Cross layer designs for OFDMA wireless systems with heterogeneous delay requirements

This paper investigates a cross layer scheduling scheme for OFDMA wireless system with heterogeneous delay requirements. Unlike most existing cross layer designs which take a decoupling approach, our design considers both queueing theory and information theory in modeling the system dynamics. The cross layer design is formulated as an optimization of total system throughput, subject to individual user's delay constraint and total base station transmit power constraint. The optimal scheduling algorithm for the delay-sensitive cross layer optimization is to dynamically allocate radio resources based on users' channel state information, source statistics and delay requirements. Specifically, optimal power allocation was found to be multilevel water-filling where urgent users have higher water-filling levels, while optimal subcarrier allocation strategy is shown to be achievable by low complexity greedy algorithm. Simulation results also show the proposed jointly optimal power and subcarrier allocation policy can provide substantial throughput gain with all delay constraints being satisfied. © 2006 IEEE.published_or_final_versio

Cross-layer design for OFDMA wireless systems with heterogeneous delay requirements

This paper proposes a cross-layer scheduling scheme for OFDMA wireless systems with heterogeneous delay requirements. We shall focus on the cross-layer design which takes into account both queueing theory and information theory in modeling the system dynamics. We propose a delay-sensitive cross-layer design, which determines the optimal subcarrier allocation and power allocation policies to maximize the total system throughput, subject to the individual user's delay constraint and total base station transmit power constraint. The delay-sensitive power allocation was found to be multilevel water-filling in which urgent users have higher water-filling levels. The delay-sensitive subcarrier allocation strategy has linear complexity with respect to number of users and number of subcarriers. Simulation results show that substantial throughput gain is obtained while satisfying the delay constraints when the delay-sensitive jointly optimal power and subcarrier allocation policy is adopted. © 2007 IEEE.published_or_final_versio

Cross-layer downlink scheduling of multi-user multi-antenna systems with heterogeneous delay constraints

Cross-layer design for multi-antenna system has been shown to offer high spectral efficiency for multiuser system due to the multi-user diversity and the spatial multiplexing in wireless fading channels. Yet, most of the existing works assumed homogeneous user type (pure delay-insensitive data application). The effect of source statistics, queueing delay and application level requirements were completely ignored. In this paper, we shall propose an analytical cross layer design framework for multi-user multi-antenna systems for wireless multimedia applications with heterogeneous delay requirements. To take delay sensitive users into consideration, we shall utilize both queueing theory and information theory to model the system dynamics. A novel cross layer scheduler is designed to exploit the spatial multiplexing gain as well as the multi-user selection diversity gain, and at the same time maintain the delay constraints of the delay sensitive users. Simulation results indicate that the proposed scheduling design provides desirable delay performance and high throughput gain compared to other heuristic schemes. © 2006 IEEE.link_to_subscribed_fulltex

Modeling Guaranteed Delay of Virtualized Wireless Networks Using Network Calculus

Wireless network virtualization is an emerging technology that logically divides a wireless network element, such as a base station (BS), into multiple slices with each slice serving as a standalone virtual BS. In such a way, one physical mobile wireless network can be partitioned into multiple virtual networks each operating as an independent wireless network. Wireless virtual networks, as composed of these virtual BSs, need to provide quality of service (QoS) to mobile end user services. One such key QoS parameter is network delay, in particular upper bound delay. This paper presents a delay model for such a wireless virtual network. This delay model considers resources (in particular queues) of both physical nodes and virtual nodes and provides a realistic modelling of the delay behaviours of wireless virtual networks. Network calculus, which usually provides finer insight into a system, is utilized to fulfil the modelling task. The numerical results have shown the effectiveness of the proposed model. The model is useful for both off-line network planning and online network admission control

Quality of Service Modelling of Virtualized Wireless Networks: A Network Calculus Approach

Wireless network virtualization is an emerging technology that logically divides a wireless network element, such as a base station (BS), into multiple slices with each slice serving as a standalone virtual BS. In such a way, one physical mobile wireless network can be partitioned into multiple virtual networks each operating as an independent wireless network. Wireless virtual networks, as composed of these virtual BSs, need to provide quality of service (QoS) to mobile end user services. Key QoS parameters include buffer queue length, network delay and effective bandwidth, in particular their upper bound forms. This paper presents a QoS model for such a wireless virtual network addressing these parameters. This QoS model considers resources of both physical nodes and virtual nodes and provides a realistic modelling of the delay and bandwidth behaviours of wireless virtual networks. Network calculus (NC), which usually provides finer insight into a system, is utilized to fulfil the modelling task. The numerical results have shown the effectiveness of the proposed model. The model is useful for both off-line network planning and online network admission control. © 2014 Springer Science+Business Media New York