Error detection methods in wireless communication systems

#1. Technical Field

#The invention relates generally to wireless communication systems and, more particularly, to error detection methods for evaluating information that is transmitted in control channels of such systems.

#2. Description of Related Art

#The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, wherein like elements are represented by like reference numerals, which are given by way of illustration only and thus are not limitative of the present invention and wherein:

#FIG. 1 illustrates a process flow for forming a typical concatenated code structure that is transmitted by a base station in accordance with the invention;

#FIG. 2 illustrates the relationship between shared control channels and shared downlink data channels in accordance with the invention;

#Although the principles of the invention are particularly well-suited for wireless communications systems based on the well-known High Speed Downlink Packet Access (HSDPA) specification in the Universal Mobile Telecommunication System (UMTS) standard, and will be described in this exemplary context, it should be noted that the embodiments shown and described herein are meant to be illustrative only and not limiting in any way. As such, various modifications will be apparent to those skilled in the art for application to other transmission systems and are contemplated by the teachings herein. Additionally where used below, user equipment (UE) is synonymous to a mobile station in a wireless communication network.

#Accordingly, there is now described a method for detecting errors in control channels of a wireless communication system that overcomes the problems of inadequate error detection and false alarm performance, which are present in the conventional scrambling or EPMD approaches described above. The conventional scrambling or EPMD approach to error detection usually does not yield adequate error detection/false alarm performance. This is because the approach is based on a path metric difference calculated at only the last level in the trellis.

#The calculated metric at this last level is usually a very noisy metric. The reason why EPMD is a noisy metric, as to the quality of a frame, is because EPMD only uses a last path metric comparison to determine if a frame is in error or not. EPMD does not consider what happened during the “journey” of the eventual winning path as it progressed through the trellis. Accordingly, the EPMD approach does not capture the fact that, at an earlier level in the decoding (as seen in the trellis diagram of FIG. 5 for example), the winning path may have come very close to another merging or competing path, thus rendering it unreliable.