To support high speed transmission and traffic offloading from cellular networks, LTE-unlicensed (LTE-U) standard was proposed by 3GPP to enable cellular data transmission in unlicensed band. The primary challenge of LTE-U is to successfully coexist with the incumbent systems (e.g., WiFi networks) in the unlicensed bands, while still maintaining the quality-of-service (QoS) for LTE-A users. This paper proposes a new framework for implementing LTE-U standard based on deployed LTE-A infrastructure and cognitive radio (CR) technology to sense radio environment and construct a spectrum map, based on which the LTE-U system can perform joint power and channel allocation to maximize the overall system throughput. We introduce a spectrum map construction scheme and evaluate the Cramer-Rao bound of the scheme. It is shown that the original NP-hard joint power and channel allocation problem can be transformed into a linear programming problem for its solution. Simulation results verify that the proposed LTE-U scheme helps improve system throughput via access collision avoidance.

中文翻译：

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支持认知无线电的 LTE-U 系统中基于位置的联合频谱感知和无线电资源分配

为了支持蜂窝网络的高速传输和流量分流，3GPP 提出了 LTE-非授权 (LTE-U) 标准，以实现非授权频段的蜂窝数据传输。LTE-U 的主要挑战是在未授权频段中与现有系统（例如 WiFi 网络）成功共存，同时仍保持 LTE-A 用户的服务质量 (QoS)。本文基于已部署的 LTE-A 基础设施和认知无线电 (CR) 技术，提出了一种实现 LTE-U 标准的新框架，以感知无线电环境并构建频谱图，基于该框架，LTE-U 系统可以执行联合功率和信道分配以最大化整个系统的吞吐量。我们引入了频谱图构建方案并评估了该方案的 Cramer-Rao 界。结果表明，原始的NP-hard联合功率和信道分配问题可以转化为线性规划问题来求解。仿真结果验证了所提出的 LTE-U 方案有助于通过避免接入冲突来提高系统吞吐量。