Overlap QRM-ML Block Signal Detection for Single-Carrier Transmission without CP Insertion

Abstract

Abstract-A block signal maximum likelihood detection (MLD) employing QR decomposition and M-algorithm (QRM-MLBD) can significantly improve the bit error rate (BER) performance of the single carrier (SC) transmissions in a frequency-selective fading channel, compared to the conventional frequency-domain equalization (FDE). In QRM-MLBD, the cyclic prefix (CP) is inserted in order to avoid inter-block interference (IBI). However, the CP insertion reduces the transmission efficiency. In this paper, we propose an overlap QRM-MLBD which requires no CP insertion. In overlap QRM-MLBD, IBI can be suppressed by overlapping consecutive observation windows and picking up only the reliable part after the block signal detection. We evaluate the average BER performance and the throughput performance by computer simulation to compare with the conventional QRM-MLBD with CP insertion.

Hybrid-Domain Sequence Detector for Training Sequence-Aided Single-Carrier Block Transmission Signals

“…QRD-M Algorithm [11], [12] It follows from (5) and (6) that, to detect s, we can consider only the first N +L h −1 entries of y, because (i) the remaining entries of y do not depend on s (they depend on the TS only), and (ii) the noise samples in n are independent. In addition, since the TS is known and assuming that the receiver has the perfect knowledge of the channel, the contribution of TS can be removed from…”

“…This process is repeated until it reaches level N ; the N -branch path with the minimum PM then gives the QRD-M solution. Finally, we note in (11) that Q H can be viewed as a TD prefilter that reveals the tree structure in z.…”

“…Although optimal in the sense of minimizing the decision-error rate for equally likely modulation symbols, the complexity of MLSD is still very high for SCBT systems, even when sphere decoding algorithm (SDA) [10] is used for complexity reduction (see Section VI-A2 for detail). Independently proposed in [11] and [12], the suboptimal sequence detector using the QRD-M algorithm [13], [14] was employed to equalize the SCBT signals. It is a time-domain approach that uses the QR decomposition (QRD) to generate the tree structure, before applying the M-algorithm to perform a reduced tree search.…”

“…They were shown to compare favorably, in terms of the performance-complexity tradeoff, with interference cancellation algorithms. In [22], the QRD-M algorithm [11], [12] was extended to become a SISO equalizer; simulations demonstrated a performance close to that of the turbo maximum a posteriori (MAP) equalizer with a lower complexity. The rest of the paper is organized as follows.…”

“…Section II describes the signal model. Section III reviews the QRD-Mbased algorithms [11], [12], [23] that serve as the baseline for comparison in terms of performance and complexity. The proposed algorithm and complexity analysis are discussed in Sections IV and V, respectively.…”