Abstract
Orthogonal frequency and code division multiplexing (OFCDM) which can be extended orthogonal frequency and code division multiple access (OFCDMA) has a good performance, because it can mitigate multi path interference while maintaining high data rate. Furthermore, cooperative OFCDM relaying system provides these advantages, and this system can effectively use the limited resource with respect to data rate and each terminal’s energy efficiency. Therefore we proposed cooperative OFCDMA relaying uplink system because of the user’s requirement of the high data rate at uplink. However, a throughput performance decreases when this system employs many relays in case of each relay allocated code channel to separate each relay’s signal. Therefore, in this paper, we present that the proposed system combines cyclic delay diversity due to complement throughput performance problem. DF (Decode-and-Forward) is assumed in this paper. It is considered that the users which want to send data to BS only decode the data from other users. In addition to that, we propose the adaptive cooperative communication for the OFCDMA uplink system. The proposed adaptive system can easily select the cooperative relay.
Highlights
Future wireless communication systems increasingly need high reliability and throughput, because consumers require high quality of service (QoS)
In this paper, we extend Orthogonal frequency and code division multiplexing (OFCDM) to orthogonal frequency and code division multiple access (OFCDMA) for efficiently embodying uplink system, and supporting multiple users as OFDMA [6]
We propose a system that combines cyclic delay diversity (CDD) and cooperative relaying system based on OFCDMA, and we call this system ‘combined CDD cooperative OFCDMA relaying system’
Summary
Future wireless communication systems increasingly need high reliability and throughput, because consumers require high quality of service (QoS). OFCDM has been mostly studied for downlink system [1,2,3,4,5,6] For these reason, in this paper, we extend OFCDM to orthogonal frequency and code division multiple access (OFCDMA) for efficiently embodying uplink system, and supporting multiple users as OFDMA [6]. Cooperative OFCDM relaying scheme is proposed in [7] This system provides high reliability through spatial diversity and frequency diversity. This scheme effectively uses the limited resource with respect to data rate and each terminal’s energy efficiency.
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