Method for propagation delay control

• US 6,205,157 B1
• Filed: 06/12/1997
• Issued: 03/20/2001
• Est. Priority Date: 11/01/1996
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Jung, Stefan Wilhelm, Galyas, Johan Karoly Peter
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): Duong, Frank
• Application Number:
  US08/873,524
• Time in Patent Office: 1,377 Days
• Field of Search: 370/315, 370/321, 370/337, 370/347, 370/350, 370/442, 370/503, 370/328, 370/336, 370/345, 370/508, 370/509
• US Class Current: 370/503
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver
• CPC Class Codes: H04L 7/043 Pseudo-noise [PN] codes variable during transmission synchronisation of spread spectrum receivers H04B1/69

Abstract

A method for maintaining synchronization between a base transceiver station (BTS) and an interworking function (IWF) within a cellular communications network is disclosed. The method utilizes a synchronization procedure between the IWF and the BTS that makes the IWF aware of propagation delays between the IWF and BTS. The IWF utilizes this information to adapt to the delays such that the correct sequence is unpacked uplink when obtained from the base transceiver station. The IWF also uses synchronization data to control transmissions from the IWF to the BTS such that frame numbers and timeslots are received at the BTS in the correct sequence.

Claims

1. A method for synchronizing transmission of a data stream between a wireline network node and a base transceiver station, the base transceiver station connected with an air interface within a cellular communications system, the method comprising the steps of:

a) transmitting from the base transceiver station to the wireline network node uplink synchronization frames containing uplink synchronization data;

b) transmitting from the wireline network node to the transceiver station downlink synchronization frames containing downlink synchronization data in response to receipt of the uplink synchronization frames;

c) determining from the uplink synchronization data, an unpacking sequence for time slots of the data stream transmitted over independently routable subchannels of a wireline transport network between the wireline network node and the base transceiver station; and

d) unpacking the data stream according to the determined unpacking sequence such that the time slots are unpacked in increasing sequence number order.

2. The method of claim 1 further including the steps of:

receiving downlink information at the wireline network node within the uplink synchronization frames;

determining delays for the subchannels from the downlink information; and

transmitting the data stream on the subchannels in accordance with the determined delays.

3. The method of claim 2 wherein the step of determining delays for the subchannels further comprises the step of delaying transmission on each subchannel such that frame numbers and timeslots are received in increasing downlink sequence number order at the base transceiver station.

4. The method of claim 1 wherein the step of determining the unpacking sequence comprises the step of determining a phase of frames from the subchannels having a same uplink frame number and uplink sequence number.

5. The method of claim 1 further including the steps of:

calculating a time margin between the downlink synchronization frames and the air interface; and

minimizing delays between the wireline network node and the base transceiver station using the time margin.

6. The method of claim 1 wherein the wireline network node comprises an interworking function.

7. The method of claim 1 wherein the wireline network node comprises a packet control unit.

8. The method of claim 1 wherein the step of transmitting from the base transceiver station to the wireline network node further includes the step of adjusting an adjusted frame number uplink of each uplink synchronization frame to a last received burst in a corresponding channel coding block.

9. The method of claim 1 wherein the step of transmitting from the base transceiver station to the wireline network node further includes the step of adding an uplink sequence number to each uplink synchronization frame.

10. The method of claim 1 wherein the step of transmitting from the base transceiver station to the wireline network node further includes the step of attaching downlink information to the uplink synchronization frame.

11. The method of claim 1 wherein the step of transmitting from the wireline network node to the base transceiver station comprises the step of attaching a downlink sequence number to the downlink synchronization frame.

12. A method for synchronizing transmission of a data stream between a wireline network node and a base transceiver station, the base transceiver station connected with an air interface within a cellular communications system, the method comprising the steps of:

a) transmitting from the base transceiver station to the wireline network node uplink synchronization frames comprising V.110 frames containing uplink synchronization data, the uplink synchronization frames each containing an adjusted frame number uplink and an uplink sequence number;

b) transmitting from the wireline network node to the base transceiver station, in response to receipt of the uplink synchronization frames, downlink synchronization frames comprising V.110 frames containing downlink synchronization data, the downlink synchronization frames each containing a downlink sequence number;

c) comparing a phase of frames from independently routable subchannels of a wireline transport network between the wireline network node and the base transceiver station with the same adjusted frame number uplink and uplink sequence number to determine an unpacking sequence for the data stream transmitted over the independently routable subchannels; and

d) unpacking the transmitted data stream according to the determined unpacking sequence such that the data stream is unpacked in increasing sequence number order.

13. The method of claim 12 further including the steps of:

receiving downlink information at the wireline network node within the uplink synchronization frames;

determining delays for the subchannels from the downlink information; and

transmitting on the subchannels according to the determined delays.

14. The method of claim 13 wherein the step of determining delays for the subchannels further comprises the step of delaying each subchannel such that frame numbers and timeslots are received in increasing downlink sequence number order at the base transceiver station.

15. The method of claim 12 further including the steps of:

calculating a time margin between downlink synchronization frames and the air interface; and

minimizing the delays of the subchannels between the wireline network node and the base transceiver station using the time margin.

16. The method of claim 12 wherein the wireline network node comprises an interworking function.

17. The method of claim 12 wherein the wireline network node comprises a packet control unit.

18. The method of claim 12 wherein the step of transmitting from the base transceiver station to the wireline network node further includes the step of adding an uplink sequence number to each uplink synchronization frame.

19. The method of claim 12 wherein the step of transmitting from the wireline network node to the base transceiver station comprises the step of attaching a downlink sequence number to the downlink synchronization frame.

20. A method for synchronizing transmission of a data stream between a first node and a second node connected within an interface of a wireline transport network within a cellular communications system, comprising the steps of:

initializing a synchronization request from the second node;

transmitting synchronization frames to determine a corresponding timing delay for independently routable subchannels of the wireline transport network between the first node and the second node in response to the synchronization request;

determining the corresponding timing delay of the independently routable subchannels of the wireline transport network between the first and the second node; and

controlling the data stream at the first node in response to the determined timing delay.

21. The method of claim 20 wherein the step of initializing further comprises the step of transmitting uplink synchronization frames from the second node to the first node.

22. The method of claim 20 wherein the step of transmitting further includes the step of transmitting downlink synchronization frames containing downlink synchronization data.

23. The method of claim 20 wherein the step of determining further includes the steps of:

calculating the timing delay at the second node from the synchronization frames; and

transmitting the timing delay back to the first node.

24. The method of claim 23, further including the step of determining an unpacking sequence for timeslots of the transmitted data stream.

25. The method of claim 24 wherein the step of controlling comprises the step of unpacking the data stream according to the unpacking sequence.

26. The method of claim 23, further including the step of determining delays for each subchannel of the wireline transport network from the timing delay.

27. The method of claim 26 wherein the step of controlling comprises the step of transmitting over the subchannels according to the determined delays.

28. The method of claim 20 wherein the second node comprises a base transceiver station and the first node comprises an interworking function.

29. The method of claim 20 wherein the second node comprises a base transceiver station and the first node comprises a packet control unit.