Lun Tang

Game-theoretic approach for pricing strategy and network selection in heterogeneous wireless networks

User selection for access network is considered to be one of the distinct features of heterogeneous wireless systems, in which users with multi-network interface terminals can freely select access network for better quality of service with lower expense. On the other hand, service providers (SPs) will have to face more intense competition for attracting more subscribers and increasing their profits, which can be achieved through either non-cooperative or cooperative strategies. In this study, the authors propose a unified quantification model for evaluating the access service of heterogeneous systems. The relation between competitive SPs and users is described by different game models, based on general assumptions and practical application scenarios. A novel network selection scheme for maximising user performance–cost ratio (PCR) is proposed. Numerical results demonstrate that all SPs can achieve Nash equilibrium price under non-cooperative game framework and coalition price for cooperative game case to maximise their absolute profits, and the maximal PCR criterion for user network selection scheme is analysed under different scenarios.

A survey on vertical handoff decision for heterogeneous wireless networks

Different kinds of wireless access systems will be integrated in next generation network. To support seamless mobility between these heterogeneous wireless access networks, efficient and reliable vertical handoff schemes are required. In this paper, a survey on vertical handoff decision algorithms is given and the algorithms are described, analyzed and compared. In the end, major existing problems and future research direction are discussed.

Handover algorithm based on movement state for cellular relaying networks

This paper firstly introduces the architecture of cellular relaying networks, and describes the additional handover scenarios in the networks. Then the handover model of cellular relaying networks is made, the traditional handover algorithm based on absolute threshold value and hysteresis level is introduced. On this basis, we propose a novel handover algorithm based on movement state for cellular relaying networks, which combines with movement direction and velocity to choose a more accurate access station as the handover target. Finally, the proposed handover algorithm is compared with the traditional algorithm. Simulation results show that the novel algorithm improves handover efficiency and reduces signaling cost, and the network performance has been optimized.

Relay protocol improvement and frame structure design base on overhearing mechanism and physical network coding

Under the background of TDD mode and LTE-Advanced scene, in this paper, we combine physical network coding with relay technology in order to make physical network coding-decode and forward(PNC-DF)together with physical network coding-amplify and forward(PNC-AF)transfer mode can be used to improve network throughput by using interference. Because of the ability to listen to the multi-user relay service, we need to optimize and select user group of physical network coding. In this paper, we use over-hearing mechanism in order to optimize user group, even more we also need to improve the department of transport protocol on delay. At last, depending on improved transport protocol, we design two kinds of frame structure which could adapt to improved transfer model. The simulation result shows that PNC-DF and PNC-AF with over-hearing mechanism could reduce the bit error rate.

Group mobility in wireless sensor network

Group mobility management in wireless sensor network (WSN) is of particular importance as it is can be found in many practical application scenarios. In this paper, a group mobility scenario in WSN is considered and the data collected by the sensor nodes in the group is assumed to transmit either inside the group or to the corresponding node (CN) through the IP-based backbone network. Traditional WSN protocols can be applied to support the data transmission inside the group. To support the data transmission through the internet, the integration of WSN with IP-based network is required and network mobility (NEMO) protocol can be employed. As NEMO is designed for IP network which is not compatible with WSN, particular consideration of NEMO protocol and the characteristics of WSN should be taken in applying the NEMO protocol. In this paper, the protocol stacks of WSN and the standard NEMO protocol are introduced. For WSN using several typical protocols supporting IP packet transmission, the application of NEMO is analyzed and summarized.

A Novel Method of Feedback Reducing and Cross-layer Scheduling Based on Traffic Rates for Relay System

This paper studies the scheduling schemes in multiuser downlink relay systems with orthogonal frequency division multiple access (OFDMA) where base station (BS) supports different traffic rates for different users. We formulate the problem as a cross-layer design of joint feedback reducing and OFDMA scheduling to support traffic rates and minimize packet loss rate. In most previous scheduling mechanisms with feedback, the parameters of traffic arrival process were not taken into account, consequently, the requirement of user traffic can not be guaranteed. In this paper, a dynamic threshold feedback mechanism (DTFM) based on traffic rates is proposed, of which the user with channel gain being larger than the dynamic threshold is only allowed to send its channel state information, thereby reducing the number of required feedback users and the computational burden of exhaustive search for best users at the BS. A cross-layer scheduling algorithm of traffic and queue proportional fairness (TQPF) taking into consideration the traffic fairness, the user queue length and the user transmission rate (related to its channel quality) is then proposed. Finally, a method of feedback reducing and cross-layer scheduling, i.e., TQPF based on DTFM (TQPF-DTFM), is proposed. Theoretical and simulation results show that DTFM reduces feedback by more than 90%, and TQPF-DTFM successfully meets user traffic rates that is, the user with high traffic rate can obtain more transmission rate than the user with low traffic rate and deceases packet loss rate of the system by almost 50% than the conventional methods.

Cross-layer design and performance comparison of HARQ schemes with imperfect CSI in cooperative relay networks

we consider cross-layer design frameworks and performance comparison of HARQ schemes in cooperative relay networks with imperfect channel state information (CSI). Firstly, we propose a state transition models to analyze and calculate the HARQ average packet error rate (PER) and latency performance over Nakagami-m channel with imperfect CSI for relay networks; Secondly, By combing the adaptive modulation and coding (AMC) at the physical layer with hybrid automatic repeat request (HARQ) at data link layer, a cross-layer optimization model that maximizing the average spectral efficiency is formulated under average transmitting delay constraints, and an iteration algorithm for the cross-layer optimization model is designed. We compared the average packet error rate (PER) and spectral efficiency of three kinds of different HARQ protocols in our cross-layer optimization schemes. The numerical results show that our schemes can achieve maximumspectral efficiency. The cross-layer design with AMC and type-III HARQ provides a larger spectral efficiency and lower PER with cooperative relay than the other two HARQ protocols.

A hybrid routing algorithm for load balancing in WLAN mesh network

While Wireless Local Network (WLAN) mesh network has been actively explored for a few years, there are still some technical challenges existing, such as optimal routing, fairness and mobility management. Hybrid Wireless Mesh Protocol (HWMP) is proposed in draft standard as a recommended routing protocol for WLAN mesh network, however, it only takes hop count into account, which may result in node/link congestion. In this paper, a novel load balancing routing algorithm based on HWMP is proposed for WLAN mesh network. The proposed algorithm addresses the problem of load balancing on MP-to-MP (mesh point) links. Through jointly considering node congestion level, flow concentration level and link Expected Transmission Time (ETT), optimal load balancing and fast recovery routing can be obtained. The simulation results show that proposed algorithm offers network fast recovery ability when congestion occurs, and achieves load balancing among multiple paths.

Performance Analysis of Two Parallel Relays with ARQ Protocol

Cooperative transmission is an efficient technique to realize diversity gain in wireless fading channels via a distributed way. In this paper, we consider a wireless network composed of a source, two parallel relays and a destination terminal. We exploit the limited feedback from the destination and propose cooperative ARQ protocols for two parallel relays. An analysis model to analyze and compare the data link layer packet error rate (PER) and throughput of cooperative transmission with joint relay selection and cooperative ARQ protocols for two parallel relays in slow fading wireless channel is established. Furthermore, The performance of this scheme are evaluated through numerical analysis and Monte-Carlo simulations and it is demonstrated that the proposed scheme can always achieve the lowest packet error rate (PER) and the highest throughput.