Enhanced coexistence beacon protocol (ECBP) for precise intercell synchronization of overlapping wireless base stations

• US 8,446,893 B2
• Filed: 12/14/2007
• Issued: 05/21/2013
• Est. Priority Date: 12/21/2006
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ji, Baowei, Semper, William Joseph
• Primary Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US11/957,292
• Publication Number:
  US 20080159258A1
• Time in Patent Office: 1,985 Days
• Field of Search: None
• US Class Current: 370/350
• CPC Class Codes: H04B 7/2696 Over the air autonomous synchronisation, e.g. by monitoring network activity H04B7/2693 takes precedence
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver
• CPC Class Codes: H04W 92/20 between access points

Abstract

A method for synchronizing overlapping cells covered by different base stations include obtaining a propagation delay between a first base station and a second base station, scheduling by the first base station a selected one of first users located in a first cell covered by the first base station to transmit a first data packet which is a part of a transmission data frame, transmitting at the selected one the first users a transmission offset indicating the difference in a time domain between the beginning of the transmission data frame and the first data packet, in response to the reception of the first data packet, recording a reception offset at a selected one of second users located in a second cell covered by the second base station, the reception offset indicating the difference in time domain between the beginning of a reception data frame and the first data packet, transmitting at the selected one of the second users the reception offset to the second base station, calculating at the second base station a frame slide by adding the transmission offset and the propagation delay, and subtracting the reception offset, and synchronizing the first cell and the second cell based upon the calculated frame slide.

Claims

1. A method for synchronizing overlapping cells, the method comprising:

receiving, from a first customer premise equipment (CPE), a first data packet and a transmission offset indicating the difference in a time domain between the beginning of a transmission data frame and the first data packet, wherein the first CPE is located in a first cell covered by a first base station;

receiving, from a second CPE located in a second cell covered by a second base station, a reception offset recorded in response to the reception of the first data packet and indicating the difference in time domain between the beginning of a frame at the second base station and the first data packet, the second CPE different than and physically separated from the first CPE;

obtaining a propagation delay between the first CPE served by the first base station and the second CPE served by the second base station;

calculating, at the second base station, a frame slide by adding the transmission offset and the propagation delay, and subtracting the reception offset; and

synchronizing the first base station and the second base station based upon the calculated frame slide,

wherein the obtaining of the propagation delay between the first CPE and the second CPE comprises;

receiving, from the first CPE, a second data packet carrying information regarding the geographical location of the first CPE; and

receiving, from the second CPE, the propagation delay of the first data packet calculated in response to reception of the second data packet based on the information regarding the location of the first CPE.

2. The method of claim 1, comprising, when a geographic location of one of the first CPE and the second CPE is unknown, calculating the propagation delay between the first CPE and the second CPE using round-trip communication information without regard to the geographical location of the first CPE.

3. The method of claim 1, wherein obtaining the propagation delay between the first CPE and the second CPE comprises:

generating location information including geographical location information of a plurality of CPEs located within the first cell, wherein the location information is associated with corresponding identifiers;

broadcasting the generated location information;

receiving from the first CPE the first data packet carrying an identifier of the first CPE; and

receiving, from the second CPE, a propagation delay calculated in dependence upon the geographical location information of the first CPE determined in response to the reception of the first data packet from the broadcast location information using the corresponding identifier for the first CPE.

4. The method of claim 1, wherein obtaining the propagation delay between the first CPE and the second CPE comprises:

selecting, by the first base station, a subset of first CPEs for data transmission, wherein the first CPEs are located in the first cell covered by the first base station;

indicating a certain one of the first CPEs that may transmit a first reference data packet in a first time interval in response to a first contention, by the subset of first CPEs, for a right to transmit a first reference data packet in a first time interval;

receiving, from the certain one of the first CPEs which won the first contention, the first reference data packet;

selecting, by the second base station, a subset of second CPEs for data reception, wherein the second CPEs are located in the second cell covered by the second base station;

in response to reception of the first reference data packet, indicating a certain one of the first CPEs that may transmit a first reference data packet in a first time interval in response to a second contention, by the selected subset of second CPEs, for a right to transmit a second reference data packet in a second time interval;

receiving, from the certain one of the second CPEs which won the second contention, the second reference data packet; and

receiving, from the certain one of the first CPEs, a propagation delay between the certain one of the first CPEs and the certain one of the second CPEs calculated by the certain one of the first CPEs.

5. The method of claim 4, further comprising receiving a third reference data packet from the certain one of the first CPEs.

6. The method of claim 4, further comprising compensating a processing delay of the first data packet when establishing base station synchronization for the certain one of the first CPEs.

7. The method of claim 1, wherein obtaining the propagation delay between the first CPE and the second CPE comprises:

scheduling, by the first base station, the first CPE to transmit a first reference data packet;

scheduling, by the second base station, the second CPE to receive the first reference data packet;

scheduling, by the second base station, the second CPE to transmit a second reference data packet; and

receiving, from the first CPA, a propagation delay of the reference data packet calculated by the first CPE in response to reception of the second reference data packet.

8. The method of claim 7, further comprising receiving a third reference data packet receiving the first CPEs.

9. The method of claim 1, wherein the first cell and the second cell overlap.

10. A wireless communication system, comprising:

a first base station configured to;

schedule a selected one of a plurality of first CPEs located within a first cell to transmit a first data packet as part of a transmission data frame, the first base station corresponding to the first cell,

wherein the selected one of the first CPEs is configured to transmit a transmission offset indicating a difference in a time domain between a beginning of the transmission data frame and the first data packet, wherein a selected one of a plurality of second CPEs located in a second cell is configured to record a reception offset in response to reception of the first data packet, the reception offset indicating a difference in the time domain between a beginning of a data frame received at the second cell and reception of the first data packet,

wherein the second CPE different than and physically separated from the first CPE,

wherein the selected one of the second CPEs is configured to transmit the reception offset to a second base station corresponding to the second cell, and

wherein the second base station is configured to;

obtain a propagation delay between the selected one of the first CPEs served by the first base station and the selected one of the second CPEs served by the second base station;

calculate a frame slide by adding the transmission offset and the propagation delay and subtracting the reception offset; and

synchronize the first base station and the second base station based upon the calculated frame slide,

wherein the obtaining of the propagation delay by the second base station comprises;

the one of the first CPEs located in the first cell configured to transmit a second data packet carrying information regarding the geographical location of the one of the first CPEs, and

the one of the second CPEs located in the second cell configured to calculate the propagation delay of the data packet in dependence upon the information regarding the geographical location of the transmitter in response to reception of the second data packet, and to transmit the propagation delay to the second base station.

11. The wireless communication system of claim 10, comprising, when the one of the second CPEs has knowledge of geographical location of itself, the one of the first CPEs configured to transmit the second data packet carrying information regarding a distance between the one of the first CPEs and the one of the second CPEs.

12. The wireless communication system of claim 10, the second base station is configured to obtain the propagation delay between the selected one of the first CPEs and the selected one of the second CPEs, the system further comprising:

a global positioning system configured to generate location information including geographical location information of a plurality of first CPEs located within the first cell, wherein the location information is associated with corresponding identifiers; and

broadcast the generated location information,

wherein the one of the first CPEs is configured to transmit a second data packet carrying an identifier of the one of the first CPEs,

wherein the one of the second CPEs is configured to retrieve the geographical location information of the one of the first CPEs from the location database in dependence upon the identifier in response to the reception of the second data packet, to calculate at a propagation delay in dependence upon the information regarding the location of the one of the first CPEs, and to transmit the propagation delay to the second base station.

13. The wireless communication system of claim 10, wherein the second base station is configured to obtain the propagation delay between the selected one of the first CPEs and the selected one of the second CPEs wherein the first base station is configured to select a subset of first CPEs in contention for a right to transmit a first reference data packet in a first time interval, and to receive, from a certain one of the first CPEs which won the contention, the first reference data packet,

wherein the second base station is configured to:

select a subset of second CPEs in contention for a right to transmit a second reference data packet in a second time interval; and

to receive, from a certain one of the second CPEs which won the contention, the second reference data packet and to receive a propagation delay between the certain one of the first CPEs and the certain one of the second CPEs calculated by the certain one of the first CPEs.

14. The wireless communication system of claim 13, wherein the first base station is configured to receive a third reference data packet from the certain one of the first CPEs.

15. The wireless communication system of claim 10, wherein the first base station is configured to compensate for a processing delay of the first data packet when establishing base station synchronization.

16. The wireless communication system of claim 10, the second base station is configured to obtain the propagation delay between the selected one of the first CPEs and the selected one of the second CPEs wherein the first base station is configured to schedule the one of the first CPEs to transmit a first reference data packet, and

wherein the second base station is configured to schedule the one of the second CPEs to receive the first reference data packet, to schedule the one of the second CPEs to transmit a second reference data packet, to receive a propagation delay of the reference data packet calculated in response to reception of the second reference data packet at said one of the first users the propagation delay to the second base station.

17. The wireless communication system of claim 16, wherein the first base station is configured to receive a third reference data packet from one of the first CPEs.

18. The wireless communication system of claim 10, wherein the first cell and the second cell overlap.

19. A method for synchronizing base stations with overlapping cells, the method comprising:

receiving, from a first CPE, a first data packet with location information of the first CPE and a transmission offset indicating the difference in a time domain between the beginning of a transmission data frame and the first data packet in a first base station corresponding to a first cell, wherein the first data packet is received by a second CPE which records the location information of the first CPE and a reception offset indicating the difference in a time domain between a beginning of a data frame and reception of the first data packet in a second base station corresponding to a second cell, the second CPE different than and physically separated from the first CPE; and

obtaining a propagation delay between the first CPE served by the first base station and the second CPE served by the second base station based on the recorded location information of the first CPE, and

wherein a frame slide is calculated by adding the transmission offset and the propagation delay and subtracting the reception offset,

wherein the obtaining of the propagation delay between the first CPE and the second CPE comprises;

receiving, from the first CPE, a second data packet carrying information regarding the geographical location of the first CPE; and

receiving, from the second CPE, the propagation delay of the first data packet calculated in response to reception of the second data packet based on the information regarding the location of the first CPE.

20. The method of claim 19, further comprising synchronizing the first base station and the second base station based upon the calculated frame slide.

21. The method of claim 19, wherein the first CPE is located in the first cell covered by a first base station, and the second CPE is located in the second cell covered by a second base station.

22. A wireless communication system comprising:

a first base station constituting a first cell; and

a second base station constituting a second cell,

wherein the second base station is configured to be synchronized with the first base station by;

receiving from a first CPE a first data packet with location information of the first CPE and a transmission offset indicating a difference in a time domain between a beginning of a transmission data frame and the first data packet in the first base station corresponding to the first cell, wherein the first data packet is received by the second CPE, which records the location information of the first CPE and a reception offset indicating the difference in the time domain between the beginning of a frame and reception of the first data packet in the second base station corresponding to the second cell, the second CPE different than and physically separated from the first CPE;

obtaining a propagation delay between the first CPE served by the first base station and the second CPE served by the second base station based on the recorded location information of the first CPE; and

calculating a frame slide by adding the transmission offset and the propagation delay and subtracting the reception offset,

wherein the obtaining of the propagation delay by the second base station comprises;

the one of the first CPEs located in the first cell configured to transmit a second data packet carrying information regarding the geographical location of the one of the first CPEs, and

the one of the second CPEs located in the second cell configured to calculate the propagation delay of the first data packet in dependence upon the information regarding the geographical location of the transmitter in response to reception of the second data packet, and to transmit the propagation delay to the second base station.

23. The wireless communication system of claim 22, wherein the first CPE is located in the first cell covered by the first base station, and the second CPE is located in the second cell covered by the second base station.