Effective interference level‐based packet transmission for multiple‐input multiple‐output systems with hybrid automatic repeat request

Error-detection-coding-aided iterative hard decision interference cancellation for MIMO systems with HARQ

“…Interference cancellation (IC) schemes [1]- [9] are a reception technique for multiple-input multiple-output (MIMO) systems; these schemes can achieve a high level of performance with reduced computational complexity compared to optimal detection approaches. Among the various IC schemes, successive hard decision IC (SIC) [1]- [3] and iterative hard decision IC (IHIC) [4] [5] utilize hard instead of soft decision values to further reduce the computational complexity.…”

“…However, if a decoded bit sequence in a hard decision IC scheme contains errors, those errors can be propagated to other decoded bit sequences. In addition, if hybrid automatic repeat request (HARQ) [9]- [15] is employed for packet retransmission, the errors in the decoded bit sequences of previous transmissions can be transferred to the decoded bit sequences of future transmissions, owing to the HARQ combining process for retransmission. That is, the errors propagated to a packet by the hard decision IC schemes in previous transmissions become additional noise components of the packet in future transmissions, which disturbs the packet decoding success after retransmission.…”

“…This phenomenon of error propagation throughout transmissions, which is termed "inter-transmission error propagation" for the first time in this paper, can degrade the error performances of MIMO systems employing HARQ with hard decision IC schemes. Furthermore, if multi-packet transmissions are allowed in an MIMO system employing HARQ [9] [10] [12]- [14], the inter-transmission error propagation of a packet can be transferred to other packets through the hard decision IC.…”

“…To prevent error propagation, error detection coding (EDC) schemes such as cyclic redundancy check (CRC) [16] [17] can be utilized for hard decision IC schemes [6] [7] [9]. Unlike the approach proposed in [8], in which EDC is utilized as a criterion to stop iteration, the hard decision IC schemes reported in [6], [7], and [9] perform IC when a decoded bit sequence is identified as error-free by the EDC. However, the hard decision IC schemes in [6] and [7] were designed for MIMO systems without HARQ, and can only be applied in the case of two simultaneously transmitted packets.…”

“…However, the hard decision IC schemes in [6] and [7] were designed for MIMO systems without HARQ, and can only be applied in the case of two simultaneously transmitted packets. Further, although the hard decision IC scheme in [9] was designed for MIMO systems employing HARQ, it is restricted to performing a CRC-based error detection procedure for every decoding iteration. Further, in [9], little effort was made to investigate the performance and operational characteristics of the utilized hard decision IC scheme.…”