Multi-Antenna Localization Method

Abstract

ABSTRACT

Source Signal Strength Independent Localization

“…All the localizators in a WSN can be aligned when their corresponding nodes are placed by turning them in the horizontal plane so that the line of antennas 1, 3 and 5 points to a given distant landmark by line of sight indicating the direction of the x-axis and this is then checked with antennas 2 and 4 pointing to a different distant landmark by line of sight indicating the direction of the y-axis. As explained in [5] it is not necessary for the local axes of each localizator to be aligned since when all the localization data is transmitted up to the base station, the base station makes the computations to determine the relative orientations of the x and y-axes of every aggregator localizator with respect to the orientation of the base station localizator. Figure 4 showing the Spiral Localizator algorithm using raw data { } The localization process for WSNs requires that the normal data collection operations of all nodes cease until the localization process of the whole WSN is completed to avoid radio interference in the measurement process though it would be possible for non-radio overlapping clusters to localize separately and in parallel.…”

“…In the WSN there are therefore 1 + N 1 N 2 nodes in total but not all nodes need localizators. As discussed in [5], only the base station and aggregators are provided with localizators. Each 5 antenna spiral localizator defines the x and y axial directions since it has antennas 1, 3 and 5 along the local x-axis and antennas 2 and 4 along the local y-axis.…”

“…For a dense 2-level balanced WSN, radio silence must be observed by all nodes of the WSN. In [5] a dense WSN was defined as one where full connectivity is initially possible. This means that the maximum separation of any two nodes in the WSN is less than the initial radius of radio reach of each node of say ρ = 10m.…”

“…However it was also shown in [5] that measuring battery levels is also not a cost effective solution. A different approach is presented in this paper enabling any node with the localizator described in this paper to determine the relative positions of all other nodes, their distances and their local signal intensities 0 ψ .…”

“…Omnidirectional antennas give us RSSI readings and therefore node to node distance measurements based on assumptions about 0 ψ . Distance measurements can be obtained from RSSI measurements using the inverse square law which in suitable intensity and distance units is [5] Recently a multi-antenna technique [5] was published which only required the use of three omnidirectional antennas and the solution of two simultaneous linear inhomogeneous equations in two unknowns for the determination of relative coordinates. However these RSSI techniques require assumptions about the signal source intensity 0 ψ such as all nodes in the network having the same value of 0 ψ or else the 0 ψ values of all nodes are locally detected and broadcast to all nodes.…”