Blind multiuser detection and blind channel estimation for ofcdm communication systems

Abstract

Wireless communication system has grown rapidly over the past years in the service type, coverage and number of users. The most important challenge for wireless system today is an increasing demand for more number of services and limited physical resources. newlineOrthogonal Frequency Code Division Multiplexing (OFCDM) is one of the attractive multiple access scheme which allows many users to share the common channel. In OFCDM, transmitted data is divided into many sub streams each of which has a low bit rate. OFCDM allows for efficient use of available bandwidth and robust against multipath environment. Due to multipath environment, the transmitted signals are suffered by Multipath Fading. Therefore, performance of the system is affected by Multiple Access Interference (MAI). Multiuser Detection (MUD) is employed to detect the desired user signal in the presence of MAI. Conventional MUD techniques require known training or pilot sequences for detection. Frequent use of pilot sequence reduces the spectral efficiency and also degrades the system performance. newline newline