Fast cell search and accurate synchronization in wireless communications

Abstract

Techniques for fast cell search, selection and reselection for wireless communication systems such as OFDM or OFDMA communication systems. In various implementations of the described techniques, downlink subframes from base stations to mobile stations are designed to include information in form of preambles or post-ambles in one or more downlink subframes to facilitate cell search at receiving mobile stations at high speeds. The described preambles and post-ambles may also be used to improve the accuracy of signal synchronization in time and frequency.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of U.S. Provisional Application No. 60 / 601,790, filed August 16, 2004, entitled "Preamble Sequences for Fast Cell Finding," which is incorporated herein by reference in its entirety, and as part of this application description. Background technique [0003] The present application relates to cell search and signal synchronization in wireless communication systems, including systems based on Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA). [0004] Wireless communication systems use a network of base stations to communicate with wireless devices registered for service in the system. Various base stations transmit radio signals carrying data, such as voice data and other data content, to wireless devices. Such signals from the base station may include overhead load in addition to data for various communication management funct...

AI Technical Summary

Problems solved by technology

However, performing correlation processing for all 114 candidate preamble sequences is time-consuming and labor-intensive

Also, since CP is only a small fraction of the FFT size, CP-based symbol timing detection methods may not be very accurate and may introduce inter-symbol interference (ISI), degrading the performance of the subsequent cell search process

Also, initial frequency estimates based on CP correlations may be crude and thus may not be reliable

The limitations of these techniques based on the preamble design of IEEEEP802.16-REVd / D5-2004 can lead to long cell search time, which may not be acceptable in some communication applications (such as wireless mobile communication services)

Images