Sum Throughput Maximization in Multi-Tag Backscattering to Multiantenna Reader

Abstract

Backscatter communication (BSC) is being realized as the core technology for pervasive sustainable Internet-of-Things applications. However, owing to the resource-limitations of passive tags, the efficient usage of multiple antennas at the reader is essential for both downlink excitation and uplink detection. This work targets at maximizing the achievable sumbackscattered-throughput by jointly optimizing the transceiver (TRX) design at the reader and backscattering coefficients (BC) at the tags. Since, this joint problem is nonconvex, we first present individually-optimal designs for the TRX and BC. We show that with precoder and combiner designs at the reader respectively targeting downlink energy beamforming and uplink Wiener filtering operations, the BC optimization at tags can be reduced to a binary power control problem. Next, the asymptotically-optimal joint-TRX-BC designs are proposed for both low and high signalto-noise-ratio regimes. Based on these developments, an iterative low-complexity algorithm is proposed to yield an efficient jointlysuboptimal design. Thereafter, we discuss the practical utility of the proposed designs to other application settings like wireless powered communication networks and BSC with imperfect channel state information. Lastly, selected numerical results, validating the analysis and shedding novel insights, demonstrate that the proposed designs can yield significant enhancement in the sum-backscattered throughput over existing benchmarks.

Massive MIMO Beamforming in Monostatic Backscatter Multi-Tag Networks

“…Unless otherwise stated, we set P = 30dBm and σ 2 = −140dBm. As in [4], we consider α min = 0.01 and α max = 0.078. β k = d −ϑ k , where = ( 3×10 8 4πf ) 2 is the average channel attenuation at unit reference distance with f = 915MHz [5] being the transmit frequency, d k is the R to T k distance, and ϑ = 3 is the path loss exponent.…”

“…However, due to limited space, a detailed discussion will be considered as an extension of our proposals in this letter in future work. In the next section, the effect of imperfect CSI will be investigated via simulation study, as considered in [4], [17], [18].…”

“…The major bottlenecks for these techniques are the limited communication range and low achievable rates [3]. The work in [4] investigated a numerical approach to maximize the sumbackscattered rate to multi-antenna reader by jointly optimizing the transceiver design at the reader and the backscattering coefficients at the tags, assuming perfect channel state information (CSI) at the reader. Channel estimation of monostatic backscattering setup for single tag was studied in [5].…”

Multi-Tag Backscattering to MIMO Reader: Channel Estimation and Throughput Fairness

“…With similar objective, cognitive ambient BSC was investigated in [10] to come up with beamforming-assisted energy detector and likelihood-ratio based detector designs for the multiantenna reader having the perfect CSI availability. More recently, under perfect CSI availability assumption, the sum-backscattered-throughput maximization problem, jointly optimizing TRX design at multiantenna reader and backscat-tering coefficient at single antenna tags, was studied in [11], [12]. Now we would like to highlight a striking similarity between BSC system [2]- [16] and the wireless powered communication network (WPCN) [17], [18].…”

Outage Analysis of Parasitic Ambient Backscatter Communication in Decode-and-Forward Relay Networks with SWIPT

“…It has been recognized as a promising solution to the massive communication requirements of internet of things (IoT) [1][2][3][4]. Generally speaking, at present there are three main ways to implement backscatter communications, i.e., monostatic, bistatic, and ambient modes [4,5]. In monostatic and bistatic modes, a dedicated carrier transmitter is required to emit excitation RF signal to the backscatter tag.…”