What is claimed is:1. A method comprising:receiving a first uplink transmission from a first wireless station (STA) by an access point (AP) in a wideband wireless communication network, wherein the first uplink transmission indicates handing over a reserved transmit opportunity (TXOP) ownership of at least a primary channel, wherein a secondary channel is busy for the first STA;transmitting multiple trigger frames to a plurality of wireless stations (STAs) over multiple subbands of the wideband, wherein the secondary channel is idle for the AP; andinitiating an uplink aggregation over the multiple subbands for the plurality of STAs sharing the same TXOP, wherein each trigger frame serves as synchronizing the uplink aggregation transmission timing and packet transmit time, and as allocating uplink aggregation resources to the plurality of STAs, wherein at least some of the plurality of STAs uses the secondary channel for the uplink aggregation.2. The method of claim 1, wherein the AP becomes the TXOP owner to initiate the UL aggregation for the plurality of STAs.3. The method of claim 1, wherein the AP continues to allocate resource to the first wireless station (STA) within the same TXOP.4. The method of claim 1, wherein the uplink aggregation comprises either an uplink orthogonal frequency division multiple access (OFDMA) transmission or an uplink multi-user multiple input multiple output (MU-MIMO) transmission over multiple secondary sub-channels.5. The method of claim 1, wherein the AP signals a second STA to transmit over the primary channel when the first STA finishes uplink data transmission.6. The method of claim 1, wherein the AP instructs the first STA to transmit dummy PHY protocol data unit(s) (PPDU(s)) after the first STA finishes uplink data transmission.7. The method of claim 1, wherein a trigger frame to a second STA before a beacon transmission indicates fragmentation, and wherein the AP starts a new TXOP for the second STA to complete data transmission after the beacon transmission.8. The method of claim 1, wherein the AP uses a subset of the multiple trigger frames to indicate contention and related parameters over a subset of the multiple subbands for random access.9. The method of claim 1, wherein the AP transmits downlink data to the plurality of STAs via the multiple trigger frames.10. The method of claim 1, wherein each trigger frame includes an ACK frame comprising a received address (RA) field, and wherein the RA field comprises an Idle Channel Indicator indicating that a secondary channel is available at the AP.11. The method of claim 1, wherein each trigger frame includes a Block ACK (BA) frame comprising a reserved field in a BA control field, and wherein the reserved field comprises an Idle Channel Indicator indicating that a secondary channel is available at the AP.12. An access point (AP), comprising:a receiver that receives a first uplink transmission from a first wireless station (STA) in a wideband wireless communication network, wherein the first uplink transmission indicates handing over a reserved transmit opportunity (TXOP) ownership of at least a primary channel, wherein a secondary channel is busy for the first STA;a transmitter that transmits multiple trigger frames to a plurality of wireless stations (STAs) over multiple subbands of the wideband, wherein the secondary channel is idle for the AP; andan uplink aggregation handling circuit that initiates an uplink aggregation over the multiple subbands for the plurality of STAs sharing the same TXOP, wherein each trigger frame serves as synchronizing the uplink aggregation transmission timing and packet transmit time, and as allocating uplink aggregation resources to the plurality of STAs, wherein at least some of the plurality of STAs uses the secondary channel for the uplink aggregation.13. The AP of claim 12, wherein the AP becomes the TXOP owner to initiate the UL aggregation for the plurality of STAs.14. The AP of claim 12, wherein the AP continues to allocate resource to the first wireless station (STA) within the same TXOP.15. The AP of claim 12, wherein the uplink aggregation comprises either an uplink orthogonal frequency division multiple access (OFDMA) transmission or an uplink multi-user multiple input multiple output (MU-MIMO) transmission over multiple secondary sub-channels.16. The AP of claim 12, wherein the AP signals a second STA to transmit over the primary channel when the first STA finishes uplink data transmission.17. The AP of claim 12, wherein the AP instructs the first STA to transmit dummy PHY protocol data unit(s) (PPDU(s)) after the first STA finishes uplink data transmission.18. The AP of claim 12, wherein a trigger frame to a second STA before a beacon transmission indicates fragmentation, and wherein the AP starts a new TXOP for the second STA to complete data transmission after the beacon transmission.19. The AP of claim 12, wherein the AP uses a subset of the multiple trigger frames to indicate contention and related parameters over a subset of the multiple subbands for random access.20. The AP of claim 12, wherein the AP transmits downlink data to the plurality of STAs via the multiple trigger frames.21. The AP of claim 12, wherein each trigger frame includes an ACK frame comprising a received address (RA) field, and wherein the RA field comprises an Idle Channel Indicator indicating that a secondary channel is available at the AP.22. The AP of claim 12, wherein each trigger frame includes a Block ACK (BA) frame comprising a reserved field in a BA control field, and wherein the reserved field comprises an Idle Channel Indicator indicating that a secondary channel is available at the AP.