White Space: Now With TD-LTE?

Posted by Sam Churchill on

The FCC today initiated its Notice of Inquiry (NOI) period, requesting comment on dynamic spectrum access technologies and techniques. The Notice of Inquiry period builds on the FCC’s ruling in September (pdf), when the commission unanimously voted to finalize rules enabling the use of TV white spaces for wireless broadband connectivity.

Cisco’s (somewhat self-servingly) projected that broadband demands will grow exponentially. That philosophy is embraced by the FCC, which would like to generate revenue for The Treasury, besides providing needed spectrum.

But selling (our) spectrum to large corporations is not the only option.

Both Microsoft and Google are vocal supporters of the movement to free up white space spectrum. White spaces, unused television frequencies, can be used for both internet access and telephony says Wireless Innovation Alliance supports White Space use with their members having experience in Software Defined Radio (SDR), Cognitive Radio (CR) and Dynamic Spectrum Access (DSA) technologies.

The Wireless Innovation Forum says that TD-LTE may be used in White Spaces, using “dynamic spectrum access”. The TD-LTE in White Space Task Group, chaired by Zhang Xiaojing of Huawei, has formed to develop a report for operators, network infrastructure and mobile service providers, baseband device manufacturers and wireless terminal manufacturers who would like to exploit the TD-LTE system in “white space” spectrum worldwide.

White Spaces utilize 6 MHz-wide channels, while WiFi uses 20 MHz channels. Speed will likely be slower than WiFi, perhaps in the 1 Mbps range, but multiple channels may be ganged together when spectrum is available.

Software Defined Radio and Cognitive Radio are enablers for Dynamic Spectrum Access, says ABI Research. Spectrum Sensing Cognitive Radio has been developed for the TV bands, but it may be broadly useful.

Microsoft submitted comments highlighting reallocation of spectrum for licensed use, but also innovative technologies – such as dynamic spectrum access – that can make higher and better use of limited spectrum.

Microsoft submitted comments and sponsored a white paper (pdf) by Professor Dirk Grunwald of the University of Colorado, Boulder, as a part of their efforts to address the growing challenges of limited spectrum. Microsoft’s ongoing “WhiteFi” trial project on their Redmond, Wash. campus was one of the first white spaces-based networks to use an experimental license from the FCC and covers the nearly 600-acre campus.

The FCC’s National Broadband Plan highlighted the importance of finding more radio spectrum. But it’s not clear how much spectrum will be left after the FCC auctions off 120 Mhz of broadcast television spectrum (the equivalent of 20, 6 MHz television channels). It doesn’t appear to leave much left for unlicensed “white space” use.

Digital television DOES use spectrum more efficiently. Unlike analog broadcasting, digital tv stations can use adjacent channels – packing as many as 10 stations between channel 20-30, for example. That means there’s now a lot of wasted spectrum below 700 MHz – and it propagates well. The Wireless Innovation Forum thinks their Dynamic Spectrum Access approach can work for both internet access and wireless telephony (using TD-LTE).

The FCC conditionally designated nine entities as TV band (“white space”) device database administrators (pdf). These databases tell TV band devices what channels they can transmit on without causing interference to TV broadcast stations, wireless microphones and other authorized broadcast auxiliary services.

White spaces aren’t likely to unset the balance of power anytime soon.

Mobile devices will be limited to 100 mW and fixed transceivers to 1 Watt (4 watts EIRP). Each Base Station is equipped with GPS and its location is sent back to centralized servers.

Frequencies in the 300-500MHz range are likely to penetrate walls and concrete much better than 1900/2100 Mhz cellular or WiFi signals. They may also be used for Smart Meters and in-home communications.

Whether the FCC ruling will launch a new era in broadband remains to be seen.

TV white spaces availability can be found for any location in the US by using the free search tool at Spectrum Bridge’s ShowMyWhiteSpace.com website, or by downloading the company’s free iPhone application.

In white space tests by Spectrum Bridge, Airspan’s WiMax gear was frequency shifted to work in UHF TV channels and controlled by Spectrum Bridge’s database technology (white space primers).

The FCC wants to encourage local TV stations to give up portions of their spectrum licenses and even pay them off with a portion of the auction proceeds, if they merge as a subchannel on a competing station. Broadcast group owners don’t pay a dime for their spectrum. But it’s all not murder shows. Today there are more than forty 24-hour local news channels across the United States.

In January 2007, Sen. John Kerry, D-Mass., reintroduced the Wireless Innovation Act, which would require the FCC to permit license-free use of the unassigned broadcast spectrum between 54 MHz and 698 MHz.

Related DailyWireless stories include; FCC Chooses White Space Administrators, FCC Okays White Spaces , Hospital Tests White Spaces, FCC to Decide on White Spaces, White Spaces Tested in Wilmington NC , First White Space Trial for “Smart Grid”, White Spaces Trialed in North Carolina, White Spaces Heating Up, FCC Moves Forward with White Space Databases, White Spaces Trialed in North Carolina, Study: White Spaces Worth $100B, Microsoft’s WhiteFi: Wi-Fi Using Whitespaces, NAB to FCC: White Spaces Illegal, Free White Space Mapping, White Spaces: It’s The Law, TV White Spaces: New Era for Wi-Fi?, NAB: Blowblack on Whitespace, White Spaces: Green Light from FCC Report, White Space Field Testing, Welcome to the White Space, Microsoft Disputes FCC Unlicensed Finding, FCC: License-free 700MHz Devices Failed Test, Broadcasters: Portable Devices Kill DTV, Mud Fight in White Space, Pushing for “White Space”, Google Launches White Space Offensive, Motorola on Whites Spaces: We’re Good, White Space Field Testing, Google Pitches White Spaces, White Spaces: Now It’s GE, CTIA: Unlicensed White Spaces Bad.

Posted by Sam Churchill on Monday, February 28th, 2011 at 11:43 am .

2 thoughts on “White Space: Now With TD-LTE?

  1. In addition to the enabling wireless access and database spectrum provisioning technologies to make use of White Spaces spectrum, the competitive market requires a vibrant supply ecosystem and ‘adoption mechanisms’.

    Success in adoption and QoS that aides it is only partly dependent on the frequency band. Frequency sets the stage because it impacts the signal propagation characteristics that greatly impacts the user experience. However, a supply ecosystem has to develop that weeds out the compatibility over large coverage areas and propels critical mass that results in lower unit pricing.

    Mobile operators have argued, with some success, that in order to get the up-front commitments to capital needed for wide area deployments, spectrum must be licensed in ways that benefit them.

    From a different perspective, studies of spectrum use across wide range from 200MHz to nominally 10 GHz has shown consistently that Wi-Fi achieves the highest concentrated utilization rates: on a per Hz, per unit area (when measured with sufficient granularity), per time basis, 802.11 Wi-Fi achieves 3X-5X higher utilization of spectrum than 2G-3G or what is expected of early 4G networks (those before massive use of microcell architectures , eg. any current plans and deployments). During MCW in Barcelona, members of CTIA including AT&T said that the industry should make more use of WiFi than femtocells because it has shown to be cost effective, significantly due to the fact that it makes use of unlicensed spectrum. Like femtocell, Wi-Fi is typically user deployed and optimized. users can figure out where to put APs to get good reception.. and that doesn’t cost operators. Users benefit, operators benefit. Sounds symbiotic until you account for the fact users pay for access at both ends. Why wouldn’t operators love the allocation and use of more unlicensed spectrum? Despite the conclusive results, we all know why.

    As you mentioned, the FCC is pursuing licensing of unfettered blocks of spectrum because the government desperately needs the money to be diverted to other (than domestic infrastructure) uses. As much as many think it should be clear that wireless access is among the most rewarding uses of OUR spectrum, the ledger shows we are in debt and thus the money will tend to be plundered.

    The FCC has considered freeing more license-exempt spectrum. I don’t have a current understanding of how discussions have progressed (or dropped off the table), but 30-90 MHz was discussed last fall.

    How does the gap between what operators want, what the government must have (more money to spend or pay back debt), and what is supposed to be the overriding purpose of the use of ‘the public’s’ airwaves?

    I have suggested to various groups that one feasible direction is to advocate for paired use of license-exempt and licensed spectrum where it can be organized into nearby or complimentary blocks. If needed, such as would be the case for cognitive radio/adaptive spectrum utilization, standards groups and suppliers would be required to develop dual/multi-MAC approaches. However, this is already the case with proposed systems and chips to be used for WiMAX+LTE, TDD-FDD LTE, and proposed TD-LTE systems and devices that would be compatible with FDD and conventional licensed access networks.

    While it is technically feasible to develop white spaces devices and systems that use the same SDR platforms and would allow roaming of devices across licensed networks, there is no requirement for commercial compliance.

    The nature of the incumbent industry is that of ‘The 3G BORG': it assimilates the technologies and business methods that it finds attractive by taking them into their sphere of control. That is only ‘human nature’ or, extended, a monopolists nature. Verizon, AT&T and other operators around the globe already have their sights set on using cognitive radio to their benefit.. most likely to similarly offload network choking capacity at little or low cost to drone subscribers.

    A better way forward, imo, is to seek out paired use of licensed and unlicensed spectrum with the requirement that devices that work on licensed spectrum must also work on the unlicensed portion and be made available on open markets without service contract requirements.

    What drives the market is a combination of the right technology, the right ecosystem mass and momentum, the right amount and ease of use spectrum, and the right amount of deployed capital and ability to roam everywhere. Having only two or three of the ingredients will fail.

  2. One important correction – the Wireless Innovation Alliance is NOT the lobbying organization of the Wireless Innovation Forum™. The two organizations are not affiliated in any capacity, although we do have 1 common member.

    The Wireless Innovation Forum (Formerly the Software Defined Radio Forum) was established in 1996as a non-profit “mutual benefit corporation”. The member organizations of the Forum are dedicated driving technology innovation in commercial, civil, and defense communications around the world. Forum members bring a broad base of experience in Software Defined Radio (SDR), Cognitive Radio(CR) and Dynamic Spectrum Access (DSA) technologies in diverse markets and at all levels of the wireless value chain to address emerging wireless communications requirements through enhanced value, reduced total life cost of ownership, and accelerated deployment of standardized families of products, technologies, and services. The Forum acts as the premier venue for its members to collaborate to achieve these objectives, providing opportunities to network with customers, partners and competitors, educate decision makers, develop and expand markets and advance relevant technologies.

    More information on the history of the Forum can be found on wikipedia (http://en.wikipedia.org/wiki/Wireless_Innovation_Forum).

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