Clearwire Provides Additional Details on Its 4G Developer Program

With its mobile WiMAX deployments on track and proceeding ahead of schedule, Clearwire has been working with silicon vendors and device makers to create tool kits, reference designs, and Application Program Interfaces (APIs) to exploit the dynamic capabilities of its mobile WiMAX network.
We will describe the functional capabilities of these platforms below, while noting that they are mostly “works in progress” and continue to evolve.   We’ll also provide a perspective on premium video services and why we think they could be a big differentiator between Mobile WiMAX and 3G.   But let’s first review the characteristics of the CLEAR network.

Positioning Clearwire’s Mobile WiMAX Network:

Clearwire’s WiMAX service (known as CLEAR) currently reaches about 30 million U.S.   residents.   The company plans to make CLEAR available to about 120 million people by the end of 2010 (that means the network will be available to that many potential subscribers).   Clearwire has stated that at the end of the third quarter of 2009 it had about 555,000 subscribers, which includes people who have subscribed to the service via its MVNO partners Sprint, Comcast, and Time Warner, which are reselling the service.   Clearwire reported it added 173,000 new WiMAX subscribers in the third quarter of 2009.

In our opinion, Clearwire’s biggest asset is its huge chunk of wireless spectrum in the 2.5 GHz range.   The company says it owns an average of 150 MHz of 2.5GHz spectrum in most major markets.   For wireless networks, the amount of spectrum owned directly translates into subscriber bandwidth and coverage area.   The more spectrum owned, the faster the data rates and/or the more subscribers served within a given sector.   This results in higher throughput and lower latency.   At the Sprint Developers Conference on October 27th, Clearwire’s Scott Richardson confidently stated that “spectrum trumps technology” and that “the spectrum owned will separate WiMAX from LTE.”

Mr. Richardson very confidently stated, “We have a super fast (wireless broadband) network which you can think of as a “bit factory” for all IP traffic- for both households and machine-to-machine (M2M ) applications.   The bits will go to retail or wholesale customers (MVNOs).   In the future, we will have other wholesale customers that will use CLEAR as a backbone network.   Our evolving business model(s) will enable a whole new set of applications.   This will enable a richer web experience for mobile users.   Clearwire will have U.S.  nationwide coverage by 2011 and will be able to fill the broadband mobile Internet vortex.   By 2011, the killer 4G application will be cloud computing on the go.”

On its last earnings call, Clearwire CEO William T. Morrow stated: “Our objective remains the same — to aggressively expand our 4G network with nationwide coverage, delivering the best possible user experience in capturing a strong share of the growing mobile data market.   At the same time we are building out new markets, we are converting most of the remaining pre-WiMAX markets to 4G.   Since we utilize many of the existing network sites, this process is less capital intensive than new market builds and our sales channels are already largely in place.   Since we have purposefully reduced our marketing efforts with this service, our expectation continues to be that we will see a higher than normal level of churn within our pre-WiMAX markets until we complete the market conversion.”

“This past quarter we also formally launched our Silicon Valley innovation network, providing developers with network tools, APIs, and free access to our WiMAX network.   This new sandbox will enable them to create, test, and build applications that leverage the unmatched combination of speed and mobility delivered by the 4G network.   After just under two months, we have developers spanning 400 companies and universities across Silicon Valley.   “

CLEAR Silicon Valley Innovation Network, December 2009
(visit website for latest maps)

On wireless net neutrality, Clearwire’s Chief Commercial Officer Mike Sievert stated: “Clearwire applauds the FCC Chairman’s efforts to safeguard an open Internet and his desire to strike a balance between consumers’ need for open, rich access to the Internet and appropriate network management practices.” For some time, Clearwire has stated that it will provide equal access on its broadband wireless network to all Internet services and applications.   We wonder how much Clearwire is influenced by Google – one of its investors and partners–which has been one of the most outspoken proponents of Net Neutrality.

Clearwire Developer Program Initiatives:

At the Sprint Developers Conference and in follow up phone calls and email exchanges, Clearwire’s Dave Rees, Aaron Hinkle, and Art Spivy provided information on the company’s development platforms, their status, and how they relate to various use cases.

There are currently three available platforms for apps developers: Location, Client Connectivity, Activation & Provisioning reference implementations.  Note: The Activation & Provisioning platform was added after this article was written.  It details the processes that devices will use to access the mobile WiMAX network.  Those processes include: network entry, IP acquisition, authentication, subscription creation, and many others.  Please refer here for details.

The Location Platform supports two network APIs.  The first is the JSON Client/Server API that allows clients on devices to access that device’s location within a Sector.  The second is a Parlay X API that allows servers to get a remote device’s location (e.g. to track the location of family or friends).  Clearwire uses certificate-based mutual authentication to secure requests against this second service.  As there are very serious privacy concerns with remote location tracking, a written agreement must be signed by each device owner who consents to be tracked.  (Editors Note: The terms for using location are specified on Clearwire’s Developer web site.  Any developer using the location platform must follow CTIA’s “Best Practices and Guidelines for Location Based Services”.  These practices include having the developer obtain opt-in consent to using location from the customer.)

On its Developers web site, Clearwire recently created a web demo based on their Client/Server JSON API.  By clicking on a link, a query will be sent to both Clearwire’s and Google’s location platforms and the results will be plotted on a map.

The Client Connectivity Platform is a Connection Manager reference implementation for connecting to WiMAX.  It is intended to help device and software developers better understand how to connect to WiMAX and support efforts to build devices that to connect to WiMAX.  The Client Connectivity Platform uses a “Common API” for accessing its drivers.  This is a proposed I/O driver API standard from the WiMAX Forum.  Clearwire has been working with chip set manufacturers and the WiMAX Forum on this effort.  When it’s considered mature, Clearwire would like to make it part of its commercial deployments.

Clearwire refers to the “Common API” concept as a “Session Information API.” It would allow developers to access network, radio, connection, and device information through a client API.  That information would be exposed by the WiMAX silicon I/O driver that implemented the API and made available on request to the application program.  In addition to the proposed Common API standard, Clearwire is also looking at the possibility of sharing the same information at the Connection Manager level to other applications.  In either case, the goal is a commercially available, distributed, public accessible API that developers can use for a variety of use cases (including alternative connection manager interfaces, determining location, and client applications adjust bit rates based on RF conditions).  While Clearwire is working hard to solidify the exact mechanism for exchanging this information between the chip set I/O driver and the Applications program, they don’t yet have a time-line on when an “official API” will be deployed on commercial devices that connect to CLEAR.

Dave Rees was kind enough to clarify and update the list of functional modules and capabilities that he and Aaron Hinkle described at the Sprint Developers conference.  These includes the Location platform which is briefly described above and in more detail on the Clear Developers web site.  Clearwire does not yet have a time-line for the realization of these capabilities for developers.

Location – The location platform is now available as a network service.  Clearwire sees location as a key enabler for the types of services that take advantage of WiMAX bandwidth and mobility.

-Client/Server location is based on the Call Sector (1/3 of a Cell) that the device is physically present.  No GPS or client hardware is required.  The result provided is a longitude/ latitude for the center of the Sector.  A corresponding street address may be optionally requested.  Accuracy was said to be within 400m to 800m.  Computation time is < 1 second.

-Server/Server location allows one server to ask another for a remote device location using the latter’s IP or 802.16 MAC address.  The resulting response is the longitude/ latitude for the center of the sector the remote device is physically in.

-Assisted GPS capability queries the network location service to more quickly fix the devices location.  Clearwire doesn’t yet have an official target date for when Assisted GPS will be released.

-Multi-lateration is the process of locating an object by accurately computing the time difference of arrival (TDOA) of a signal emitted from that object to three or more receivers.  It also refers to the case of locating a receiver by measuring the TDOA of a signal transmitted from three or more synchronized transmitters.  In Clearwire’s planned implementation, a given device type will be connected to one Base Station, but will also been scanned by Base Station receivers in neighboring sectors.  Clearwire doesn’t yet have an official target date for when multi-lateration will be released.

Access Authentication is a secure authentication mechanism for an API.  It is not actually a functional module.

RF Awareness – Will be provided as part of the Session Information API described above.  While the WiMAX chip set I/O driver will provide the relevant RF parameters (e.g.  received signal quality, signal strength, transmit power, etc) the client applications will be responsible for using that information to do things like adjust bit rate, video frame rate or resolution.  Some video clients already do this based on packet loss (e.g.  Slingbox on a 3G network), but that is primitive compare to pre-emptive packet loss adjustments.  RF Awareness information will surely help video clients (both one way and bidirectional chat/conferencing) make even better decisions about adjusting video parameters sooner.

Editors Note: Mobile Internet video is much more variable and dynamic than fixed line broadband Internet video.  A mobile network will produce very different downstream bit rates as the subscriber transits a cell or sector or from one network (3G) to another (mobile WiMAX).  This is because the mobile subscriber experiences different RF signal characteristics while in motion.  The changing signal conditions will negatively impact the mobile video experience, unless the video resolution, video frame rate or bit rate is adjusted to match the received signal quality and strength.  For a good video experience, we recommend an optimized mobile video player from all of the proponent companies (e.g.  Adobe Flash, Microsoft Media Player, Real Player, Apple Quicktime, etc).

A couple of competing ways of offering mobile video are described at:
http://www.flotv.com/whats-on-flo-tv/guide
http://www.openmobilevideo.com/

Data Session Continuity (between 3G and CLEAR) – This is currently in concept phase.  Clearwire is looking at ways of providing it, but they don’t have a time-line yet for when it might be publicly available.

Device Management – This really is a function of the connection manager, so it’s not a separate developer platform or API.  Clearwire does plan to provide device information through the Session Information API.  In fact, Clearwire hopes to eventually provide more information (like historical info) through the Session Information API.

Diagnostics – This is also is currently in concept phase.  Clearwire is examining ways of providing it, but like Data Sesssion Continuity, they don’t have a time-line yet for when it might be publicly available.

Service Level QoS – Clearwire has an internal QoS implementation that is said to be compliant with IEEE 802.16e standard and the WiMAX Forum profiles (see Table 1.  below), but the actual QoS mechanism to be made available to value added services and applications is still in the planning stage.  There are currently active discussions occurring with their business, technical, legal and policy teams.

While there are five QoS classes defined in the IEEE 802.16e standard (see Table 1.  below) and implemented in WiMAX silicon, there are other ways to provide QoS.  For example, it can be done via IP v6 priority bits, DiffServ, MPLS, or other higher layer mechanisms that are combined with port information and deep packet inspection.  But at this time, Clearwire has not selected a QoS mechanism and does not yet have a time-line for how and when to make QoS more generally available.

Table 1.  IEEE 802.16e-2005 QoS classes
Note:  The base station and the subscriber station use a service flow with an appropriate QoS class (plus other parameters, such as bandwidth and delay) to ensure that application data receives QoS treatment appropriate to the application.

Comment:  Without agreed upon QoS mechanisms, there are no special provisions for delay sensitive apps (like mobile VoIP or music), real time high bandwidth apps (like premium content streaming video), jitter sensitive apps (like real time video conferencing or video surveillance), or other high priority services (e.g.  emergency or first responder/ public safety communications).  Of course, there may be sufficient overall bandwidth in a given cell or sector such that delay, jitter and throughput sensitive apps get what they need and there is no congestion to bypass.

Perspective:  While Clearwire would like to have more platforms and APIs available now, it takes time to develop them in conjunction with chip set vendors, device makers, systems integrators and other partners.  When Clearwire representatives talk about these APIs with developers and partners, they also emphasize the speed and the capacity of the CLEAR network.

Clearwire believes that “the APIs described above will certainly help many developers, but a much larger set of developers and customers will benefit from having broadband speeds on the go – not just on laptops, but handsets, and other types of consumer electronics as well.  And those services won’t necessarily come from us, lots of folks are working on higher bandwidth mobile services (e.g.  Hulu, Google and others are working on higher quality video conferencing, augmented reality).  We plan to provide a network that attracts customers by enabling and encouraging all of these services.”

Assessment and Conclusions:

Clearwire has said they won’t compete with incumbent wireless operators who are serving “a different market all together.” Clearwire wants to emphasize high speed, low latency and mobility.   We agree that will differentiate CLEAR from 3G and DSL/Cable broadband access.   But we firmly believe that in addition to a broadband Internet bit factory over the airwaves, services and applications are urgently needed for CLEAR.   And Clearwire is trying to make this happen with tools planned for developers.

But despite the commendable efforts on tool kits, platforms and APIs, Clearwire will be late to the apps party.   In arecent front page article, the San Jose Mercury states, “apps woo Web traffic and consumer interest back to the platform, the way flowers attract honeybees to their pollen.   The popularity of Apple’s iPhone and its more than 100,000 apps that allow users to check everything from surf conditions to a bank balance has accelerated the trend.”

The premium video services that this author envisions (with better quality than best effort Internet) include: Sprint TV premium content (like NFL Sunday ticket), Comcast On-Demand On line, live sporting events (mlb.com, nba leage pass broadband, nhl.com, etc), video surveillance and alarming (via an IP VPN), 2 way live video chat, closed circuit TV for e-learning or other use.   The video services that would be acceptable over best effort mobile WiMAX include: You Tube, playback of news or sports clips, or any other “bite sized” chunks of video from a web site.   However, even those would be more appreciated with dynamic video parameter adjustment based on RF Awareness.

If hooks were available to realize differentiated services like those described above, software developers might be encouraged to create useful applications for notebooks, netbooks, and other devices with embedded mobile WiMAX interfaces.   That in turn, will entice more subscribers to sign up for mobile WiMAX service, which will encourage more applications and devices.   We submit that such a virtuous cycle will NOT occur if WiMAX just offers fast Internet access on notebooks, netbooks, and through portable WiFi hot spots.

Since CLEAR coverage won’t be nationwide for some time, it will be essential to have 3G/4G data cards in WiMAX enabled PCs so that 3G-EVDO is available when CLEAR is not.   That is starting to happen now thanks to Sprint.   (This author has a 3G/4G USB data card).   Session continuity between 3G and mobile WiMAX will be important for mobile users on the go.   But apps and hand held devices will be even more important.   Let’s hope we see lots of activity in both areas in 2010.