Method and Apparatus for Scheduling in a Wireless Network

Abstract

Techniques for scheduling flows and links for transmission are described. Each link is an oriented source-destination pair and carries one or more flows. Each flow may be associated with throughput, delay, feedback (e.g., acknowledgments (ACKs)) and/or other requirements. A serving interval is determined for each flow based on the requirements for the flow. A serving interval is determined for each link based on the serving intervals for all of the flows sent on the link. Each link is scheduled for transmission at least once in each serving interval, if system resources are available, to ensure that the requirements for all flows sent on the link are met. The links are also scheduled in a manner to facilitate closed loop rate control. The links are further scheduled such that ACKs for one or more layers in a protocol stack are sent at sufficiently fast rates.

1 . A method of scheduling transmission, comprising:
 identifying at least one link to be scheduled for data transmission in a first direction;   scheduling the at least one link for reverse transmission in a second direction opposite to the first direction; and   scheduling the at least one link for data transmission in the first direction.   
     
     
         2 . The method of  claim 1 , wherein the at least one link is scheduled for reverse transmission in a first frame and for data transmission in a second frame after the first frame. 
     
     
         3 . The method of  claim 2 , wherein the second frame immediately follows the first frame. 
     
     
         4 . The method of  claim 1 , wherein the scheduling the at least one link for reverse transmission comprises
 for each link with no data to send in the second direction, scheduling the link for reverse transmission of a null packet with at least one rate to use for the data transmission in the first direction.   
     
     
         5 . An apparatus in a wireless network, comprising:
 a selector operative to identify at least one link to be scheduled for data transmission in a first direction; and   a scheduler operative to schedule the at least one link for reverse transmission in a second direction opposite to the first direction and to schedule the at least one link for data transmission in the first direction.   
     
     
         6 . The apparatus of  claim 5 , wherein the reverse transmission for each link comprises a pilot. 
     
     
         7 . The apparatus of  claim 5 , wherein the reverse transmission for each link comprises at least one rate or at least one signal-to-noise ratio (SNR) estimate for the link. 
     
     
         8 . The apparatus of  claim 5 , wherein the reverse transmission for each link comprises acknowledgments for prior data transmission in the first direction for the link. 
     
     
         9 . An apparatus in a wireless network, comprising:
 means for identifying at least one link to be scheduled for data transmission in a first direction;   means for scheduling the at least one link for reverse transmission in a second direction opposite to the first direction; and   means for scheduling the at least one link for data transmission in the first direction.   
     
     
         10 . A method of scheduling data transmission, comprising:
 identifying at least one data flow to be scheduled for data transmission;   determining a rate for sending acknowledgments for each of the at least one data flow; and   scheduling reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.   
     
     
         11 . The method of  claim 10 , further comprising:
 determining a serving interval for each data flow to achieve the acknowledgment rate for the flow.   
     
     
         12 . The method of  claim 10 , further comprising:
 identifying at least one acknowledgment (ACK) flow corresponding to the at least one data flow:   determining a rate of transmission for each ACK flow; and   scheduling each ACK flow at the rate determined for the ACK flow.   
     
     
         13 . The method of  claim 10  further comprising:
 determining an amount of time to schedule for the reverse transmission for each data flow based on an estimated data rate for the data flow, physical layer overhead, acknowledgment (ACK) block size, or any combination thereof.   
     
     
         14 . An apparatus in a wireless network, comprising:
 a selector operative to identify at least one data flow to be scheduled for data transmission;   a computation unit operative to determine a rate for sending acknowledgments for each of the at least one data flow; and   a scheduler operative to schedule reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.   
     
     
         15 . The apparatus of  claim 14 , wherein the acknowledgments are Medium Access Control (MAC) acknowledgments. 
     
     
         16 . The apparatus of  claim 15 , wherein the computation unit is further operative to determine a serving interval for each data flow to achieve the acknowledgment rate for the flow. 
     
     
         17 . The apparatus of  claim 14 , wherein the selector is further operative to identify at least one ACK flow corresponding to the at least one data flow, wherein the computation unit is further operative to determine a rate of transmission for each ACK flow, and wherein the scheduler is further operative to schedule each ACK flow at the rate determined for the ACK flow. 
     
     
         18 . The apparatus of  claim 17 , wherein each ACK flow carries Transmission Control Protocol (TCP) ACKs for a corresponding data flow. 
     
     
         19 . An apparatus in a wireless network, comprising:
 means for identifying at least one data flow to be scheduled for data transmission;   means for determining a rate for sending acknowledgments for each of the at least one data flow; and   means for scheduling reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.   
     
     
         20 . The apparatus of  claim 19 , further comprising:
 means for determining a serving interval for each data flow to achieve the acknowledgment rate for the flow.   
     
     
         21 . The apparatus of  claim 19 , further comprising:
 means for identifying at least one ACK flow corresponding to the at least one data flow;   means for determining a rate of transmission for each ACK flow; and   means for scheduling each ACK flow at the rate determined for the ACK flow.