Collision avoidance in IEEE 802.11 contention free period (CFP) with overlapping basic service sets (BSSs)

• US 20060029073A1
• Filed: 10/19/2005
• Published: 02/09/2006
• Est. Priority Date: 07/07/2000
• Status: Abandoned Application

• Current Assignee: Gerard Cervello, Sunghyun Choi
• Original Assignee: Gerard Cervello, Sunghyun Choi
• Inventors: Choi, Sunghyun, Cervello, Gerard
• Application Number:
  US11/253,777
• Publication Number:
  US 20060029073A1
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 80/02 Data link layer protocols
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/10 adapted for operation in multiple networks, e.g. multi-mode access points

Abstract

A medium access control (MAC) protocol is provided for avoiding collisions from stations (STAs) comprising two or more IEEE 802.11 basic service sets (BSSs) collocated and operating in the same channel during contention free periods (CFPs). The MAC protocol includes hardware/software for utilizing ready-to-send (RTS)/clear-to-send(CTS) exchange during CFPs to avoid potential collision from STAs in overlapping BSSs and hardware/software for providing overlapping network allocation vectors (ONAV) in addition to a network allocation vector (NAV), the ONAV included to facilitate the effectiveness of the RTS/CTS during CFPs.

Claims

1-11. -11. (canceled)

12. A medium access control (MAC) protocol for avoiding collisions from stations (STAs) comprising two or more IEEE 802.11 basic service sets (BSSs) collocated and operating in the same channel during contention free periods (CFPs), comprising:

a network allocation vector (NAV);

means for utilizing ready-to-send-(RTS)/clear-to-send(CTS) exchange during CFPs to avoid potential collision from STAs in overlapping BSSs;

means for providing overlapping network allocation vectors (ONAV) in addition to the network allocation vector (NAV) for processing by the means for utilizing;

means for updating a duration/ID of both the RTS and CTS frames during the CFP and maintaining that the overlapping STA(s) will not interfere with transmission between an STA and its corresponding AP following the RTS/CTS exchanges; and

means for implementing ONAV rules.

13. A medium access control (MAC) protocol for avoiding collisions from stations (STAs) comprising two or more IEEE 802.11 basic service sets (BSSs) collocated and operating in the same channel during contention free periods (CFPs), comprising:

a rules engine for utilizing ready-to-send-(RTS)/clear-to-send (CTS) exchange during CFPs to avoid potential collision from STAs in overlapping BSSs.

14. A wireless local area network (WLAN) which utilizes time slot allocation, virtual token passing and polling where necessary to maximize utilization of bandwidth, and contention free overlapping, the WLAN operating in accordance with a medium access control (MAC) protocol and at a variable bit rate (VBR) in an isochronous transmission mode, where the LAN comprises an Access Point (AP) and a plurality of mobile stations (STAs), wherein the MAC protocol is implemented in accordance with the following steps:

transmitting a beacon from the AP that includes time slot allocation information for each STA recognized by the AP, and AP information required for new STAs to join the WLAN;

transmitting by any STA comprising the WLAN in an order delegated by the AP;

utilizing, by any STA with a subsequently scheduled time slot, any unused time in a time slot allocated to a preceding STA when the STA with the subsequently scheduled time slot has a strong link to the preceding STA; and

generating a polling mechanism at the AP directed to the STAs with subsequently scheduled time slots in order to offer STAs with subsequently scheduled time slots the preceding STA'"'"'s remaining time when the preceding STA has clearly stopped transmitting, and before the time allocated for the subsequent STA to transmit.