Ji Lianghai

System capacity optimization algorithm for D2D underlay operation

Device-to-Device (D2D) communications is considered as one of the key technologies for 5G wireless communications system, since it offers several advantages compared with traditional cellular network, i.e. low end-to-end latency and high spectral efficiency. By allowing underlaying direct D2D communications, a D2D link which reuses the spectral resources of a cellular user causes increased interference to this cellular link. Further, the D2D link suffers from interference caused by the cellular user. In this paper, we propose a network controlled algorithm with low computation complexity to efficiently maximize the reuse of cellular network spectrum with the help of using channel information at base station. This algorithm can be used to select the transmission mode of potential D2D pairs. Besides, we also propose to use an auction algorithm for maximizing system capacity. The low complexity of these two algorithms reduces the setup delay of D2D links. Simulation results demonstrate improved system performance in terms of overall system capacity and number of established D2D links.

Applying Device-to-Device Communication to Enhance IoT Services

Massive machine type communication (mMTC) to serve billions of IoT devices is considered to offer the potential to open a potential new market for the next generation cellular network. Legacy cellular networks cannot meet the requirements of emerging mMTC applications, since they were designed for human-driven services. In order to provide support for mMTC services, current research and standardization work focuses on the improvement and adaptation of legacy networks. However, these solutions face challenges to enhance the service availability and improve the battery life of mMTC devices simultaneously. In this article, we propose to exploit a network controlled sidelink communication scheme to enable cellular networks with better support for mMTC services. Moreover, a context-aware algorithm is applied to ensure the efficiency of the proposed scheme and multiple context information of devices are taken into account. Correspondingly, signaling schemes are also designed and illustrated in this work to facilitate the proposed technology. The signaling schemes enable the network to collect required context information with light signaling effort and thus the network can derive a smart configuration for both the sidelink and cellular link. In order to demonstrate the improvements brought by our scheme, a system-level simulator is implemented and numerical results show that our scheme can simultaneously enhance both the service availability and battery life of sensors.

Context-aware cluster based device-to-device communication to serve machine type communications

Billions of Machine Type Communication (MTC) devices are foreseen to be deployed in next ten years and therefore potentially open a new market for next generation wireless network. However, MTC applications have different characteristics and requirements compared with the services provided by legacy cellular networks. For instance, an MTC device sporadically requires to transmit a small data packet containing information generated by sensors. At the same time, due to the massive deployment of MTC devices, it is inefficient to charge their batteries manually and thus a long battery life is required for MTC devices. In this sense, legacy networks designed to serve human-driven traffics in real time can not support MTC efficiently. In order to improve the availability and battery life of MTC devices, context-aware device-to-device (D2D) communication is exploited in this paper. By applying D2D communication, some MTC users can serve as relays for other MTC users who experience bad channel conditions. Moreover, signaling schemes are also designed to enable the collection of context information and support the proposed D2D communication scheme. Last but not least, a system level simulator is implemented to evaluate the system performance of the proposed technologies and a large performance gain is shown by the numerical results.

Physical Layer Authentication for Mission Critical Machine Type Communication Using Gaussian Mixture Model Based Clustering

The application of Mission Critical Machine Type Communication (MC-MTC) in wireless systems is currently a hot research topic. Wireless systems are considered to provide numerous advantages over wired systems in e.g. industrial applications such as closed loop control. However, due to the broadcast nature of the wireless channel, such systems are prone to a wide range of cyber attacks. These range from passive eavesdropping attacks to active attacks like data manipulation or masquerade attacks. Therefore it is necessary to provide reliable and efficient security mechanisms. Some of the most important security issues in such a system are to ensure integrity as well as authenticity of exchanged messages over the air between communicating devices. In the present work, an approach on how to achieve this goal in MC-MTC systems based on Physical Layer Security (PHYSEC) is presented. A new method that clusters channel estimates of different transmitters based on a Gaussian Mixture Model is applied for that purpose. Further, an experimental proof-of-concept evaluation is given and we compare the performance of our approach with a mean square error based detection method.

Radio Link Enabler for Context-Aware D2D Communication in Reuse Mode

Device-to-Device (D2D) communication is considered as one of the key technologies for the fifth generation wireless communication system (5G) due to certain benefits provided, e.g. traffic offload and low end-to-end latency. A D2D link can reuse resource of a cellular user for its own transmission, while mutual interference in between these two links is introduced. In this paper, we propose a smart radio resource management (RRM) algorithm which enables D2D communication to reuse cellular resource, by taking into account of context information. Besides, signaling schemes with high efficiency are also given in this work to enable the proposed RRM algorithm. Simulation results demonstrate the performance improvement of the proposed scheme in terms of the overall cell capacity.

Variance Transfer Chart Analysis of an OFDM-IDMA System with Carrier Frequency Offset

We analyze the performance of an orthogonal frequency-division multiplexing interleave-division multiple access (OFDM-IDMA) system for channels with a carrier frequency offset. First we introduce a vector-valued transmission model for the OFDM-IDMA system, including an improved chip detector. A semi-analytical technique is applied to generate variance transfer charts and predict the performance of the iterative receiver. Based on this analysis and Monte Carlo simulations we conclude that the performance of OFDM-IDMA over channels with carrier frequency offset is improved substantially by the new receiver concept.