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Small Wireless, Community Networking, Community-Owned LTE Network — University of Washington, 2021-02-10

Summary

This document describes the University of Washington ICTD research group, an established research group focusing on technology and poverty, with Professor Richard Anderson and Professor Kurtis Heimerl named. It covers community networking, with Guifi.net listed at > 35,000 nodes and a community-owned LTE network being built in the Puget Sound, whose first installation is in the Hilltop neighborhood of Tacoma with Tacoma Cooperative Network. Other installations are on the way with funding from City of Seattle. The pages then explain the Shannon limit of a channel and new frequencies, and state that small cells maximize frequency reuse, allowing more frequency to be available to operators.

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“Small Wireless, Community Networking, Community-Owned LTE Network — University of Washington, 2021-02-10.” Archived at Pandemic Darlings, https://pandemicdarlings.com/source-documents/2021-02-10-a28592-d228285-university-of-washington-small-wireless-902f8ca3c5/, SHA-256 3a2bc141f32825b918f4c6240640b2698a914adda51a960615e5e23ce3f6629e.

Full text

                                     @
●   http://ictd.cs.washington.edu
●   Established research group focusing on technology and
    poverty (ICTD)
●   Professor Richard Anderson
     ○   ~6 Students
     ○   Focus on health and financial services
●   Professor Kurtis Heimerl (https://kurti.sh)
     ○   ~4 Students
     ○   Focused on Internet access and conservation
My Work: Community Networking
●   Networks built, owned, and operated by citizens and users
    in a participatory and open manner
●   Many examples throughout the world:
     ○   Guifi.net > 35,000 nodes
     ○   Freifunk, Altermundi, NYC Mesh, etc
●   We’ve built community-owned networks lots of places
     ○   Hawaii, Mexico, Philippines, Indonesia, etc
●   Building a community-owned LTE network here in the
    Puget Sound
     ○   First installation in Hilltop neighborhood of Tacoma with Tacoma
         Cooperative Network
     ○   Other installations on the way with funding from City of Seattle
Why Small Wireless Facilties?
Shannon Limit of a Channel
●   Developed by Claude Shannon well before the advent of modern systems
●   Basically indicates the maximum theoretical data rate possible




C = Capacity (LTE = 300Mbps)

B = Bandwidth (LTE = 20MHz)

S = Signal Power (LTE = -20 dBm)

N = Noise (LTE = -110 dBM)
Shannon Limit of a Channel
●   Developed by Claude Shannon well before the advent of modern systems
●   Basically indicates the maximum theoretical data rate possible




C = Capacity (LTE = 300Mbps)     Key Points:
B = Bandwidth (LTE = 20MHz)
         1. Increasing  power (S) has diminishing returns
S = Signal 2. Increasing
           Power          bandwidth
                 (LTE = -20 dBm)    (frequencies) increases
             capacity linearly
N = Noise (LTE = -110 dBM)
Options for increasing bandwidth

1. Open up new frequencies
2. Use frequencies more efficiently
Both lead to small cells/wireless facilities
New Frequencies
●   Vast majority of bands (specifically low ones) already taken
         ○   850MHz, 1800MHz is traditional cellular
         ○   600MHz, 900MHz, ~50 others are now LTE
         ○   900MHz is ISM (cordless phones,microwaves mostly)
         ○   2.4GHz/5GHz is ISM (Wifi)
●   Higher bands (6GHz+) are largely fallow but have very poor characteristics
         ○   Low penetration (e.g., do not make it through walls)
         ○   High weather attenuation (e.g., rain makes them suck)
New Frequency Examples
●   LTE Unlicensed/LAA - Cellular in Wifi Bands
●   Wifi 6 - Wifi in new 6GHz ISM band
     ○   Some stuff around here remains licensed
●   “Millimeter Wave” - ~60GHz bands
     ○   5G Frequency Band 2 - 24.25 GHz to 52.6 GHz
          ■ Normal cellular models
     ○   60GHz unlicensed (Terragraph)
New Frequency Examples
●   Wifi 6 - Wifi in new 6GHz ISM band
     ○   Some stuff around here remains licensed
●                           Conclusion:
    “Millimeter Wave” - ~60GHz bands
     ○ 5G Frequency Band 2 - 24.25 GHz to 52.6 GHz
     New    frequencies are all high, meaning they
        ■ Normal cellular models
     ○have
       60GHz limited        range and need lots of access
              unlicensed (Terragraph)

         points to provide ubiquitous coverage
More efficient use of spectrum - Spatial Reuse
Spectrum Access: CBRS
●   Bands opened in April 2020
●   Provides 150mhz of “open” access
     ○   Can be bought by incumbents but if not actively used it is
         available
●   50mhz of “unlicensed” access
     ○   GAA only: no incumbents allowed
●   Coordinates spectrum through third-party SAS
     ○   Google has graciously given us access
                Conclusion:
   Small cells maximize frequency reuse,
allowing for more frequency to be available
                to operators
     Thanks!
kheimerl@cs.washington.edu
       https://kurti.sh

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