Radio Resource Allocation for Achieving Ultra-Low Latency in Fog Radio Access Networks

Fog radio access network (F-RAN) has the significant advantages of local radio signal processing, cooperative radio resource management, and distributed storage capability to tackle the massive users demand at the edge. However, due to constrained fronthaul capacity, achieving ultra-low latency for emerging cellular networks is still challenging. This paper focuses on alleviating the heavy burden on fronthaul and achieving ultra-low latency by proposing a loosely coupled architecture in the F-RAN where a large number of F-RAN nodes are able to participate in joint distributed computing and content sharing regardless of nearness communication by satisfying the minimum latency demand. A mixed-integer nonlinear programming problem is formulated to achieve the ultra-low latency under the constraint of fronthaul capacity and computing capability of each F-RAN node. To solve this problem, a joint distributed computing scheme and a distributed content sharing scheme are proposed with the greedy algorithm to find a sub-optimal solution, in which the weighted minimum mean square error approach is adopted to optimize the transmission rate. Numerical results reveal that the ultra-low latency can be achieved in F-RANs by properly utilizing the loosely coupled architecture.