Cross-layer Based Delay-constraint Adaptive Polling for High Density Subscribers in IEEE 802.16 WiMAX Networks

Abstract

The IEEE 802.16 standard (namely WiMAX) is proposed to support QoS-aware transmission of real-time service in Wireless Metropolitan Area Networks (WMANs). WiMAX also can operate as a wireless backbone, and then cooperates with WiFi to form a heterogeneous wireless network. Thus, hot spots of WiFi belonging to different WiMAX networks can communicate with each other. For achieving that a Base Station (BS) serves a large number of Subscriber Stations (SSs), WiMAX uses a centralized polling access mechanism instead of a random access mechanism. WiMAX thus avoids occurring access collisions but causes long polling delay under a high-density SSs situation. Consequently, IEEE 802.16 does not schedule real-time service (rtPS) while the BS is in multicast polling mode. This problem of long polling delay becomes worse when the BS serves high-density SSs, because the BS only polls some SSs or groups in every frame time. This paper thus proposes an adaptive polling approach with a cross-layer mechanism, which dynamically polls SSs among different polling modes while continuously supporting the rtPS service. The approach consists of two phases. The first phase adopts two hysteresises of number of SSs and residual bandwidth to determine the optimal polling mode for each connection. The second phase presents a novel QoS-aware rtPS service (QrtPS) that provides an Average Delay requirement instead of the Maximum Delay requirement to take over the rtPS service when a SS is polled by the multicast mode. Additionally, a cross-layer mechanism is proposed to achieve that the real-time applications can be sent with a high-quality or low-quality video codec when the SS is in unicast or multicast mode, respectively. Numerical results demonstrate that the proposed approach significantly outperforms IEEE 802.16 in average delay and network utilization. Furthermore, the collision probabilities of using different numbers of contention slots of an uplink subframe and different numbers of groups within a BS are evaluated for the multicast mode. The results meet the experiments.

Cross-Layer Application of Video Streaming for WiMAX: Adaptive Protection with Rateless Channel Coding

“…This can cause excessive delay to multimedia applications. To avoid this, in Chang & Chou (2007) knowledge of the application types and their delay constraints is conveyed to the datalink layer, where the scheduling mode is decided upon. The network layer can also benefit from communication with the datalink layer in order to synchronize www.intechopen.com WiMAX and IP handoff management (Chen & Hsieh, 2007) and in that way reduce the number of control messages.…”

Applications of the cross-layer paradigm for improving the performance of WiMax [Accepted from Open Call

“…However, BSs are not normally aware of the subchannel allocations of nearby BSs. Thus, the authors con- -Wireless medium aware multimedia streaming [3,4] -Link condition aware encoding [5] -Transport layer protocol aware uplink/downlink scheduler [8] -Transport layer parameter aware scheduler [9] -Integrated WiMAX and IP handover [10,11] -Routing based on the L2 mesh topology -Dynamic routing using the load on the mesh links to increase capacity [12,13] -Application type aware scheduling [6] -Multicasting based on the mesh topology [7] -Wireless medium aware scheduling [14,15] -Link condition aware subchannel allocation [16] -Location aware subchannel allocation [17] Application layer The handover procedure of Mobile WiMAX is a break-before-make mechanism that is very similar to the handover mechanisms in current second generation (2G) networks (e.g., GSM). sider a distributed system architecture where nearby BSs are managed by radio network controllers (RNCs).…”

Game Theoretic Access Probability based Bandwidth Request mechanism for WiMAX Point to Multipoint network

“…This means they will not access with the probability of 1 -(apf:~b) k,l and 1 -(apf:~b) k,l. Hence the payoff for the successful access can be calculated as V k,l == 1 to n (6) to unilaterally deviate the strategy. In general uniqueness and existence of NE is not guaranteed; neither is convergence to equilibrium when one exists.…”

“…Solution for the aforementioned drawback could be multicasting, adaptive multicasting and broadcasting. Broadcasting is similar to contention based access while adaptive multi casting needs some more further modification in the standard with the definition of new QoS class namely Q-rtPS (Quasi Real Time Polling Service) an additional signaling as in [6]. In this paper, however, we tried a simple solution which needs no additional signaling and no modification in the standard with the broadcasted access probability based contending BW-REQ mechanism applicable to delay constraint rtPS class.…”