Towards Fresh and Low-Latency Content Delivery in Vehicular Networks: An Edge Caching Aspect

Mobile edge caching which exploits the similarity in content requests to reduce duplicated transmissions, is considered as an effective solution to address the challenge of increasing mobile traffic demand and constrained radio resources. Different from conventional networks, vehicular networks are highly dynamic, and thus the cached contents should update timely to guarantee the freshness of vehicle received information. However, content update also consumes radio resource and results in a tradeoff between content freshness and service latency, calling for the joint optimization of content update, delivery, and radio resource allocation. To address this issue, this work proposes a cache-assisted lazy update and delivery (CALUD) scheme to balance content freshness and service latency in vehicular networks. Firstly, the age of information (AoI) and service latency of vehicular-received contents are derived in closed form under the CALUD scheme. Then, the CALUD scheme is further optimized jointly with the radio resource allocation from the network aspect to meet the diversified service latency and AoI requirements of different applications. Extensive simulations are conducted to validate the theoretical analysis using the OMNET++ simulator. The results demonstrate that the proposed CALUD scheme can reduce the service latency to milliseconds while guaranteeing the required content freshness.