Radio resource management schemes in relay-based cellular networks

Choi, Bumgon Sungkyunkwan University 2013 국내박사

Introduction of relay node (RN) into cellular networks is considered a cost-effective solution to increase system capacity and to achieve ubiquitous high data rate service coverage. RN can improve throughput of user equipment (UE) located in hotspot and cell-edge regions, by relaying user data from evolved nodeB (eNB) to UEs and vice versa. In addition, RN can reduce deployment cost of cellular equipments and wired backhaul, because it has less functionality than eNB and forms wireless backhaul between donor eNB and RN. In relay-based cellular networks, radio resource management schemes, such as subband assignment and resource allocation, are important factors to determine the performance. Therefore, radio resource management schemes which can efficiently utilize RN's inherent advantages should be developed to improve the performance of relay-based cellular networks. There are three types of radio resource management schemes in relay-based cellular networks, i.e. centralized, distributed, and semi-distributed. The centralized schemes require high signaling overhead and computational complexity to obtain and manage all information on all nodes, but provide benchmark performance to evaluate the capability of distributed and semi-distributed schemes. The distributed and semi-distributed schemes are attractive solutions to practically adopt RNs in the relay-based cellular network due to their low signaling overhead and complexity. In this dissertation, we propose centralized, distributed, and semi-distributed radio resource management schemes for relay-based cellular networks. The centralized scheme considers the qualities of backhaul and direct links for efficiently selecting UE's serving node and allocates subchannels to RNs concerning available resources of RNs using optimal or heuristic resource allocation algorithm. In the distributed scheme, eNB allocates subchannels to UEs and RNs considering buffer status of RNs and different channel status of the UEs attached to eNB in relay and access zones when eNB and RN reuse the frequency band in access zone. The semi-distributed scheme improves the signal-to-interference-plus-noise ratios (SINRs) of macro UEs (MUEs) by preventing adjacent RNs from using the subchannels designated by eNB and allocates subchannels through optimal or heuristic resource allocation algorithm. Simulation results show that the centralized scheme significantly enhances the system throughput of the relay-based cellular network as well as user throughput in cell-edge region. In addition, the proposed distributed and semi-distributed schemes can considerably improve user throughput regardless of UE's location with limited information on relay UEs (RUEs). 이동통신 네트워크에서의 릴레이 도입은 적은 비용으로 이동통신 시스템의 용량을 증대시키고 이동통신 서비스 영역을 확장시킬 수 있는 방법으로 많은 관심을 받고 있다. 릴레이는 사용자 밀집 지역과 셀 외각 지역에 설치되어 기지국으로부터 전송된 데이터를 중계함으로써 이동통신 사용자의 서비스 품질을 향상시킬 수 있다. 또한 릴레이는 기지국에 비해 설치가 용이하고 기지국과의 백홀(backhaul) 링크를 무선으로 형성하기 때문에 기지국 증설 비용과 백홀 통신망의 유지비용을 줄일 수 있다. 릴레이 기반 이동통신 네트워크에서는 릴레이 선택, 자원 할당과 같은 무선자원 관리 기법이 네트워크 성능에 큰 영향을 미친다. 따라서 릴레이 기반 이동통신 네트워크의 성능을 향상시키기 위해서는 릴레이가 가지는 장점을 효과적으로 활용할 수 있는 효율적인 무선자원 관리기법의 개발이 필수적이다. 릴레이 기반 이동통신 네트워크의 무선자원 관리방안으로는 중앙 집중형(centralized) 자원관리 기법과 분산형(distributed) 자원관리 기법, 그리고 준분산형(semi-distributed) 자원관리 기법이 있다. 릴레이 기반 이동통신 네트워크에 중앙 집중형 자원관리 방식을 적용하기 위해서는 많은 양의 제어신호 전송과 자원할당을 위한 높은 계산량이 필요하지만 중앙 집중형 자원관리 방식의 연구는 분산형 자원관리 기법의 성능을 평가하기 위한 기준(benchmark) 성능을 제공할 수 있다는 점에서 의의가 있다. 반면, 분산형 자원관리 기법과 준분산형 자원관리 기법은 제어신호 전송과 계산량에 대한 부담이 적기 때문에 실제 이동통신 시스템에 적용 가능한 기술로 각광을 받고 있다. 본 논문에서는 기지국과 릴레이가 액세스 존(access zone)의 주파수 대역을 재사용하는 릴레이 기반 이동통신 네트워크의 성능을 향상시키기 위한 중앙 집중형, 분산형, 준분산형 무선자원 관리기법의 세 가지 무선자원 관리기법을 제안한다. 제안하는 중앙 집중형 자원관리 기법에서 기지국은 사용자가 접속할 릴레이 선택을 위해 백홀 링크와 액세스 링크의 채널상태를 고려하고, 최적(optimal) 또는 휴리스틱(heuristic) 자원할당 기법을 이용하여 릴레이에게 무선자원을 할당한다. 분산형 자원관리 기법에서 기지국은 기지국에 접속한 사용자가 릴레이 존(relay zone)과 액세스 존에서 다르게 경험하는 채널상태를 고려하여 사용자 또는 릴레이에게 무선자원을 할당한다. 준분산형 자원관리 기법은 릴레이가 특정 무선자원을 사용하지 못하도록 제안함으로써 기지국에 접속한 사용자의 신호 대 간섭 잡음비(Signal-to-Noise-plus-Interference Ratio, SINR)를 높인다. 또한 최적 또는 휴리스틱 자원할당 기법을 이용하여 사용자가 높은 SINR을 가지는 무선자원을 할당받을 수 있도록 한다. 모의실험 결과 제안하는 중앙 집중형 자원관리 기법이 셀 외각에 위한 사용자의 수율뿐만 아니라 시스템 전체의 용량을 크게 향상시킴을 확인하였으며, 분산형 및 준분산형 자원관리 기법은 적은 제어신호 전송과 계산량으로도 셀 외각 사용자의 수율과 사용자간 공평성(fairness)을 향상시킬 수 있음을 확인하였다.

Relay-based cooperative transmission systems for high data throughput

권재우 Graduate School, Korea University 2012 국내박사

With the demand of high data rate and link reliability to support multimedia services in wireless communication, there has been growing interest in the cooperative transmission systems. This dissertation studies the cooperative transmission systems that rely on the help of additional relays to improve the system capacity and reliability in wireless communication. First, we propose the efficient and adaptive relaying scheme based on adaptive modulation to prevent a loss in spectral efficiency by half-duplex transmission and provide its performance analysis in terms of average spectral efficiency. We focus on the statistical analysis on the combined signal-to-noise ratio with amplify-and-forward relaying and obtain the closed-form solutions for some practical scenarios. Moreover, we extend the proposed relaying scheme to the multiple-relay system. Next, we propose the cooperative joint precoding schemes in the downlink of the cellular system with a shared relay to maximize the system capacity while minimizing the interferences at both the relay station and the mobile stations. We formulate the optimization problems to maximize the system capacity and design the optimal multiuser precoding vectors, assuming the decode-and-forward relaying protocol in a half-duplex operation. We quantify the ergodic rate performance of the proposed precoding schemes and derive the closed-form solutions. Lastly, we propose the alternate relay transmission schemes to eliminate the inter-cell interference for the relay enhanced cellular system. We present the design of the precoding method for the proposed transmission scheme and analyze its performance in terms of the ergodic rate.

Design and performance analysis of relay-enhanced cellular system for mobile broadband services

류현석 Graduate School, Korea University 2011 국내박사

The very high system throughput and spectral efficiency are required to support the emerging multimedia applications and services in the future wireless systems. These requirements have traditionally been met by increasing the bandwidth of the radio frequency (RF) sub-carriers, better modulation techniques, but above all by spectrum reuse, which has been achieved by dividing the coverage area into smaller cells. Meanwhile, the spectrum that will be released for future systems will almost certainly be located well above the 2 GHz band used by the third-generation (3G) or fourth-generation (4G) systems. The radio propagation in these bands is significantly more vulnerable to non-line-of sight conditions, e.g., shadowing and multi-path fading. The brute force solution to these problems is to significantly increase the density of base stations (BSs), i.e., shrinking cell sizes. However, it requires larger numbers of BSs per unit area, which results in considerably higher deployment costs and makes the operators wonder about scalability of the conventional cellular systems. Toward this end, in addition to advanced transmission techniques and collocated antenna technologies, some major modifications in the wireless network architecture itself are required. As evident from the current and upcoming standards, the most promising architectural upgrade will be the integration of multi-hop relaying capability into conventional cellular systems due to its potential gains in throughput enhancement and coverage extension. However, multi-hop relaying has many challenges as well as opportunities in mobile broadband services. The objective of this work is to characterize these challenges and opportunities, and to analyze the performance limitation in multi-hop relaying, and then to provide promising solutions for maximizing its potential gains. In this thesis, we first investigate generalized relay selection criteria for opportunistic relaying. It improves the system outage performance over a more general interference-limited environment, in which both the relay station and mobile station suffer from the different number of interferers. Next, we propose a spectrally-efficient communication technique for bi-directional relaying over an asymmetric wireless channel, in which a packet size to be transmitted through downlink and uplink as well as the link qualities between bi-directional links are asymmetric. Moreover, we propose a selection strategy in cooperation to maximize the system throughput, while maintaining the target outage performance. Our criterion allows for employing different cooperative relaying schemes, depending on the position of the mobile stations throughout the cell coverage. Finally, we provide a mutually cooperative relaying (MCR) scheme, which can provide not only full diversity but also substantial coding gain as long as two active users are simultaneously communicating with the same destination node. According to our through analyses, our proposed schemes will turn out to be useful means for reducing the system outage, enhancing the average spectral efficiency, maximizing the average system throughput, and extending the system coverage of multi-hop relaying systems, respectively.

Relay-assisted D2D communication Underlying Cellular network

류진숙 연세대학교 대학원 2014 국내석사

In recent years, a rapid growth of mobile data traffic has been a major obstacle to provide high quality of data services to mobile operators. Also, the trend of service characteristics has been changed along with the growth of mobile data traffic. Tremendous increase of multime-dia services and social networking services has addressed the change of contents transmission aspect from long range to short one. Thus the Device-to-Device (D2D) communication has been strongly considered as a next cellular communication technology. D2D communication realizes direct communication between a source device and a destination device without rout-ing user data traffic through the cellular network such as LTE/LTE-A network. Further it has already been shown the performance gain of the D2D communication in terms of spectral effi-ciency to reuse the resource allocated to cellular user [6]. Research on a relay-assisted direct communication together with D2D communication is also currently underway. In this case, a relay helps the direct communication while the D2D communication is not sustainable or the relay-assisted direct communication provides better performance. In this scenario, the relay is a mobile device such as cell phones or other devices including Human-to-Human communica-tion as well as Machine-to-Machine device.However, the decision method when and how to switch to relay-assisted direct communica-tion and the procedure how to select a proper relay depending on a given condition is not suf-ficiently studied. Therefore this paper studies two major problems in order to realize a proper relay-assisted direct communication. Eventually it is expected to enhance the robustness of the D2D communication.First, the aspects of the relay-assisted direct communication have been analyzed and com-pared with direct communication aspects. The evaluation results show that the relay-assisted direct communication provides better spectral utilization in certain cases. In these cases, a base station may determine data path setup with a relay-assisted direct communication or switch an ongoing direct communication path to relay-assisted direct communication. There-fore secondly, we propose relay-assisted direct communication setup procedures in regard to practical LTE/SAE system. Especially, UE’s mobility behavior and bearer QCI (QoS Class Identifier) have been analyzed. Then we propose two basic elements ‘UE operating mode’ and ‘Relay applicability’ for the usage of the relay-assisted direct communication setup procedure. It is assumed that the proposed relay-assisted direct communication setup procedures provide more robust service connectivity for D2D communication underlying cellular network.

Radio Resource Management Schemes in Relay-Based Cellular Networks

최범곤 성균관대학교 일반대학원 2013 국내박사

Introduction of relay node (RN) into cellular networks is considered a cost-effective solution to increase system capacity and to achieve ubiquitous high data rate service coverage. RN can improve throughput of user equipment (UE) located in hotspot and cell-edge regions, by relaying user data from evolved nodeB (eNB) to UEs and vice versa. In addition, RN can reduce deployment cost of cellular equipments and wired backhaul, because it has less functionality than eNB and forms wireless backhaul between donor eNB and RN. In relay-based cellular networks, radio resource management schemes, such as subband assignment and resource allocation, are important factors to determine the performance. Therefore, radio resource management schemes which can efficiently utilize RN's inherent advantages should be developed to improve the performance of relay-based cellular networks. There are three types of radio resource management schemes in relay-based cellular networks, i.e. centralized, distributed, and semi-distributed. The centralized schemes require high signaling overhead and computational complexity to obtain and manage all information on all nodes, but provide benchmark performance to evaluate the capability of distributed and semi-distributed schemes. The distributed and semi-distributed schemes are attractive solutions to practically adopt RNs in the relay-based cellular network due to their low signaling overhead and complexity. In this dissertation, we propose centralized, distributed, and semi-distributed radio resource management schemes for relay-based cellular networks. The centralized scheme considers the qualities of backhaul and direct links for efficiently selecting UE's serving node and allocates subchannels to RNs concerning available resources of RNs using optimal or heuristic resource allocation algorithm. In the distributed scheme, eNB allocates subchannels to UEs and RNs considering buffer status of RNs and different channel status of the UEs attached to eNB in relay and access zones when eNB and RN reuse the frequency band in access zone. The semi-distributed scheme improves the signal-to-interference-plus-noise ratios (SINRs) of macro UEs (MUEs) by preventing adjacent RNs from using the subchannels designated by eNB and allocates subchannels through optimal or heuristic resource allocation algorithm. Simulation results show that the centralized scheme significantly enhances the system throughput of the relay-based cellular network as well as user throughput in cell-edge region. In addition, the proposed distributed and semi-distributed schemes can considerably improve user throughput regardless of UE's location with limited information on relay UEs (RUEs). 이동통신 네트워크에서의 릴레이 도입은 적은 비용으로 이동통신 시스템의 용량을 증대시키고 이동통신 서비스 영역을 확장시킬 수 있는 방법으로 많은 관심을 받고 있다. 릴레이는 사용자 밀집 지역과 셀 외각 지역에 설치되어 기지국으로부터 전송된 데이터를 중계함으로써 이동통신 사용자의 서비스 품질을 향상시킬 수 있다. 또한 릴레이는 기지국에 비해 설치가 용이하고 기지국과의 백홀(backhaul) 링크를 무선으로 형성하기 때문에 기지국 증설 비용과 백홀 통신망의 유지비용을 줄일 수 있다. 릴레이 기반 이동통신 네트워크에서는 릴레이 선택, 자원 할당과 같은 무선자원 관리 기법이 네트워크 성능에 큰 영향을 미친다. 따라서 릴레이 기반 이동통신 네트워크의 성능을 향상시키기 위해서는 릴레이가 가지는 장점을 효과적으로 활용할 수 있는 효율적인 무선자원 관리기법의 개발이 필수적이다. 릴레이 기반 이동통신 네트워크의 무선자원 관리방안으로는 중앙 집중형(centralized) 자원관리 기법과 분산형(distributed) 자원관리 기법, 그리고 준분산형(semi-distributed) 자원관리 기법이 있다. 릴레이 기반 이동통신 네트워크에 중앙 집중형 자원관리 방식을 적용하기 위해서는 많은 양의 제어신호 전송과 자원할당을 위한 높은 계산량이 필요하지만 중앙 집중형 자원관리 방식의 연구는 분산형 자원관리 기법의 성능을 평가하기 위한 기준(benchmark) 성능을 제공할 수 있다는 점에서 의의가 있다. 반면, 분산형 자원관리 기법과 준분산형 자원관리 기법은 제어신호 전송과 계산량에 대한 부담이 적기 때문에 실제 이동통신 시스템에 적용 가능한 기술로 각광을 받고 있다. 본 논문에서는 기지국과 릴레이가 액세스 존(access zone)의 주파수 대역을 재사용하는 릴레이 기반 이동통신 네트워크의 성능을 향상시키기 위한 중앙 집중형, 분산형, 준분산형 무선자원 관리기법의 세 가지 무선자원 관리기법을 제안한다. 제안하는 중앙 집중형 자원관리 기법에서 기지국은 사용자가 접속할 릴레이 선택을 위해 백홀 링크와 액세스 링크의 채널상태를 고려하고, 최적(optimal) 또는 휴리스틱(heuristic) 자원할당 기법을 이용하여 릴레이에게 무선자원을 할당한다. 분산형 자원관리 기법에서 기지국은 기지국에 접속한 사용자가 릴레이 존(relay zone)과 액세스 존에서 다르게 경험하는 채널상태를 고려하여 사용자 또는 릴레이에게 무선자원을 할당한다. 준분산형 자원관리 기법은 릴레이가 특정 무선자원을 사용하지 못하도록 제안함으로써 기지국에 접속한 사용자의 신호 대 간섭 잡음비(Signal-to-Noise-plus-Interference Ratio, SINR)를 높인다. 또한 최적 또는 휴리스틱 자원할당 기법을 이용하여 사용자가 높은 SINR을 가지는 무선자원을 할당받을 수 있도록 한다. 모의실험 결과 제안하는 중앙 집중형 자원관리 기법이 셀 외각에 위한 사용자의 수율뿐만 아니라 시스템 전체의 용량을 크게 향상시킴을 확인하였으며, 분산형 및 준분산형 자원관리 기법은 적은 제어신호 전송과 계산량으로도 셀 외각 사용자의 수율과 사용자간 공평성(fairness)을 향상시킬 수 있음을 확인하였다.

안테나 선택을 고려한 오퍼튜니스틱 릴레잉 기법의 성능

후세인아야즈 한양대학교 2010 국내석사

Ever increasing demand for higher data rates in wireless systems has imposed serious challenges on system design and link budget planning. In many scenarios, the desired ubiquitous high rate coverage cannot be achieved by the direct transmission. Dual-hop relaying has emerged as an intuitive approach to this challenge. The opportunistic relaying scheme with antenna selection can eliminate the insufficient use of the channel resources and is a low-cost low-complexity alternative to capture many of the advantages of MIMO systems. In such a scheme, the “best” relay as well as “best” antennas at source and destination can be selected for communication. This thesis analyzes the performance of single relay selection wireless networks using amplify and forward relaying with antenna selection. First, we propose opportunistic relaying without direct path using antenna selection, where we will observe the performance behavior with different number of antennas and relays in identical and non-identical channels. Secondly, the opportunistic relaying with direct link using antenna selection at source only will be proposed, where we will observe the performance behavior with different number of antennas and relays. It will be concluded in this scheme that increasing number of antennas is a better choice than increasing the number of relays.

Multihop relaying in uniformly random networks

이재영 Graduate School, Korea University 2014 국내박사

To account for randomly distributed nodes in a wireless network, this thesis investigates a multihop relaying in uniformly random networks, where all transmitters or interferers are spatially distributed following a Poisson distribution. Before studying multihop relaying, we consider a basic single hop transmission equipped with multiple antennas in Poisson network which is suitable for cellular networks assisted device-to-device (D2D) communications. In addition, to represent the probability density function (PDF) of this system model, we define a new super-Erlang variate, which encompasses the hyper-Erlang distribution used for the phase-type (PH) distribution of heavy-tailed network models. To determine the capacity of uniformly random networks, this thesis considers two metrics such as transmission capacity and random access transport capacity, where all transmitters are located in a homogeneous Poisson point process (PPP). Firstly, we use the transmission capacity defined as the number of successful transmissions taking place in the network per unit area under an outage constraint. For expanding direct transmission to dual-hop relaying, the transmission capacity is derived using the exact outage probability for AF and decode-and-forward (DF) protocols in a Poisson field without neglecting noise at all nodes. From the numerical results, it is noted that the dual-hop relaying is still beneficial in terms of transmission capacity in uniformly random networks. Secondly, we consider the random access transport capacity, proposed as the average maximum rate of successful end-to-end transmission in the distance, for multihop relaying to find the end-to-end throughput of uniformly random networks, where each node relays the signal using an AF strategy. In particular, we analyze the exact outage probability for multihop AF relaying in the presence of both co-channel interference and thermal noise, where interferers are spatially distributed following a Poisson distribution. From our numerical results, it is observed that the maximum random access transport capacity is achieved at a specific spatial density of transmitting nodes due to the throughput-reliability tradeoff as the number of transmitting nodes (=interferers) increases. Thus, we compute the optimal spatial density of transmitting nodes that maximize their random access transport capacity. Meanwhile, in a linear multihop network, an increase in the number of transmission hops degrades the performance of the multihop relaying due to a higher occupation of bandwidth or time and the waste of network resources. Thus, we identify the optimal linear multihop system in uniformly random networks, such as optimal resource allocation, optimal placement of the relay nodes, and optimal number of hops, for multihop DF relaying to minimize their outage probability. Particularly, since interferers that form a PPP in each hop can be located at the same placement across the hops, we consider a spatial correlation in the interference. Our results reveal that the multihop DF relaying with the optimal number of hops can achieve the minimum outage probability using equidistant relay nodes with the same transmission power and time fraction for each hop. In addition, for the practical communication system, this dissertation considers a new relay selection protocol defined as selection the nearest relay from the desired relay nodes located at the same distance in a direct line. Then, we analyze the outage probability based on the Euclidean distance distribution of linear multihop relaying. Compare with the optimal case using equidistant relay nodes in a direct line, we need relatively small transmission hops to achieve the minimum outage probability for the practical environment.

IMPACT OF OUTDATED CSI ON OPPORTUNISTIC RELAYING SCHEME

김석중 연세대학교 대학원 2013 국내박사

Next generation wireless communications demand improved system capacity for high quality multimedia services. To this end, various cooperative systems have attracted much interest as a new way of providing significant capacity and multiplexing gain in wireless networks. In particular, the opportunistic relaying scheme has emerged as a promising technology with a low complexity. In addition, when the adaptive transmission technique is applied to the opportunistic relaying scheme, the performance of the system can be achieved significantly. Enhancing the system capacity in this environment requires to send the knowledge of the channel from the destination to the source. In practical wireless communication systems, however, the channel state information (CSI) employed in the relay selection differs from the actual channel experienced in the data transmission phase due to the time- varying nature of the wireless channel. As a result, the performance of the opportunistic relaying scheme is degraded by inaccurate channel information. In this dissertation, we investigate the impact of outdated channel information on the performance of the opportunistic relaying scheme with and without the adaptive trans- mission technique. To this end, we derived the closed-form expression of the outage probability and average symbol error rate (ASER) for the opportunistic relaying scheme are derived. To provide the design insights and useful observations about outdated CSI, we also analyze the asymptotic analysis for performance of the opportunistic relaying scheme in terms of the diversity order and coding gain. In addition, in conjunction with the adaptive transmission technique, the channel capacity of the opportunistic relaying scheme are derived. In particular, the effect of outdated CSI on the performance of the adaptive transmission technique is investigated. As a result, as long as the CSIs in either the source-relay or relay-destination links are outdated, the diversity order of the opportunistic relaying scheme is reduced to one. The overall performance of the opportunistic relaying scheme is mainly degraded by inaccurate CSI in the relay-destination link. Conversely, CSI accuracy in the sourcerelay link has a negligible effect on the performance of the opportunistic relaying scheme unless the CSI is perfect. In addition, the proactive strategy in the opportunistic relaying scheme outperforms the reactive one in terms of the outage probability, average SER, and channel capacity.

TCP-X.25와 TCP-FRAME RELAY 프로토콜의 성능비교

김정호 서강대학교 공공정책대학원 1992 국내석사

WiMedia 무선개인영역 네트워크에서의 분산매체접근제어를 위한 릴레이 프로토콜

신현미 고려대학교 대학원 2009 국내석사

A relay transmission is a promising technology for improving the throughput (Mbps: total transmitted data considering overhead and delay) and energy efficiency in multi-rate wireless personal area networks (WPANs). In this thesis, we propose a distributed relay MAC (DR-MAC) protocol in WiMedia WPANs. DR-MAC extends a distributed reservation protocol (DRP) in WiMedia MAC and collects a neighbor’s information for relay transmission during the beacon period (BP) using newly defined relay mode information element (RMIE). DR-MAC can minimize control overhead for relay transmission because all devices should send and listen to the beacons during BP. Compatibility to the standard WiMedia MAC protocol is supported by adopting RATE-REQ and RATE-RSP procedures. We also introduce relay decision mechanism and a medium access slot (MAS) allocation procedure for maximizing the efficiency in DR-MAC. Distributed reservation protocol information element (DRP IE) helps the source to reserve MAS allocation while RMIE with Relay-REQ notifies the decided relay device and the schedule for the relay transmission. In the simulation studies, we describe the implementations using pseudo codes and the throughput comparison between relay and direct considering BER, the effect of packet size, the effect of block size and the energy consumption. Compared with direct transmission, extensive simulation results demonstrate that DR-MAC can improve the throughput about 10% and reduce the energy consumption about 25%. In the simulation of throughput and energy consumption, the throughput improvement tends to grow when the number of nodes increases.