Token Bucket-based Throughput Constraining in Cross-layer Schedulers

In this paper we consider upper and lower constraining users' service rates in a slotted, cross-layer scheduler context. Such schedulers often cannot guarantee these bounds, despite the usefulness in adhering to Quality of Service (QoS) requirements, aiding the admission control system or providing different levels of service to users. We approach this problem with a low-complexity algorithm that is easily integrated in any utility function-based cross-layer scheduler. The algorithm modifies the weights of the associated Network Utility Maximization problem, rather than for example applying a token bucket to the scheduler's output or adding constraints in the physical layer. We study the efficacy of the algorithm through simulations with various schedulers from literature and mixes of traffic. The metrics we consider show that we can bound the average service rate within about five slots, for most schedulers. Schedulers whose weight is very volatile are more difficult to constrain.Comment: 11 pages, 10 figures. Presented at 6th International Conference on Computer Science, Engineering and Information. Published in AIRCC http://airccse.org/csit/V9N13.htm

Real-time dynamic spectrum management for multi-user multi-carrier communication systems

Dynamic spectrum management is recognized as a key technique to tackle interference in multi-user multi-carrier communication systems and networks. However existing dynamic spectrum management algorithms may not be suitable when the available computation time and compute power are limited, i.e., when a very fast responsiveness is required. In this paper, we present a new paradigm, theory and algorithm for real-time dynamic spectrum management (RT-DSM) under tight real-time constraints. Specifically, a RT-DSM algorithm can be stopped at any point in time while guaranteeing a feasible and improved solution. This is enabled by the introduction of a novel difference-of-variables (DoV) transformation and problem reformulation, for which a primal coordinate ascent approach is proposed with exact line search via a logarithmicly scaled grid search. The concrete proposed algorithm is referred to as iterative power difference balancing (IPDB). Simulations for different realistic wireline and wireless interference limited systems demonstrate its good performance, low complexity and wide applicability under different configurations.Comment: 14 pages, 9 figures. This work has been submitted to the IEEE for possible publicatio

Cross-Layer Optimization with Real-Time Adaptive Dynamic Spectrum Management for Fourth Generation Broadband Access Networks

Part 7: Ph.D. Student Workshop — Monitoring and Information SharingInternational audienceThe upcoming fourth generation of broadband access systems (4GBB) needs to address data rates of up to 1 Gbit/s over twisted-copper pairs. Physical layer techniques like dynamic spectrum management (DSM) aid in increasing the data rate by optimizing the space and frequency domain. However, there is room for improvement in the time dimension that both physical and upper layers can use to their advantage. This paper proposes a bidirectional cross-layer approach to optimize DSM using techniques like scheduling and statistical multiplexing, to mitigate crosstalk, the dominant cause of signal degradation. This in turn should lead to better data rates, more stable networks, and “greener” devices