QoS and Flow Management for Future Multi-Hop Mobile Radio Networks

Mobile radio networks of the IMT-Advanced systems family promise ubiquitous broadband access and high area coverage, with rates of several 100 MBit/s. They claim to guarantee QoS support in terms of low delay and guaranteed throughput. However, with the availability of flat rate plans and bandwidth-hungry applications of future mobile devices the systems are facing a hard challenge in satisfying all demands at the same time in a traffic load situation which can best be characterized as total overload or full buffer. In this situation the basic voice service must still be operational to full Erlang capacity, no matter what load the data traffic offers. In this paper the hierarchical static priority scheduling scheme is used to accomplish the required separation. Candidate technologies like LTE-Advanced, WiMAX are based on OFDMA access which allows flexible radio resource allocation, but has an inherent near-far heterogeneity which leads to unfairness if it is optimized for spectral efficiency. Multi-hop relaying is one way to diminish the near-far problem, which is why it is an important part of the system concepts. The scheduling scheme is designed with this multihop capability in mind and results show that in heterogeneous scenarios a proportional fair substrategy achieves the desired fairness. To achieve QoS distinction a flow management must be provided in OSI layer two, so that flows of different classes can be treated separately. This paper treats the flow management concept for multi-hop mobile radio systems, a key enabling technology for QoS aware resource scheduling. It features the cross-layer signaling of QoS requirements by the Application Layer to the Data Link Layer.