Power management for throughput enhancement in wireless ad-hoc networks

• US 6,735,448 B1
• Filed: 11/07/2000
• Issued: 05/11/2004
• Est. Priority Date: 11/07/2000
• Status: Expired due to Fees

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: ElBatt, Tamer, Connors, Dennis, Krishnamurthy, Srikanth
• Primary Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US09/708,271
• Time in Patent Office: 1,281 Days
• Field of Search: 455/522, 455/70, 455/69, 455/575, 455/445, 370/312, 370/313, 370/315, 370/318, 370/445
• US Class Current: 455/522
• CPC Class Codes: H04L 1/1692 Physical properties of the supervisory signal, e.g. acknowledgement by energy bursts
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04W 40/08 based on transmission power
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/30 for proactive routing
• CPC Class Codes: H04W 40/32 for defining a routing cluster membership
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/46 in multi hop networks, e.g. wireless relay networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The present invention relates to power management within the context of wireless ad-hoc networks. More specifically to the effects of using different transmit powers on the average power consumption and end-to-end network throughput in a wireless ad-hoc environment. This power management approach reduces the system power consumption and thereby prolongs the battery life of mobile nodes. Furthermore, the invention improves the end-to-end network throughput as compared to other ad-hoc networks in which all mobile nodes use the same transmit power. The improvement is due to the achievement of a tradeoff between minimizing interference ranges, reduction in the average number of hops to reach a destination, reducing the probability of having isolated clusters, and reducing the average number of transmissions including retransmissions due to collisions. The present invention provides a network with better end-to-end throughput performance, and lower transmit power.

Claims

1. A method for improving end-to-end network data throughput in wireless ad hoc networks by optimizing transmitter output power, comprising the steps of:

a. setting the transmittance power of a first node such that the transmittance power is sufficient only to contact said first node'"'"'s closest neighboring nodes;

b. operating the node for a pre-specified period of time;

c. computing end-to-end network throughput of said node when said pre-specified period of time has elapsed, and storing a first value, η

<sub>N−

1</sub>;

d. increasing the transmittance power of said first node such that a connectivity range includes at least one additional node;

e. operating the node for a pre-specified period of time;

f. computing a new value of the average end-to-end network throughput and storing this second value, η

_N;

g. comparing said first value to said second value

i. if(η

_N>

η

<sub>N−

1</sub>) then increase the transmittance power such that the connectivity range to includes at least one additional node and go to step h;

ii. else reduce the transmittance power and connectivity range to exclude at least one node, and go to step h;

h. comparing, at each pre-specified period of time, the end-to-end network throughput with the throughputs achieving greater and lesser transmittance power, and so long as the existing power level provides results that are superior to those obtained with greater or lesser transmittance power, not changing the transmittance power;

i. periodically determining if a greater transmittance power achieves a higher throughput, then further increasing the transmittance power in order to discover a new maximum throughput;

j. going to step h.

2. The method for improving end-to-end network data throughput in wireless ad hoc networks of claim 1 wherein the pre-specified period of time may be varied depending on movement patterns of the wireless ad-hoc network.

3. The method for improving end-to-end network data throughput in wireless ad hoc networks of claim 1 wherein the pre-specified period of time is specified remotely.

4. The method for improving end-to-end network data throughput in wireless ad hoc networks of claim 1 wherein the pre-specified period of time is vanishingly small.

5. The method for improving end-to-end network data throughput in wireless ad hoc networks of claim 1 wherein a full range of transmittance powers are initially tested so as to minimize the possibility of selecting a local extreme.

6. The method of optimizing power consumption in a network, the network having a first node, a second node, and a third node, the method comprising steps of:

sending a beacon signal from the first node at a known transmit power;

measuring a received power level of the beacon signal at the second node;

calculating an optimum transmit power from the second node to the first node based upon the known transmit power and the received power level of the beacon;

utilizing the optimum transmit power when sending data from the second node to the first node;

transmitting a second beacon signal from the third node at a known transmit power level;

measuring a received power level of the second beacon signal at the second node;

ranking, by the second node, the first and third nodes based upon the received power level of the beacon signal from the first node and the received power level of the second beacon signal from the third node; and

picking a closest node based upon the step of ranking.