Telefonaktiebolaget Lm Ericsson (publ)

Johan Nystr&ouml;m

Karim Jamal

Tor Bj&ouml;rn Minde

Erik Bengt Dahlman

Branislav M Popovic

Sandeep Chennakeshu

Patrik Nils Lundqvist

Mats Cedervall

Riaz Esmailzadeh

Fredrik Klas Jansson

Roar Hagen

Tomas Svensson

Mikael H{umlaut Over (oo)}k

Erik Bengt Lennart Dahlman

Bo Lyckeg&aring;rd

A method for improving the performance of a random access communications system in a variable radio environment is disclosed, whereby at least one valid set of burst signatures is used for transmission by one or more mobile stations. Each set includes at least one signature with a different signature-length than the signatures in other sets. The different signature-lengths can be optimized for the operational environments involved (e.g., longer signatures for slower-moving mobile stations, and shorter signatures for high-speed mobile stations). Alternatively, at least one differentially-encoded signature is used for random access transmissions, in order to reduce the radio channel's sensitivity to large doppler spreads and frequency errors.

Random access in a mobile telecommunications system

Methods and apparatus for synchronization of a transmitter and a receiver are based on orthogonal sequences having optimized correlation properties. The transmitter may generate signed versions of S-Hadamard sequences that are obtained by position-wise scrambling a set of Walsh-Hadamard sequences with a special sequence having complex elements of constant magnitude. The receiver estimates a time location and sequence identity of a received version of the synchronization signal.

Communication methods and apparatus based on orthogonal hadamard-based sequences having selected correlation properties

A method and system are disclosed for facilitating the timing (e.g., the known relative timing differences) of base stations (BSs) in asynchronous CDMA mobile communications systems. A plurality of mobile stations (MSs) measure the relative time differences between various pairs of BSs, and these measurements are stored by the BSs. A source BS sends to an MS, in a neighbor list message, estimates of the relative time difference between the source BS and each of the BSs on the neighboring cell list. Each BS on the list can maintain a relative time difference estimate table, which can be updated continuously from the reports received from MSs. Subsequently, the BSs can send entries from this table to the MS in the neighbor list message. Using this novel technique, the BSs have known relative timing differences. Consequently, when the MS initiates a cell-search for a candidate BS, the MS already has an estimate of the timing of that BS as compared to its source BS. As such, the resulting cell-search procedure has a lower level of complexity and thus can be accomplished much quicker than with prior procedures. In addition, the relative time difference estimates can be compared with corresponding time differences that are measured by a second mobile station. Based on this comparison, the propagation delays of signals between the second MS and various BSs can be calculated to determine the position of the second MS.

Method and system for facilitating timing of base stations in an asynchronous CDMA mobile communications system

The present invention relates to a method and an arrangement for communicating packet information in a digital telecommunications system. Through the invention is selected a set of designated communication resources (ch -chn) from an available amount of resources. Every packet (P) is forward error correction encoded into an encoded packet (P ), via one of at least two different coding schemes (c ), prior to being transmitted to a receiving party, over the designated communication resources (ch -chn). An estimated transmission time is calculated for all combinations of coding scheme (c ) and relevant distribution (d ) of the encoded data blocks (B -B ), in the encoded packet (P ) over the set of designated communication resources (ch -chn), and the combination (c ,d ) is selected, which minimises the estimated transmission time.

Digital telecommunication system with selected combination of coding schemes and designated resources for packet transmission based on estimated transmission time

A channel optimized vector quantization apparatus includes a device for weighting a sample vector x by a weighting matrix A and a device for weighting a set of code book vectors &ccirc;,by a weighting matrix B. Device form a set of distance measures &lcub;d,(Ax,B&ccirc;,)&rcub; representing the distance between the weighted sample vector Ax and each weighted code book vector B&ccirc;,. Other device form a set of distortion measures &lcub;,(x)&rcub; by multiplying each distance measure by a channel transition probability P,that an index r has been received at a decoder when an index i has been sent from an encoder and adding together these multiplied distance measures for each possible index r. Finally device determine an index i,corresponding to the smallest distortion measure,(x) and represents the sample vector by this index i,.

Distance and distortion estimation method and apparatus in channel optimized vector quantization

In a digital cellular radio communication system, a base station selects a speech/channel encoding mode based on measurements of the local radio environment. The mobile station determines the selected mode by trial decoding possible modes to find the most probable mode and uses the same mode for transmission to the base station on the return link. The coding gain/loss obtained by this mode switching may be used to adjust the output power of transmitters, thereby reducing the overall interference level in the system.

Growing community of inventors

Stockholm, Sweden

Johan Nyström

Growing community of inventors

Stockholm, Sweden

Johan Nystr&ouml;m

Johan Nyström