DIMSUMNet: New Directions in Wireless Networking Using Coordinated Dynamic Spectrum Access

Current FCC mandated static partitioning of spectrum has led to an artificial spectrum scarcity even though large swath of spectrum remains underutilized [4]. The new paradigm of "Dynamic Spectrum Access" enabled by recent advances in Software Defined Radio (SDR), wide band spectrum sensing, and environment aware real-time spectrum allocation [23,19,7] promises to alter this scenario and usher in new form of wireless networks. In this paper, we present a pragmatic approach that offers coordinated, real-time access to spectrum instead of free-for-all, opportunistic methods common in ad-hoc military applications [19,22,23,26,28]. We first introduce two new concepts, namely, "Coordinated Access Band" (CAB) and "Statistically Multiplexed Access" to spectrum that form the basis of our work. We then describe their implementation in the new DIMSUMnet network architecture consisting of four elements: base stations, clients, a Radio Access Network Manager (RANMAN) that obtains spectrum leases, and a per-domain spectrum broker that controls spectrum access. We describe two new protocols, namely SPEctrum Lease (SPEL) protocol for spectrum leasing and SPectrum Info (SPI) protocol for conveying spectrum usage. We elaborate the issues in the design of spectrum brokers and spectrum allocation policies and algorithms. We also describe a multi-hop all-wireless architecture called DIMSUM-RelayCluster that employs bandwidth-on-demand backhaul links and does not require changes to client devices.