Dynamically reconfigurable soft output MIMO detector

Abstract

MIMO systems (with multiple transmit and receive antennas) are becoming increasingly popular, and many next-generation systems such as WiMAX, 3-GPP LTE and IEEE802.11 n wireless LANs rely on the increased throughput of MIMO systems with up to four antennas at receiver and transmitter. High throughput implementation of the detection unit for MIMO systems is a significant challenge. This challenge becomes still harder, because the above mentioned standards demand support for multiple modulation and coding schemes. This implies that the MIMO detector must be dynamically reconfigurable. Also, to achieve required bit error rate (BER) or frame error rate (FER) performance, the detector has to provide soft values to advanced forward error correction (FEC) schemes like turbo Codes. This paper presents an ASIC implementation of a novel MIMO detector architecture that is able to reconfigure on the fly and provides soft values as output. The design is implemented in 45 nm predictive technology library, and has a parallelism factor of four. The detector has many qualities of a systolic architecture and achieves a continuous throughput of 1 Gbps for QPSK, 500 Mbps for 16-QAM, and 187.5 Mbps for 64-QAM. The total area is estimated to be approximately 70 KGates equivalent, and power consumption is estimated to be 114 mW.