Method and apparatus for providing a distributed architecture digital wireless communication system
A communication system supports H-ARQ, AMC, active set handoff, and scheduling functions in a distributed fashion by allowing a mobile station (MS) to signal control information corresponding to an enhanced reverse link transmission to Active Set base transceiver stations (BTSs) and by allowing the BTSs to perform control functions that were supported by an RNC in the prior art. The communication system allows time and SIR-based H-ARQ flush functions at the BTSs during soft handoff (SHO), provides an efficient control channel structure to support scheduling, H-ARQ, AMC functions for an enhanced reverse link, or uplink, channel in order to maximize throughput, and enables an MS in a SHO region to choose a scheduling assignment corresponding to a best TFRI out of multiple assignments it receives from multiple active set BTS. As a result, the enhanced uplink channel can be scheduled during SHO without any explicit communication between the BTSs.
1. A method for scheduling mobile station uplink transmissions by a base station comprising steps of:
receiving scheduling information from a mobile station, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
determining an uplink channel scheduling assignment for the mobile station using at least one of the scheduling information and a base station interference metric and a link quality corresponding to the selected mobile station;
transmitting the uplink channel scheduling assignment to the mobile station, wherein the uplink channel scheduling assignment comprises a maximum traffic channel to control channel power ratio that the mobile station is allowed to use in a subsequent reverse link transmission; and
receiving, from the mobile station, an indication of a selection of a modulation and coding scheme that is based on the transmitted a maximum traffic channel to control channel power ratio and that is for an uplink transmission wherein receiving an indication of a selection of a modulation and coding scheme comprises receiving an indication of a selection of transport format and resource-related information (TFRI) that is based on the maximum traffic channel to control channel power ratio and that is for an uplink transmission.
2. The method of claim 1 , wherein the power status corresponds to a power level of a Dedicated Physical Control Channel (DPCCH).
3. The method of claim 1 , wherein the power status is based on a difference between a Dedicated Physical Control Channel (DPCCH) power level and a maximum power level supported by the mobile station.
4. The method of claim 1 , wherein the queue status corresponds to a size of a data queue.
5. The method of claim 4 , wherein the queue status further indicates a size of a layer 3 signaling queue.
6. The method of claim 4 , wherein the queue status further indicates that a layer 3 signaling queue is non-empty.
7. The method of claim 1 , further comprising conveying base station interference information to the mobile station via a forward link control channel.
8. The method of claim 1 , wherein the link quality is one or more of a link quality of an uplink channel from the mobile station and a link quality of a downlink channel from the base station to the mobile station.
9. The method of claim 1 , further comprising:
receiving, from the selected mobile station, a first transmission of data, which transmission of data is conveyed by the mobile station during the transmission interval and comprises transport format and resource-related information (TFRI);
decoding the first transmission of the data;
when the first transmission of the data is not successfully decoded, receiving communications from the selected mobile station corresponding to at least one retransmission of the data;
combining each of the at least one retransmission of the data with the previously received data to produce combined data until the first to occur of a successful decoding of the combined data or a flushing of a Hybrid Automatic Repeat Request (H-ARQ) buffer;
when one of the first transmission of data and the combined data is successfully decoded, conveying an acknowledgment to the selected mobile station; and
in response to conveying the acknowledgment, flushing the H-ARQ buffer.
10. The method of claim 9 , wherein the scheduling information is received via a first reverse link control channel and the transport format and resource-related information (TFRI) is received via a second reverse link control channel.
11. A base station capable of scheduling mobile station uplink transmissions, the base station comprising:
means for receiving scheduling information from a mobile station, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
means for determining an uplink channel scheduling assignment for the mobile station using at least one of the scheduling information and a base station interference metric and a link quality corresponding to the selected mobile station; and
means for transmitting the uplink channel scheduling assignment to the mobile station, wherein the uplink channel scheduling assignment comprises a maximum traffic channel to control channel power ratio that the mobile station is allowed to use in a subsequent reverse link transmission.
12. A method for controlling communications with a mobile station by a base station comprising steps of:
storing, by the base station, traffic data from the mobile station in a traffic data buffer;
transmitting, by the base station, first control data to the mobile station on a downlink control channel;
upon transmitting the first control data, starting, by the base station, a timer; and
when a predetermined period of time expires prior to receiving second control data from the mobile station on an uplink control channel, flushing the traffic data buffer.
13. A method for scheduling in a mobile station for uplink transmission comprising steps of:
transmitting scheduling information by the mobile station, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
receiving, by the mobile station from a base station, an uplink channel scheduling assignment, wherein the uplink channel scheduling assignment comprises a maximum power margin target map of uplink sub-frame transmission intervals;
selecting uplink subframe transmission intervals based on the map of uplink sub-frame transmission intervals
selecting, by the mobile station and based on the maximum power margin target, a modulation and coding scheme for an uplink transmission; and
transmitting, by the mobile station based on the received modulation and coding scheme, an indication of the selected modulation and coding scheme during the selected uplink sub-frame transmission intervals.
14. The method of claim 13 , further comprising:
receiving, by the mobile station, a modulation and coding scheme for an uplink transmission; and
transmitting, by the mobile station, based on the received modulation and coding scheme during the uplink sub-frame transmission intervals.
15. A mobile station comprising:
means for transmitting scheduling information, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
means for receiving, from a base station, an uplink channel scheduling assignment that is based on the scheduling information, wherein the uplink channel scheduling assignment comprises a map of uplink subframe transmission intervals;
means for selecting uplink subframe transmission intervals based on the map of uplink sub-frame transmission intervals; and
means for transmitting during the selected uplink sub-frame transmission intervals.
16. The mobile station of claim 15 , further comprising:
means for receiving, by the mobile station a modulation and coding scheme for an uplink transmission; and
means for transmitting based on the received modulation and coding scheme during the uplink sub-frame transmission intervals.
17. A method for scheduling a mobile station uplink transmission comprising steps of:
transmitting scheduling information by the mobile station, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
receiving, by the mobile station from a base station, an uplink channel scheduling assignment, wherein the uplink channel scheduling assignment comprises a maximum power margin target; and
selecting, by the mobile station, a modulation and coding scheme based on the maximum power margin target and for an uplink transmission; and
transmitting, by the mobile station, an indication of the selected modulation and coding scheme.
18. The method of claim 17 , wherein selecting comprises selecting, by the mobile station, transport format and resource-related information (TFRI) based on the maximum power margin target and wherein transmitting comprises transmitting an indication of the selected TFRI.
19. A mobile station comprising:
means to transmit scheduling information, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
means to receive, from a base station, an uplink channel scheduling assignment that is based on the scheduling information, wherein the uplink channel scheduling assignment comprises a maximum power margin target;
means to select a modulation and coding scheme based on the maximum power margin target and for an uplink transmission; and
means to transmit an indication of the selected modulation and coding scheme to the base station.
20. The mobile station of claim 19 , wherein the means to select a modulation and coding scheme comprises means to select transport format and resource-related information (TFRI) based on the maximum power margin target and wherein the means to transmit an indication of the selected modulation and coding scheme comprises means to transmit an indication of the selected TFRI.
21. A method for scheduling mobile station uplink transmissions by a base station comprising steps of:
receiving scheduling information from a mobile station, wherein the scheduling information comprises at least one of a queue status and a power status of the mobile station;
determining an uplink channel scheduling assignment for the mobile station using at least one of the scheduling information and a base station interference metric and a link quality corresponding to the selected mobile station;
transmitting the uplink channel scheduling assignment to the mobile station, wherein the uplink channel scheduling assignment comprises a maximum traffic channel to control channel power ratio that the mobile station is allowed to use in a subsequent reverse link transmission;
receiving, from the selected mobile station, a first transmission of data, which transmission of data is conveyed by the mobile station during the transmission interval and comprises transport format and resource-related information (TFRI);
decoding the first transmission of the data;
when the first transmission of the data is not successfully decoded, receiving communications from the selected mobile station corresponding to at least one retransmission of the data;
combining each of the at least one retransmission of the data with the previously received data to produce combined data until the first to occur of a successful decoding of the combined data or a flushing of a Hybrid Automatic Repeat Request (H-ARQ) buffer;
when one of the first transmission of data and the combined data is successfully decoded, conveying an acknowledgment to the selected mobile station; and
in response to conveying the acknowledgment, flushing the H-ARQ buffer.
22. The method of claim 21 , wherein the scheduling information is received via a first reverse link control channel and the transport format and resource-related information (TFRI) is received via a second reverse link control channel.