Channelization and Bandwidth Modes for 802.11ah

1. Channelization and Bandwidth Modes for 802.11ah Authors: Date:2011-9-18 Rolf de Vegt, Qualcomm

2. In this document we propose the transmission bandwidths and channelization for 802.11ah • Transmission bandwidths (BW) refer to the channel widths (or BW modes) for which the 802.11ah PHY should provide support • Impacts the actual clause on 802.11ah PHY specification • Channelization refers to the process of breaking down the available spectrum in different regions into ‘channels’ • Mainly impacts sections analogous to Annex J of Std-802.11-2007 Abstract Rolf de Vegt, Qualcomm

3. Sub 1GHz Spectrum Availability in Key Geographies 8 MHz 5.6 MHz 26 MHz 779 787 863 868.6 902 928 MHz US (max erp <=1 W) China (max erp <= 10 mW) EU 6.5 MHz Korea 917 923.5 13.8 MHz Japan 929.7 915.9 928 MHz (Max BW = 1MHz) Rolf de Vegt, Qualcomm

4. Practical Applicability of Use Cases by Geography based on Spectrum Availability Considerations Rolf de Vegt, Qualcomm

5. Definitely need a 1MHz mode • Japan has a max BW limit • Need enough channels in regions like EU/Korea • Limited spectrum • 2 MHz mode needed for the following reasons • Accommodate waveforms that are multiples of 2 MHz channels, to meet the extended range Wi-Fi use-case requirement • Need higher BWs for satisfying that use-case • Ensure that 1 MHz waveforms can inter-operate globally with higher BWs • We propose that the following BWs be supported in the standard • 1 MHz (Mandatory) • 2 MHz (Mandatory) • 4, 8 and 16 MHz (Optional) Proposal for Transmission Bandwidths in 11ah Rolf de Vegt, Qualcomm

6. Propose to have the same tone spacing for all BW modes • Different BWs should be achieved through different FFT sizes • Helps in achieving co-existence if we have same symbol duration • Propose to have 64 tones for the 2 MHz mode • Gives a long enough CP for outdoor deployments • Minimizes new design work as 11ac already has designs for up-to 512 pt FFT • Modes >= 2 MHz become 10x down-clocking (expansion) in terms of symbol times and other related parameters in 11ac • 1 MHz mode is the only mode which will need a new design PHY Numerology for the Transmission BWs Rolf de Vegt, Qualcomm

7. For the US market alone, a minimum BW of 2 MHz would be highly feasible • May be preferable in some aspects • However, we assume vendors’ desire to create global products as much as possible • Experience of Wi-Fi technology thus far • Global market requires a 1 MHz bandwidth mode • Full interoperability and coexistence between 1MHz and 2MHz modes • Stakeholders in 802.11ah likely to demand this • Makes the standard less vulnerable to potential regulatory changes • Simplifies co-existence and transmission of management frames • Assuming that the standard will contain a 1 MHz mode, there is no way to control where devices in 1 MHz are deployed • Regulatory bodies don’t police this • WFA does not test for this either Considerations regarding Mandatory 1MHz and 2MHz BW Modes Rolf de Vegt, Qualcomm

8. Channelization for different regions • 2, 4, 8, 16 MHz in the US • With 26 MHz of spectrum, provides 13 channels • No wastage of spectrum at the edges • 1, 2, 4 MHz in EU/ Korea • Limited spectrum makes 1 MHz channels necessary • 1 MHz in Japan • Max BW limit in Japan makes 1 MHz necessary • Channelization much smaller than 1 MHz would encourage modes which are difficult to design as interoperable modes with higher BW modes • China, TBD • Two possible options (contingent on regulatory developments) • Ability to use 779~787MHz (TV Bands) • Expansion of channel width to1 or 2 MHz in the future in some of the other bands Proposal for Channelization Rolf de Vegt, Qualcomm

9. Resulting Global Channel Availability Rolf de Vegt, Qualcomm