Abstract: In dense small cell networks, a task-dependency-based collaborative offloading scheme is proposed to cope with the limited computational resources in small cell base station (SBS), which can further reduce the total execution delay. Firstly, the parallel tasks are offloaded to different SBSs to reduce computing delay,while sequential tasks are offloaded to the same SBSs to reduce the number of required SBS. Then,based on whether different SBSs have the same load pressure or not,the optimal offloading strategies are proposed in two different scenarios by introducing the longest path theory and the graph coloring theory,respectively. The strategies jointly considerate the user energy constraint,dependencies among tasks,the amount of available computational resources and channel conditions of different SBSs. Simulation shows that the proposed strategies can reduce total execution delay compared with existing strategies in both scenarios.

Key words: small cell networks, mobile edge computing, collaborative computation offloading, latency optimization