PS-Poll Transmission Opportunity in WLAN

• US 20100189024A1
• Filed: 01/25/2010
• Published: 07/29/2010
• Est. Priority Date: 01/23/2009
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Du, Shu, Swaminathan, Arvind, Xhafa, Ariton E.
• Application Number:
  US12/692,783
• Publication Number:
  US 20100189024A1
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Embodiments of the invention provide a dynamic priority adjustment algorithm for PS-Poll packets in WLAN and dynamic CW (contention window) management algorithm for PS-Poll packets in WLAN. These improve the performance of traffic flows associated with STAs in power save mode. Maintain the QoS requirements of the traffic flows. When PS-Poll packets are not able to be sent, the QoS STA will experience a long delay of the downlink data, even if the downlink data has been assigned a higher AC. The delay may potentially violate the QoS bound required by the data flow. Using the embodiments can significantly decrease the probability of this event.

Claims

1. A method for packet transmission in a communications network, said method comprising:

generating a PowerSave Polling (PS-Poll) frame having an access category (AC);

assigning best effort (BE) to said access category (AC-BE);

determining if a station (STA) has any active flows with down link expectation and an high AC;

If a STA in PS-mode does have at least one active flow that has an access category (AC) higher than the BE and the flow expects downlink data from AP, dynamically adjusting priority comprising;

setting a time threshold T_MaxWaiting for guarding a maximum waiting time after a PS-Poll packet is inserted into an AC queue;

triggering a timer t_waiting;

when t_waiting is greater than T_MaxWaiting, then said AC is moved to the next higher AC;

restarting said timer t_waiting;

assigning a different time threshold T_MaxWaiting value; and

repeating the above steps from “

triggering a timer t_waiting”

till “

assigning a different time threshold T_MaxWaiting value”

until said AC of said PS-Poll has moved to the maximum AC.

2. The method of claim 1, further comprising:

cancelling timer if PS-Poll packet is transmitted before t_waiting is greater than T_MaxWaiting,

3. The method of claim 1, wherein said time threadhold T_MaxWaiting may have different values for different access catagories and wherein the higher the AC is, the smaller shall be the value of said time threadhold T_MaxWaiting.

4. The method of claim 1, further comprising upon PS-Poll transmission failure:

setting a random number x is set from [0,1];

determining if x is less than a predetermined probability P_fixCW

maintaining a current contention window if x is less than probability P_fixCW,

increasing said contention window based on the current AC, if x is not less than probability P_fixCW.