Patent ID: 8121629

Claim:
A radio device for use in an autonomously established radio network by which radio communication is carried out between a source and a destination comprising: threshold determining unit for determining a threshold used to detect a radio characteristics equal to or more than the minimum radio characteristic of radio waves transmitted and received in a stable radio wave environment based on a plurality of radio waves received from n radio devices, said n being a positive integer; and table producing unit for producing a routing table that indicates routing information between said source and said destination based on the routing information of routes having a radio wave characteristic equal to or more than said determined threshold, wherein: said threshold determining unit determines a threshold used to detect a strength equal to or more than the minimum strength of radio waves transmitted and received in said stable radio wave environment, and said table producing unit produces said routing table based on the routing information of a route having a strength equal to or more than said determined threshold, said threshold determining unit comprises: signal strength detecting unit for carrying out signal strength detection processing to detect a first set of m pairs of signal strengths including m maximum reception signal strengths and m minimum reception signal strengths corresponding to said m maximum reception signal strengths based on said plurality of received radio waves, said m being an integer equal to or more than a prescribed number; rearranging unit for carrying out rearranging processing to rearrange said detected first set of m pairs of signal strengths so that said m maximum reception signal strengths are in descending or ascending order, thereby producing a second set of m pairs of signal strengths; and setting unit for detecting first and second minimum reception signal strengths corresponding to two adjacent first and second maximum reception signal strengths having the largest difference among the m maximum reception signal strengths in said second set of m pairs of signal strengths and setting said threshold in the range defined as having the detected first and second minimum reception signal strengths as end values, wherein if packet error is at least a prescribed value, said signal strength detecting unit carries out said signal strength detection processing again to detect a new first set of m pairs of signal strengths, said rearranging unit carries out said rearranging processing based on said new first set of m pairs of signal strengths to produce new second set of m pairs of signal strengths, and said setting unit detects a new pair of first and second minimum reception signal strengths based on said new second set of m pairs of signal strengths and updates said threshold by setting said threshold in the range defined as having the detected new pair of first and second minimum reception signals as end values.