Electronics and Telecommunications Research Institute

Korea Telecommunication Authority

Yoon Seok Nam

Kwang Roh Park

Jae Doo Huh

Jung Sik Kim

Sung Rae Cho

There is provided a method for estimating a position of a mobile node in a wireless sensor network. The method includes estimating a frequency offset between anchor nodes and estimating a difference between times when ranging frames from a mobile node are received by two anchor node, without use of a separate synchronization unit, such as a network synchronized clock supply unit that supplies a network synchronized clock via a cable, in a wireless sensor network, unlike a conventional method of estimating Time of Flight (TOF) using Two-Way Ranging (TWR) and Symmetric Double Sided-TWR (SDS-TWR) schemes. The estimated receiving time difference is directly applied to a Time Difference Of Arrival (TDOA) algorithm in order to estimate the position of the mobile node.

Method of estimating position of mobile node in wireless sensor network

The present invention relates to a method of estimating the position of a mobile node in a wireless sensor network using a passive mode OWR method. The method includes: estimating frequency offsets of anchor nodes and a mobile node; allowing the anchor nodes to sequentially transmit ranging frames; allowing the mobile node to receive the ranging frames and to estimate the difference between the reception times of signals from two anchor nodes; and applying the estimated difference between the reception times of the signals to time difference of arrival (TDOA) to estimate the position of the mobile node. According to the above-mentioned structure of the present invention, a plurality of mobile nodes can estimate their positions with a minimum number of ranging frame transmissions, without using a separate network synchronization unit. In addition, it is possible to easily construct a wireless sensor network for position recognition, and rapidly and accurately perform distance estimate using an OWR method.

The present invention relates to a method of controlling a re-emission interval of an asynchronous transfer mode interval controller using a theoretical departure time. The present invention controls the generation of CDV in a controller of the current RDT similarly to the existing RDT method for controlling the intervals of ATM cells by processing the time which a cell is outputted from an interval controller as a theoretical departure time and registering by a little earlier time in CSQ compensating for the queuing delay of OQ, and solves the problem of the queuing delay accumulation in the existing RDT method.

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Seoul, South Korea

Yoon Seok Nam