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160 MHz PHY Transmission. Authors:. Date: 2010-05-17. Outline. Motivation Usefulness of 160 MHz PHY transmission mode Contiguous and non-contiguous 160 MHz Coexistence Summary. Motivation (1/2). WLAN continues to provide wireless alternatives to wired LAN 10BASE-T Ethernet: 11a/g
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160 MHz PHY Transmission Authors: Date: 2010-05-17 Youhan Kim, et al.
Outline • Motivation • Usefulness of 160 MHz PHY transmission mode • Contiguous and non-contiguous 160 MHz • Coexistence • Summary Youhan Kim, et al.
Motivation (1/2) • WLAN continues to provide wireless alternatives to wired LAN • 10BASE-T Ethernet: 11a/g • 100BASE-T Ethernet: 11n • Ability to meet the 1000BASE-T Ethernet throughput (Gigabit wireless) in 11ac would be beneficial • Parallelism with past efforts lends additional legitimacy to 11ac • Could be a clear and simple part of the answer to “what is 11ac?” • Including this capability increases the chance of a major upgrade cycle, and provides better differentiation with previous generation equipments Youhan Kim, et al.
Motivation (2/2) • However, for Gigabit wireless to succeed, it needs to be practical • Achieve 1Gb/s TCP/IP throughput robustly over a reasonable range • Allow wide range of devices, each with different physical limitations (e.g number of antennas), to achieve 1 Gb/s TCP/IP throughput We believe this capability would be instrumental in broader acceptance of 11ac by consumers Youhan Kim, et al.
Usefulness of 160 MHz PHY Transmission • WLAN is becoming prevalent in all types of devices • Different devices have different physical (e.g. number of antenna) limitations • 160 MHz allows even wider range of devices to achieve Gigabit wireless • Opens the door for even more variety of applications * Short GI, 70 % efficiency Youhan Kim, et al.
Benefits of Wide Bandwidth • A wide channel shared among multiple users is more efficient for transporting bursty computer networking data • Modern media codecs use variable bit rates • Wide shared channels are more efficient due to statistical multiplexing • Streams with highly varying bit rate may be more robust with wide channels • Allows sufficient excess BW to meet the peak requirements • Particularly with prioritized QoS • Spectrum that is not used is permanently wasted Youhan Kim, et al.
Contiguous and Non-Contiguous 160 MHz • Contiguous 160 MHz • Transmitted signal consists of a single contiguous frequency spectrum with 160 MHz bandwidth • Non-contiguous 160 MHz • Transmitted signal consists of two frequency segments, each 80 MHz wide • Limit to two non-contiguous segments for reasonable tradeoff between complexity and flexibility WLAN - 160 MHz U-NII 1 U-NII 2 U-NII Worldwide U-NII 3 WLAN - 160 MHz Radar Radar WLAN WLAN 80 MHz WLAN 80 MHz U-NII 1 U-NII 2 U-NII Worldwide U-NII 3 Youhan Kim, et al.
Non-Contiguous 160 MHz • The two frequency segments may be placed in any two 11ac 80 MHz channels • When the two frequency segments are placed next to each other, a non-contiguous 160 MHz device and a contiguous 160 MHz device shall be interoperable • The two frequency segments are used synchronously • Both in TX or both in RX mode • Signal on the two segments are destined to the same receiver(s) WLAN - 160 MHz Radar Radar WLAN WLAN 80 MHz WLAN 80 MHz U-NII 1 U-NII 2 U-NII Worldwide U-NII 3 Youhan Kim, et al.
Contiguous and Non-Contiguous 160 MHz • Contiguous 160 MHz • Suitable for devices with limitation on complexity, area, power, etc. • Non-contiguous 160 MHz • Higher probability of being able to operate in wide bandwidth mode [1] • Able to move around 80 MHz segments to avoid radar and WLAN • Able to utilize U-NII 3 • More effort and cost required to build than contiguous 160 MHz devices • To allow different implementations to independently decide on the tradeoffs between contiguous and non-contiguous operation • Allow 160 MHz devices that support only contiguous 160 MHz operation • 160 MHz devices may optionally support non-contiguous 160 MHz operation as well WLAN - 160 MHz Radar Radar WLAN WLAN 80 MHz WLAN 80 MHz U-NII 1 U-NII 2 U-NII Worldwide U-NII 3 Youhan Kim, et al.
160 MHz Tone Allocation: Non-Contiguous • Each frequency segment shall follow the 80 MHz tone allocation [2] WLAN - 160 MHz 80 MHz 80 MHz 6 Guard Tones 121 Data/Pilot Tones 3 DC Tones 121 Data/Pilot Tones 5 Guard Tones 6 Guard Tones 121 Data/Pilot Tones 3 DC Tones 121 Data/Pilot Tones 5 Guard Tones Tone Index Tone Index -128 -122 -2 2 122 127 -128 -122 -2 2 122 127 Youhan Kim, et al.
160 MHz Tone Allocation: Contiguous • Tone allocation equivalent to placing two 80 MHz tone allocations next to each other in frequency • Allows contiguous and non-contiguous 160 MHz devices to interoperate when the two segments of the non-contiguous devices are placed next to each other in frequency • Single PHY rate table for both contiguous and non-contiguous 160 MHz 80 MHz Tone Allocation [2] 80 MHz Tone Allocation [2] 6 Guard Tones 121 Data/Pilot Tones 3 Null Tones 121 Data/Pilot Tones 121 Data/Pilot Tones 3 Null Tones 121 Data/Pilot Tones 5 Guard Tones 11 DC Tones -256 -250 -130 -126 -6 6 126 130 250 255 Subcarrier Index Youhan Kim, et al.
Coexistence • Not as hard as 11n at 2.4GHz • No 11b and Bluetooth • No partially overlapping channels (i.e., 5MHz channel spacing at 2.4GHz) • No limited capabilities of pre-standard 11ac devices (as in 11n) • Various mechanisms may be investigated to ensure coexistence with legacy devices (11a/n) • Some examples of existing 11n mechanisms • Immediate CCA sensing on all BW units • RTS/CTS protection • L-SIG spoofing • Intolerant bit • Some examples of possible new mechanisms • Channel activity profiling on extension channels • More information exchanges between AP and STA on channel profiling • Ability to reserve certain channels for high QoS data Youhan Kim, et al.
Summary • 160 MHz PHY transmission would be a valuable optional feature in 11ac • Allows even wider range of devices to achieve Gigabit wireless • Allow both contiguous and non-contiguous 160 MHz operation • Non-contiguous and contiguous modes shall interoperate when the two 80 MHz non-contiguous segments are placed next to each other • Allow 160 MHz devices that support only contiguous 160 MHz operation • Allow each implementation to independently decide on the tradeoffs between contiguous and non-contiguous operation • Tone allocation for 160 MHz • Contiguous 160 MHz • Equivalent to placing two 80 MHz tone allocations next to each other in frequency • Non-contiguous 160 MHz • Each frequency segment shall employ 80 MHz tone allocation Youhan Kim, et al.
Strawpoll #1 • Do you support adding the following section and item into the specification framework document, 11-09/0992? • Section 3.1.1 160 MHz PHY Transmission • R3.1.1.A: The draft specification shall include support for 160 MHz PHY transmission. • Yes: • No: • Abstain: Youhan Kim, et al.
Strawpoll #2 • Do you support adding the following item into the specification framework document, 11-09/0992? • R3.1.1.B: Tone allocation for 160 MHz operation shall consist of two 80 MHz tone allocations. • Yes: • No: • Abstain: Youhan Kim, et al.
Strawpoll #3 • Do you support adding the following item into the specification framework document, 11-09/0992? • R3.1.1.C: The draft specification shall include support for non-contiguous 160 MHz PHY transmission whose frequency spectrum consists two segments, each transmitted using any two 11ac 80 MHz channels, possibly non-adjacent in frequency. Contiguous and non-contiguous 160 MHz devices shall be capable of transmitting and receiving frames between each other when the two segments of the non-contiguous 160 MHz device are placed in frequency to match the tone allocation of the contiguous 160 MHz device. • Yes: • No: • Abstain: Youhan Kim, et al.
Strawpoll #4 • Do you support adding the following item into the specification framework document, 11-09/0992? • R3.1.1.D: The draft specification shall include support for 160 MHz capable devices that support contiguous operation only. • Yes: • No: • Abstain: Youhan Kim, et al.
References • [1] Cariou, L. and Benko, J., Multichannel transmissions, IEEE 802.11-10/0103r1, Jan. 2010 • [2] Srinivasa, S. et al., 80MHz Tone Allocaiton, IEEE 802.11-10/0370r0, Mar. 2010 Youhan Kim, et al.