Receiving data in a sensor network

Abstract

A sensor network has a plurality of wireless sensors which transmit to an intermediate receiving device which relays data to a central server. A method is provided for receiving data packets at the intermediate receiving device from a plurality of the transmitting devices. Data packets are sensed on a communication medium at the receiving device and the total traffic intensity of data packets from the transmitting devices is estimated. A detection threshold for data packets is provided and adapted as a function of the total intensity. The receiving device receives data packets with a signal strength above the current detection threshold.

1 . A method for receiving data packets from a plurality of transmitting devices at a receiving device, comprising: 
 sensing data packets transmitted on a communication medium;    estimating the total traffic intensity of data packets generated by the transmitting devices;    adapting a detection threshold for receiving data packets as a function of the total traffic intensity;    ignoring data packets with a received signal strength below the current detection threshold; and    receiving data packets with a received signal strength above the current detection threshold.    
   
   
       2 . A method as claimed in  claim 1 , wherein when the total traffic intensity is low, the detection threshold is decreased.  
   
   
       3 . A method as claimed in  claim 1 , wherein when the total traffic intensity increases, the detection threshold is increased.  
   
   
       4 . A method as claimed in  claim 1 , wherein the detection threshold is adapted for every data packet sensed.  
   
   
       5 . A method as claimed in  claim 1 , wherein the method includes tracking and estimating the traffic intensity and the utilisation at the receiving device and adapting the detection threshold to keep the utilisation at a maximum.  
   
   
       6 . A method as claimed in  claim 5 , wherein the traffic intensity is estimated by a packet duration divided by the average idle time at the receiving device.  
   
   
       7 . A method as claimed in  claim 5 , wherein the utilisation at the receiving device is estimated by a packet duration divided by the average time between two successful packet receptions.  
   
   
       8 . A method as claimed in  claim 5 , wherein the estimated traffic intensity and utilisation are continually updated.  
   
   
       9 . A method as claimed in  claim 5 , wherein the method includes maintaining a list of active transmitting devices and their received signal strengths.  
   
   
       10 . A method as claimed in  claim 1 , wherein the total traffic intensity is maintained at approximately 75% of the physical layer data rate and the utilization is maintained at approximately 22%.  
   
   
       11 . A method as claimed in  claim 1 , wherein the detection threshold is conservatively increased.  
   
   
       12 . A method as claimed in  claim 11 , wherein the detection threshold is increased if it is detected a predetermined number of times in succession that the total traffic intensity is greater than 75% and the utilization is less than 22%, and wherein the detection threshold is decreased if the total traffic intensity is less than 75% and the utilization is less than 22%.  
   
   
       13 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing reception of data packets from a plurality of transmitting devices at a receiving device, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect the steps of  claim 1 .  
   
   
       14 . A receiving device for receiving data packets from a plurality of transmitting devices, comprising: 
 a receiving circuit for receiving data packets with a received signal strength above a current detection threshold;    estimator for the total traffic intensity of data packets generated by transmitting devices;    controller for adapting the detection threshold for receiving data packets as a function of the total traffic intensity.    
   
   
       15 . A device as claimed in  claim 14 , including at least one of: 
 a sensor for data packets on a communication medium at the receiving device, and    a list of active transmitting devices and their received signal strengths.    
   
   
       16 . A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing reception of data packets from a plurality of transmitting devices at a receiving device, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of  claim 14 .  
   
   
       17 . A computer program product stored on a computer readable storage medium, comprising computer readable program code means for performing the steps of: 
 sensing data packets transmitted on a communication medium;    estimating the total traffic intensity of data packets generated by the transmitting devices;    adapting a detection threshold for receiving data packets as a function of the total intensity;    ignoring data packets with a received signal strength below the current detection threshold; and    receiving data packets with a received signal strength above the current detection threshold.    
   
   
       18 . A sensor network comprising: 
 a plurality of wireless sensors having transmitters;    one or more receiving devices; and    a central server for receiving data from the one or more receiving devices;    wherein the one or more receiving devices comprising:    a receiving circuit for receiving data packets from the sensors, the data packets having a signal    strength above a current detection threshold;    an estimator for the total traffic intensity of data packets generated by the sensors; 
 a controller for adapting the detection threshold for receiving data packets as a function of the total traffic intensity; and 
 a transmitter for transmitting received data to the central server.  
 
   
   
   
       19 . A sensor network as claimed in  claim 18 . wherein the network operates on a pulse-based ultra-wide band physical layer.  
   
   
       20 . A method for receiving data from a plurality of transmitting devices at a receiving device, comprising: 
 detecting a first data packet with a first signal strength;    detecting a second data packet with a second signal strength;    comparing the first and second signal strengths;    receiving the data packet with the stronger signal strength.    
   
   
       21 . A method as claimed in  claim 20 , wherein the first and second data packets are detected in parallel.  
   
   
       22 . A method as claimed in  claim 20 , wherein the method includes 
 receiving a first data packet with a first signal strength;    detecting a second data packet with a second signal strength during the receiving process of the first data packet;    determining if the second signal strength is greater than the first signal strength;    discontinuing the receipt of the first data packet and switching to the second data packet if the second signal strength is greater than the first signal strength.    
   
   
       23 . A receiving device for receiving data packets from a plurality of transmitting devices, comprising: 
 first and second detection circuits for detecting the arrival of data packets;    a controller for comparing the signal strengths of detected data packets and selecting a data packet with the strongest signal strength;    a receiving circuit for receiving the selected data packet.    
   
   
       24 . A receiving device as claimed in  claim 23 , wherein a detection circuit detects the arrival of a second data packet with a greater signal strength than the signal strength of a first data packet in the process of being received by the receiving circuit, and the controller instructs the receiving circuit to discontinue the receipt of the first data packet and switch to the second data packet.  
   
   
       25 . A receiving device as claimed in  claim 23 , wherein the controller includes a comparator for estimating and comparing the signal strengths of data packets and a selection multiplexer for forwarding the selected data packet to the receiving circuit.