Method and apparatus for fast closed-loop rate adaptation in a high rate packet data transmission

Abstract

In a high data rate communication system capable of variable rate transmission, an open loop rate control can be adjusted with a closed loop rate control to maximize throughput. An access point generates interleaved multi-slot packets that allow an access terminal to transmit indicator messages to the access point in accordance with recently received data carried within slots of the multi-slot packets.

1 . A method for increasing the data throughput rate of a communication network, comprising the steps of: 
 generating a plurality of data slots and a plurality of gap slots at an access point, wherein the plurality of data slots are interleaved with the plurality of gap slots to form a plurality of packets;    transmitting the plurality of packets to an access terminal; and    detecting the plurality of packets at the access terminal, wherein the access terminal transmits at least one indicator message to the access point indicating a reception status.    
   
   
       2 . The method of  claim 1 , wherein the plurality of data slots are interleaved with the plurality of gap slots in an alternating pattern.  
   
   
       3 . The method of  claim 1 , wherein the plurality of data slots are interleaved with the plurality of gap slots such that every N th  slot is a gap slot.  
   
   
       4 . The method of  claim 1 , wherein the plurality of data slots are interleaved with the plurality of gap slots in accordance with an aperiodic structure.  
   
   
       5 . A method for increasing the data throughput rate for transmissions from an access point to an access terminal, comprising the steps of: 
 generating a plurality of data packets at the access point for transmission to the access terminal, wherein each of the plurality of data packets comprises at least one slot, and the access point designates each slot in each of the plurality of data packets as a data slot or a gap slot;    transmitting the plurality of data packets to the access terminal at an initial data rate;    determining a set of estimated channel parameters at the access terminal;    transmitting a data request message to the access point based on the set of estimated channel parameters, wherein the step of transmitting the plurality of data packets to the access terminal is performed in accordance with the data request message;    determining a set of actual channel parameters at the access terminal;    transmitting an indicator message to the access point if the set of actual channel parameters passes a predetermined quality amount, wherein the step of transmitting is performed during a time period associated with at least one gap slot; and    modifying a subsequent data packet for transmission to the access terminal in accordance with the indicator message received at the access point.    
   
   
       6 . The method of  claim 5 , wherein the indicator message is a stop indicator message if the set of actual channel parameters indicates a noise level less than a noise level associated with the set of estimated channel parameters.  
   
   
       7 . The method of  claim 5 , wherein the indicator message is an extend indicator message if the set of actual channel parameters indicates a noise level greater than a noise level associated with the set of estimated channel parameters.  
   
   
       8 . The method of  claim 5 , wherein the indicator message comprises a bit received during a slot n, and the access point designates each slot in the plurality of data packets in accordance with an alternating pattern, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n−1;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n−1 and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       9 . The method of  claim 5 , wherein the indicator message comprises a bit received during a slot n, and the access point designates each slot in the plurality of data packets in accordance with a period p, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n-p+1;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n-p+1, and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       10 . The method of  claim 5 , wherein the indicator message comprises a bit received during a slot n, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n-N(i), wherein N(i) is the number of gap slots between data slots and i indicates a data rate index number;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n-N(i), and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       11 . The method of  claim 5 , wherein the set of actual channel parameters comprises a signal-to-interference and noise ratio.  
   
   
       12 . The method of  claim 5 , wherein the step of determining a set of actual channel parameters comprises the step of decoding the plurality of data packets at the access terminal to determine a packet error event, wherein the packet error event indicates a good data packet reception or a bad data packet reception.  
   
   
       13 . The method of  claim 12 , wherein the step of decoding the plurality of data packets at the access terminal comprises the steps of: 
 decoding a plurality of cyclic redundancy check (CRC) bits; and    comparing the decoded plurality of CRC bits with an estimated quality metric, wherein the estimated quality metric is computed from the set of estimated channel parameters.    
   
   
       14 . The method of  claim 5 , wherein the step of transmitting the indicator message to the access point comprises the steps of: 
 processing code symbols to determine a probability value for transmission errors; and    transmitting an extend indicator message if the probability value for transmission errors is greater than a predetermined amount.    
   
   
       15 . The method of  claim 12 , wherein the indicator message comprises a bit received during a slot n, and the access point designates each slot in the plurality of data packets in accordance with an alternating pattern, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n−1;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n−1 and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       16 . The method of  claim 12 , wherein the indicator message comprises a bit received during a slot n, and the access point designates each slot in the plurality of data packets in accordance with a period p, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n-p+1;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n-p+1, and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       17 . The method of  claim 12 , wherein the indicator message comprises a bit received during a slot n, wherein the step of modifying the subsequent data packet for transmission to the access terminal comprises the steps of: 
 deciding the bit is a request for a termination of transmission if a repetition of one of the plurality of data packets is already scheduled for slot n+1;    deciding the bit is a request for retransmission if an already transmitted packet ended transmission in slot n-N(i), wherein N(i) is a number of gap slots between data slots and i indicates a data rate index number;    deciding the bit is a request for retransmission if a previous indicator bit caused a retransmission of an already transmitted packet in slot n-N(i), and fewer than a predetermined number of retransmissions have been already processed for the plurality of data packets; and    deciding the bit is a false alarm if no conditions are satisfied.    
   
   
       18 . A system for increasing the data throughput rate of transmissions from an access point to an access terminal, comprising a processor at the access point configured to generate a plurality of interleaved data slots and gap slots for transmission to the access terminal.  
   
   
       19 . The system of  claim 18 , further comprising a processor at the access terminal configured to decode the plurality of interleaved data slots and gap slots, determine a quality value associated with transmissions from the access point to the access terminal, generate data rate request messages for transmission in accordance with the quality value, and generate indicator messages in accordance with the quality value, wherein the indicator message is generated and transmitted to the access point during a time period associated with at least one gap slot.  
   
   
       20 . The apparatus of  claim 19 , wherein the quality value is determined by a channel noise and interference value.  
   
   
       21 . The apparatus of  claim 19 , wherein the quality value is determined by a packet error value based on the decoded plurality of data slots.  
   
   
       22 . An apparatus for adjusting an open loop rate control process, comprising: 
 a scheduler at an access point for scheduling a plurality of interleaved data slots and gap slots, wherein the schedule is coupled to at least one buffer that stores data to be transmitted on a forward link channel;    a data rate request message decoder coupled to the scheduler for decoding a plurality of data request messages received on a reverse link channel, and for inputting data rate request information to the scheduler; and    an indicator message decoder coupled to the scheduler for decoding the plurality of indicator messages received on the reverse link channel and for inputting decoded indicator messages to the scheduler.    
   
   
       23 . An apparatus for adjusting an open loop rate control process, comprising: 
 an estimation element at the access terminal for determining a quality value associated with a forward link channel;    an open loop rate control element coupled to the estimation element for generating a plurality of data rate request messages, wherein the open loop rate control element uses the quality value received from the estimation element for the determining the contents of the plurality of data rate request messages;    a closed loop rate control element coupled to the estimation element and a decoder for generating a plurality of indicator messages based on either the quality value from the estimation element or an error value from the decoder, wherein the decoder is configured to decode a plurality of interleaved data slots and gap slots received on the forward link channel;    a controller coupled to the decoder and the estimation element for enabling the closed loop rate control element in accordance with a set of threshold values.