Method and apparatus for supporting wideband and multiple bandwidth transmission protocols
Enhanced protocols and devices may be used to alleviate loss of spectrum efficiency in wideband transmission. The protocols may implement a wideband transmission opportunity (TXOP) truncation where one or more of the channels involved in communication over the wideband are released. In one scenario, a wireless transmit/receive unit (WTRU) may obtain a TXOP for a 2 MHz bandwidth mode frame transmission with another device capable of operating in a 2 MHz bandwidth mode and a 1 MHz bandwidth mode. The WTRU may conduct a request-to-send (RTS)/clear-to-send (CTS) frame exchange in the second bandwidth mode, and truncate the TXOP by transmitting a contention free (CF)-End frame in the first and second bandwidth modes. In another scenario, an AP may obtain a TXOP for a 2 MHz bandwidth mode frame transmission with a WTRU capable of both 2 MHz and 1 MHz bandwidth modes.
1. A method for use in a first wireless transmit/receive unit (WTRU), the method comprising:
maintaining a network allocation vector (NAV);
receiving a contention free (CF)-End frame from a second WTRU, wherein the CF-End frame includes a duration field and a basic service set identifier (BSSID) field indicating a medium access control (MAC) address associated with an access point (AP), wherein the BSSID field includes an individual/group bit; and
on a condition that the individual/group bit of the BSSID field has a value of one (1), determining that a scrambling sequence of the CF-End frame indicates a bandwidth associated with a transmit opportunity (TXOP) being truncated by the second WTRU and resetting the NAV.
2. The method of claim 1 further comprising:
updating the NAV of the first WTRU based on a value set in the duration field of the received CF-End frame.
3. The method of claim 1 further comprising:
maintaining a TXOP holder MAC address for a basic service set (BSS) based on a transmitter address in a received frame from the TXOP holder.
4. The method of claim 1 further comprising:
maintaining a TXOP holder MAC address for a basic service set (BSS) based on a receiver address in a received frame from the TXOP holder.
5. The method of claim 1 further comprising:
maintaining a TXOP holder MAC address for a basic service set (BSS) based on the duration field in a received frame from the TXOP holder.
6. The method of claim 1 further comprising:
receiving a second CF-END frame from the AP; and
determining whether to attempt to access a wireless medium based on the NAV.
7. A first wireless transmit/receive unit (WTRU) comprising:
a processor configured to maintain a network allocation vector (NAV);
a receiver configured to receive a contention free (CF)-End frame from a second WTRU, wherein the CF-End frame includes a duration field and a basic service set identifier (BSSID) field that indicates a medium access control (MAC) address associated with an access point (AP), wherein the BSSID field includes an individual/group bit;
wherein on a condition that the individual/group bit of the BSSID field has a value of one (1), the processor is further configured to determine that a scrambling sequence of the CF-End frame indicates a bandwidth associated with a transmit opportunity (TXOP) being truncated by the second WTRU and reset the NAV.
8. The first WTRU of claim 7 , wherein the processor is further configured to update the NAV of the first WTRU based on a value set in the duration field of the received CF-End frame.
9. The first WTRU of claim 7 , wherein the processor is further configured to maintain a TXOP holder MAC address for a basic service set (BSS) based on a transmitter address in a received frame from the TXOP holder.
10. The first WTRU of claim 7 , wherein the processor is further configured to maintain a TXOP holder MAC address for a basic service set (BSS) based on a receiver address in a received frame from the TXOP holder.
11. The first WTRU of claim 7 , wherein the processor is further configured to maintain a TXOP holder MAC address for a basic service set (BSS) based on the duration field in a received frame from the TXOP holder.
12. The first WTRU of claim 7 , wherein the receiver is further configured to receive a second CF-END frame from the AP, and wherein the processor is further configured to determine whether to attempt to access a wireless medium based on the individual/group bit of the BSSID field.