Uplink capacity improvement through orthogonal code hopping in uplink-synchronized CDMA systems

• Published in: IEEE transactions on wireless communications Vol. 8; no. 11; pp. 5404 - 5410
• Main Authors: Jung, Bang, Cho, Sung, Sung, Dan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Applied sciences; Channelization code restriction; Code division multiple access; Coding, codes; Data communication; Exact sciences and technology; Gain; Information technology; Information, signal and communications theory; Laboratories; Mathematical analysis; Multiaccess communication; Multiple access; Multiple access interference; noise rise; orthogonal code hopping multiple access; Performance analysis; Quality of service; Research and development; Signal and communications theory; Symbols; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Time division synchronous code division multiple access; Transmission and modulation (techniques and equipments); uplink capacity; uplink synchronization; Wireless communication; Access control; Performance evaluation; Multiple access; Channel capacity; uplink synchronization; Wireless telecommunication; orthogonal code hopping multiple access; uplink capacity; Channelization code restriction; Synchronization; Jamming; Finite sets; Frequency selection; Orthogonal code; Code division multiple access; noise rise; Uplink
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.081355

We propose an orthogonal code hopping multiple access (OCHMA) scheme in order to improve the capacity of an uplink-synchronized code division multiple access (CDMA) systems. When orthogonal codes (OCs) are used for channelization in uplink-synchronized CDMA systems, a finite set of OCs tends to severely limit the capacity gain of the uplink-synchronized CDMA systems. The OCHMA system allows each user to use a different OC for each symbol according to an allocated hopping pattern (HP). It also allows multiple users to use the same OC at a specific symbol time, which is called an HP collision. Thus, the proposed OCHMA scheme can accommodate more users than the number of available OCs. We analyze the capacity of the OCHMA scheme and compare the performance of the OCHMA with that of conventional schemes including the system using multi-scrambling codes (MSC) which have also been proposed to overcome a code-limited situation.