Utility and profit maximization in dynamic spectrum allocation.

摘要

Demand driven, short term allocation of spectrum will be important for future wireless systems. Engineering and economics will jointly determine optimal ways to operate such systems. In this thesis, we characterize two operating principles of dynamic spectrum access: decentralized commons and centralized property right.;In decentralized commons, co-located devices sense spectrum for vacant bands to transmit. Assuming an OFDM based physical layer, this means that a device can transmit in non contiguous tones. We analyze how symbol timing synchronization can be achieved using cyclic prefix based algorithms. For different spectral occupancies of the transmitter and fading conditions, we identify scenarios where synchronization algorithms yield satisfactory results and scenarios where they do not.;For the centralized property rights regime, we develop a two tiered spectrum allocation model where spectrum is first allocated to service providers (SPs) by a broker and then to customers by SPs.;First we assume that the users transmit to the SPs in the uplink after spectrum allocation, who maximize the sum utility of the users. We derive optimal allocation for different system parameters. We introduce a spectrum price and use it to demonstrate several key results about spectrum allocation. The spectrum price proves to be the regulatory mechanism that brings about coordination amongst the SPs with minimal control messaging. Our approach thus strikes a balance between a total and no central coordination.;Next we consider a downlink scenario where SPs sell spectrum to users and then transmit data. The SPs operate to maximize their profits. Each SP transmits at a specific power spectral density which is an indicator of the modulation and coding technology used for transmission. When there is only one SP, it can act as a monopolist and when there are multiple SPs, they compete. We characterize the customer to SP interactions in monopoly and SP price competition. We derive the prices charged and profits made by the SPs and show how they vary with provider efficiencies and spectrum costs charged by the broker. We show that an SP should invest in better technology if the broker cost of spectrum is high.