Saving power in wireless local area network

• US 20050047386A1
• Filed: 08/17/2004
• Published: 03/03/2005
• Est. Priority Date: 09/03/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yi, Sang-Kug
• Granted Patent: US 7,519,017 B2
• Time in Patent Office: Days
• US Class Current: 370/345
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 68/025 Indirect paging
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus includes: at least one AP (Access Point) arranged to set and transmit a bit of a beacon message corresponding to a station for exchanging traffic, to register the station on a PS-polling list upon an acknowledgment of the beacon message being received, to assign a predetermined time slot to the station, and to transmit the traffic during the time slot, when at least one piece of traffic is exchanged for wireless voice communication; and at least one station adapted to be awakened into an active mode to parse the received beacon message, to calculate the assigned time slot when a bit of the station is set, and to awaken into the active mode during the assigned time slot to exchange the traffic, when the beacon message has been received from the AP upon being in a doze mode.

Claims

1. An apparatus comprising:

at least one AP (Access Point) arranged to set and transmit a bit of a beacon message corresponding to a station for exchanging traffic, to register the station on a PS-polling list upon an acknowledgment of the beacon message being received, to assign a predetermined time slot to the station, and to transmit the at least one piece of traffic during the time slot, when at least one piece of traffic is to be exchanged for wireless voice communication; and

at least one station adapted to be awakened into an active mode to parse the received beacon message, to calculate the assigned time slot when a bit of the station is set, and to awaken into the active mode during the assigned time slot to exchange the at least one piece of traffic, when the beacon message has been received from the AP upon being in a doze mode.

2. An apparatus comprising:

a beacon message processor adapted to detect at least one of a plurality of stations intended to receive at least one piece of traffic, to set a bit of a TIM (Traffic Indication Map) corresponding to the detected station to generate a beacon message, and to transmit the generated beacon message to each station, when there is at least one piece of the traffic to be transmitted to the plurality of stations;

a time slot processor adapted to calculate a predetermined time slot to be assigned to each station; and

a table management unit adapted to provide number information to the station, to generate and manage a table storing address information and time slot information of the station upon an acknowledgment message of the beacon message being received from the station intended to receive the at least one piece of traffic.

3. An apparatus comprising:

a message processor adapted to parse a TIM (Traffic Indication Map) of a beacon message received from an AP (Access Point) and to determine whether or not a bit of the TIM of a station has been set;

a time slot calculator adapted to calculate a time when the beacon message is to be received, a start time of a time slot when traffic is to be initially received from the AP and an end time of the time slot when reception of traffic is to be terminated, upon a determination that the bit of the TIM of the station has been set by the message processor; and

a mode processor, adapted to be awakened into an active mode upon the beacon message being received when in a doze mode, awakened into the active mode at the start time of the time slot calculated by the time slot calculator upon the determination that the bit of the TIM of the station has been set by the message processor, and to be placed into the doze mode again at the end time of the slot time.

4. The apparatus according to claim 3, wherein the time slot calculator is adapted to determine that the start time of the time slot has varied upon frames not being exchanged for a predetermined number of times between the start time of the time slot assigned by the AP and the end time of the time slot, and to recalculate the start time of the time slot in response to the determination.

5. The apparatus according to claim 3, wherein the mode processor is adapted to maintain the active mode so as to allow the start time of the time slot to be calculated by the time slot calculator upon a determination that there is traffic to be received by parsing the beacon message received from the message processor, and to then maintain the active mode only between the start time of the time slot and the end time of the time slot while maintaining the doze mode.

6. A method comprising:

setting a bit of a TIM (Traffic Indication Map) corresponding to a station to generate a beacon message and transmitting the generated beacon message to each station upon there being traffic to be transmitted to an arbitrary station;

calculating a predetermined time slot and assigning the time slot to each station;

assigning number information to the stations and registering the stations on a PS-polling list upon an acknowledgment message of the beacon message being received from the station; and

assigning the calculated time slot according to the number information assigned to the stations registered on the PS-polling list, and transmitting the traffic during the time slot assigned to the stations.

7. The method according to claim 6, wherein the PS-polling list includes at least one of number information of the stations transmitting the acknowledgment message, information of the stations, and information on the start time of the time slot assigned to the stations.

8. A method comprising:

awakening at least one station from a doze mode into an active mode and parsing a TIM (Traffic Indication Map) of a beacon message upon the beacon message being received from an AP (Access Point);

generating and transmitting an acknowledgment message of the beacon message upon a bit of the TIM assigned to the station being set;

calculating a time between the next beacon message being received and the traffic being received after transmission of the acknowledgment message; and

placing the station in the doze mode upon the traffic being received, awakening the station into the active mode again upon the calculated time having elapsed, and receiving the traffic from the AP.

9. The method according to claim 8, further comprising recalculating a time for awakening the station into the active mode to receive the traffic upon traffic not being received for a predetermined number of times during the time slot assigned by the AP.

10. A method comprising:

setting a bit of a TIM (Traffic Indication Map) of a station to generate and transmit a beacon message;

awakening the station from a doze mode into an active mode and parsing the TIM of a received beacon message upon the beacon message being received;

transmitting an acknowledgment message of the beacon message to calculate a time when the traffic is to be received from an AP (Access Point) as the parsed result upon the TIM of the station being set;

registering the station on a PS-polling list at the AP upon the acknowledgment message being received from the station;

transmitting the traffic during a time slot assigned to the station with reference to the PS-polling list at the AP;

calculating a time from the station receiving the beacon message to a time that the traffic begins to be received;

placing the station from the active mode into the doze mode upon reception of the traffic from the AP being completed; and

awakening the station into the active mode after being on standby for the calculated time in the doze mode, and receiving the next traffic from the AP.

11. The method according to claim 10, further comprising awakening the station into the active mode during the time slot assigned by the AP to transmit the traffic upon there being traffic to be transmitted to the AP.

12. The method according to claim 10, further comprising recalculating a time for awakening the station into the active mode to receive traffic upon traffic not being received for a predetermined number of times during the time slot assigned by the AP.