Wireless Fronthauling Technologies for Future Generation Wireless Networks

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Cisco Systems predicts that mobile data traffic will exceed 30 exabytes per month by 2020. To address the skyrocketing mobile data volume, research activities in wireless network architecture have indicated two trends. The first trend is to densify the access points by massive deployment of lower-power and low-cost access points. The second trend is to separate network functionalities by shifting the computational power of a traditional base station to a base band unit (BBU) pool with centralized computing power. As a result, the cloud radio access network (C-RAN) has emerged as suitable network architecture for future generation wireless networks. In C-RAN, signal processing is centralized in the BBU pool and radio frequency processing is handled by remote radio heads (RRHs), which are low-power and low-cost access points connecting to the mobile users. In C-RAN, the links that connect the RRHs to BBU pool are called fronthaul links. Fronthauling is defined as the transportation of large user data volume from RRHs to the BBU pool. The current technology implements the fronthaul links via wired line such as optical fibers and high-speed IP backbone. However, connecting massive number of RRHs to the BBU pool via dedicated wirelines is economically infeasible and lacks the required deployment flexibility that the carrier operators desire. Therefore, fronthauling is particularly challenging for a C-RAN and has been identified as a bottleneck problem for future wireless networks. This proposal addresses various wireless fronthauling technologies for C-RAN, and these technologies include the millimeter wave based beamforming, free-space optical communications, unlicensed spectrum band transmission and caching. For each of these wireless fronthauling technology, we identify key challenging issues and propose potential solutions. We anticipate that the proposed novel fronthauling technologies can facilitate the introduction of new data-centric real-time mobile applications, which will take more than 80% of the total network traffic in 2020. The proposed vertical fronthauling configuration will lead to several new research directions. This architecture can provide high data rate and cost effective coverage for the rural areas, where about 19% of the Canadian residents live. This study can also give birth to a new research direction for defense applications. After some modifications, the unmanned aerial vehicles (UAVs) that are equipped with BBU pool can be used in a battlefield scenario when the satellite based communication is disabled. The success of the proposed research program can give birth to a new industry sector such as manufacturing of specialized UAVs equipped with sophisticated computing and communication devices, and can have the potential to revive the Canadian telecommunication industry in the new era.