Abstract
It is necessary to improve the energy efficiency of batteries in wireless sensor networks (WSNs). The multiple-input multiple-output (MIMO) technique has become an important means to ameliorate WSNs, and interference management is the core of improving energy efficiency. A promising approach is interference alignment (IA), which effectively reduces the interference and improves the throughput of a system in the MIMO interference channels. However, the IA scheme requires perfect channel state information (CSI) at all transceivers in practice, which results in considerable feedback overhead. Thus, limited IA feedback has attracted much attention. In this paper, we analyze the throughput loss of the K-user MIMO interference channels when each transmitter delivers multiple streams in one slot, and derives the upper-bound of the system interference leakage and throughput loss. Then, to reduce the interference leakage and throughput loss for the MIMO interference alignment with limited feedback, a joint power and feedback bit allocation optimization scheme is proposed. The simulation results show that, compared with the conventional schemes, the presented optimal scheme achieves less residual interference and better performance in the system throughput.
Highlights
Composed of inexpensive and low-power-consumption sensors that have the ability to compute and communicate, wireless sensor networks (WSNs) have various applications in military defense, environmental testing, space exploration, home intelligence, traffic surveillance, and other fields [1].it is hard to supply energy for battery-powered sensors in bad environments
As shown in the previous section, Interference alignment (IA) can effectively mitigate the interference over the multiple-input multiple-output (MIMO) interference channel and improve the performance, the performance can be significantly degraded by the residual interference due to the limited feedback
When the transmitted power was larger than 35 dBm, it was expected that the sum rate of the three limited feedback schemes would be much lower than a perfect channel state information (CSI) feedback scheme, because the performance of the IA system was significantly degraded by the interference leakage
Summary
Composed of inexpensive and low-power-consumption sensors that have the ability to compute and communicate, wireless sensor networks (WSNs) have various applications in military defense, environmental testing, space exploration, home intelligence, traffic surveillance, and other fields [1]. The subspace IA scheme with limited feedback is optimized by minimizing the chordal distance of real CSI and Grassmannian quantization codeword in [24], and the outage capacity is analyzed for the MIMO interference channels employing IA with limited feedback in [25]. The feedback allocation scheme is extended to a case with multiple data streams [31], considering heterogeneous path loss and spatial correlations, and a dynamic quantization scheme via bit allocations is proposed Another consideration is that power allocation plays an important role in improving the energy efficiency and throughput in interference networks [32,33]. This paper formulates the transmitted power and feedback bit allocation problem in the K-user MIMO interference channels, and a joint power and feedback-bit allocation scheme (JPFAS) is proposed to reduce the residual interference and improve the throughput of the IA interference network. E[·] denotes expectation, |·| denotes the absolute value, ||·|| and ||·|| F denote the L2-norm, and Frobenius norm respectively. vec(A) denotes matrix vectorization
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