Collaborative Wireless Energy and Information Transfer in Interference Channel
Collaborative Wireless Energy and Information Transfer in Interference Channel
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DOI：
10.1109/twc.2014.2354335
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发表时间：
2014-02
影响因子：
10.4
通讯作者：
Seunghyun Lee;Liang Liu;Rui Zhang
中科院分区：
文献类型：
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作者：
Seunghyun Lee;Liang Liu;Rui Zhang
本文研究了多用户无线系统中的同时无线信息和功率传输(SWIPT)问题，在该系统中，分布式发射机向各自的接收机发送独立的消息，同时通过能量波束成形将无线功率协同地发送到接收机。因此，从无线信息传输(WIT)的角度来看，感兴趣的系统可以被建模为经典的干扰信道，同时它也可以被视为用于协作无线能量传输(WET)的分布式多输入多输出(MIMO)系统。为了在SWIPT中同时实现信息解码(ID)和能量采集(EH)，我们在每个接收端采用低复杂度的时间切换操作来在预定时间内在ID和EH模式之间进行切换。对于混合系统，我们的目标是通过不同的发射端协作方案来表征可实现的速率-能量(R-E)权衡。具体地说，为了便于协作能量波束形成，我们在发射端提出了一种新的信号拆分方案，每个发送信号通常被拆分成信息信号和能量信号，分别用于WIT和WEAT。首先，我们研究了衰落信道下的双用户SWIPT系统，推导了接收端的最优模式切换规则以及相应的发送信号优化，以实现各种R-E折衷。我们还比较了我们提出的方案在发射能量波束形成和信号分离的情况下的R-E性能，以及两种现有的发射机部分合作或不合作的方案。其次，研究了多用户SWIPT系统的一般情况，通过推广两用户情况的结果，提出了一种实用的传输协作方案：将用户分组为不同的用户对，并将两用户情况下得到的协作方案应用到每个配对的组中。此外，在干扰对齐原则的启发下，我们提出了一种基于所有发射机联合协作的基准方案，并与该方案的性能进行了比较。
This paper studies the simultaneous wireless information and power transfer (SWIPT) in a multiuser wireless system, in which distributed transmitters send independent messages to their respective receivers, and at the same time cooperatively transmit wireless power to the receivers via energy beamforming. Accordingly, from the wireless information transmission (WIT) perspective, the system of interest can be modeled as the classic interference channel, while it also can be regarded as a distributed multiple-input multiple-output (MIMO) system for collaborative wireless energy transmission (WET). To enable both information decoding (ID) and energy harvesting (EH) in SWIPT, we adopt the low-complexity time switching operation at each receiver to switch between the ID and EH modes over scheduled time. For the hybrid system, we aim to characterize the achievable rate-energy (R-E) trade-offs by various transmitter-side collaboration schemes. Specifically, to facilitate the collaborative energy beamforming, we propose a new signal splitting scheme at the transmitters, where each transmit signal is generally split into an information signal and an energy signal for WIT and WET, respectively. With this new scheme, first, we study the two-user SWIPT system over the fading channel and derive the optimal mode switching rule at the receivers as well as the corresponding transmit signal optimization to achieve various R-E trade-offs. We also compare the R-E performance of our proposed scheme with transmit energy beamforming and signal splitting against two existing schemes with partial or no cooperation of the transmitters. Next, the general case of SWIPT systems with more than two users is studied, for which we propose a practical transmit collaboration scheme by extending the result for the two-user case: we group users into different pairs and apply the cooperation schemes obtained in the two-user case to each paired group. Furthermore, we present a benchmarking scheme based on joint cooperation of all the transmitters inspired by the principle of interference alignment, against which the performance of the proposed scheme is compared.