Packet Scheduling in Multi-Flow Carrier Aggregation with QoS Provisioning: Cross-Layer Design and Performance Analysis

Multi-flow carrier aggregation (CA) is a key solution for improving data rates in heterogeneous networks (HetNets). Efficient data splitting is important to enhance the performance of multi-flow CA. In this paper, packet scheduling in multi-flow CA is investigated via a cross-layer design approach with comprehensive quality of service (QoS) provisioning. In particular, an approximation of the average queuing delay (AQD) in terms of the average buffers' length and the average packet arrivals is presented. Then, using the presented AQD approximation, various packet scheduling schemes are developed in this paper. First, a low-complexity buffer and link aware heuristic packet scheduling scheme is proposed. Next, in order to reduce backhaul signalling overhead, a hybrid packet scheduling scheme that combines heuristic packet scheduling and random packet scheduling is considered. Then, an optimal packet scheduling scheme, albeit of high computational complexity, is proposed as a benchmark for other packet scheduling schemes. Also, the performances of the proposed packet scheduling schemes are analyzed and various data link layer performance parameters such as AQD, packet loss probability (PLP) and statistical queuing delay bound (SDB) are taken into consideration. Moreover, the complexity and the signalling overhead of the proposed packet scheduling schemes are investigated. Presented numerical results demonstrate that the heuristic packet scheduling scheme can achieve a performance that is similar to the performance of the optimal packet scheduling scheme while overcoming complexity and feasibility issues of the optimal packet scheduling scheme. Also, the hybrid packet scheduling scheme reduces signalling overhead while reaping some of the benefits of using buffer and link aware packet scheduling