Joint Power And Spectrum Allocation In Wireless Localization Networks

In recent years, high-precision positioning systems are getting more and more people’s attention and the application of which also influences every aspect of our life,such as item tracking, search and rescue, battlefield soldiers positioning and so on. GPS positioning system is the most common positioning system, but because the GPS signal does not have the ability to penetrate walls, such as in a complex indoor environment,the localization accuracy is limited. In this case, wireless localization network becomes an important alternative in the shadowed environments, such as indoor, mine and forest. In wireless localization network, system accuracy and energy efficiency are affected by the power and spectrum allocation, besides network topology, transmissionchannel and measuring method. Resource allocation is an effective way to improve position accuracy subject to the limited resources and low cost, instead of increasing the number of nodes and improving the power of transmitted signals.In typical range-based localization techniques, “agents” try to perform position estimation through ranging with respect to “anchors” with known positions. According to the general wideband signal model, effective bandwidth is decided by both carrier frequency and real signal bandwidth. And then, carrier frequency is introduced in the field of resources allocation in wireless location networks. Carrier plays an important role in ranging and localization. Based on the definition of squared positional error bound(SPEB), the localization accuracy can be determined by the transmit power, carrier frequency and signal bandwidth, etc. This paper analyzes the joint power and spectrum allocation(JPSA) optimization problems in resource restricted wireless localization systems.Assuming that the agent’s position is known, we first formulate the optimal JPSA problems, which provides the useful method and performance reference to the actual positioning environment. Considering frequency bands overlaps or not, we formulated both optimal interference-free and interference-concerned JPSA problems. We then formulate the robust counterparts of the problems in the presence of uncertainty of the agents’ positions. Based on the far field condition, a robust method is presented to deal with the uncertainty of the agent’s positions. Since all JPSA problems are non-convex, we give some accurate and efficient algorithms, which are able to find solutions close to the global optimum in the investigated cases.Numeric results validates our analysis and shows that resources allocation can obviously improve the localization accuracy and the energy efficiency. Although the uncertainty area is large, we also can find the optimal/robust resource deployment in wireless localization networks based on the proposed frameworks.