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Coverage and capacity of next generation cellular radio systems: Bandwidth sharing and massive mimo.

机译：下一代蜂窝无线电系统的覆盖范围和容量：带宽共享和大规模的mimo。

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摘要

In the first part of the thesis we investigate bandwidth allocation in next generation cellular systems employing relays similar to LTE advanced systems with type-I relays. We jointly optimize the bandwidth and power usage under constraints on required rate, bandwidth and transmit power. We study scenarios wherein, the relay acts as a forwarder for multiple User Equipments (UEs/users) in both uplink and/or downlink. This includes scenarios when the relay has its own data to send along with forwarding the data of other users. We examine the weighted power minimization problem for relaying with multiple users. We also show specifi c results with N user scenario and also single user case in order to understand how the bandwidth and power are allocated. Numerical evaluations with N users on a three sector LTE-A cell employing Fractional Frequency Reuse (FFR) indicate that power savings of at least 3 dB can be achieved by optimizing over both bandwidth and power. Base stations with a large number of transmit antennas have the potential to serve a large number of users simultaneously at higher rates. They also promise a lower power consumption due to coherent combining at the receiver. However, the receiver processing in the uplink relies on the channel stimates which are known to su ffer from pilot contamination. In the second part of the thesis, we perform an uplink large system analysis of multi-cell multi-antenna system when the receiver employs a matched fi ltering and MMSE fi ltering with a pilot contaminated estimate. We find the asymptotic Signal to Interference plus Noise Ratio (SINR) as the number of antennas and number of users per base station grow large while maintaining a fixed ratio. To do this, we make use of the similarity of the uplink received signal in a multi-antenna system to the representation of the received signal in CDMA systems. The asymptotic SINR expression for both matched fi lter and the MMSE fi lter explicitly captures the e ffect of pilot contamination and that of interference averaging. This also explains the SINR performance of receiver processing schemes at di fferent regimes such as instances when the number of antennas are comparable to number of users as well as when antennas exceed greatly the number of users. Specifi cally, we explore the scenario where the number of users being served are comparable to the number of antennas at the base station. It is seen that MMSE fi lter is capable of suppressing the in-cell interference and that the interference power due to pilot contamination is the same as in a matched fi lter with a pilot contaminated estimate. We find the expression for the amount of interference suppression obtained using an MMSE filter which is an important factor when there are signi ficant number of users in the system as compared to the number of antennas. We validate the asymptotic expression through simulations and compare with an MMSE fi lter with a perfect estimate. Simulation results for achievable rate is close to theory for even a 10-antenna base station with 3 or more users per cell. In a typical set up, in terms of the five percentile SIR, the MMSE fi lter is shown to provide signifi cant gains over matched fi ltering and is within 5 dB of MMSE fi lter with perfect channel estimate. We also show that the achievable rates are within a 1 bit/symbol of the MMSE with perfect estimate when the number of users is comparable to the number of antennas.
机译：在本文的第一部分中，我们研究了下一代蜂窝系统中的带宽分配，这些系统采用的中继类似于具有I型中继的LTE高级系统。我们在所需速率，带宽和发射功率的约束下共同优化带宽和功率使用。我们研究的场景中，中继在上行链路和/或下行链路中充当多个用户设备（UE /用户）的转发器。这包括中继具有自己的数据要发送以及转发其他用户的数据时的方案。我们研究了用于与多个用户进行中继的加权功率最小化问题。我们还显示了N个用户场景以及单个用户案例的特定结果，以了解如何分配带宽和功率。在采用小数频率复用（FFR）的三扇区LTE-A小区中，对N个用户进行的数字评估表明，通过在带宽和功率上进行优化，可以节省至少3 dB的功率。具有大量发射天线的基站具有以更高的速率同时服务大量用户的潜力。由于在接收机处的相干组合，它们还保证了较低的功耗。然而，上行链路中的接收机处理依赖于已知受到导频污染的信道激励。在论文的第二部分中，当接收器采用匹配滤波和MMSE滤波且导频被污染的估计值时，我们对多小区多天线系统进行上行大型系统分析。随着天线数量和每个基站用户数量的增加，同时保持固定比率，我们发现渐近信号干扰加噪声比（SINR）。为此，我们利用多天线系统中上行链路接收信号与CDMA系统中接收信号表示的相似性。匹配滤波器和MMSE滤波器的渐近SINR表达明确捕获了导频污染和干扰平均的影响。这也解释了在不同情况下接收机处理方案的SINR性能，例如天线数量与用户数量相当以及天线大大超过用户数量时的情况。具体来说，我们探讨了被服务的用户数量与基站天线数量相当的情况。可以看出，MMSE滤波器能够抑制小区内干扰，并且由于导频污染而引起的干扰功率与具有导频污染估计的匹配滤波器相同。我们找到了使用MMSE滤波器获得的干扰抑制量的表达式，这是与天线数量相比在系统中有大量用户时的重要因素。我们通过仿真验证渐近表达式，并与具有理想估计值的MMSE滤波器进行比较。即使每个单元有3个或更多用户的10天线基站，可实现速率的仿真结果也接近理论。在一个典型的设置中，就5个百分点的SIR而言，MMSE滤波器显示出比匹配滤波器更大的增益，并且在MMSE滤波器的5 dB以内，具有完美的信道估计。我们还表明，当用户数量与天线数量相当时，可实现的速率在MMSE的1位/符号以内，并且具有完美的估计。

著录项

  • 作者

    Krishnan, Narayanan.;

  • 作者单位

    Rutgers The State University of New Jersey - New Brunswick.;

  • 授予单位 Rutgers The State University of New Jersey - New Brunswick.;
  • 学科 Engineering Electronics and Electrical.;Engineering Computer.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 87 p.
  • 总页数 87
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:41:11

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