Contention mechanism for access to random resource units in an 802.11 channel
In an 802.11ax network with an access point, a trigger frame offers random resource units to nodes for data uplink communication to the access point. To dynamically adapt the contention mechanism used by the nodes to access the random resource units, the AP updates a correcting TBD parameter at each new TXOP and includes the updated adjusting parameter in the trigger frame for the next TXOP. The nodes use the TBD parameter to generate a local random RU backoff value from a contention window range, for contending for access to the random resource units. The TBD parameter may directly impact the contention window size CWO or boundaries values of a selection range from which CWO is selected.
1. A wireless communication method in a wireless network comprising an access point and a plurality of nodes, the method comprising the following steps, at one of said nodes:
receiving a trigger frame from the access point, the trigger frame reserving a transmission opportunity on at least one communication channel of the wireless network, the trigger frame defining resource units forming the communication channel including a plurality of random resource units that the nodes are configured to access using a contention scheme, wherein the node has a resource unit, RU, backoff value to be used to contend for access to the random resource units, in order to transmit data, wherein the RU backoff value is distinct from a backoff value to be used by the node to contend access using an enhanced distributed channel access, EDCA, scheme;
based on a current RU backoff value, accessing a random resource unit to transmit data to the access point,
after having transmitted the data, computing a new RU backoff value to contend for new access to random resource units, the new RU backoff value being a value randomly selected within a contention window range defined by a RU contention window size, wherein the RU contention window size is updated depending on a success or failure in transmitting the data in the random resource unit, wherein the RU contention window size is distinct from a contention window size from which the EDCA backoff value is randomly selected.
2. The wireless communication method of claim 1 , wherein the RU contention window size is set to a low boundary value in case of transmission success.
3. The wireless communication method of claim 2 , wherein the low boundary value is predetermined.
4. The wireless communication method of claim 1 , wherein the RU contention window size is doubled in case of transmission failure.
5. The wireless communication method of claim 4 , wherein due to the doubling, the RU contention window size equals CWO min *2 n , where CWO min is a low boundary of the RU contention window size and n is the number of successive transmission failures.
6. The wireless communication method of claim 1 , further comprising computing a new value for the RU contention window size and a new RU backoff value upon receiving a new trigger frame following the step of transmitting data.
7. The wireless communication method of claim 1 , wherein computing the new RU backoff value includes randomly selecting a value within a contention window range [0, CWO], wherein CWO is the RU contention window size for the RU backoff value.
8. A communication device in a wireless network comprising an access point and a plurality of nodes, the communication device being one of the nodes and comprising at least one microprocessor configured for carrying out the steps of:
receiving a trigger frame from the access point, the trigger frame reserving a transmission opportunity on at least one communication channel of the wireless network, the trigger frame defining resource units forming the communication channel including a plurality of random resource units that the nodes are configured to access using a contention scheme, wherein the node has a resource unit, RU, backoff value to be used to contend for access to the random resource units, in order to transmit data, wherein the RU backoff value is distinct from a backoff value to be used by the node to contend access using an enhanced distributed channel access, EDCA, scheme;
based on a current RU backoff value, accessing a random resource unit to transmit data to the access point,
after having transmitted the data, computing a new RU backoff value to contend for new access to random resource units, the new RU backoff value being a value randomly selected within a contention window range defined by a RU contention window size, wherein the RU contention window size is updated depending on a success or failure in transmitting the data in the random resource unit, wherein the RU contention window size is distinct from a contention window size from which the EDCA backoff value is randomly selected.
9. The communication device of claim 8 , wherein the microprocessor is configured to set the RU contention window size to a low boundary value in case of transmission success.
10. The communication device of claim 9 , wherein the low boundary value is predetermined.
11. The communication device of claim 8 , wherein the microprocessor is configured to double the RU contention window size in case of transmission failure.
12. The communication device of claim 8 , wherein the microprocessor is configured to compute a new value for the RU contention window size and a new RU backoff value upon receiving a new trigger frame following the transmission of data to the access point.
13. The communication device of claim 8 , wherein the microprocessor is configured, in order to compute the new RU backoff value, randomly select a value within a contention window range [0, CWO], wherein CWO is the RU contention window size for the new RU backoff value.
14. A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a device of a wireless network, causes the device to perform the method of claim 1 .