Internal signaling method to support clock synchronization of nodes connected via a wireless local area network

• US 20030169774A1
• Filed: 12/13/2002
• Published: 09/11/2003
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Choi, Sunghyun, Del Prado Pavon, Javier
• Granted Patent: US 7,236,502 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04J 3/0652 Synchronisation among time division multiple access [TDMA] nodes, e.g. time triggered protocol [TTP] bus network with centralized control in which slots are of a TDMA packet structure H04L12/4035

Abstract

This invention discloses a set of internal signaling (i.e., management primitives) to support a clock-synchronization protocol for wirelessly synchronizing clock registers of wired or wireless nodes via a wireless local area network (i.e., 802.11 network). The clock synchronization is performed between two higher-layer protocol entities residing within two different wireless stations (STAs).

Claims

1. In a communication system including a plurality of non-master nodes communicatively coupled to a network, each of said plurality of non-master nodes having a local time base, one of said plurality of non-master nodes being designated as a master node having a master time base which serves as a master clock against which said non-master local time bases are synchronized, a method for supporting clock synchronization in a higher-layer protocol of said master and non-master nodes, the method comprising the steps of:

(a) making a synchronization request at a higher-layer protocol of said master node;

(b) issuing a request primitive from a station management entity (SME) associated with said node to a MAC layer management entity (MLME) requesting a synchronization-support mechanism;

(c) determining, at said MLME, whether to accept said synchronization-support-mechanism request at said step (b);

(d) issuing a confirm primitive, from said MLME to said SME indicating that said synchronization-support mechanism is supported, where said request is accepted at said step (c).

(e) reporting one of a reception and transmission of a frame from a physical layer (PHY) associated with said node to said MLME; and

,

(f) issuing an indication primitive from said MLME to said SME responsive to said step (e).

2. The method of claim 1, further comprising the steps of:

terminating the synchronization request by said MLME in the case where it is determined by said MLME not to accept said synchronization-support mechanism at step (c); and

,

issuing an MLME-HL-SYNC.confirm primitive with a ResultCode parameter equal to “

Not accepted.”

3. The method of claim 1, wherein said indication primitive issued from said MLME to said SME is issued when a last symbol on air of a received or transmitted synchronization frame is detected and announced by the PHY layer.

4. The method of claim 1, wherein said request primitive transmitted from said SME to said MLME is an MLME-HL-SYNC request primitive having the general form:

5. The method of claim 1, wherein said confirmation primitive issued from said MLME to said SME is an MLME-HL-SYNC request primitive having the general form:

6. The method of claim 1, wherein the indication primitive issued from said MLME to said SME is an MLME-HL-SYNC indication primitive having the general form:

7. The method of claim 1, wherein said network is one of a wireless and wired network.

8. In a communication system including a plurality of non-master nodes communicatively coupled to a network, each of said plurality of non-master nodes having a local time base, one of said plurality of non-master nodes being designated as a master node having a master time base which serves as a master clock against which said non-master local time bases are synchronized, the system comprising:

means for making a synchronization request at a higher-layer protocol of master said node;

means for issuing a request primitive from a station management entity (SME) associated with said node to a MAC layer management entity (MLME) requesting a synchronization-support mechanism;

means for determining, at said MLME, whether to accept said synchronization-support mechanism request at said step (b);

means for issuing a confirm primitive, from said MLME to said SME indicating that said synchronization-support mechanism is supported, where said request is accepted at said step (c);

means for reporting one of a reception or transmission of a frame from a physical layer (PHY) associated with said node to said MLME; and

,

means for sending an indication primitive from said MLME to said SME responsive to said step (e).

9. The system of claim 8, further comprising:

means for terminating the synchronization request by said MLME in the case where it is determined by said MLME not to accept said synchronization-support mechanism at step (c); and

means for issuing an MLME-HL-SYNC.confirm primitive with a ResultCode parameter indicating non-acceptance of said synchronization-support mechanism.

10. The system of claim 8, wherein said means for sending an indication primitive further comprises means for indicating when a last symbol on air of a received or transmitted synchronization frame is detected and announced by the PHY layer.

11. The system of claim 8, wherein said request primitive includes at least one parameter specifying a multicast address.

12. The system of claim 8, wherein said indication primitive includes at least a first parameter for specifying the address of the MAC entity sending the synchronization frame, and a second parameter for specifying the sequence number of the synchronization frame, and a third parameter for specifying the estimated time between the generation of the primitive and the time at which some predetermined detection point of the frame that generated the primitive is detected in the air.

13. The system of claim 8, wherein said network is one of a wireless and wired network.