Changjia Chen

Dynamic Bandwidth Allocation for QoS Provisioning in IEEE 802.16 Networks with ARQ-SA

In this paper, bandwidth allocation, in terms of distributing available data slots among different users, is studied for QoS provisioning in IEEE 802.16 networks. By considering the automatic repeat request with selective acknowledgement (ARQ-SA) scheme for erroneous wireless channels, a mathematical model is established to theoretically analyze the delay performance of transmitting service data unit (SDU) under a multiuser environment. The analytical results indicate that the delivery delay of the SDU is dominated by the time spent for the first transmission of all its protocol data units (PDUs). Based on this observation, a novel dynamic bandwidth allocation algorithm is proposed and a detailed performance analysis is provided. Simulation results show that the proposed bandwidth allocation algorithm can significantly improve the delay performance of SDUs and ensure the fairness among different users.

Multiple frequency reuse schemes in the two-hop IEEE 802.16j wireless relay networks with asymmetrical topology

In this paper, throughput performance of the access links (i.e., base station to mobile station and relay station to mobile station) is analyzed for the two-hop IEEE 802.16j wireless relay networks with asymmetrical topology. In specific, three frequency reuse schemes are proposed to improve the spectrum efficiency of the access links: (1) an isolation band based frequency reuse scheme (IBFRS) which introduces an isolation band surrounding each relay station (RS) cluster (i.e, a separate RS or several adjacent RSs) so that the throughput of the access link can be improved by allowing frequency reuse between RSs and the base station (BS); (2) the dynamic frequency power partition (DFPP) scheme for reusing the frequency among RSs; (3) the selective reuse (SR) scheme for the RSs to further selectively reuse the frequency in the isolation band according to the interference measurement. Comprehensive simulation shows that by applying the proposed IBFRS+DFPP+SR, the throughput of the access link can be significantly improved.

Isolation band based frequency reuse scheme for IEEE 802.16j wireless relay networks

In this paper, the throughput performance of the access links (i.e., base station to mobile station and relay station to mobile station) is analyzed for the wireless relay networks based on IEEE 802.16j. An isolation band based frequency reuse scheme (IBFRS) is proposed, which introduces an isolation band around each relay station cluster so that the throughput of the access link can be maximized by allowing frequency reuse between the relay stations and the base station. An analytic method is also proposed to determine the optimal isolation band. A comprehensive simulation shows that by applying the proposed IBFRS, the throughput of the access link can be significantly improved.

A fast delay-constrained multicast routing algorithm

In this paper, we propose a fast multicast routing heuristic, called DCMA, for delay-sensitive applications. The running complexity of DCMA is O(m log m+|V|), where m is the size of the multicast group and |V| is the number of nodes in the network. We first present a unicast version of DCMA, called SDCR, which is used to setup an end-to-end, cost effective delay-constrained path between two nodes. SDCR can always find a delay-constrained path if one exists. Its running complexity is O(|V|). SDCR is used in constructing DCMA, which is guaranteed to be loop free. Simulation results are used to demonstrate the high performance and cost effectiveness of the proposed heuristic.

NXG02-6: Performance Analysis of ARQ Scheme in IEEE 802.16

IEEE 802.16, also known as WiMax (worldwide interoperability for microwave access), introduces the automatic repeat request with selective acknowledgement (ARQ-SA) scheme to improve the reliability of the wireless link. For ARQ-SA, packets or protocol data units (PDUs), several of which compose one service data unit (SDU) from the upper layer, are transmitted orderly, but only those negatively acknowledged packets are retransmitted. We analyze the delay performance of SDU under ARQ-SA in a multiuser network environment. Our analysis shows that the SDU delay is mainly determined by the first transmission of all its PDUs. Further more, we propose a simple scheme to reduce the delivery delay of SDU. Simulation results are given to demonstrate the accuracy of the analytical one.

Unified Radio Network for Broadcasting and Broadband Wireless Access [Advances in Mobile Multimedia]

In this article we propose a unified radio network architecture, broadband wireless multimedia (BWM), which integrates broadcasting service and broadband wireless access service at both the application and physical layers. A simple, flexible, and comprehensive radio resource management framework is developed for the unified radio network. It is shown that the proposed radio network architecture has many advantages over existing ones. In addition, the new architecture is currently being considered in China for the system level design.

Four-Antenna Based Structure for Cellular Networks with Frequency Reuse Factor of One

In this paper, a new four-antenna based structure (FAS) is introduced for capacity improvement in future cellular networks with frequency reuse factor of 1. In FAS, each cell consists of one omni-directional antenna located at the cell center and three 120-degree directional antennas located at the cell edge. In order to achieve effective system bandwidth allocation among four antennas, novel spectrum planning schemes for both downlink (DL) and uplink (UL) are proposed. Theoretical analysis and simulation demonstrate that the proposed cellular structure can significantly improve the system capacity in both DL and UL, especially at the cell edge.

Flow-Satisfaction-Degree Based Scheduling Algorithm in Static Reuse Partitioning System

Reuse partitioning (RP), a promising technique for constructing high efficient multi-cell OFDM systems, has brought a lot of attentions from both industry and academia. In this paper, by considering the characteristics of various service flows, we first introduce a new performance metric, called flow-satisfaction-degree (FSD), and then formulate an optimization problem for maximizing the FSD over the whole system. We then propose a FSD-based scheduling (FSDS) algorithm for the static RP system. Simulation results demonstrate that the proposed algorithm greatly outperforms the traditional static allocation scheme in terms of FSD and system throughput for the fully loaded system.

A hop-by-hop delay-constrained routing algorithm with explicit loop avoidance and backup routing information

QoS Routing is crucial for QoS provisioning in high-speed networks. In general, QoS routing can be classified into two paradigms: source routing and hop-by-hop routing. In source routing, the entire path to the destination node of a communication request is locally computed at the source node based on the global state that it maintains, which does not scale well to large networks. In hop-by-hop routing, a path-selecting process is shared among intermediate nodes between the source node and the destination node, which can largely improve the protocol scalability. In this paper, we present the design of hop-by-hop routing with backup route information such that each intermediate node can recursively update the best known feasible path, if possible, by collectively utilizing the routing information gathered thus far and the information that it locally stores. Such a route is kept as a backup route and its path cost is used as a reference to guide the subsequent routing process to search for a lower-cost constrained path and avoid performance degradation. In this way, the information gathered is maximally utilized for improved performance. We prove the correctness of our presented algorithm and deduce its worst message complexity to be O(∣V∣2), where ∣V∣ is the number of network nodes. Simulation results indicate that, however, the designed algorithm requires much fewer messages on average. Therefore it scales well with respect to the network size. Moreover, simulation results demonstrate that the cost performance of our algorithm is near-optimal. Copyright