one of three detection procedures is selected based on the time offset detected and optionally the signal strength of the co-channel interferer burst. If a first or second time offset is detected, then a joint detection or an iterative detection procedure is selected and performed, respectively. Finally, if a third time offset is detected or if the co-channel interferer has a low signal strength, then a conventional detection procedure is selected and performed.

Abstract: In a communication system including a transmitter and a receiver, the receiver is synchronized with the transmitter, and a modulation type in a signal transmitted by the transmitter and received by the receiver is detected. A first portion of the received signal is correlated with one or more signals representing modulation types used by the communication system to detect the type of modulation being used in the received signal. Synchronization is established between the transmitter and the receiver. The first portion may be correlated with each of one or more different signals representing various modulation types used in the communication system to detect the type of modulation used. Alternately, the first portion of the received signal may be derotated by different amounts to produce a plurality of derotated signals that are correlated with the signal representing modulation used by the communication system in order to detect the type of modulation used.

Abstract: A method and system for blind detection of modulation in a wireless telecommunications network. In accordance with the method and system, a plurality of bursts are transmitted over an air interface to a receiving station using a first modulation scheme. Modulation detection statistics for the plurality of received bursts are calculated at the receiving station. Based on the modulation statistics, however, it is determined that at least one of the plurality of received bursts has been transmitted using a second modulation scheme. As a result, the modulation detection statistics are analyzed to identify a single modulation scheme that was most likely used in modulating the plurality of bursts. Any faulty received bursts, for which a detected modulation scheme differs from the identified single modulation scheme, are then processed to reduce the effect of the faulty bursts.

Abstract: In order to increase accuracy of DC-offset compensation within radio receivers and to ensure that such compensation does not erode the dynamics of the decoders located within the receivers, the present invention separately performs mean value estimation and channel estimation. Additionally, a bias DC offset value caused by the use of a training sequence to perform mean value estimation can be corrected for in the channel estimator and equalizer.

Abstract: The invention relates to a mobile station adapted to be used in a radio communications system, said mobile station including: receiver means adapted to receive blocks of distorted information bits at a first rate from a transmitter via a communications link, and first detecting means adapted to detect information bits from said distorted information bits. The mobile station also includes second detecting means adapted, when the quality of said received blocks of information bits is above a given level, to detect information bits from said distorted information bits using fewer computation resources than said first detecting means.