Cache-enabled Networks Research Articles

Cache-Enabled Cooperative Edge Networks for Intelligent Connected Vehicles

This paper investigates the effects of outdated channel state information on cache-enabled cooperative networks for intelligent connected vehicles, where part of the relay nodes can cache the files requested from the destinations. As the performance benchmark, the system outage probability with perfect and outdated CSIs is derived. The impacts of the system parameters, such as the number of relay nodes, the correlation coefficient, the channel fading power as well as the target data rate are analyzed by deriving the closed-form expressions on the system outage probability. From the analysis, we conclude that the diversity order of system outage probability with perfect CSIs is equal to the total number of relay nodes. While with outdated CSIs the diversity order remains one, regardless of the number of relay nodes. Specifically, the large number of cached relay and large correlation coefficient can significantly improve the system performance. Simulation results are present to validate the theoretical analysis.

Jointly Optimizing User Association and BS Muting for Cache-Enabled Networks With Network-Coded Multicast and Reconstructed Interference Cancelation

In this paper, we strive to improve the throughput of heterogeneous cellular networks by exploiting the pre-cached files at user end to manage interference. We consider a transmission scheme, where network-coded multicast is employed to help cancel multi-user interference, and reconstructed interference cancelation (RIC) is used to help eliminate inter-cell interference. Because RIC is opportunistic, base station (BS) muting is used to coordinate the residual strong interference. Since user association affects residual interference and is coupled with BS muting while both are operated in a very different timescale from content caching, we jointly optimize user association and BS muting for a given caching policy to maximize the number of users simultaneously served by the transmission scheme. By transforming the formulated problem into a maximal independent set problem with constructed conflict graph, the global optimal solution is found with graph theory methods. By exploiting the topology feature of heterogeneous networks, we proceed to propose two low-complexity algorithms, respectively, implemented in a centralized and distributed manner, which are viable for large-scale networks. Simulation results show that the optimized transmission scheme achieves a remarkable performance gain over the existing schemes.

Delay Analysis of Network Coding in Multicast Networks With Markovian Arrival Processes: A Practical Framework in Cache-Enabled Networks

We develop an analytical framework for queueing and delay analysis in the case of a number of distinct flows arriving at a network node, where asynchronous partial network coding is applied for an efficient packet transmission. In order to perfectly model and analyze the practical communication networks, the arriving flows are assumed to be general Markovian arrival processes. As a key example, we apply the proposed model to the problem of coded caching in single bottleneck caching networks. In addition, we verify the accuracy of the proposed model through simulations and real trace-driven experiments.

Distributed Packet Forwarding and Caching Based on Stochastic Network Utility Maximization

Cache-enabled network architecture has great potential for enhancing the efficiency of content distribution as well as reducing the network congestion. This, in turn, has called for joint optimization of traffic engineering and caching strategies while considering both network congestion and content demands. In this paper, we present a distributed framework for joint request/data forwarding and dynamic cache placement in cache-enabled networks. Specifically, to retrieve the information about content demands and network congestion over the network, we establish a dual queue system for both requests and data, and define a dynamic mapping between the two queues with the help of dummy data such that the nodes can determine packet forwarding and caching strategies based only on local information. As the local objective function associated with Lyapunov optimization is time-varying due to the stochastic evolution of request/data queues, we develop a low-complexity distributed forwarding and caching algorithm via stochastic network utility maximization. We also prove the proposed algorithm achieves queue stability, and derive its region stability property for time-varying local optimization to demonstrate the convergence behavior. The simulation results verify queue stability and shows the proposed algorithm outperforms the existing ones.

Joint cache policy and transmit power for cache‐enabled D2D networks

The cache-enabled device-to-device (D2D) communication is a burgeoning technique to offload cellular traffic. In this study, the authors conducted the joint cache policy and transmit power to maximise the content-related energy efficiency (CREE) for the cache-enabled D2D network. Specifically, the authors model the random distribution of mobile users by the Poisson point process and derive the closed-form CREE via considering the D2D establishment threshold and signal-to-interference ratio threshold at the same time. Then the authors aim to determine the optimal cache policy and transmit power for maximising the CREE in two practical cases, respectively. Since the optimisation problem in both cases are non-linear non-convex problems and share the same mathematical form, the authors focus on the first case and propose a two-step iterative algorithm to find a stationary solution due to its intractability. This iterative algorithm builds on two subproblems which are proved to have optimal solutions. Numerical simulations show that the joint optimisation can obtain more than two times the CREE compared with either of the single optimisation for cache policy or transmit power.

Interference Management in Cache-Enabled Stochastic Networks: A Content Diversity Approach

In wireless networks, the performance is degraded by the intensity of the interference received from concurrent transmissions. Considering a stochastic cache-enabled network where some users have caching ability to store the most popular packets, we propose a novel interference management scheme to eliminate the interference by exploiting the content diversity. First, cache-enabled users can exploit cached packets as side information to cancel the interference. Second, considering that different access points may transmit the same contents to different users simultaneously, they should be regarded as useful signals rather than interference. The performance improvement with these two content diversity schemes is theoretically analyzed in this paper. The probabilities for the interference cancellation case and the signal enhancement case are derived, respectively, followed by the investigation of the signal to interference plus noise ratio improvement with our proposed content diversity schemes. Based on this, the effective content capacity of the system is analyzed. In addition to the simulations to validate the accuracy of the theoretical analysis, the impacts of caching ability and the proposed interference management schemes on the effective content capacity are investigated.

Modeling and Analysis for Cache-Enabled Networks With Dynamic Traffic

Instead of assuming fully loaded cells in the analysis on cache-enabled networks with tools of stochastic geometry, we focus on the dynamic traffic in this letter. With modeling traffic dynamics of request arrivals and departures, probabilities of full-, free-, and modest-load cells in the large-scale cache-enabled network are elaborated based on the traffic queue state. Moreover, we propose to exploit the packets cached at cache-enabled users as side information to cancel the incoming interference. Then the packet loss rates for both the cache-enabled and cache-untenable users are investigated. The simulation results verify our analysis.