A V2V communication system with enhanced multiplicity gain

Abstract

Abstract-Vehicle to vehicle (V2V) communication has gained renewed interest among research community which is further signified by the allocation of dedicated spectrum and an IEEE standard for their usage in recent years. However, 802.11p, the current IEEE standard for vehicular communications, has a relatively low multiplicity (the number of links that it can simultaneously support). In this work, we propose a new vehicular communication scheme based on sectored antennas in order to improve the multiplicity performance. We first show that a sectored antenna based vehicular communication system has higher multiplicity than 802.11p. To further enable multiple transmit sectors to communicate with a receive node simultaneously in a single receive sector, using an OFDMA system design, we propose a new sector-specific pilot design and corresponding channel estimation over time and frequency domains of the channels corresponding to various sectors. Finally, the performance characteristics of the proposed scheme are shown through simulations.

Near Maximum-Likelihood Detector and Channel Estimator for Uplink Multiuser Massive MIMO Systems With One-Bit ADCs

“…where x R is the true transmitted vector andẍ R ∈ S K R \ {x R }. In words, it can happen that the original ML detector makes the correct decision as in (33) and (34) while the estimated vectorx (2) R,ML from (28) is closer toẍ R that is not the true transmitted vector. The suboptimality, however, will not come into play when N r is large as shown in [38].…”

“…R,ML is selected from a ball x R 2 ≤ K. Note that (26) can have multiple local optimal solutions due to non-convexity of the constraint. If we let X (1) be a set of all possible solutions of (26), the following lemma shows the relation between X (1) andx (2) R,ML in the high SNR regime. Lemma 1.…”

“…The figure clearly shows that the nML detector outperforms the ZF-type detector even for this practical setting. Further improvements could be expected if further work is put into deriving an appropriate soft decision decoding metric, which requires the probability distribution of x (2) R,ML in (28). It is also possible to exploit the approximated soft metric as in [49], but we leave this for future work.…”

“…With enough antennas, massive MIMO can eliminate inter-user interference completely using matched beamforming for downlink and matched combining for uplink if the base station has full channel state information (CSI). Because of its simple beamforming and combining structures, massive MIMO will be beneficial not only for cellular systems but also for other wireless communication systems, e.g., vehicular-to-everything (V2X) communications using many antennas [2].…”

Compact four-element MIMO SIW cavity backed slot antenna with high front-to-back ratio

“…Different techniques are reported to design compact antenna with improved isolation using grounded slot and grounded stub . However, their gain and front‐to‐back ratio (FTBR) are poor which limits the performances in vehicular communication . Many techniques are introduced to achieve directive radiation characteristics of antenna with high FTBR in Refs.…”