Research On Location System In Wireless Region Based On ZigBee Protocol

Wireless node positioning technology is an internal demand of wireless sensor network, but in in the most practical applications, wireless sensor node is uncontrollable during the arranging process, causing the location of the nodes in network deploy area uncertain. However, for most application, it is meaningless that the obtained date has no accurate location information. As a burgeoning and developing technology, the best and acknowledged positioning algorithm has not emerged yet. So how to propose a high-accuracy position system in the premise of low hardware cost, low node density, few reference nodes and low algorithm complexity is a hotspot nowadays.For this purpose, the author had briefly summarized the research status and trends of wireless node position technology both domestic and overseas, compared and analysised the principle, cost, algorithm complexity and position accuracy of the several different localization algorithm in current. Proposed an improved scheme based on RSSI ranging and multilateral positioning principle: First, established a mapping relationship between RSSI and distance based Log-distance Path Loss Model. Then utilized the weighted average recursive filtering algorithm and smooth factor to do a simple process for the RSSI signal which is collected from the front end of RF hardware, after so ,the interference from the noise signal had been effectively reduced. Subsequently, in order to effectively reduce the influence caused by unilateral ranging error in the calculation of multilateral positioning process, added an adjacent correction node near to the blind node, and applied adjacent correction algorithm to correct the distance values which calculate via RSSI ranging. The simulation indicated that the average absolute error of the improved algorithm is 1.36m and the relative error is 1.92% in the simulative positioning area 70m×70m. After simulation, the author have choosed the CC2430 and CC2431 wireless nodes as hardware platform, realized the improved algorithm based on Z-Stack-1.4.2-1.1.0 protocol stack.At last chapter,the author had done a summary for the whole paper and a prospect for the succeeding works.