Power efficient wireless system for sensor network

• US 20050122231A1
• Filed: 11/08/2004
• Published: 06/09/2005
• Est. Priority Date: 12/08/2003
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Coleri Ergen, Sinem, Varaiya, Pravin
• Granted Patent: US 7,738,413 B2
• Time in Patent Office: Days
• US Class Current: 340/870.10
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 52/0238 where the received signal is an unwanted signal, e.g. interference or idle signal
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 52/0254 detecting a user operation or a tactile contact or a motion of the device
• CPC Class Codes: H04W 72/1268 of uplink data flows
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 84/22 with access to wired networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A power efficient system architecture that exploits the characteristics of sensor networks in order to decrease the power consumption in the network. The primary characteristic of sensor networks is that the destination of all the data packets in the network is a central data collector and this central data collector, which is usually denoted as access point (AP), has unlimited transmission power and energy whereas the sensor nodes have limited battery energy and transmission power. The system uses the AP to directly synchronize and explicitly schedule the nodes'"'"' transmissions over Time Division Multiple Access (TDMA) time slots.

Claims

1. A power efficient wireless system for a sensor network comprising:

a) at least one access point including a processor and a transceiver for transmitting signals to and receiving signals from a plurality of sensor nodes,

b) a plurality of sensor nodes each including a processor and a transceiver for receiving signals from the access point and transmitting data packets to the access point, and

c) a communication network including wireless one hop broadcast of downlink signals from the access point to the plurality of sensor nodes, and transmission of uplink signals from the plurality of sensor nodes to the access point through a plurality of channels using time division multiple access and assigned to the sensor nodes by the access point using a scheduling mechanism.

2. The system as defined by claim 1 wherein said communication network includes a carrier sense multiple access mode for sensor nodes responding to the access point with neighbor and interferer information in response to a starting topology communication from the access point.

3. The system as defined by claim 2 wherein the starting topology communication includes a tree construction packet the sensor nodes determining neighbors and interferers based on the tree construction packet, and the parent node based on lowest cost to the access point.

4. The system as defined by claim 3 wherein the access points starts a topology collection phase by transmitting a coordination packet to the plurality of sensor nodes in one hop, the sensor nodes then sending neighbor and interferer information using carrier sense multiple access protocol.

5. The system as defined by claim 4 wherein the access point responds to neighbor and interferer information from the plurality of sensor nodes by scheduling assigned channels and transmission time to the plurality of sensor nodes.

6. The system as defined by claim 4 wherein the access point transforms the original sensor node network into a linear network, colors nodes the same color from a maximal independent set of the linear network, and schedules links of the original network based on coloring of the linear network.

7. A power efficient wireless system for a sensor network comprising:

a) a plurality of sensor nodes each including a transceiver,

b) at least one access point including a transceiver for transmitting signals to and receiving signals from the plurality of sensors,

c) a communication network for communication between the sensor nodes and the access point, wherein the access point determines a communication schedule for the sensor using time division multiple access uplink channels from the sensors to the access point based on neighbor and interferer information received from each sensor node.

8. The system as defined by claim 7 wherein the access point initially transmits a coordination packet and a tree construction packet to all sensor nodes in one hop, the sensor nodes responding using carrier sensing multiple access to communicate neighbor and interferer information to the access point.

9. The system as defined by claim 8 wherein the sensor nodes are traffic sensors.

10. The system as defined by claim 9 wherein the traffic sensors are acoustic.

11. The system as defined by claim 9 wherein the traffic sensors are magnetic.

12. The system as defined by claim 8 wherein the sensor nodes are parking sensors.

13. A method of controlling a wireless system for communicating between a plurality of sensor nodes each including a sensor, a processor, and a transceiver and an access point including a processor and a transceiver having more power than each of the sensor nodes, said method comprising:

a) the access point transmitting in one hop to all sensor nodes a coordination packet and a tree construction packet,

b) each sensor node responding to the access point using carrier sense multiple access with neighbor and interferer information, and

c) said access point responding to received neighbor and interferer information by assigning time division multiple access channels to the sensor nodes whereby the sensor nodes have a sleep mode except during the assigned time division channel.

14. The method of claim 13 wherein the access point responds to neighbor and interferer information from the plurality of sensor nodes by scheduling assigned channels and transmission time to the plurality of sensor nodes.

15. The method of claim 14 wherein the access point transforms the original sensor node network into a linear network, colors nodes a same color from a maximal independent set of the linear network, and schedules links of the original network based on coloring of the linear network.

16. A traffic control radio communication system comprising:

a) a plurality of nodes each including a vehicle detection sensor,

b) an access point coupled to the plurality of nodes for gathering information on the node network and broadcasting periodic schedules to the nodes for listening, transmitting data using a carrier sense multiple access (CSMA) protocol, and sleeping, and

c) a communication link of the plurality of nodes to the access point.

17. The traffic control radio communication system as defined by claim 16 wherein the communication link uses time division multiple access (TDMA) for defining communication channels.

18. The traffic control radio communication system as defined by claim 16 wherein the vehicle detection sensor is magnetic.

19. The traffic control radio communication system as defined by claim 16 wherein the vehicle detection sensor is acoustic.