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The time of arrival (ToA) and received signal strength (RSS) estimation errors are modelled based on channel measurements in a non-line-of-sight indoor environment. It is found interesting that their errors are largely independent. Suboptimal hybrid ToA/RSS ranging estimators are derived in closed form based on the obtained error models, and shown to achieve near-optimal performance. The performance of all the estimators improves as the bandwidth increases.Introduction: State-of-the-art ranging systems exploit the time of arrival (ToA) or the received signal strength (RSS) of wireless signals [1]. Owing to the weak direct path and rich scattering, it is a challenging task to design and evaluate the performance of indoor ranging systems under non-line-of-sight (NLoS) scenarios. To the best of our knowledge, ToA and RSS error models have been studied separately [2, 3], but never jointly, through real-world measurement under NLoS scenarios.In this Letter, we study the ToA-and/or RSS-based ranging performance in a typical NLoS indoor environment, under the OFDM system assumption. Our main contributions are: (i) a channel measurement campaign, taking both the ToA-and the RSS-based ranging into account, was carried out in the indoor environment; (ii) the ToA and the RSS estimation errors are modelled into functions of the bandwidth based on the measurement; (iii) suboptimal hybrid ToA/RSS ranging estimators are derived in closed form and shown to achieve near-optimal performance, especially when the bandwidth is large.

The single-radio-frequency (RF) multiple-inputmultiple-output (MIMO) system has been proposed to pursue a high spectral efficiency while keeping a low hardware cost and complexity. Recently, the available degrees of freedom (DoF) in the polarization domain has been exploited to reduce the size of the transmit antenna array and provide 1 bit per channel use (bpcu) multiplexing gain for the single-RF MIMO system. Nevertheless, the polarization domain resource still has the potential to provide a higher multiplexing gain in the polarized single-RF MIMO system. In this paper, we propose a generalized polarization shift keying (PolarSK) modulation scheme that uses polarization states in the dual-polarized transmit antenna as an information-bearing unit to increase the overall spectral efficiency. At the receiver, the optimum maximum likelihood (ML) detector is employed to investigate the ultimate performance limit of the PolarSK. A closed-form union upper bound on the average bit error probability (ABEP) of the PolarSK with the optimum ML receiver is derived. Inspired by the analytic ABEP, a constellation diagram optimization algorithm is proposed. To reduce the computational complexity of the receiver, a linear successive interference cancellation (SIC) detection algorithm and a sphere-decoding (SD) detection algorithm are introduced. Through numerical results, performances of the proposed Po-larSK in terms of ABEP and computational complexity are analyzed. Furthermore, the PolarSK is analyzed over measured indoor channels. Numerical and measurement results show that the PolarSK scheme outperforms the state of the art dualpolarized/uni-polarized SM schemes. , respectively.With his students/colleagues, he has pioneered research in femto/small cell and HetNets and published some of the earliest and/or most cited publications in these topics. Since 2005, he has been awarded more than 20 grants by the Engineering and Physical Sciences Research Council, the EC FP6/FP7/H2020, and industry, including some of world's earliest research projects on femtocell/HetNets. He cofounded Ranplan Wireless Network Design Ltd., Cambridge, U.K., which produces a suite of world-leading in-building distributed antenna systems, indoor-outdoor small cell/HetNet network planning, and optimization tools iBuildNet that have been used by Ericsson, Huawei, and Cisco.Liqin Ding (M'17) received the B.S., M.S., and Ph.D degree in Information and Communication Engineering

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The cooperative perception of the driving environment via the sharing of locally sensed information among automated vehicles plays a fundamental role in ensuring the basic safety of automated driving in complicated public traffic. However, demanding requirements ranging from high data rate and large user density to ultra-high reliability and low latency, are imposed on the 5G network, which is considered the key enabler of cooperative automated driving. In this paper, we propose a novel ultra-dense 5G vehicular network architecture, which features the kinematic information aided user-centric access, to address these requirements. In particular, distributed local access and application centers (LAACs) are designed to perform application implementation and access control collectively, such that the kinematic information of the vehicles extracted at the application layer can be exploited in the dynamic management of network resources to sustain consistently high-performance wireless communications between vehicles and their serving LAACs. Focusing on the uplink transmission of the periodic cooperative sensing messages (CSMs), the possible design of key elements in the kinematic information aided user-centric access, including access point association, radio resource allocation, and mobility support, are discussed. Issues brought about by the practical network deployment and constraints are also considered. In addition, a practical benchmarking access strategy set, which addresses both the reliability and the latency requirements of CSMs, is proposed and evaluated by simulation under the freeway and intersection scenarios. INDEX TERMS Vehicular communications, user-centric access, ultra-reliable and low-latency communications, automated driving, cooperative perception.