Weixiao Meng

Smart Grid Communication: Its Challenges and Opportunities

The necessity to promote smart grid (SG) has been recognized with a strong consensus. The SG integrates electrical grids and communication infrastructures and forms an intelligent electricity network working with all connected components to deliver sustainable electricity supplies. Many advanced communication technologies have been identified for SG applications with a potential to significantly enhance the overall efficiency of power grids. In this paper, the challenges and applications of communication technologies in SG are discussed. In particular, we identify three major challenges to implement SG communication systems, including standards interoperability, cognitive access to unlicensed radio spectra, and cyber security. The issues to implement SG communications on an evolutional path and its future trends are also addressed. The aim of this paper is to offer a comprehensive review of state-of-the-art researches on SG communications.

Smart grid neighborhood area networks: a survey

Smart grid is an intelligent power network featured by its two-way flows of electricity and information. With an integrated communication infrastructure, smart grid manages the operation of all connected components to provide reliable and sustainable electricity supplies. Many advanced communication technologies have been identified for their applications in different domains of smart grid networks. This paper focuses on wireless communication networking technologies for smart grid neighborhood area networks (NANs). In particular, we aim to offer a comprehensive survey to address various important issues on implementation of smart grid NANs, including network topology, gateway deployment, routing algorithms, and security. We will identify four major challenges for the implementation of NANs, including timeliness management, security assurance, compatibility design, and cognitive spectrum access, based on which the future research directions are suggested.

Optimal KNN Positioning Algorithm via Theoretical Accuracy Criterion in WLAN Indoor Environment

This paper proposes the optimal K nearest neighbors (KNN) positioning algorithm via theoretical accuracy criterion (TAC) in wireless LAN (WLAN) indoor environment. As far as we know, although the KNN algorithm is widely utilized as one of the typical distance dependent positioning algorithms, the optimal selection of neighboring reference points (RPs) involved in KNN has not been significantly analyzed. Therefore, in order to fill this gap, the optimal KNN positioning algorithm based on the best TAC is introduced. And this algorithm is beneficial to construct the reliable WLAN indoor positioning system and provide the efficient location based services (LBSs). The relationship among theoretical expectation accuracy, unit interval of neighboring RPs and dimensions of target location region is also revealed. Furthermore, the feasibility and effectiveness of optimal KNN positioning algorithm are verified based on the experimental comparisons respectively in the regular office room, straight corridors, static positioning and dynamic tracking situations.

Optimal Power Allocation for Dual-Hop Full-Duplex Decode-and-Forward Relay

The full-duplex relayed transmission is an expansion of relay technique. In this paper, we investigate an optimal power allocation strategy for the dual-hop full-duplex decode-and-forward (DF) relay system with joint constraint of individual and global power. We prove that the optimal allocation solution is located on the three boundary conditions of the constraint domain. The golden section search algorithm is used to obtain the highly accurate numerical solution of the optimal allocation strategy. Simulation results indicate that the optimal power allocation strategy enhances the outage performance.

Physical layer implementation of network coding in two-way relay networks

Network coding, which works in the network layer, is an effective technology to improve the throughput of two-way relay networks. In this paper, we compare the existing network coding schemes: traditional network coding (NC) scheme, physical-layer network coding (PNC) scheme and soft network coding (SNC) scheme, and propose a new physical layer scheme which can be seen as the implementation of network coding in two-way relay networks. Relay nodes combine the received signals from two source nodes before demodulation and channel decoding. The computational complexity and BER performance of the proposed scheme are analyzed compared with the previous schemes. Theoretical analysis show that the proposed scheme can save 50% computational cost of demodulation and channel decoding processes compared with NC scheme, meanwhile increase the power efficiency of the relay nodes in two-way relay networks significantly. Future works with the proposed scheme are also discussed.

Multi-User Interference Cancellation in Complementary Coded CDMA with Diversity Gain

This letter analyzes the performance of complementary coded code division multiple access (CC-CDMA) systems in frequency selective fading channels. Based on the evaluation of various combining algorithms for the correlation functions of M element sequences of a CC, a per-carrier parallel interference cancellation scheme based on minimum mean square error combining (MMSEC) is proposed for CC-CDMA to achieve a frequency diversity gain and multi-user interference resistance. Both analytical and simulation results verify the superiority of the proposed scheme. It is shown that combining algorithms and correlation properties of element sequences have a significant impact on the performance of CC-CDMA systems in frequency selective fading channels.

Optimized access points deployment for WLAN indoor positioning system

Indoor positioning in wireless local area network (WLAN) has been attracting increasing attentions for its cost effectiveness and reasonable positioning accuracy. Existing positioning methods all pay attention to establish more accurate relationship between received signal strength (RSS) and physical locations. However, the deployment of access points (APs) is ignored. This paper proposes an optimized APs deployment method for improving WLAN positioning accuracy. The objective of APs deployment is to maximize the RSS Euclidean distance between physical locations. We investigate and demonstrate the importance of RSS Euclidean distance to WLAN positioning. Simulation studies and experimental results show that the proposed APs deployment method can improve positioning accuracy significantly.

A Survey on Complementary-Coded MIMO CDMA Wireless Communications

In this paper, we present a comprehensive survey on complementary code (CC)-based multiple-input multiple-output (MIMO) code-division multiple access (CDMA) for futuristic wireless communications. This paper starts with the construction of CCs and then proceeds to describe the design of CC-based CDMA and MIMO wireless communication systems. Complementary-coded chip-level space-time coding offers a unique paradigm to implement multiuser MIMO systems, opening up a new dimension to combine multiple-access and multiple-antenna techniques in a unified platform for a possible system design optimization of a wireless communication system in the future. In this paper, we will also discuss various potential research topics and technical challenges that need to be tackled before a complementary-coded MIMO CDMA system can be implemented in practical wireless applications.

A Complete Complementary Coded MIMO System and Its Performance in Multipath Channels

In this paper, we propose a new system architecture using complete complementary (CC) codes for a multicarrier MIMO CDMA system to combat multipath fading in wireless channels. Unlike traditional MIMO systems, complementary codes were designed at chip-level to achieve time and frequency-spreading for each antenna. We analyze the system performance in multipath fading channels. A closed form expression of bit error rate (BER) performance is obtained. Extensive simulations were conducted to verify the analytical results. Our results indicate that a CC coded MIMO system can effectively decrease BER and take advantage of diversity gain.

A configurable dual-mode algorithm on delay-aware low-computation scheduling and resource allocation in LTE downlink

Long Term Evolution (LTE) has been proposed as a promising radio access technology to bring higher peak data rates and better spectral efficiency. However, scheduling and resource allocation in LTE still face huge design challenges due to their complexity. This paper divides the complex problem into three sub-problems: scheduling pattern, scheduling priority and quantity of scheduled data. Based on analysis of three sub-problems, a configurable dual-mode (CD) algorithm is proposed. CD algorithm is able to guarantee queuing delay with low loss of resource utilization and fairness by employing dual-mode scheduling mechanism. And it can be configured by three parameters catering to different performance requirements. By utilizing QoS Class Identifier (QCI) and Channel Quality Indicator (CQI) defined by LTE, low computation is realized in CD scheduler. Finally, performance evaluation of the proposed scheduler is presented. The results and correlative analysis testify effectiveness of CD algorithm.