Partial association identifier computation in wireless networks

• US 8,971,213 B1
• Filed: 10/20/2011
• Issued: 03/03/2015
• Est. Priority Date: 10/20/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hart, Brian Donald
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Mansoury, Nourali
• Application Number:
  US13/317,512
• Time in Patent Office: 1,230 Days
• Field of Search: 370/255
• US Class Current: 370/255
• CPC Class Codes: H04L 2101/604 Address structures or formats
• CPC Class Codes: H04L 61/5038 for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

In one embodiment, a method includes generating for a client device associated with an access point, a partial association identifier based on an association identifier assigned to the client device and a hash of a basic service set identifier the client device is associated with, and transmitting a packet to the client device, the packet comprising the partial association identifier. The partial association identifier indicates that the packet is intended for the client device. An apparatus is also disclosed.

Claims

1. A method comprising:

generating for a client device associated with an access point, a partial association identifier based on an association identifier assigned to the client device and a hash of a basic service set identifier the client device is associated with; and

transmitting a packet to the client device, the packet comprising the partial association identifier, wherein the partial association identifier indicates that the packet is intended for the client device;

wherein the hash of the basic service set identifier comprises an offset computed based on the basic service set identifier and an exclusive OR of bits of the basic service set identifier and wherein the partial association identifier is equal to a modulo sum of a set number of least significant bits of the association identifier and the offset computed based on the basic service set identifier;

wherein generating the partial association identifier for the client device comprises calculating the partial association identifier that reduces a likelihood of partial association identifier collisions for overlapped access points.

2. The method of claim 1 wherein the offset is equal to

dec(BSSID[44:

47]⊕

BSSID[40;

43])×

2⁵

wherein;

BSSID is the basic service set identifier;

BSSID[b;

c] represent bits b through c inclusive of the BSSID, with BSSID[47] a last bit transmitted in time in an IEEE 802.11 frame;

⊕

is a bitwise exclusive OR operation; and

dec (A[b;

c]) is a cast to decimal operator where b is scaled by 2⁰ and c by 2^c-b.

3. The method of claim 1 wherein the partial association identifier is equal to

(dec(AID[0:

8])+dec(BSSID[44;

47]⊕

BSSID[40;

43])×

2⁵ mod 2⁹

wherein;

AID is the association identifier;

BSSID is the basic service set identifier;

AID [b;

c] represents bits b through c inclusive of the AID of the client device with bit 0 being the first transmitted;

BSSID[b;

c] represent bits b through c inclusive of the BSSID, with BSSID[47] a last bit transmitted in time in an IEEE 802.11 frame;

⊕

is a bitwise exclusive OR operation;

mod X indicates an X-modulo operation; and

dec (A[b;

c]) is a cast to decimal operator where b is scaled by 2⁰ and c by 2^c-b.

4. The method of claim 1 wherein the partial association identifier is located in a physical layer convergence procedure header in the packet.

5. The method of claim 1 wherein the partial association identifier is located in a very high throughput signal field in the packet.

6. An apparatus comprising:

a processor for creating a watch list comprising a partial association identifier generated based on an association identifier assigned to the apparatus and a hash of a basic service set identifier the apparatus is associated with, determining if a received packet contains the partial association identifier on said watch list, and processing the packet if the packet contains the partial association identifier and stopping receiver processing if the packet does not contain the partial association identifier so that the processor sleeps through a remainder of a frame; and

memory for storing the partial association identifier;

wherein the hash of the basic service set identifier comprises an offset computed based on the basic service set identifier; and

wherein generating the partial association identifier for the client device comprises calculating the partial association identifier that reduces a likelihood of partial association identifier collisions for overlapped access points.

7. The apparatus of claim 6 wherein the offset is equal to

dec(BSSID[44:

47]⊕

BSSID[40;

43])×

2⁵

wherein;

BSSID is the basic service set identifier;

BSSID[b;

c] represent bits b through c inclusive of the BSSID, with BSSID[47] a last bit transmitted in time in an IEEE 802.11 frame;

⊕

is a bitwise exclusive OR operation; and

dec (A[b;

c]) is a cast to decimal operator where b is scaled by 2⁰ and c by 2^c-b.

8. The apparatus of claim 6 wherein the hash of the basic service set identifier comprises an exclusive OR of bits of the basic service set identifier.

9. The apparatus of claim 6 wherein the partial association identifier is equal to a modulo sum of a set number of least significant bits of the association identifier and the offset computed based on the basic service set identifier.

10. The apparatus of claim 6 wherein the partial association identifier is located in a physical layer convergence procedure header in the packet.

11. The apparatus of claim 6 wherein the partial association identifier is located in a very high throughput signal field in the packet.

12. An apparatus comprising:

a processor for generating a partial association identifier for a client device associated with an access point, the partial association identifier based on an association identifier assigned to the client device and a hash of a basic service set identifier the client device is associated with, and creating a packet for transmittal to the client device, the packet comprising the partial association identifier; and

memory for storing the partial association identifier;

wherein the partial association identifier indicates that the packet is intended for the client device and is equal to;

(dec(AID[0;

8])+dec(BSSID[44;

47]⊕

BSSID[40;

43])×

2⁵)mod 2⁹

wherein;

AID is the association identifier;

BSSID is the basic service set identifier;

AID [b;

c] represents bits b through c inclusive of the AID of the client device with bit 0 being a first transmitted;

BSSID[b;

c] represent bits b through c inclusive of the BSSID, with BSSID[47] a last bit transmitted in time in an IEEE 802.11 frame;

⊕

is a bitwise exclusive OR operation;

mod X indicates an X-modulo operation; and

dec (A[b;

c]) is a cast to decimal operator where b is scaled by 2⁰ and c by 2^c-b.

13. The apparatus of claim 12 wherein the partial association identifier is located in a physical layer convergence procedure header in the packet.

14. The apparatus of claim 12 wherein the packet is an IEEE 802.11ac packet.