On Limits of Wireless Communications in a Fading Environment when UsingMultiple Antennas
Wireless Personal Communications: An International Journal
Binary signature sets for increased user capacity on the downlink of cdma systems
IEEE Transactions on Wireless Communications
Space-time block codes from orthogonal designs
IEEE Transactions on Information Theory
The golden code: a 2×2 full-rate space-time code with nonvanishing determinants
IEEE Transactions on Information Theory
A simple transmit diversity technique for wireless communications
IEEE Journal on Selected Areas in Communications
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Conventional multi-antenna receiver front-ends require multiple RF/baseband chains and analog-to-digital converters (ADC). This increases power consumption and chip area substantially. In this letter, we introduce a new Code-Modulated Path-Sharing Multi-Antenna (CPMA) receiver architecture suitable for any multi-antenna scheme including spatial multiplexing, spatial diversity, and beamforming. The receiver uses code modulation to distinguish the antenna signals before combining them in the analog domain. The combined signal propagates through shared-path blocks and all the original signals are later recovered in the digital domain for further processing. Due to the spread spectrum nature of code modulation, a larger bandwidth is needed for the blocks in the shared path. To alleviate this effect, the use of non-orthogonal coding is examined. An effective channel matrix is derived and the system capacity is evaluated in terms of the cross-correlation between signature codes. Implementation and code selection issues are discussed. Analysis and simulation results indicate that by properly selecting non-orthogonal code sets, the spreading factor, and therefore, the overall analog signal bandwidth is reduced while incurring minimal performance degradation.