QoS-kognitiv dynamische Scheduling und Ressource- Zuweisung in OFDMA drahtlose Multimedia-Netzwerke
Inhalt
The next generation wireless communication systems will provide a wide range of multimedia services while guaranteeing the required quality of service (QoS) of mobile users. In orthogonal frequency-division multiple access (OFDMA) systems the channel gains of subcarriers are quite different, due to the frequency selectivity of the channel. In terms of maximizing the system throughput, max carrier-to-interference ratio (CIR) is the best scheduling scheme such that subcarriers are allocated for only users with the best channel conditions. However, for the medium access control (MAC) layer, required QoS as well as system throughput should be satisfied. To maintain high system performance of both layers, it is necessary to design a MAC-PHY cross-layer optimized resource allocation scheme.
Scheduling and subchannel allocation algorithms are two very widely accepted key functions in the MAC layer to exploit the cross-layer information and improve performances. The multiuser diversity gain promotes system throughput substantially while it requests adaptive modulation and coding (AMC) scheduler to consider PHY channel state information (CSI) as well as MAC QoS requirements. Due to these considerations, in this work an appropriate MAC-PHY cross-layer scheduling scheme that joints packet scheduling and subchannel allocation together for AMC subchannel, one of the subchannel building methods in IEEE 802.16e PHY OFDMA modes, shall be designed and implemented in an open Wireless Network Simulator (openWNS) which is based on C++ and Python.
The goal of proposing such a dynamic cross-layer scheduling scheme is to maximize the total system throughput while supporting QoS guarantees for diverse multimedia services out of consideration for providing a fair resource sharing among users. In order to evaluate the performance of the proposed joint scheduling scheme, intensive simulations shall be performed in comparison with other popular scheduling algorithms such as the Throughput-oriented Maximum scheme (TMS), QoS-oriented Priority scheme (QPS) as well as the Round Robin (RR) scheme. In detail the following tasks should be fulfilled:
- Design of a MAC-PHY cross-layer model
- Parameterization of the five service types specified in the IEEE 802.16e standard (UGS, ertPS, rtPS, nrtPS and BE)
- Development and implementation priority elevation mechanism for multi-level QoS traffics within the openWNS
- Implementation of a cross-layer design for QoS-oriented resource allocation scheme within the openWNS
- Performance evaluation of the designed MAC-PHY cross-layer scheduling scheme with respect to QoS parameters like system throughput, mean packet delay of non-real-time (NRT) traffics and packet drop rate of real-time (RT) traffics
Letzte Änderung: 29-01-08
