Fast switching of forward link in wireless system
View Patent ↗A technique for distributing channel allocation information in a demand access communication system. In a preferred embodiment, for use with Code Division Multiple Access (CDMA) type communication, multiple access codes are used that have a defined code repeat period or code epoch. For each such epoch duration, a central controller, such as located at a base station in the case of operating a forward link, determines a schedule of assignment of traffic channels to active terminals for each epoch. For each terminal designated as active during the epoch, an active terminal unit identifier is assigned. For each terminal designated as active during the epoch, the base station assigns a list of active channels for such terminal unit. Prior to the start of each epoch, a channel set up message is sent on one of the forward link channels, such as a paging channel. The channel set up message indicates the terminal unit identifiers and the lists of active channels for epochs of the associated traffic channel(s) that are to follow. At the remote terminal unit, upon receiving a paging channel message, an active terminal identifier is determined from each paging channel message and compared to a previously assigned terminal identifier. On a predetermined subsequent epoch, the indicated active traffic channel, as indicated from the list of active traffic channels indicated by a received paging channel message, are then processed.
1. In a system which supports Code Division Multiple Access (CDMA) communication among a group of terminals wherein the terminals share access to a predetermined number of coded traffic channels, a method comprising the steps of:
determining a schedule of assignment of traffic channels to active terminals for a sequence of predetermined time periods;
for each terminal designated as active during such time periods, assigning a terminal unit identifier;
for each terminal designated as active during each time period, assigning an identifier of a list of active channels for such terminal unit; and
prior to the start of each time period, sending messages on a paging channel, the messages indicating terminal unit identifier and the indentifier of the list of active channels for such time period.
2. A method as in claim 1 wherein the predetermined time period is a code epoch repeat duration associated with codes that are used to encode the transmissions of the traffic channels.
3. A method as in claim 2 additionally comprising the step of:
for at least one selected terminal unit, receiving the paging channel messages, and detecting a paging channel message intended for itself by comparing a received terminal identifier from the paging channel message to a previously assigned terminal identifier.
4. A method as in claim 3 additionally comprising the step of:
at the selected terminal unit, on a predetermined subsequent epoch, processing the active traffic channels as indicated from the list of active traffic channels indicated by a received paging channel message.
5. A method as in claim 1 wherein the paging channel messages are time slotted.
6. A method as in claim 1 wherein the list of active channels is indicated by a pipe group identifier, each pipe group identifier indicating a list of active channels that are assigned in groups.
7. A method as in claim 1 wherein the paging channel forms a portion of a forward link communication channel.
8. A method as in claim 7 wherein the steps of assigning a terminal unit identifier and a list of active channels are performed at a central base station location.
9. A method as in claim 6 wherein the terminals are remote located wireless subscriber access units.
10. A method as in claim 2 wherein the paging channel messages are sent at least one-half epoch duration prior to the epoch contained associated active traffic channel data.
11. A method as claim 2 wherein the paging channel messages are sent at a time advanced sufficiently to permit code setup in a receiver prior to the epoch containing the associated traffic channel data.
12. A method as in claim 1 wherein the paging channel messages also indicate a coding rate for the associated traffic channels.
13. A method as in claim 2 wherein the paging channel message also indicates a reverse link channel identifier for the terminal to use during the associated epoch.
14. A method as in claim 1 wherein the paging channel message also includes a controller message field for carrying a message to a control processor located in the terminal.
15. A method as in claim 1 wherein a coded traffic channel is shared among multiple terminal units, and the paging channel message further specifies how the traffic channel data in the associated epoch is to be allocated among the terminal units.
16. A system which supports Code Division Multiple Access (CDMA) communication among a group of terminals wherein the terminals share access to a predetermined number of coded traffic channels, the system comprising:
a controller that contains a traffic channel assignment scheduler that determines a schedule of assignment of traffic channels to active terminals for predetermined time periods; and
a transmitter, for prior to the start of each predetermined time period, sending a message on a paging channel that indicates active terminals and active channels for such time period.
17. A system as in claim 16 additionally comprising:
a traffic channel pipe configurer, that determines a list of active channels for the predetermined time period, and assigns a pipe identifier to the list; and
wherein the paging channel message transmitter message that indicates active channels by sending the pipe identifier.
18. A system as in claim 16 additionally comprising:
a receiver, located at one of the terminal units, for receiving the paging channel messages, and detecting a paging channel message intended for itself by comparing a received terminal identifier from the paging channel message to a previously assigned terminal identifier.
19. A system as in claim 17 additionally comprising the step of:
at the receiver in the terminal unit, on a predetermined subsequent time period, processing active traffic channels as indicated from the list of active traffic channels indicated by the pipe identifier in a received paging channel message.
20. A system as in claim 16 wherein the paging channel messages are time slotted.
21. A system as in claim 16 wherein the paging channel forms a portion of a forward link communication channel.
22. A system as in claim 16 wherein the terminals are remote located wireless subscriber access units.
23. A system as claim 17 wherein the transmitter sends the paging channel message at a time advanced sufficiently to permit code setup in the receiver prior to a time period containing the associated traffic channel data.
24. A system as in claim 16 wherein the paging channel messages also indicate a coding rate for the associated traffic channels.
25. A method as in claim 16 wherein the paging channel message also indicates a reverse link channel identifier for the terminal to use during the associated time period.
26. A system as in claim 16 wherein the paging channel message also includes a controller message field for carrying a message to a control processor located in the terminal.
27. A system as in claim 16 wherein a coded traffic channel is shared among multiple terminal units, and the paging channel message further specifies how the traffic channel data in the associated epoch is to be allocated among the terminal units.