Diversity Combining for Wireless Communication-Digital Camera

MERL Murray Hill developed an advanced multi-user receiver for the next generation wireless communication systems. In order to maintain good communication quality in high mobility and high data rate transmission environments, this receiver utilizes joint space-time-frequency diversity combining technique and adaptive interference cancellation techniques to mitigate multiple access interference (MAI) and channel impairments in Code Division Multiplex Access (CDMA) communication systems. The performance improvement, in terms of error rate and system capacity, over the conventional receiver can be shown through the computer simulations.

Background & Objective: CDMA technology is the key technology in the 3rd generation wireless communication systems. Multi-user detection is an important issue in CDMA systems since each user shares the same frequency band and time interval. In order to support multimedia communication in the future, a high performance CDMA receiver with high data rate transmission in high mobility environments is desired.

Technical Discussion: Diversity techniques are used in practice to combat fading channels. The increased mobility of users in cellular communication often results in fast fading or large Doppler spreads and the degradation of system performance is expected. The use of joint time-frequency diversity techniques provides significant performance improvement over the existing systems in the single user receiver design. Unlike the time-frequency diversity is the wireless channel characteristics, one can create diversity dimension artificially, such as space-time diversity for multi-user detection in CDMA systems. Diversity gains can be achieved by using multiple elements for antenna arrays processing and adaptively combining space-time-frequency diversity signals. However, due to heavy computational complexity, the trade off between performance and complexity become an importance issue when applying this technique.

Diversity Combining for Wireless Communication-Digital Camera