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Date: 2013-07-15

Opportunistic Transmissions in Multiple Alternative Channels in 802.11aj (60 GHz). Date: 2013-07-15. Presenter:. Author List. Proposed 6 logical channels for 802.11aj (60 GHz) [1]: 2 large bands with 2.16 GHz bandwidth: 2 & 3 4 small bands with 1.08 GHz bandwidth: 5, 6, 7 & 8. Background.

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Date: 2013-07-15

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  1. Opportunistic Transmissions in Multiple Alternative Channels in 802.11aj (60 GHz) Date: 2013-07-15 Presenter: Qian Chen

  2. Author List Qian Chen

  3. Proposed 6 logical channels for 802.11aj (60 GHz) [1]: • 2 large bands with 2.16 GHz bandwidth: 2 & 3 • 4 small bands with 1.08 GHz bandwidth: 5, 6, 7 & 8. Background Figure 1. Proposed Channelization for 802.11aj (60GHz). Qian Chen

  4. Objective:To increase the system throughput of a network . • Definitions: • Assume that a network with PCP/AP1 setting up in Channel 5. • Channel 5 is called dedicated channel and other channels, i.e., 6, 7, 8 and 3, are called alternative channels. • Method: If PCP/AP 1 cannot allocate enough time slots in Channel 5 to satisfy the traffic scheduling requirement, we can use an opportunistic transmission mechanism to schedule the transmissions (e.g., pair of STAs Src 1 and Dst 1, and pair of STAs Src 2 and Dst 2) in alternative channels 6, 7 or/and 8 or 3. Motivations 2 3 5 6 7 8 PCP/AP 1 Src 1  Dst 1 Src 2  Dst 2 Figure 2. Example of opportunistic transmission mechanism. Qian Chen

  5. Source STA Src 1 sends the allocation request, then PCP/AP 1 grants to allocate the service period (SP) for transmission pair (Src 1, Dst 1) in Channel 7 (8 or 3). Both Src 1 and Dst 1 scan in Channel 3 for at least aMaxBIDuration.If Channel 3 is available, Src 1 and Dst 1 proceed to do beamforming and transmit in the assigned SPs. Otherwise, Src 1 or Dst 1 will report the failure reasons to PCP/AP 1 after the scanning. The allocated SPs in Channel 7 (8 or 3) cannot extend the duration up to N × aMaxBIDuration. After that, Src 1 and Dst 1 can either switch back to Channel 5 or stay in Chanel 7 (8 or 3). In either way, they must suspend transmissions in Channel 7 (8 or 3) for a period of (B – 1) × aMaxBIDuration. Opportunistic Transmission Mechanism Figure 3. Example of opportunistic transmission mechanism Qian Chen

  6. PCP/AP 1 will schedule time slots in Channel 7 (8 or 3) at the end of the scanning period assigned to each device • If PCP/AP 1 does not receive any report, it will assume that the alternative channel is unoccupied and the devices have proceeded with their scheduled transmissions. • If any devices report that Channel 3 is occupied, PCP/AP 1 will inform the other devices to stop transmissions in Channel 7 (8 or 3) when they next return to Channel 5. • After the scanning period, (Src 1, Dst 1) and (Src 2, Dst 2) will commence on their scheduled SP1 and SP2, respectively, if they did not detect the existence of a network in operation in the alternative channel. • For each pair of devices, data transmission is preceded by a setup phase where the source and destination device exchange information to facilitate the data transmission. • If the setup phase failed, both devices will also return to Channel 5 and report accordingly to PCP/AP 1. The detailed Solution Src 1, Src 2, Dst 1 and Dst 2 scan Channel 3 for at least aMaxBIDuration during which any networks in operation in Channel 3 will have transmitted a notification packet to broadcast its existence. Figure 4. Modified SSW-Feedback/SSW-ACK frame format and SSW Feedback field Qian Chen

  7. The scheduled transmissions of the two pairs of devices can either run successively or concurrently if interferences between the pairs are minimal. • If the transmissions are scheduled to run successively, the second pair of devices, Src 2 and Dst 2 can continue to scan Channel 3 to ensure that no devices, other than Src 1 and Dst 1, are transmitting in Channel 3. • Regardless of successive or parallel transmissions, the total duration of the scheduled transmissions shall be upper-bounded by N × aMaxBIDuration. • At the end of the N × aMaxBIDuration, the devices can either switch back to the dedicated channel or stay in the alternative channel. • In either way, the devices will suspend any transmissions in the alterative channel for a minimum period of (B - 1) × aMaxBIDuration. • One of the source devices is designated as the prime source which will, at the start of each transmission block, transmit an echo beacon frame in Channel 3 that mimics the beacon frame sent by PCP/AP 1 in Channel 2. • All other transmissions in Channel 3 from other devices in the network are not allowed during the transmission of the echo beacon frame. The detailed Solution (Cont’d) Qian Chen

  8. At the end of (B - 1) × aMaxBIDuration where transmissions are suspended, all the devices will again scan Channel 3 for a duration exceeding aMaxBIDuration before the transmissions begin anew. • (Src 1, Dst 1) and (Src 2, Dst 2) will periodically, if required, return to Channel 5 when PCP/AP 1 is scheduled to transmit a beacon frame to maintain coordination and synchronization with PCP/AP 1. • Changes in scheduled transmissions can be made by PCP/AP 1 during these times too. • At the end of the scheduled transmissions, Src 1, Dst 1 and Src 2, Dst 2 will return to Channel 5 to await new schedules. • To maintain the coordination and synchronization, Src 1, Dst 1 and Src 2, Dst 2 synchronize with PCP/AP 1 through receiving time stamps in the PCP/AP 1’s broadcast periodically with the time interval between consecutive receptions of the time stamp short enough that a rough synchronization can be achieved throughout the transmission in Channel 7 (8 or 3). The detailed Solution (Cont’d) Qian Chen

  9. Increase network throughput in an opportunistic way when the adjacent channel is available without necessitating additional hardware complexity on the devices in the network. Enables a single network to be operated across multiple channel bands, where the network controller co-ordinate spectrum access in a dedicated channel band and schedule opportunistic spectrum access in other alternative channel bands. Ensures that scheduled opportunistic transmissions in alternative channels do not disrupt other networks operating in the alternative channels. Ensures other networks that want to start up in the alternative channels will not be hindered by a single network operating in multiple channel bands. Is well-suited for implementation as a set of MAC protocols which allows efficient coordination of a network operating across multiple channel bands. Benefits of the proposed solution Qian Chen

  10. Proposed a solution for opportunistic transmission over alternative channels to increase the network throughput; It may be useful for some applications, e.g. data center; It applies to both large band and small band. Conclusions Qian Chen

  11. [1] IEEE 802.11-12/1197r0 - Physical Channel Consideration for Chinese 60GHz Band Reference Qian Chen

  12. Thank YOU Qian Chen

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