Design of concatenated extended complementary sequences for inter-base station synchronization in WCDMA TDD mode

The Universal Mobile Telecommunications System (UMTS) being specified by the Third Generation Partnership Project (3GPP) and based upon Wideband Code Division Multiple Access (WCDMA) consists of a frequency division duplex (FDD) mode and a time division duplex (TDD) mode. In the UMTS Terrestrial Radio Access (UTRA) TDD mode, system capacity is maximized with base stations (Node B's) in a UTRA TDD mode deployment area operating synchronously. A Node B synchronization mechanism based upon transmissions and timing measurements of synchronization bursts between neighboring Node B's has been specified as part of release 2000 (now called release 4) in 3GPP. A family of new synchronization codes, so-called Concatenated Extended Complementary (CEC) sequences have been chosen for the Node B synchronization bursts. CEC sequences are derived from Polyphase Complementary Pairs which facilitate the use of efficient and low-complexity receiver implementations. CEC sequences have perfect aperiodic auto-correlation properties within a window of adjustable size and excellent overall auto-correlation properties. This paper describes how to derive CEC sequences and their auto-correlation properties and details the design of CEC sequences adapted to the inter-base station synchronization over the air process. Index terms — Third generation mobile radio system, UMTS, WCDMA, TDD mode, inter-base station synchronization, complementary sequences, multiple code offsets