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: 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: 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: 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.