1 / 16

US Channelization

US Channelization. Authors:. Date: 2011-11-07. From 2011-11-1329r1/1296-r3 (Rolf de Vegt , Qualcomm) . US Channelization (902 – 928MHz). 902 MHz. 928 MHz. 1 MHz. 2 MHz. 4 MHz. 8 MHz. 16 MHz.

thelma
Download Presentation

US Channelization

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. US Channelization Authors: Date: 2011-11-07 Raja Banerjea, et. Al.

  2. From 2011-11-1329r1/1296-r3 (Rolf de Vegt, Qualcomm) US Channelization (902 – 928MHz) 902MHz 928MHz 1 MHz 2 MHz 4 MHz 8 MHz 16 MHz Note:Devices operating in the 1 MHz PHY mode are expected to operate in the lower 1 MHz of each 2 MHz wide channel Channels >= 4 MHz are right aligned to prevent interference on the 1 and 2 MHz channels at the lower edge of spectrum. Raja Banerjea, et. Al.

  3. Use Case 1 : Sensors and meters Use Case 2 : Backhaul Sensor and meter data Use Case 3 : Extended range Wi-Fi TGah Use Cases Raja Banerjea, et. Al.

  4. Use Case 3a : Outdoor Extended Range Hot Spot : Requirements (11/0457) Raja Banerjea, et. Al.

  5. November 2011 Cellular Offload Use case • US allows 26 MHz of spectrum from 902 – 928 MHz for unlicensed transmission • Maximum EIRP = 1W • IEEE 802.11ah includes • <= 4 Spatial stream MIMO • Transmit beamforming • DL-MU MIMO • 1/2/4/8/16 MHz channel BW • TGah could provide cellular offload with adequate coexistence to low power sensor devices Raja Banerjea, et. al.

  6. Scenario • AP transmits 1/2/4 MHz BW PPDU • Transmit power for all bandwidth and modulation is the same • STA receives 1 MHz PPDU with one higher MCS than 2 MHz • STA receives 2 MHz PPDU with one higher MCS than 4 MHz • DBPS number are based on 11 ac 20 MHz 1 spatial stream • The throughput calculation considers a single frame exchange with medium access, IFS, Ack overhead • Parameters used Raja Banerjea, et. Al.

  7. Modulation Parameters used • 11ac 20/40/80 down clocked by 10 for 2/4/8 MHz • PHY parameters as defined in TGac • 1 MHz with 24 data tones • 1MHz Rep 2 with 12 effective data tones DBPS Values used Raja Banerjea, et. Al.

  8. Throughput comparison • 2MHz transmission is more efficient than 1 MHz Throughput comparison for 200 Byte (Mbps) Raja Banerjea, et. Al.

  9. Power consumption comparison • Sensors which can receive 2 MHz transmission achieve ~20% improvement in battery life Transmission duration for 200 Byte (us) Raja Banerjea, et. Al.

  10. Support of extended range with 2 MHz BSS • In a 2 MHz BSS an AP could transmit both 1 MHz and 2 MHz Beacon • If all sensors in the BSS can receive a 2 MHz BW beacon then the network overhead of supporting longer range is limited • 3.5 ms ever 100 ms (64 Byte beacon) • If some sensors can receive only the 1MHz repetition coded beacon then they would operate at the most robust MCS of the BSS. • As sensors transmit limited amount of data, the network performance is not adversely affected Raja Banerjea, et. Al.

  11. Overhead Comparison • Fixed overhead include • ACK packets 50% of the packets are ACK packets • Beacon (255 byte) • TIM for large number of STA (255 byte) • 2 MHz BSS 44% more efficient than a 1 MHz BSS Overhead in 100 ms [1] Assumption 10 data packets transmitted every 100ms, so 10 ACKs are required. Raja Banerjea, et. Al.

  12. Offload use case • 1 MHz PPDU transmission may not support offload • PPDU duration beyond maximum PPDU duration of packet for lower MCS • PPDU duration beyond channel coherence time for lower MCS • Long PPDU duration causes sensor devices to stay awake for longer time for medium to be free • Higher bandwidth required for Offload use case Transmission time for 1500 Byte (us) Effective Throughput for 1500 Byte (Mbps) Raja Banerjea, et. Al.

  13. 2MHz Channelization is Preferred • 11ah STAs support both 1MHz and 2MHz PHYs • It is NOT recommended that a 11ah STA (either a sensor STA or a 3G offloading STA) uses 1MHz PHY mode unless it has difficulty to reach the peer STA by 2MHz/MCS0 • 1MHz PHY suffers large overhead and very low throughput due to long preamble (2x rep) and narrow bandwidth • 2MHz PHY is much more efficient from both throughput and power saving aspects • Allowing 1MHz BSS may increase sensor power consumption – since 2MHz is mandatory it doesn’t make sense for BSS to limit communication to 1MHz • Sensor applications have higher priority to access a shared channel and will not suffer from low availability of 2MHz channels • Allowing 1MHz only BSS will eventually fragment the bulk bandwidth available and downgrade most BSSs to 1MHz BSS • Any sophisticated and mandatory coexistence rules to prevent such fragmentation are, in reality, hard to be enforced (11ac is facing the same problem now) Raja Banerjea, et. Al.

  14. Conclusion • 1 MHz channelization has the following issues • Long PPDU duration can’t support offload use case • Longer transmission time at 1 MHz causes lower battery life for sensors • Less efficient than larger bandwidth transmission • Higher overhead • 1MHz channelization should only be a result of regulatory requirements or very limited spectrum (e.g. only two 2MHz channels in Europe) Raja Banerjea, et. Al.

  15. Straw Poll:US Channelization (902 – 928MHz) 902MHz 928MHz 2 MHz 4 MHz 8 MHz 16 MHz Note:2MHz BSS allows 1MHz transmission in the TBD (lower/higher) 1MHz for improved range by 6dB [1] Yes: No: Abstain: Raja Banerjea, et. Al.

  16. Reference • [1] IEEE 802.11/1484r0 “11ah PHY Transmission flow” Raja Banerjea, et. Al.

More Related