Modeling and Analysis of Energy Efficiency and Interference for Cellular Relay Deployment

Abstract

By relying on a wireless backhaul link, relay stations enhance the performance of cellular networks at low infrastructure cost, but at the same time, they can aggravate the interference issue. In this paper, we analyze for several relay coding schemes the maximum energy gain provided by a relay, taking into account the additional relay-generated interference to neighboring cells. First, we define spatial areas for relaying efficiency in log-normal shadowing environments and propose three easily-computable and tractable models. These models allow the prediction of 1) the probability of energy-efficient relaying, 2) the spatial distribution of energy consumption within a cell and 3) the average interference generated by relays. Second, we define a new performance metric that jointly captures both aspects of energy and interference, and characterize the optimal number and location of relays. These results are obtainable with significantly lower complexity and execution time when applying the proposed models as compared to system simulations. We highlight that energy-efficient relay deployment does not necessarily lead to interference reduction and conversely, an interference-aware deployment is suboptimal in the energy consumption. We then propose a map showing the optimal utilization of relay coding schemes across a cell. This map combines two-hop relaying and energy-optimized partial decode-forward as a function of their respective circuitry consumption. Such a combination not only alleviates the interference issue, but also leads to a reduction in the number of relays required for the same performance.

Energy‐efficient relay deployment in cellular systems using fractional frequency reuse and transmit antenna selection techniques

“…The EE of the entire system can vary significantly due to changes of the overall transmission power and radio channel condition in the network according to the relay deployment, as described in previous studies. [23][24][25][26][27][28] Furthermore, the relocation of installed RSs may be an expensive work. Therefore, to achieve a high EE while operating the RACN, network operators need to determine the initial relay deployment through an elaborate cell planning with taking account of following two factors.…”

“…Then, if there is no the coordination for the co-channel interference (CCI), then the EE can be severely degraded. However, most of studies on relay deployment [23][24][25] did not take the ICI into account, and some studies under consideration of the ICI 26,27 did not take account of the interference coordination in depth. According to Oh et al 28 and Jeon and Jeong, 29 the severe CCI in the RACN can be efficiently reduced through FFR-based resource management, since different frequency resources are used in adjacent areas and the same resources are reused among remote areas.…”

“…In Saleh et al 26 and Parzysz et al, 27 the end-to-end user performance was investigated according to the number and location of RSs with a simple single-interferer model. In Saleh et al 26 and Parzysz et al, 27 the end-to-end user performance was investigated according to the number and location of RSs with a simple single-interferer model.…”

“…On the other hand, there are some previous researches taking account of the ICI factor. In Saleh et al 26 and Parzysz et al, 27 the end-to-end user performance was investigated according to the number and location of RSs with a simple single-interferer model. Since there is merely an interference source in Saleh et al, 26 performance results might be an upper bound performance in the general multicell case.…”

“…According to studies, [18][19][20][21][22] it is possible to efficiently improve the EE in the RACN by utilizing the MIMO-based techniques. [23][24][25][26][27][28] Furthermore, the relocation of installed RSs may be an expensive work. The EE of the entire system can vary significantly due to changes of the overall transmission power and radio channel condition in the network according to the relay deployment, as described in previous studies.…”