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

Abstract

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, the system capacity is maximized with base stations (Node Bs) 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 Bs 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. The CEC sequences are derived from polyphase complementary pairs which facilitate the use of efficient and low-complexity receiver implementations. The CEC sequences have perfect aperiodic auto-correlation properties within a window of adjustable size and excellent overall autocorrelation properties. This paper describes how to derive the CEC sequences and their auto-correlation properties and details the design of the CEC sequences adapted to the inter-base station synchronization over the air process.