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Views on 802.11ah Use Cases

Views on 802.11ah Use Cases. Authors:. Date: 2011-03-14. Background. 802.11ah goal is to standardize a new amendment for unlicensed S1G frequencies [1].

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Views on 802.11ah Use Cases

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  1. Views on 802.11ah Use Cases Authors: Date: 2011-03-14 Ron Porat, Broadcom

  2. Background • 802.11ah goal is to standardize a new amendment for unlicensed S1G frequencies [1]. • However, since those frequencies are unlicensed, there are currently 802.11b/g products that are sold in the 900MHz band (by re-banding) to provide improved outdoor WiFi (for example see [2]). The reason being is that lower frequencies provide improved propagation characteristics. • Note that typically S1G frequencies have been used for long range outdoor systems such as broadcast terrestrial TV, cellular and military systems. • The value of this spectrum is high - recently Verizon Wireless paid ~$10B for 20MHz of spectrum in the 700MHz band to deploy LTE • It is unlikely that more unlicensed S1G spectrum will be allocated in the future since this spectrum is considered ‘beach front property’ coveted by many entities such as broadcasters and cellular carriers • Hence, we should support applications that benefit most from S1G frequencies which are given to us for free Ron Porat, Broadcom

  3. 802.11ah Applications • Currently, a large range of applications are proposed for 802.11ah and are summarized in [3]. • They can be classified into several categories in several ways. For example: • Indoor and Outdoor extensions of 802.11 • To be used for any application used today by WiFi users as an added option for extended range (albeit at lower maximum rates) and preferably in conjunction with 802.11n and/or 802.11ac to allow for efficient usage of S1G spectrum when necessary • The required bit rate is only limited by user demand • A typical range may be few tens and up to few hundreds meters in NLOS conditions • Indoor and Outdoor extensions for 802.11 for M2M applications • Rates can be high for Video applications such as surveillance • Rates can be extremely low for other applications such as healthcare, home and industrial automation and control, menu and coupon distribution , transportation control • Can be easily accommodated by using <500KHz channels • A typical range may be few tens and up to few hundreds meters in NLOS conditions • In general M2M rates are somewhat more predictable Ron Porat, Broadcom

  4. Cont. • Outdoor smart grid • Rates per client are extremely low (can also be accommodated by using <500KHz channels) but the required range is highest among the proposed applications. • The number of STA per AP is also highest (several thousands) among other scenarios • To summarize, a mix of very low rate and medium rate applications in LAN and WAN scenarios (all four options) Ron Porat, Broadcom

  5. Similarities With TVWS • S1G frequencies under consideration are similar to TVWS frequencies and we can expect the same applications to benefit from both TGah and Tgaf amendments. • In particular we refer to [4] for a good description of TVWS use cases and briefly state them below. It is clearly seen that they are quite similar to what has been proposed for TGah • Extended Coverage Wi-Fi • Bridge among Small Networks • In home media distribution • WISP/WAN • Cellular Offloading • Wi-Fi Direct • M2M • Smart Grid Ron Porat, Broadcom

  6. Views • Scenarios - 802.11ah benefits range extension scenarios when compared to current 802.11. As such, use cases 1a-1d, 2,3,4a,5 from [3] are more inline with TGah PAR with the following comments: • Mobility – some outdoor use case can benefit from mobility support. The system should be optimized for up to pedestrian speeds. Support for higher speeds is FFS. • Medium rates use cases are supported provided they meet the system capability based on its BW and MIMO configuration (number of concurrent HDTV transmissions may be very limited and usage of SDTV instead of HDTV may be preferred). • System BW – in order to have a manageable number of modes we propose bandwidths of 2.5/5/10MHz. Narrower bandwidths are FFS • Dynamic usage of frequencies – many of the scenarios proposed can benefit from the new 900MHz but can also be deployed at 5GHz at least to some extent. For example video streaming can use 5GHz for shorter distance and 900MHz for far away clients – to the extent possible we support efficient and dynamic usage of all available frequencies. Ron Porat, Broadcom

  7. Cont. • Interference between low BW applications and high BW applications - many schemes can be explored i.e. per country channel maps whereby for example in the case of the US the lowest X (e.g. 5) MHz of the available 26MHz spectrum can be reserved to low BW applications. • Indoor applications - some indoor applications can benefit from the improved propagation at 900MHz but low bit rate applications (e.g. 1e-1h) can definitely also work at higher frequencies as the plot in the Appendix shows and using current 802.11b/g/n/ac. Ron Porat, Broadcom

  8. References [1] 11-10-0001-13-0wng-900mhz-par-and-5c.doc [2] http://www.caworldwifi.com/900-Mhz-WiFi.html [3] 11-11-0301-00-00ah-categories-of-use-cases-and-straw-polls.pptx [4] TVWS MTG Use Cases Draft v0.03_clean.doc Ron Porat, Broadcom Slide 8

  9. Appendix Ron Porat, Broadcom Slide 9

  10. Indoor Link Budget • The following plot shows the SNR for a low power indoor system at 5.5Ghz • Assumptions: • 11n path loss formula • 10m breaking point, 5db shadowing std • Path loss includes one shadowing std • NF=5dB • Transmit power 0dBm • Transmission BW – 100KHz Ron Porat, Broadcom Slide 10

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