Auction Based Spectrum Management In Cognitive Radio Networks

Spectrum prediction, spectrum decision, spectrum sharing and spectrum mobility are four main functionalities of cognitive radio technology. Among them, spectrum decision and spectrum sharing are collectively known as spectrum management. Undoubtedly, spectrum management is a vital element related to the performance of cognitive radio technology as it determines the efficient utilization of available spectrum resource. However, the implementation of cognitive radio technology faces two critical challenges:how to encourage primary users to open the access of licensed spectrum, which is called incentive problem, and how to allocate available spectrum resource among secondary users, which is called allocation problem. To overcome these two challenges, researchers introduce the concept of auction in microeconomics into the studies on spectrum management in cognitive radio networks. Through auction, secondary users can pay for the exclusive use of idle licensed spectrum while the primary users can get additional profits, which benefit the network performance and enhance the practicability of cognitive radio technology. Existing studies on spectrum auction always hold some simple and impractical assumptions on spectrum resource, without fully considering the diversities on spectrum supply/demand among primary/secondary users. Moreover, how to allocate the spectrum resource in decentrialized environment and how to jointly allocate spectrum channels and transmitting power, are both worth exploring for the promotion of cognitive radio technology. The thesis focuses on auction based spectrum management in cognitive radio networks and tackles the aforementioned issues as follows:1. Considering the homogeneity assumption in previous researches cannot fully reflect the diversities on spectrum supply/demand among the auction participants, we propose a novel multi-attribute combinatorial auction, wherein the diversity on spectrum resource is reflected through multiple attributes. Specifically,1) we use "bandwidth, starting time, ending time" the three attributes to describe a spectrum channel in both frequency and time domain; 2) we build an attributed based valuation function to express the valuation of a secondary user towards a particular channel; 3) we allow secondary users to bid a combination of spectrum channels rather than just an individual channel. A combinatorial spectrum auction scheme is proposed under’single channel-single secondary user’scenario, which has been verified to achieve the individual rational, budget balance, truthfulness of buyers and weak truthfulness of sellers; 4) we allow a set of non-conflict secondary users to share a single spectrum and extend the proposed scheme to this’single channel-multiple secondary users’scenario. The extended scheme is conducted in a multi-round fashion and achieves the same economic properties as previous step.2. Motivated by the fact that a practical cognitive radio network is more likely to be in distributed structure, which brings the difficulty to find or deploy a certain agent to host the auction process and solve complex optimization problems, we propose a market-driven auction scheme to aim at such decentralized environments. Specifically,1) we divide the whole network into multiple sub-networks with a single primary user locating in each sub-network; 2) in each sub-network, the primary user adjusts the unit bandwidth price to balance the amount of bandwidth supply and demand, and finally achieves the market equilibrium (i.e., supply equals demand); 3) we prove that as long as the step size of price adjustment is small enough, all the sub-networks can achieve the equilibrium and the allocation under equilibrium is optimal; 4) we extend the proposed scheme to the scenario with QoS provisioning. Users’QoS requirements are mainly reflected on restrictions of bandwidth supply and demand.3. Traditional auction studies only concentrate on a single type of resource, either spectrum channel or transmitting power. However, secondary users sometimes may have requirements on both types of resource. Therefore, the study of auction based joint resource allocation is well motivated. Specifially,1) when the interference to primary users caused by secondary users’transmissions is unlimited, we treat the joint resource allocation as a single-side auction problem, and take account of two types of secondary user’s request, i.e., strict request and range request; 2) we propose an auction scheme under this scenario and prove that the proposed scheme can achieve the individual rational, budget balance and truthfulness; 3) we extend the study to the scenario that the interference to primary users is limited and treat it as a double auction problem. We further consider single-channel and multi-channel these two types of secondary user’s demand; 4) we design corresponding double auction schemes for each type of demand and prove that they both achieve the same economic properties.The thesis consists of 6 chapters, including 43 figures,4 tables and 105 references.