The Research And Implementation Of High-precision Indoor Positioning Based On CSS Technology

Pervasive computing trying to change computer-centric model to a human-centric computing model, the goal is to build a ubiquitous computing and communication environment, and provide human-centered services transparently on it. Getting object position information is the key to achieve ubiquitous computing, Global Positioning System(GPS) can be achieved the obtaining of object position information under the conditions of pervasive computing, but GPS positioning accuracy is reduced and can’t reach the requirements of pervasive computing in indoor environments. So it is significative in practice and theory to develop a position system to suit indoor environment.Existing positioning systems have advantages and disadvantages, which is relatively high positioning accuracy of the system there is too wide signal bandwidth, high cost problems, and positioning accuracy is relatively low system exists relatively low and not stably enough. This paper analyzes the various positioning system technology, then proposed a high-precision indoor positioning methods based on Chirp Spread Spectrum (Chirp Spread Spectrum, CSS). Aim to the signal collision in the positioning process and initial estimate coordinate precision is not high, proposed the corresponding solutions, the work accomplished as follows.(1) Analyzed two types of classic anti-collision algorithm, and referenced the dynamic frame slot anti-collision algorithm (DFSA), then proposed acknowledge dynamic frame slot ALOHA anti-collision algorithm (ADFSA). ADFSA inherited the principle of the dynamic adjustment of the frame slot from DFSA, and using the historical identification information to determine which slot to transmit data, thereby reduced the case of random transmitting data. Experimental results show that throughput of the proposed algorithm ADFSA has increased significantly relative to the previous algorithm.(2) Aim at the smart home needing high-precision positioning, in order to overcome the adverse effects of indoor environment on the positioning accuracy, the paper proposed a weighted correction positioning algorithm combined with trilateration. positioning system first use trilateration to estimate the initial position of the tags, then the weighted correction algorithm determine the extent of neighbor of the testing tag and reference tags by the initial coordinate calculated by trilateration, then bound to the error between the estimated coordinates and actual coordinates of reference tags, to correct the initial coordinates of the testing tags to improve the positioning accuracy.(3) Based on the existing hardware as well as the proposed weighted correction positioning algorithm, designed and developed a positioning system prototype, and achieved high-precision CSS-based indoor positioning methods. The average positioning accuracy is0.8890m, which meet the requirements of pervasive computing positioning basically.The work above shows that the CSS-based indoor positioning method is feasible, and it can provide an indoor positioning solution, which is low cost and can meet the requirements of pervasive computing positioning accuracy basically.