Techniques for reducing overhead in a communications system

• US 20030176191A1
• Filed: 01/22/2003
• Published: 09/18/2003
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Tantivy Communications Incorporated (InterDigital, Inc.)
• Inventors: Johnson, Kevin P., Nelson, George Rodney Jr., Cornett, John B. Jr.
• Granted Patent: US 8,320,298 B2
• Time in Patent Office: Days
• US Class Current: 455/445
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/20 Negotiating bandwidth
• CPC Class Codes: H04W 28/24 Negotiating SLA [Service Level Agreement]; Negotiating QoS [Quality of Service]
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/14 Separate analysis of uplink or downlink
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

Parallel demodulators are provided in field units. Forward and reverse channel allocation information may be broadcast to the field units in the same epoch as traffic data but on first and second channels, such as paging and traffic channels. This assures that all field units are able to receive forward and reverse channel allocation information every epoch. By having parallel demodulators in the field unit, switching between the first and second channels is avoided and channel allocation information is not lost.

Claims

1. A method for reducing overhead in a time division multiplexed (TDM) communications system having a base station and a field unit communicating over forward and reverse links, and having at least first and second channels in the forward link and a channel in the reverse link, the method comprising:

receiving TDM slot allocation control data over the first channel in the forward link;

determining whether the TDM slot allocation control data is specified for the field unit; and

if the TDM slot allocation control data is specified for the field unit, setting up at least one traffic TDM slot in at least one traffic channel according to the TDM slot allocation control data for communicating traffic data with the base station in the second channel in the forward link or the channel in the reverse link.

2. The method according to claim 1 wherein the first channel carries non-traffic data.

3. The method according to claim 2 wherein the first channel is a paging channel.

4. The method according to claim 1 further including demodulating the TDM slot allocation control data from the first channel in parallel with demodulating the traffic data from the second channel at the field unit.

5. The method according to claim 1 wherein receiving slot allocation control data occurs every TDM time slot.

6. The method according to claim 1 wherein the TDM slot allocation control data defines channel parameters, including at least one of the following:

CDMA code channels, TDM slot starting position, number of TDM slot positions, FEC code rate, or power control.

7. The method according to claim 1 wherein receiving the TDM slot allocation control data includes receiving TDM slot deallocation control data based on a channel performance parameter, wherein the channel performance parameter includes at least one of the following:

fading, packet loss rate, Carrier-to-Interference (C/I) ratio, Signal-to-Noise (S/N) ratio, or power level.

8. An apparatus for reducing overhead in a time division multiplexed (TDM) communications system having a base station and a field unit communicating over forward and reverse links, and having at least first and second channels in the forward link and a channel in the reverse link, the apparatus comprising:

a first demodulator to demodulate a first modulated signal received over the first channel in the forward link, the demodulated signal including TDM slot allocation control data; and

a logic unit coupled to the first demodulator to determine whether the TDM slot allocation control data is specified for the field unit and, if yes, the logic unit sets up at least one traffic TDM slot in at least one traffic channel according to the TDM slot allocation control data for communicating traffic data from the base station in the second channel of the forward link or the channel in the reverse link.

9. The apparatus according to claim 8 wherein the first channel is a paging channel.

10. The apparatus according to claim 8 further including a second demodulator to demodulate a second modulated signal received over the second channel in the forward link in parallel with the first demodulator, the second demodulator configured to receive the second channel based on the TDM slot allocation control data from the first demodulator.

11. The apparatus according to claim 8 wherein the first demodulator receives TDM slot allocation control data every epoch.

12. The apparatus according to claim 8 wherein the TDM slot allocation control data defines channel parameters, including at least one of the following:

CDMA code channels, TDM slot starting position, number of TDM slot positions, FEC code rate, or power control.

13. The apparatus according to claim 8 wherein the demodulated signal includes TDM slot deallocation control data based on a channel performance parameter, wherein the channel performance parameter includes at least one of the following:

fading, packet loss rate, C/I ratio, S/N ratio, or power level.

14. An apparatus for reducing overhead in a time division multiplexed (TDM) communications system having a base station and a field unit communicating over forward and reverse links, and having at least first and second channels in the forward link and a channel in the reverse link, the apparatus comprising:

means for receiving TDM slot allocation control data over the first channel in the forward link;

means for determining whether the TDM slot allocation control data is specified for the field unit; and

if the TDM slot allocation control data is specified for the field unit, means for setting up at least one TDM slot in at least one traffic channel according to the TDM slot allocation control data for communicating traffic data with the base station in the second channel in the forward link or the channel in the reverse link.

15. A method for reducing overhead in a time division multiplexed (TDM) communications system, comprising:

demodulating a first modulated signal received over a first channel of a forward link, the demodulated signal including TDM slot allocation control data; and

using the TDM slot allocation control data, demodulating a second modulated signal received over a second channel of the forward link.

16. The method according to claim 15 wherein the first channel carries non-traffic data.

17. The method according to claim 16 wherein the first channel is a paging channel.

18. The method according to claim 15 further including demodulating the TDM slot allocation control data in parallel with demodulating the traffic data at the field unit.

19. The method according to claim 15 wherein receiving slot allocation control data occurs every TDM time slot.

20. An apparatus for reducing overhead in a time division multiplexed (TDM) communications system, comprising:

a first demodulator to demodulate a first modulated signal received over a first channel of a forward link, the demodulated signal including TDM slot allocation control data; and

a second demodulator to demodulate a second modulated signal received over a second channel of the forward link, the second demodulator configured to receive the second modulated signal based on the TDM slot allocation control data from the first demodulator.

21. The apparatus according to claim 20 wherein the first channel is a paging channel.

22. The apparatus according to claim 20 wherein the second demodulator demodulates the second modulated signal in parallel with the first demodulator demodulating the first modulated signal.

23. The apparatus according to claim 20 wherein the first demodulator receives TDM slot allocation control data every TDM time slot.

24. An apparatus for reducing overhead in a time division multiplexed (TDM) communications system, comprising:

means for demodulating a first modulated signal received over a first channel of a forward link, the demodulated signal including TDM slot allocation control data; and

means for demodulating a second modulated signal received over a second channel of the forward link according to the TDM slot allocation control data.

25. A method for communicating over forward or reverse links in a time division multiplexed (TDM) communications system having a base station and multiple field units, the method comprising:

transmitting TDM slot allocation control data over a first channel in the forward link in a first TDM slot from the base station to a given field unit; and

as specified by the TDM slot allocation control data, transmitting traffic data over a second channel in the forward link in a second TDM slot to the given field unit.

26. The method according to claim 25 wherein the first channel is a paging channel.

27. The method according to claim 25 further including modulating the allocation control data and traffic data for parallel demodulation at the field unit prior to the respective traffic transmissions.

28. The method according to claim 25 wherein transmitting the TDM slot allocation control data occurs every TDM time slot.

29. The method according to claim 25 further including receiving traffic data over a reverse link in a manner specified by the TDM slot allocation control data.

30. An apparatus for communicating over forward or reverse links in a time division multiplexed (TDM) communications system having the base station and multiple field units, the apparatus comprising:

at least one transmitter to transmit (i) TDM slot allocation control data over a first channel in the forward link in a first TDM slot, from the base station to a given field unit and (ii) traffic data over a second channel in the forward link in a second TDM slot to the given field unit as specified by the TDM slot allocation control data.

31. The apparatus according to claim 30 wherein the first channel is a paging channel.

32. The apparatus according to claim 30 further including at least one modulator to modulate the TDM slot allocation control data and traffic data for parallel demodulation at the given field unit prior to the transmitter transmitting the traffic data.

33. The apparatus according to claim 30 wherein the transmitter transmits the allocation control data every TDM slot.

34. The apparatus according to claim 30 further including a receiver to receive traffic data over a reverse link in a manner specified by the TDM slot allocation control data.

35. An apparatus for communicating over forward or reverse links in a time division multiplexed (TDM) communications system having the base station and multiple field units, the apparatus comprising:

means for transmitting TDM slot allocation control data over a first channel in the forward link in a first TDM slot from the base station to a given field unit; and

as specified by the TDM slot allocation control data, means for transmitting traffic data over a second channel in the forward link in a second TDM slot to the given field unit.