Communication apparatus and communication method for multi-band random access

1. A station (STA) apparatus comprising:

a receiver which, in operation, receives a Trigger frame allocating Random Access Resource Units (RA-RUs) over multiple bands,

the Trigger frame including a first User Info field that comprises a first Band Indication subfield for specifying a first band among the multiple bands, a first RU Allocation subfield for indicating a first RA-RU of one or more contiguous RA-RUs in the first band specified by the first Band Indication subfield, and a first Number of RA-RU subfield for indicating a number of the contiguous RA-RUs minus one in the first band specified by the first Band Indication subfield; and

a controller which, in operation:

sets a first Orthogonal Frequency Division Multiple Access (OFDMA) random access backoff (OBO) counter to 0 if an initial value of the first OBO counter is not larger than a number of first eligible RA-RUs in the first band, which is a first subset of contiguous RA-RUs specified by the Trigger frame; and

randomly selects one of the first eligible RA-RUs in the first band.

2. The STA apparatus of claim 1 , wherein an RA-RU is determined to be eligible if the STA apparatus supports all transmit parameters indicated in a Common Info field of the Trigger frame and in the first User Info field of the Trigger frame corresponding to the RA-RU; and if the STA apparatus is not associated with a Basic Service Set (BSS) it intends to transmit to and a predetermined subfield of the first User Info field of the Trigger frame corresponding to the RA-RU is a first predetermined number.

3. The STA apparatus of claim 1 , wherein an RA-RU is determined to be eligible if the STA apparatus supports all transmit parameters indicated in a Common Info field of the Trigger frame and in the first User Info field of the Trigger frame corresponding to the RA-RU; and if the STA apparatus is an associated communication apparatus and a Transmitter Address (TA) field of the Trigger frame is set to a BSS identifier (ID) of an associated BSS and a predetermined subfield of the first User Info field of the Trigger frame corresponding to the RA-RU is a second predetermined number.

4. The STA apparatus of claim 1 , wherein the first OBO counter corresponds to the multiple bands.

5. The STA apparatus of claim 1 , wherein

the Trigger frame includes a second Band Indication subfield for specifying a second band among the multiple bands, a second RU Allocation subfield for indicating a second RA-RU of one or more contiguous RA-RUs in the second band, and a second Number of RA-RU subfield for indicating a number of the contiguous RA-RUs minus one in the second band, and wherein a second subset of the contiguous RA-RUs specified by the Trigger frame constitutes second eligible RA-RUs in the second band, from which one eligible RA-RU is randomly selected, and

the STA further comprises:

a transmitter which, in operation, transmits a first Trigger Based Physical layer Protocol Data Unit (TB PPDU) in the selected first eligible RA-RU in the first band and transmits a second TB PPDU in the selected second eligible RA-RU in the second band if both the selected first eligible RA-RU in the first band and the selected second eligible RA-RU in the second band are considered to be idle, wherein the first and second TB PPDUs carry a same Medium Access Control Protocol Data Unit (MPDU) or Aggregate MPDU.

6. The STA apparatus of claim 1 , wherein a range of a first OFDMA Contention Window (OCW), which corresponds to the first OBO counter, is specific to the type of STA apparatus.

7. The STA apparatus of claim 6 , wherein the first OBO counter corresponds to the first band.

8. The STA apparatus of claim 6 , wherein a second Band Indication subfield further specifies a second band among the multiple bands, and

the controller, when in operation:

sets a second OBO counter to 0 if an initial value of the second OBO counter is not larger than a number of eligible RA-RUs in the second band; and

randomly selects one of the eligible RA-RUs in the second band for Trigger Based Physical layer Protocol Data Unit (TB PPDU) transmission;

wherein the second OBO counter is initialized according to a second OCW.

9. The STA apparatus of claim 8 , wherein the range of the first OCW is specific to the first band and a range of the second OCW is specific to the second band.

10. The STA apparatus of claim 9 , further comprising:

a transmitter which, in operation, transmits a first TB PPDU in the selected eligible RA-RU in the first band and a second TB PPDU in the selected eligible RA-RU in the second band if both the selected eligible RA-RUs are considered to be idle, wherein the first and second TB PPDUs carry a same Medium Access Control Protocol Data Unit (MPDU), or a same Aggregated MPDU (A-MPDU), or different MPDUs, or different A-MPDUs.

11. The STA apparatus of claim 1 , wherein the first User Info field includes a subfield that is set to a first predetermined value to indicate the RA-RU(s) allocated by the first User Info field are reserved for associated STA apparatuses operating in one of the multiple bands.

12. The STA apparatus of claim 11 , wherein the subfield is set to a second predetermined value to indicate the RA-RU(s) allocated by the first User Info field are reserved for STA apparatuses which are operating in one of the multiple bands and are not associated with a BSS they intend to transmit to.

13. A communication method for uplink Orthogonal Frequency Division Multiple Access (OFDMA) based random access, the method comprising:

initializing a first Orthogonal Frequency Division Multiple Access (OFDMA) random access backoff (OBO) counter according to a first OFDMA Contention Window (OCW);

receiving a Trigger frame having Random Access Resource Units (RA-RUs) over multiple bands, the Trigger frame including a first User Info field that comprises a first Band Indication subfield for specifying a first band among the multiple bands, a first RU Allocation subfield for indicating a first RA-RU of one or more contiguous RA-RUs in the first band specified by the first Band Indication subfield, and a first Number of RA-RU subfield for indicating a number of the contiguous RA-RUs minus one in the first band specified by the first Band Indication subfield;

setting the first OBO counter to 0 if an initial value of the first OBO counter is not larger than a number of first eligible RA-RUs in the first band, which is a first subset of contiguous RA-RUs specified by the Trigger frame; and

randomly selecting one of the first eligible RA-RUs in each of the multiple bands.

14. The method of claim 13 , further comprising:

randomly selecting one of eligible RA-RUs in a second band further specified by a second Band Indication subfield; and

transmitting a first Trigger Based Physical layer Protocol Data Unit (TB PPDU) carrying a Medium Access Control Protocol Data Unit (MPDU) or Aggregate MPDU in the selected eligible RA-RU in the first band and a second TB PPDU carrying the same MPDU or Aggregate MPDU in the selected eligible RA-RU in the second band if both the selected eligible RA-RUs are considered to be idle.

15. The method of claim 13 , wherein a second Band Indication subfield further specifies a second band among the multiple bands, and the method further comprising:

initializing a second OBO counter according to a second OCW;

setting the second OBO counter to 0 if an initial value of the second OBO is not larger than a number of eligible RA-RUs in the second band, which is a second subset of the contiguous RA-RUs in the Trigger frame; and

randomly selecting one of the eligible RA-RUs in the second band for Trigger Based Physical layer Protocol Data Unit (TB PPDU) transmission.