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Dynamic Spectrum Sharing in Cognitive Radio and Device-to-Device Systems

机译:认知无线电和设备到设备系统中的动态频谱共享

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摘要

Cognitive radio (CR) and device-to-device (D2D) systems are two promising dynamic spectrum access schemes in wireless communication systems to provide improved quality-of-service, and efficient spectrum utilization. This dissertation shows that both CR and D2D systems benefit from properly designed cooperation scheme.;In underlay CR systems, where secondary users (SUs) transmit simultaneously with primary users (PUs), reliable communication is by all means guaranteed for PUs, which likely deteriorates SUs' performance. To overcome this issue, cooperation exclusively among SUs is achieved through multi-user diversity (MUD), where each SU is subject to an instantaneous interference constraint at the primary receiver. Therefore, the active number of SUs satisfying this constraint is random. Under different user distributions with the same mean number of SUs, the stochastic ordering of SU performance metrics including bit error rate (BER), outage probability, and ergodic capacity are made possible even without observing closed form expressions. Furthermore, a cooperation is assumed between primary and secondary networks, where those SUs exceeding the interference constraint facilitate PU's transmission by relaying its signal. A fundamental performance trade-off between primary and secondary networks is observed, and it is illustrated that the proposed scheme outperforms non-cooperative underlay CR systems in the sense of system overall BER and sum achievable rate.;Similar to conventional cellular networks, CR systems suffer from an overloaded receiver having to manage signals from a large number of users. To address this issue, D2D communications has been proposed, where direct transmission links are established between users in close proximity to offload the system traffic. Several new cooperative spectrum access policies are proposed allowing coexistence of multiple D2D pairs in order to improve the spectral efficiency. Despite the additional interference, it is shown that both the cellular user's (CU) and the individual D2D user's achievable rates can be improved simultaneously when the number of D2D pairs is below a certain threshold, resulting in a significant multiplexing gain in the sense of D2D sum rate. This threshold is quantified for different policies using second order approximations for the average achievable rates for both the CU and the individual D2D user.
机译:认知无线电(CR)和设备到设备(D2D)系统是无线通信系统中两个有希望的动态频谱访问方案,可提供改进的服务质量和有效的频谱利用率。论文表明,CR和D2D系统都受益于设计合理的协作方案。在底层CR系统中,次要用户(SU)与主要用户(PU)同时传输,则保证了可靠的通信,可能会恶化PU。 SU的性能。为了克服此问题,通过多用户分集(MUD)实现了SU之间的排他性协作,其中每个SU在主接收器处都受到瞬时干扰约束。因此,满足该约束的SU的有效数量是随机的。在具有相同平均数量的SU的不同用户分布下,即使不遵守闭式表达式,也可以实现SU性能指标的随机排序,包括误码率(BER),中断概率和遍历容量。此外,假定在主要和次要网络之间进行协作,其中那些超过干扰限制的SU通过中继中继器的信号来促进PU的传输。观察到主要网络和次要网络之间的基本性能折衷,并且从系统总体BER和可达到的总速率的意义上说,所提出的方案优于非合作式底层CR系统。接收器过载,必须管理来自大量用户的信号。为了解决这个问题,已经提出了D2D通信,其中在紧邻的用户之间建立直接传输链路以减轻系统业务量。提出了几种允许多个D2D对共存的新合作频谱访问策略,以提高频谱效率。尽管存在额外的干扰,但事实表明,当D2D对的数量低于某个阈值时,可以同时提高蜂窝用户(CU)和单个D2D用户的可实现速率,从而在D2D意义上带来显着的复用增益总费率。使用针对CU和单个D2D用户的平均可达到速率的二阶近似,针对不同策略对此阈值进行量化。

著录项

  • 作者

    Zeng, Ruochen.;

  • 作者单位

    Arizona State University.;

  • 授予单位 Arizona State University.;
  • 学科 Electrical engineering.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 132 p.
  • 总页数 132
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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