System and method for reducing power consumption in a wireless communications network

• US 6,996,368 B2
• Filed: 01/21/2003
• Issued: 02/07/2006
• Est. Priority Date: 01/21/2003
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Zhang, Jinyun, Sahinoglu, Zafer, Orlik, Philip
• Primary Examiner(s): Vuong, Quochien B.
• Application Number:
  US10/347,896
• Publication Number:
  US 20040198467A1
• Time in Patent Office: 1,113 Days
• Field of Search: 455/7, 455/11.1, 455/12.1, 455/13.1, 455/427, 455/445, 455/522, 455/343.1, 455/574, 375/211
• US Class Current: 455/7
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04W 52/0277 according to available power supply, e.g. switching off when a low battery condition is detected
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/288 taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method reduces power consumption in a multi-hop wireless communications network including a plurality of nodes. At a source node, a first power requirement for relaying a signal to a destination node through an intermediate node using an amplification mode is determined. A second power requirement for relaying the signal the destination node through the intermediate node using a regeneration mode is also determined at the source node. A relay request message is transmitted to the intermediate node, the relay request message including the first and second power requirements.

Claims

1. A method for reducing power consumption in a multi-hop wireless communications network including a plurality of nodes, comprising;

determining, at a source node, a first power requirement for relaying a signal to a destination node through an intermediate node using an amplification mode;

determining, at the source node, a second power requirement for relaying the signal to the destination node through the intermediate node using a regeneration mode; and

transmitting a relay request message to the intermediate node, the relay request message including the first and second power requirements.

2. The method of claim 1 wherein the source node determines a required transmission power on a direct path from the source node to the destination node by α

_te^AB=α

_red_ab^γ

10^xab/10, watts, where α

_re is a required received power at a destination node to meet a bit error rate requirement, Pr_e, d_ab is a distance between the source node and the destination node, where γ

is a pathloss exponent and x_ab is a shadowing loss, in decibels.

3. The method of claim 2, wherein a power savings is a difference between the first or second power requirement and the required transmission power on the direct path (α

_te^A, α

_te^C), respectively, and further comprising;

determining the power savings using regeneration mode as Δ

α

_regen=α

_te^A+α

_te^C−

α

_te^AB+P_c, where P_c is the power consumption of the intermediate node.

4. The method of claim 3 wherein optimal bit error rates at the intermediate node and the destination node are

(*Pr_e^ac, *Pr_e^cb), respectively, a bit error rate requirement,

*Pr_e^ac+*Pr_e^cb=Pr_e, for relay mode will satisfy $\begin{array}{c}\ln \end{array}$

(dacγ

⁢

10xac/10dcbγ

⁢

10xcb/10)=⁢

ln⁡

(Q-1⁡

(log2⁢

M(1-1/M)⁢

(Preab-Preac)))+⁢

(erf-1⁡

(1-2⁢

log2⁢

M(1-1/M)⁢

(Preab-Preac))2-⁢

(erf-1⁡

(1-2⁢

log2⁢

M4⁢

(1-1/M)⁢

Preac))2-⁢

ln⁡

(Q-1⁡

(2⁢

log2⁢

M4⁢

(1-1/M)⁢

Preac))

where M is a number of signal constellations, d_ab is a distance between the source node and the destination node, d_cb is a distance between the intermediate node and the destination node, and *Pr_e^cb is found by *Pr_e^cb=Pr_e−

*Pr_e^ac, and where * is an optimal operator.