Network and Telecom Strategies Blog

QoS Problems With VoIP Over Wireless

Posted by: Eric Siegel

A fascinating article, "Coexistence of VoIP and TCP in Wireless Multihop Networks," was just published in the June 2009 edition of IEEE Communications Magazine (vol 47, issue 6, pp 75-81; the authors are Kyungtae Kim and Dragos Niculescu [NEC Laboratories America] and Sangjin Hong [Stony Brook University - SUNY]).

Burton Group has been warning that using VoIP over wireless LAN (VoWLAN) is tricky because "QoS alone cannot completely regulate the bandwidth provided to flows on a wireless network... a single wireless station on a shared wireless channel can degrade performance for all other stations on the channel...." We've been saying that: "A reasonable alternative is to avoid voice over WLAN altogether, substituting cellular voice, possibly with femtocell or in-building repeater technology." (See the Burton Group reports "Quality of Service (QoS) Alternatives" and "Demystifying Radio Management" along with the Technical Position "Quality of Service".)

This new article shows that the problems created by VoIP over wireless LAN are even worse than I'd thought. The authors did some experiments, and they found that TCP and VoIP do not coexist well on a wireless LAN. TCP's large frame sizes, large receive windows (RWIN), bursty traffic, and retransmission when a frame is lost make it interfere with short, evenly-spaced VoIP frames. The TCP frames will dominate radio transmissions because of the frame lengths and frequency during a burst. (Frames can't be interrupted after they start to transmit; therefore, long, frequent TCP frames will dominate over infrequent, short VoIP frames.)

Worse, the self-interference and half-duplex characteristics of a wireless LAN system increase the probability that the long TCP data bursts will need retransmission, further increasing their burstiness and their domination of the channel when compared to short VoIP frames. (Self-interference occurs when a single flow interferes with itself as it travels over the wireless system. When transmission and reception share the same half-duplex radio channel, a stream may compete with its own acknowledgements for radio time, delaying or destroying some data and acknowledgement packets. If transmission hops over a couple of radio links in sequence, then each hop's transmission may interfere with transmissions on other hops that are within reception range; a flow may interfere with itself.)

The authors of the new article show that no standard type of queuing algorithm in routers adjacent to the wireless network, even Priority Queuing (PQ), can handle these problems. And they also show that five standard TCP variants used in end stations (TCP Reno, TCP Vegas, TCP Westwood, TCP CUBIC [used in Linux], and C-TCP [used in Windows Vista and Server 2008]) do not handle these problems. In all cases, the TCP flows dominate and degrade the VoIP flows.

What should be done? Well, Burton Group has recommended that cellular should be considered instead of VoWLAN. The authors of the study make additional suggestions that sound interesting, but they also warn that none of them is a panacea - they all are only partial solutions, at best. The authors warn that "the methods examined here have straight-forward application only when the wireless capacity is fixed. In reality, the capacity is highly variable." They also warn that P2P, uploading traffic, and interactive streaming, such as Skype, that use TCP for voice will complicate the situation even more.

The paper's most interesting recommendations are:

• Use unusually-small TCP receive windows and eliminate TCP bursts on the wireless LAN. This may need to be done by gateways at the wired:wireless interface. The gateway would use smaller TCP packets and a small receive window; it would also use a buffer to ensure that any bursts were smoothed out and that TCP packets were spaced out to reduce self-interference and interference with VoIP frames. 

• Use a traffic shaping system. The article says, "After a packet of size pkt_size goes out over the air, the next packet is scheduled no earlier than pkt_size/R. The gateway chooses R based on the network status to determine how much to send as well as when to send."

Other papers have recommended different methods, such as doing priority queuing at all intermediate wireless nodes and combining that with traffic shaping.

At this time, it seems to me that avoiding sharing the same channel between TCP and voice is still the best solution.

What were they thinking????

Posted by: Michael Disabato

By now, you've no doubt read about the Baby Shaker app that briefly hit the iTunes App Store. Apple has profusely apologized, which they should, but this brings up the topic of Apples control of the App Store. There still seems to be little rhyme or reason to what they are doing. I have a handful of apps that still randomly crash, and I though Apple was supposed to keep apps like that from being posted.

Then there's the interference with Skype, restricting it to WiFi connections. And don't even get me started about NetShare. Luckily I managed to snag that one before it was removed.

Apple needs to do several things:

Learn that people who buy iPhones do not want limits on how their property is used
Take more care about the content of an application before it is released
Be much more transparent about the approval process

As a parent, I found the baby shaker app abhorrent to say the least. But I find Apple's behavior surrounding the App Store reprehensible.

Michael

Palm's Pre: the iPhone Killer - Not

Posted by: Michael Disabato

After too many years to remember, and more changing of owners and management than I care about, Palm is finally releasing a new handset based on a new operating system. The press has had a lot of favorable comment, including "iPhone killer." I'm here to tell you that's ludicrous and why the Pre, and Palm, are destined for less success than everyone thinks.

First, it's the software, stupid! Palm used to have 15,000 - 20,000 developers writing really good code for the Palm OS. When Palm abandoned that, they abandoned them, and many have moved on to other projects like iPhone, Android, and Windows Mobile. It will be hard to convince them to come back to a new OS requiring new skills and investment during these economic times.

Second, there is the uncertainty of Palm's future. The company has been sold and handed around several times in the last few years, with no clear indication of its solvency or direction. No clearer indication of this could be had by seeing that Palm's last Windows Mobile device was shunned by all the mobile operators and ended up being sold directly by Palm to customers as an unlocked device with no subsidies.

Lastly, the Pre is a CDMA device with exclusivity on Sprint. If you wanted to find a smaller network that is in trouble or about to be acquired, I don't know where you'd look. Sprint's problems with ClearWire, and their insistence on sticking with WiMAX for voice (say what??) is making subscribers think twice about it's future. I don't know... Maybe Palm could not find any GSM takers for Pre, but without a GSM handset in the offing. you have a marginalized handset maker on the edge of oblivion partnered with a marginalized carrier who may be joining them.

iPhone killer? Gimme a break. The thing will be lucky to survive.

Michael

Mobility generational gap

Posted by: Paul DeBeasi

Younger workers are pushing many enterprises to embrace mobility solutions. These younger workers are often referred to as Gen-Y. However, since there is no precise definition for the Gen-Y cohort, I simply use the term “younger workers” in this post. Younger workers prefer instant/text messaging instead of e-mail, and they frequently use social networking services like Facebook, MySpace, and Friendster. They often prefer to use personal, consumer-oriented, devices (both laptops and handhelds) in the work environment and they adapt quickly to new technology.

In contrast, enterprises often describe how their older workers are sometimes slow to accept mobility solutions and how they rely almost entirely upon voice communications and e-mail. These workers often don’t see the benefit of instant messaging, and social networking. Interestingly, older workers are often in positions of authority that control staffing and budget, and they can therefore greatly influence mobility policy.

These different points of view between younger and older workers have created a mobility generational gap. Older workers sometimes see younger workers as being “spoiled” or “entitled”. Conversely, younger workers sometimes see older workers as a barrier to progress.

Enterprises should recognize the fact that a mobility generational gap can exist even between groups of younger workers, where there is as little as 5 years difference in age. This is because the Internet, mobile cellular services, mobile devices, social networking, wireless technology, and online usage norms, have evolved rapidly over the last 5 – 10 years. This can lead to a situation where some workers become “mobility laggards” while an advanced group of workers become “mobility leaders”.

It is not surprising that younger workers are more likely to take advantage of mobile services since they grew up in a world of pervasive mobile communication. However, it is interesting to see the degree to which age-based differences in mobility usage, proficiency, and expectations can create problems within the enterprise. In my discussions with enterprises I sense frustration and even shielded animosity that some employees have toward their co-workers.

Two distinct groups characterize the mobility generational gap. One group is comfortable with mobile technology, and uses that technology to integrate work and professional lives. The other group is less comfortable with the technology and tends to compartmentalize work and professional lives. As more mobile-savvy younger workers enter the workforce, the mobility generational gap will widen. As it widens, both groups may become more disconnected and distrusting of each other.

Enterprises should consider the following recommendations:

• Recognize the extent to which a mobility generational gap exists in their workplace, and then put programs in place, such as mobility training, to help employees become proficient with mobile technology and services.

• Re-think device use policies and take into consideration the expectations of younger workers for ubiquitous information access, collaboration services, and personal device usage within the enterprise.

• Learn to manage and secure sensitive data on personal, consumer-oriented, devices. Carefully evaluate risk tolerance for each consumer device under consideration.

Mobility governance is a mess

Posted by: Paul DeBeasi

Mobility has far-reaching effects on the enterprise in areas such as security risk, use policies, manageability, and governance. Mobility governance refers to the people, processes, and policies associated with mobility deployment within the enterprise. With few exceptions, enterprise mobility deployment is often reactive and tactical. The lack of a corporate mobility strategy results in the deployment of incompatible point solutions, coordination issues, and inconsistent policies.

In addition, most enterprises have no coordinated approach to mobility funding. This includes decisions to deploy a wireless LAN, purchase mobile devices, and select mobile cellular service plans. Some managers demand that business case analysis be applied to the decision-making process for such things as wireless deployment, and social networking implementation. IT managers often express frustration with how difficult it is to develop a business case for mobility products and services. Other managers go to the other extreme and simply mandate mobility technology deployment without any upfront analysis.

Personal use policies on handheld devices often vary widely. Some enterprises prohibit personal calls, forcing employees to carry two phones, one for business use and one for personal use. Others allow personal phone calls only if employees do not exceed their minutes-of-use plan limit. Some enterprises have a “no text messaging” policy, although it is unclear how that policy would be enforced if the employee owns the phone.

Similarly, handheld ownership policies vary widely. Most enterprises allow only company owned devices to access the network. Some allow personal laptops to access the network when using an enterprise-provided USB key that contains an approved bootable image.

Enterprises often struggle to balance the needs of IT staff to secure and manage mobile devices, with the desire of employees to use mobile devices whenever and wherever they want. Some organizations opt for a laissez-faire approach that provides users with broad device usage and ownership flexibility. However, this approach often exposes the enterprise to inordinate security and legal risk. Alternatively, concerns over insufficient mobility security and management, coupled with the lack of coherent mobility governance, cause many IT organizations to simply reject user demands for greater mobility solutions. This approach can lead to users finding ways to bypass the IT staff and enterprise policies.

Some enterprises are using the Information Technology Infrastructure Library(ITIL) for mobility service management. ITIL is a widely adopted framework for IT service management. ITIL can help organizations create a mobility strategy, personal use policies, security best practices, and funding procedures.

Enterprises should consider the following recommendations:

• Embrace mobility as a strategic imitative rather than simply a technology purchase decision.
• Consider applying the Information Technology Infrastructure Library concepts and policies to the challenge of enterprise mobility.
• Consistently adhere to security best practices and avoid making exceptions to security policies.

Mobility drivers and risks

Posted by: Paul DeBeasi

Introduction

Enterprise mobility is driven by the need for seamless access to information anytime, anywhere, and from any device. One of the biggest drivers for enterprise mobility is the need for seamless access to information anytime, anywhere, and on any device.  Employees have grown accustomed to having ubiquitous information access in their personal lives, and expect the same in their professional lives. In the past, employees would try to compartmentalize their personal and work lives, in order to protect their personal time from job encroachment. But now the opposite is true.  Many employees move seamlessly between work and personal lives, and expect that their employers will support this new work paradigm.

Some enterprises struggle to create a business case that quantifies productivity gains and calculates a return on investment for mobility technology. However, this is very difficult to do and most enterprises simply accept the idea that mobility results in productivity improvement. For many employees, a mobile work environment is now an expectation, analogous to the expectation that their employer will provide a local area network and Internet access. Therefore, many enterprises often deploy mobility technology without any upfront justification or global planning.

Data leakage

The most profound risk to enterprise mobility is data leakage on mobile devices. Once a user transfers sensitive data to a handheld device, that data can be compromised if the handheld is lost or stolen, or the data is transferred to another device. This concern is exacerbated by the fact that the design of most mobile devices is being driven by the needs of consumers, rather than businesses, and therefore is often not suitable for the enterprise. Lastly, the mobile device has become the new network perimeter so enterprises can no longer simply rely upon firewalls in order to lock down their sensitive information.

Some organizations have a policy that requires users to encrypt sensitive data on a laptop hard drive. However, few organizations encrypt sensitive data stored on handheld devices such as the BlackBerry. This means that sensitive data on a handheld is oftentimes more vulnerable to theft.  In the event of a lost or stolen handheld device, many enterprises will remotely “wipe” the device, thereby removing sensitive information. Some vendors, such as Research In Motion (RIM), enable the IT manager to remotely disable the device and restore it to factory defaults.  Some enterprises have invested in technology to find lost or stolen laptops, such as Computrace’s LoJack for Laptops product.

Many organizations encrypt sensitive information that is transmitted between the handheld device and enterprise servers by using virtual private network (VPN) technology. This “in transit” encryption is typically performed while users communicate on the road or at home. A few organizations even enforce the use of VPNs while users communicate over the office wireless LAN (WLAN).

Although many organizations enforce the use of two-factor authentication on laptops, handheld authentication policies lag behind laptop authentication policies. For example, many organizations require a simple four-digit personal identification number (PIN), or no password at all. If a handheld device does not have a password, and it is lost or stolen, then any sensitive data stored on that device is easily accessible. The small size of handheld devices makes it easy for them to fall out of a pocket or purse, and thus become a security risk.

Conclusion

Data leakage on mobile devices is a major risk for virtually every enterprise. Unfortunately, handheld security policies often lag behind similar laptop security policies. This can result in security breaches and increased legal liability. Enterprises must carefully evaluate their risk tolerance, and then must secure sensitive informtion before users are granted mobile device access privileges.

The (not so) Perfect Storm

Posted by: Chuck Bessant

 

Did I learn my lesson when I purchased the new Volvo S70 in 1997 in the first production month? No. Warranty covered everything, but I had a lot of stuff replaced which takes time, my time, at the dealership.

 

Did I learn my lesson when I built a house this year and used a new model KitchenAid oven? No. After self-cleaning it this summer, a module burned out and the oven wouldn’t heat up for cooking. I discovered this “feature” when I tried to bake a nice Copper River salmon, well, it would have been nice. Had it fixed, under warranty, then cleaned it again on Monday (1-Dec), and it did the same thing. Appliance guy, “Oh yeah, they came out with an updated module. We didn’t install the new module? Your oven should be fixed by Christmas.” WHAT (on so many levels)!

 

So, now I have a Blackberry Storm. I’ve learned a lot since 25-Nov.

 

·         The battery seems much better than the iPhone. The 480x360 color display is sharp. The SurePress touch screen operates well as long as you are not Andre the Giant. The SureType and QWERTY keyboards work OK. Lots of ring tones if you get board; I go for the Zen sounds myself. I was able to order it via the Verizon 800-number so no lines at the Verizon store. Broadband over Verizon’s EV-DO network, nice. GSM so it will work in Europe, very nice. Reception is great. This is all good.

 

·         SurePress action response is slow. When you press a key, there is a noticeable response delay that is very annoying. Navigation to the phone directory is a bit awkward. Once the keypad is up, and you want to Mute or go to Speakerphone it is a bit awkward. My Plantronics Bluetooth ear piece doesn’t stay synched very well, although it does with my Samsung cell phone. When physically turning Storm from portrait to landscape, the display doesn’t always rotate as advertised. Annoying? Yes - I’m getting a stiff neck.  

 

·         Verizon does not have their Backup Assistant applet for Blackberry, even though the instruction sheet from Verizon says to use it to download your directory. This feature on cell phones backs up your phonebook when changes are made to a Verizon server via a call. Seamless, fast, easy, automated, effortless. You can even access the phonebook by going to your wireless account on-line. Sweet! But for Storm, from what I’ve been told, and all Blackberries, sour. This feature does not exist. You can do an upload to Blackberry, or to Outlook via a cable to your computer. OK, I get that. Verizon’s response when I asked how to get my directory to Storm was “re-type or take it to a Verizon store”; I live 25 miles from the nearest Verizon store, and no one told me I couldn’t download my directory via Backup Assistant. I have got to believe that Verizon could provide a Backup Assistant to at least get your phonebook directory seeded to a Blackberry without going to a store, getting a number and waiting for help. All this great technology, wireless, EV-DO, yadda, yadda, yadda, and I still have to shag to a store. Boo, hiss.

 

I am new to the Blackberry, and maybe this is all normal. I expected Storm to be more responsive and a better first generation release than it is given RIMM’s reputation. This is not like Windows 3.0. Blackberry has been around for years. Verizon has carried it for years. The SurePress thing is new, granted. And so is Storm technology for Blackberry. Why is response slow? I have no idea, nor do I care, it is slow, I don’t like that so that is that – Sam I am.

 

I plan to return it. I’ll wait for Storm 2.0 to be released, or just maybe 2.1 so I can say I learned my lesson on new/major releases. Overall, the concept is excellent. I am just not impressed with v1.0, and having the user help fund the next generation release by releasing a device that should have been gang busters out the door.

Real Time Location Systems

Posted by: Paul DeBeasi

Introduction

Real-time location systems (RTLS) have been around for years. Retailers use these systems to track inventory and trucking companies use them for fleet tracking.  Although the applications sound similar, the underlying RTLS technology for both applications is quite different. This blog post provides an introduction to real-time location technology and a description of several common applications.

Technology

Real-time location systems determine the position and location of a target.  Position identifies a spot on the Earth using a geographic coordinate system (e.g., 32° 49’ 49.7964’ – 116° 49’ 9.9228”).  Location refers to a certain place in the real world (e.g., “Boston’s North End”).  RTLSs determine position and location using a variety of technology as described below:

§  RFID: Radio frequency identification (RFID) systems consist of low-cost electronic tags that can be interrogated by electronic readers. In most RFID environments, the primary purpose of the system is to identify the tagged items (e.g., inventory tracking). These items might be constantly in transit, such as on a manufacturing line, or they may be tracked as they are moved from a retailer’s shelf.  Most RFID readers and tags operate only at very close range, offering proximity location within inches or at most a few feet.

§  Wireless LAN: A WLAN with one or more location servers has the ability to locate WLAN-enabled devices anywhere within the facility or campus. Any device that is communicating with the WLAN has the potential to be located in real time using the WLAN system. These WLAN location capabilities have been extended to locate individual users on the network, including WLAN phones for Enhanced 911 (E911) services.

§  Mobile Cellular: Mobile cellular phone systems have incorporated location-detection and tracking mechanisms, such Time Difference of Arrival (TDOA) and Triangulation. These mechanisms enable mobile operators to offer location-based services, such as fleet tracking, and enable first responders to dispatch emergency personnel to the appropriate location.

§  Global Positioning System (GPS): GPS receivers rely upon a constellation of satellites circling the world. Unfortunately, the signals from the GPS satellites do not generally penetrate to the interiors of buildings and can be blocked by tall buildings in dense urban areas. This limits the use of GPS to outdoor environments where there is a clear line of sight to at least three of the satellites.

§  IP Geolocation: The most established RTLS is not based on wireless networking technology at all, but relies on Internet Protocol (IP) addresses to provide geolocation information. Geolocation provides the ability to route users to different websites according to the presumed location of the origination IP address. This capability is often utilized to route users to data centers that are closer to the user in hopes of providing better performance and faster response times.

Applications

Location applications are quite varied.  The list below highlights some of the more common applications: 

§  Fleet Tracking: Fleet-tracking systems utilizing GPS technology have been available for many years. These systems enable an enterprise to analyze fleet activities (e.g., trucking) in real time and include the ability to track vehicle location and speed, optimize routes, schedule jobs, aid navigation, and analyze driver efficiency.

§  Navigation: In its simplest form, navigation services provide directions for how to get from Point A to Point B. Navigation services from companies such as Garmin and TomTom rely on ever-changing map databases from companies such as Tele Atlas and NAVTEQ to translate GPS-supplied position information into user-friendly location information. In October 2007, Nokia agreed to acquire NAVTEQ for $8.1 billion. The combination of GPS, mapping, and mobile cellular technology will enable mobile devices to offer new navigation services.

§  Inventory and Asset Tracking: RFID technologies are widely used for asset and inventory tracking. RFID readers are distributed throughout the enterprise in order to wirelessly communicate with the RFID tag on the target. The wireless readers must be connected to a network to allow real-time communication with a management console. Placing RFID readers at specific “chokepoints” will allow the tracking of inventory as it enters and leaves a facility and will enable an alarm to be activated when tagged items are removed from authorized areas.

§  Personnel Tracking: The underlying technology for personnel tracking differs according to whether personnel reside inside the enterprise or whether they are fieldworkers who are located many miles away from the enterprise. Fieldworker solutions typically rely on GPS technology embedded in mobile phones. The drawback of such services is that they are limited to the coverage area of the mobile operator. In contrast, in-building personnel tracking systems often uses RFID technology. RFID-enabled badges, and RFID readers at specific locations, can provide details on when personnel are within range of a given location.

§  Network Security: One of the more interesting applications of location detection is the ability to enable logical “boundary” enforcement. The use of WiFi Protected Access (WPA) can eliminate the ability of an eavesdropper to decode transmissions, but it is also advantageous to be able to limit the physical area from which a user can connect. By creating logical boundaries, the enterprise can restrict user access based on where the user may be located.

Privacy

For many enterprises, the biggest issue with RTLS is that of privacy. Employees may be concerned that their manager is tracking their whereabouts throughout the day. Other important questions include: How will the location information be used? Who has access to location information? When is the information legally discoverable? How long will location information be stored? Enterprises must create and enforce privacy policies that protect employee and employer privacy.

Conclusion

Real-time location systems are poised to make a significant impact on the enterprise. Advances in location technology and expanding enterprise wireless applications will drive the deployment of the next-generation RTLS throughout the enterprise.  However, enterprises must create privacy policies and establish processes that ensure policy adherence. 

Has the iPhone met the perfect Storm?

Posted by: Chuck Bessant

When the iPhone was released, they should have included the 1984 Mac Super Bowl Commercial that shook the world. Mac really changed the desktop productivity environment as did the iPhone with the way it changed the face of the smartphone. Except the battery, not so much.

One of the biggest complaints I heard early on with the iPhone was about poor battery life. Somehow Apple has this thing about battery technology; even the iPod has had battery issues. The use of EDGE to provide smartphone network data access was done to conserve battery power. Smartphones have lower bandwidth demands so EDGE was a good choice from ATT’s perspective: smartphone bandwidth needs are less than a laptop, and battery life is better at lower data rates.

The Internet Generation, iGen, has been treated to a lot of free stuff. Prior to the Internet being commercialized in the early 1990s, a lot of information and services had to be paid for, or you had to drive someplace to get what you wanted. The iGen expected the iPhone would provide broadband 1Mbps+ speeds rather than EDGE’s rate of 175KB at no additional cost. The iPhone was an innovative product that needed some place to grow; this is still (for now) a capitalist market economy. Adding new features like broadband would be a good upgrade path, especially as bugs are shaken out.

A lot of users have complained they can’t use their PC (or Mac) with their iPhone as a network gateway. Obviously, connecting a computer to an iPhone via a USB or FireWire cable would be an additional drain on the already taxed iPhone battery, and using a faster broadband network would add more battery drain. Unless, of course, the iPhone would pull power via the USB cable from the computer thus saving/charging the battery like is done with an iPod.

Sure, it will cost more to move up-to WiFi for computer/tethered access but you are getting more bandwidth. Verizon offers broadband EV-DO access with a PC Card for $60/month with unlimited access (kind of like something being “fat-free”, there is a limit of like 5GB) and I’ve experienced data rates over 1.5MB. I like this service as I’d rather carry a PC Card around in my laptop bag than a cable. And, it frees my smartphone to do its thing. Since I use Verizon I can’t comment on whether you’ll have iPhone’s smartphone functionality while a computer is using the iPhone as the network gateway. And yes, the PC Card is $50, and a cable should be cheaper – keyword is should.

At the end of the day, $60/month seems to be the magic broadband number for ATT and Verizon, plus a cable or PC Card. Verizon is releasing Research in Motion’s Blackberry Storm on 21-Nov-2008. The Storm can provide broadband EV-DO for a connected device for the same price as using a PC Card in your laptop.

It should be interesting if the same excitement will be had for the Storm as was for the iPhone especially given our bummer of an economy.

WiFi Everywhere

Posted by: Michael Disabato

I just returned from a trip to Prague in conjunction with our Catalyst Europe conference. (It's a rough job, but someone gets to do it.) One thing I noticed was the profusion of free WiFi hot spots throughout the city. I do not know how the mobile operators feel about this (and I don't really care, having found a nice way to cut my data bill), but a common sight is people sitting in a restaurant or cafe, enjoying a spot of Internet with their coffee and strudel (yummy strudel!). Needless to say, This was a good thing and I made use of it as I walked the city.

Several questions come out of this:

1 - How do they make money giving away Internet connectivity?

2 - Does anyone there understand the Channel 6 problem and the need for spectrum management?

3 - Over the long term, how will this affect the mobile operators?

I'd love to hear from others who have found cities with free WiFi and your thoughts on this.

Michael