Ang Yang

Performance Analysis and Location Optimization for Massive MIMO Systems With Circularly Distributed Antennas

We analyze the achievable rate of the uplink of a single-cell multi-user distributed massive multiple-input-multiple-output (MIMO) system. Each user is equipped with single antenna and the base station (BS) is equipped with a large number of distributed antennas. We derive an analytical expression for the asymptotic ergodic achievable rate of the system under zero-forcing (ZF) detector. In particular, we consider circular antenna array, where the distributed BS antennas are located evenly on a circle, and derive an analytical expression and closed-form bounds for the achievable rate of an arbitrarily located user. Subsequently, closed-form bounds on the average achievable rate per user are obtained under the assumption that the users are uniformly located. Based on the bounds, we can understand the behavior of the system rate with respect to different parameters and find the optimal location of the circular BS antenna array that maximizes the average rate. Numerical results are provided to assess our analytical results and examine the impact of the number and the location of the BS antennas, the transmit power, and the path-loss exponent on system performance. Simulations on multi-cell networks are also demonstrated. Our work shows that circularly distributed massive MIMO system largely outperforms centralized massive MIMO system.

The Role of Large-Scale Fading in Uplink Massive MIMO Systems

In this paper, we analyze the ergodic achievable rate of a large uplink multiuser multiple-input-multiple-output (MU-MIMO) system over generalized-

Symbol Error Rate of Space–Time Network Coding in Nakagami-

K

m

fading channels. In the considered scenario, multiple users transmit their information to a base station equipped with a very large number of antennas. Since the effect of fast fading asymptotically disappears in massive MIMO systems, large-scale fading becomes the most dominant factor for the ergodic achievable rate of massive MIMO systems. Regarding this fact, in our work, we concentrate our attention on the effects of large-scale fading for massive MIMO systems. Specifically, some interesting and novel asymptotic expressions of ergodic achievable rate have been derived with both perfect channel state information (CSI) and imperfect CSI. Simulation results assess the accuracy of these analytical expressions.

Fading

In this paper, we analyze the symbol error rate (SER) of space-time network coding (STNC) in a distributed cooperative network over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-m fading channels. In this network, multiple sources communicate with a single destination with the assistance of multiple decode-and-forward (DF) relays. We first derive new exact closed-form expressions for the SER with M-ary phase-shift keying modulation (M-PSK) and M-ary quadrature-amplitude modulation (M-QAM). We then derive new compact expressions for the asymptotic SER to offer valuable insights into the network behavior in the high signal-to-noise ratio (SNR) regime. Importantly, we demonstrate that STNC guarantees full diversity order, which is determined by the Nakagami-m fading parameters of all the channels but independent of the number of sources. Based on the new expressions, we examine the impact of the number of relays, relay location, Nakagami-m fading parameters, power allocation, and nonorthogonal codes on the SER.

Design of Binary Network Codes for Multiuser Multiway Relay Networks

We study multiuser multiway relay networks where N user nodes exchange their information through a single-relay node. We use network coding (NC) in the relay to increase the throughput. Due to the limitation of complexity, we only consider the binary multiuser NC (BMNC) in the relay. We study the BMNC matrix [in GF(2)] and propose several design criteria on the BMNC matrix to improve the symbol error probability (SEP) performance. Closed-form expressions of the SEP of the system are provided. Moreover, an upper bound of the SEP is also proposed to provide further insights into system performance. Then, BMNC matrices are designed to minimize error probabilities.

Performance analysis for uplink massive MIMO systems with a large and random number of UEs

In this paper, we analyze the ergodic achievable rate of an uplink massive multi-user multipleinput multiple-output (MIMO) system with a large and Poisson distributed number of users. In the considered scenario, multiple user equipments (UEs) transmit their information to a base station equipped with a very large number of antennas. New asymptotic expressions for the ergodic achievable rate for large and deterministic number of users are derived for both maximum ratio combining (MRC) detector and zero-forcing (ZF) detector, as well as the ergodic achievable rate for large and random number of users. Simulation results assess the accuracy of these analytical expressions. It is shown that compared with the MRC detector, ZF detector can achieve much higher spectrum efficiency. Also, the results provide a meaningful fact that with different settings the randomness of the number of users will result in different extents of impact on the performance of massive MIMO.创新点在本文中,我们分析了服务大数目随机用户的上行大规模天线系统的遍历可达速率。在该场景中,多个用户发送信息至一个装备大量天线的基站。对于固定数目和随机数目的用户,我们分别给出了采用最大比合并接收机和迫零接收机时的遍历可达速率。仿真结果说明了我们理论推导的准确性。与最大比合并接收机相比,迫零接收机能给系统带来更高的频谱效率。此外,随机用户数目的不同设置也会给大规模天线系统的性能带来不同的影响。

Performance of Superposition Coding for Downlink Coordinated Two-Point System

In this correspondence, we consider a downlink coordinated two-point (DCTP) system, where two users communicate with two base stations. A superposition-coding (SC)-based transmission scheme is proposed to improve its error performance. A joint interference-cancellation and maximum-ratio-combining (IC-MRC) detection algorithm is proposed for the SC scheme, which reduces the error probability of the system compared with the classic SC (CSC) detector. Closed-form expressions of the bit error probability (BEP) of the proposed scheme are derived. Under the same power and time constraint, a signal-to-noise ratio (SNR) gain is obtained when the SC scheme is employed. Tight upper bounds of the BEP are derived to provide insight. Optimal power allocation is also derived to optimize the system performance in terms of the BEP.

On the Performance of Joint Relay Selection and Beamforming with Limited Feedback for AF Cooperative Networks

In this paper, we focus on a two-hop amplify-and-forward (AF) cooperative network, in which one source node equipped with multiple antennas communicates with a single-antenna destination, relying on a single-antenna relay. In order to implement beamforming, channel state information (CSI) is feeded back to the source from relay using random vector quantization (RVQ) codebook. Furthermore, one relay with the best CSI is selected in each communication. An upper bound of the outage probability of the whole system is derived and the simulation results show that this bound is very tight.

Multiple-access decode-and-forward relaying with iterative detection and decoding

In this paper, we propose a novel protocol for cooperative diversity based on decode-and-forward (DF) with iterative detection and decoding (IDD) receiver. Closed-form expression of outage probability is derived under quasi-static fading channels. Numerical results show that the proposed scheme achieves higher diversity order than traditional DF scheme without additional transmitter power.