WIRELESS TRANSMISSION SYSTEM

• US 20150036619A1
• Filed: 07/29/2014
• Published: 02/05/2015
• Est. Priority Date: 08/01/2013
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: MIYAZAKI, Masayuki, NISHIMURA, Haruki, FUJIWARA, Ryosuke, KATAGISHI, Makoto
• Granted Patent: US 9,967,895 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Provided is a wireless transmission system including a plurality of access points and an access controller. The access controller determines a start standard time for a polling period for the plurality of access points to perform polling communication with a plurality of wireless terminals. The access controller generates a scheduling setting information indicating timings when the plurality of access points perform polling communication with the plurality of wireless terminals during the polling period. The access controller transmits, to each of the plurality of access points, a polling period start signal including the start standard time and a corresponding portion of the scheduling setting information for each of the plurality of access points. The plurality of access points perform polling communication with the plurality of wireless terminals based on respective polling period start signals.

Claims

1. A wireless transmission system comprising:

a plurality of access points configured to communicate with wireless terminals connected with the plurality of access points; and

an access controller configured to communicate with the plurality of access points,

wherein each of the plurality of access points retains first information indicating wireless terminals included in a corresponding coverage area of each of the plurality of access points, and second information indicating wireless terminals connected with the corresponding access point within the corresponding coverage area,

wherein each of the plurality of access points transmits updated information of the first information and the second information to the access controller,

wherein the access controller retains third information indicating correlations between the plurality of access points and wireless terminals included in coverage areas of the plurality of access points, and fourth information indicating correlations between the plurality of access points and the wireless terminal connected with the plurality of access points,

wherein the access controller updates the third information and the fourth information based on the updated information received from the plurality of access points,

wherein the access controller determines a start standard time for a polling period for the plurality of access points to perform polling communication with a plurality of wireless terminals,

wherein the access controller generates a scheduling setting information indicating timings when the plurality of access points perform polling communication with the plurality of wireless terminals during the polling period based on the updated third information and updated fourth information,

wherein the access controller transmits, to each of the plurality of access points, a polling period start signal including the start standard time and a corresponding portion of the scheduling setting information for each of the plurality of access points, and

wherein the plurality of access points perform polling communication with the plurality of wireless terminals based on respective polling period start signals.

2. The wireless transmission system according to claim 1,

wherein the scheduling setting information regulates a communication phase for each of the plurality of access points to perform communication with the plurality of wireless terminals during the polling period, and

wherein the communication phases of the plurality of access points are scheduled to include no overlapping portion mutually.

3. The wireless transmission system according to claim 2,

wherein the communication phase includes an exhaustive polling phase in which polling communication is performed to all wireless terminals connected to an access point, and a selective polling phase in which polling communication is performed with a wireless terminal failed communication during the exhaustive polling phase, and

wherein the access controller determines a length of the selective polling phase based on the number of wireless terminals connected with the access point.

4. The wireless transmission system according to claim 1,

wherein the scheduling setting information regulates a communication phase for each of the plurality of access points to communicate with the plurality of wireless terminals during the polling period,

wherein the communication phase includes a polling phase in which polling communication is performed, and a CSMA phase in which CSMA communication is performed after the polling phase, and

wherein the polling phase is scheduled to include no overlapping portion with communication phases of other access points, and CSMA phases of all of the plurality of access points are scheduled to coincide with one another.

5. The wireless transmission system according to claim 4,

wherein the plurality of access points transmit polling phase end notices to the access controller,

wherein the access controller instructs a start of the polling phase to the plurality of access points sequentially in response to the polling phase end notices, and

wherein the access controller instructs all of the plurality of access points to start the CSMA phase in response to a last polling phase end notice from one of the plurality of access points.

6. The wireless transmission system according to claim 1,

wherein the scheduling setting information regulates an exhaustive polling phase for each of the plurality of access points to perform polling communication with all of wirelessly connected wireless terminal during the polling period, and

wherein the access controller receives, from each of the plurality of access points, an exhaustive polling phase end notice indicating the number of wireless terminals which failed communication during the exhaustive polling phase,

wherein the access controller generates second scheduling setting information after receiving the exhaustive polling phase end notices from all of the plurality of access points,

wherein the second scheduling setting information regulates a selective polling phase for each of the plurality of access points to perform polling communication with the wireless terminals which failed communication during the exhaustive polling phase,

wherein the access controller determines the selective polling phase based on the number of the wireless terminals which failed the communication during the exhaustive polling phase indicated in the end notification,

wherein the access controller transmits, to each of the plurality of access points, a selective polling phase start signal including a corresponding portion of the second scheduling setting information for each of the plurality of access points, and

wherein each of the plurality of access points performs selective polling communication based on the received selective polling phase start signal.

7. The wireless transmission system according to claim 1,

wherein the scheduling setting information regulates an exhaustive polling phase for each of the plurality of access points to perform communication with all connected wireless terminals during the polling period,

wherein at least a portion of exhaustive polling phases of the plurality of access points overlap with one another, and

wherein, during the exhaustive polling phases of the plurality of access points, when one wireless terminal is performing polling communication with one of the plurality of access points, other wireless terminals of the plurality of access points which are located in a coverage area of the wireless terminal performing the polling communication are prohibited from performing polling communication.

8. A method to control a plurality of access points configured to communication with connected wireless terminals,

wherein each of the plurality of access points retains first information indicating wireless terminals included in a corresponding coverage area of each of the plurality of access points, and second information indicating wireless terminals connected with the corresponding access point within the corresponding coverage area,

the method comprising:

receiving updated information of the first information and the second information to the access controller from each of the plurality of access points,

updating, based on the updated information received from the plurality of access points, third information indicating correlations between the plurality of access points and wireless terminals included in coverage areas of the plurality of access points, and fourth information indicating correlations between the plurality of access points and the wireless terminal connected with the plurality of access points,

determining a start standard time for a polling period for the plurality of access points to perform polling communication with a plurality of wireless terminals,

generating a scheduling setting information indicating timings when the plurality of access points perform polling communication with the plurality of wireless terminals during the polling period based on the updated third information and updated fourth information, and

transmitting, to each of the plurality of access points, a polling period start signal including the start standard time and a corresponding portion of the scheduling setting information for each of the plurality of access points

9. The method according to claim 8,

wherein the scheduling setting information regulates a communication phase for each of the plurality of access points to perform communication with the plurality of wireless terminals during the polling period, and

wherein the communication phases of the plurality of access points are scheduled to include no overlapping portion mutually.

10. The method according to claim 9,

wherein the communication phase includes an exhaustive polling phase in which polling communication is performed to all wireless terminals connected to an access point, and a selective polling phase in which polling communication is performed with a wireless terminal failed communication during the exhaustive polling phase,

the method further comprising determining a length of the selective polling phase based on the number of wireless terminals connected with the access point.

11. The method according to claim 8,

wherein the scheduling setting information regulates a communication phase for each of the plurality of access points to communicate with the plurality of wireless terminals during the polling period,

wherein the communication phase includes a polling phase in which polling communication is performed, and a CSMA phase in which CSMA communication is performed after the polling phase, and

wherein the polling phase is scheduled to include no overlapping portion with communication phases of other access points, and CSMA phases of all of the plurality of access points are scheduled to coincide with one another.

12. The method according to claim 11, further comprising:

receiving polling phase end notices from the plurality of access points;

instructing a start of the polling phase to the plurality of access points sequentially in response to the polling phase end notices; and

instructing all of the plurality of access points to start the CSMA phase in response to a last polling phase end notice from one of the plurality of access points.

13. The method according to claim 8,

wherein the scheduling setting information regulates an exhaustive polling phase for each of the plurality of access points to perform polling communication with all of wirelessly connected wireless terminal during the polling period,

the method further comprising:

receiving, from each of the plurality of access points, an exhaustive polling phase end notice indicating the number of wireless terminals which failed communication during the exhaustive polling phase,

generating second scheduling setting information after receiving the exhaustive polling phase end notices from all of the plurality of access points, the second scheduling setting information regulating a selective polling phase for each of the plurality of access points to perform polling communication with wireless terminals which failed communication during the exhaustive polling phase;

determining the selective polling phase based on the number of wireless terminals which failed the communication during the exhaustive polling phase indicated in the end notification;

transmitting, to each of the plurality of access points, a selective polling phase start signal including a corresponding portion of the second scheduling setting information for each of the plurality of access points in the second scheduling setting information

14. The method according to claim 8,

wherein the scheduling setting information regulates an exhaustive polling phase for each of the plurality of access points to perform communication with all connected wireless terminals during the polling period,

wherein at least a portion of exhaustive polling phases of the plurality of access points overlap with one another, and

wherein, during the exhaustive polling phases of the plurality of access points, when one wireless terminal is performing polling communication with one of the plurality of access points, other wireless terminals of the plurality of access points which are located in a coverage area of the wireless terminal performing the polling communication are prohibited from performing polling communication.