More Bandwidth Will Enable Video On Smart Phones
by Scott Thompson
President Oberon, Inc.
October 15^th 2011

Have you ever had trouble connecting or completing a mobile phone call? Am I trying to be funny!? Despite the billions of dollars invested in cellular infrastructure, there are still apparent voids in coverage. Are these actually voids in signal coverage, or is there another problem with the connection? In some cases, what appears to be a void in signal coverage is actually a void in capacity. As more mobile devices attempt to connect to a given cellular basestation, the collective interference raises the noise floor in which that basestation is operating. This has the same effect of "reducing coverage". So a location which may seem to have good service at off-peak periods in time, may not have good service during peak periods. At the extreme, if enough mobile devices are trying to connect to the basestation, the radio access network cannot accept additional requests for service, so the call is blocked entirely. And, of course, with the proliferation of Smart Phones, this problem will only get worse. As mentioned in my earlier blog dated 6-26-2011, the Federal Communications Commission (FCC) predicts a critical shortage in useable spectrum for cellular systems, particularly in urban areas, by mid 2012. The attempt of AT&T to acquire T-Mobile is entirely to satisfy AT&T's need to aggregate more spectrum for 3 G and 4G services, and T-Mobile's recognition that it does not have enough spectrum to compete. Currently, the combination of Cellular and PCS spectrum provides only 170MHz of widely available public spectrum, although the FCC is now freeing up an additional 377 MHz of spectrum, for a total of 547 MHz of public spectrum. This will take years (if not decades) for the carriers to deploy.

Forward looking industry product designers recognize this shortage, resulting in the integration of Wi-Fi chipsets into virtually all tablet and Smartphone devices. The anticipation, and reality, is that Wi-Fi will be as ubiquitous as cellular coverage for network applications. Thus Apple's recent announcement that the iPhone 4S will support text messaging over Wi-Fi, so that the wireless LAN can augment, or off-load, traffic from the congested public cellular network. Although text messaging is a relatively low bandwidth utilization of spectrum, Apple's Facetime, which is essentially mobile video calling, uses much greater bandwidth, and thus is restricted to the Wi-Fi network. The Android Bionic supports video chat over Wi-Fi.

Again, as discussed in a previous Blog, Wi-Fi or wireless LAN offers a means to offload some of the wireless Internet (and voice) traffic from the cellular network to a local premises or public LAN. Wi-Fi offers 480 MHz of much needed spectrum at 2.4 GHz and between 5 and 6 GHz, which can be deployed relatively quickly in private and public spaces. Most of this spectrum (420MHz) is between 5 and 6 GHz, with about 80 MHz available in the 2.4 GHz band. Fortunately, most of the commercial wireless routers and Wi-Fi access points are dual band, meaning they operate in both the 2.4 GHz and 5 GHz bands simultaneously. And many mobile client devices are dual band also, including most laptops and tablets (including the Apple iPad and the Cisco Cius). Unfortunately, Even though there is about 7 times more bandwidth available at 5-6 GHz versus 2.4 GHz, most client operate in the 2.4 GHz band. This is so because 2.4 GHz is a default setting in many mobile clients. Smart phones generally operate in the 2.4 GHz band only, further contributing to this congestion. This scenario, however, is changing (more about this in a moment).

An informal survey of college campuses I monitored reveals that only about 20% - 25% of wireless LAN devices are connecting through the 5 GHz band, and 75% in the 2.4 GHz band, even though the 5 GHz band offers 7 times the bandwidth. This appears to be largely driven by the fact that smart phones are 2.4 GHz band only. In one scenario, when a course syllabus requested that students bring laptops, and leave the phone turned off, the 5 GHz connection ratio jumps to over 40%. Thus the density of 2.4 GHz users appears to be largely driven by the fact that smart phones are largely 2.4 GHz band only.

So if so much more spectrum is available at 5 GHz, and laptops and tablets are already using dual band chipsets, why are few Smartphones dual band? Smart Phones batteries are, of course, much smaller than a laptops battery, so phone designers are very sensitive to the power drawn by radio frequency chips. Presumably, a dual band Wi-Fi chip set is going to draw more power than a single band chip, but this differential is becoming less consequential. A new generation of dual band chips, designed specifically for Smart Phones, is emerging. These chips engage the same highly effective power miserly techniques that the phones use in the cellular band, including shutting off the transmit power amplifier stage when not transmitting. As the impact on battery charge is mitigated, and the advantage of selling "DualBand Wi-Fi" smart phones emerges, more users will migrate to the relatively underutilized 5 GHz spectrum. The new Motorola Atrix is dual band.

Many wireless LAN operators have planned diligently for 5 GHz operation, including investing in densely packed dual band access points and antennas to provide for high capacity, only to be disappointed in the paucity of 5 GHz band users. What is an administrator to do? How does one encourage more users to homestead on the open range of 5 GHz? Many wireless LAN vendor's offer "band steering" capabilities in their products which communicate with the client device about capabilities, and they steer the client device to the best available band. Another step is to disable 802.11b functionality in the AP. 802.11b is 2.4 GHz only, so by disabling it, some clients may then move to 5 GHz. (802.11b slows down 802.11g devices at 2.4 GHz also, so disabling 802.11b is doubly advantageous). Another method is to name the 5 GHz band SSID something like "fast Internet" or "Hi-speed Internet" to encourage users to select that band. Some dedicated laptops, tablets, and PCs can be configured to operate in the 5 GHz band only. Certainly, as wireless network users seek better connections for video and image downloads and video chat, they will be actively seeking more open range of spectrum. Engaging the 5 GHz band more fully will mitigate cellular and 2.4 Wi-Fi GHz congestion, help to satisfy bandwidth requirements and more fully utilize the capabilities of emerging Smart Phones.

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See Additional Blogs

• Directives and Instructions Regarding Security and Installation of Wireless LAN in DoD Federal Facilities March 15^th, 2012
• Wireless Installation In Healthcare Facilities Jan 27^th, 2012
• More Bandwidth Will Enable Video On Smart Phones October 15^th, 2011
• The Emerging Wireless Infrastructure June 26^th, 2011
• High Speed Wireless LAN Options March 13^th, 2011
• For the Discriminating Mobile User: Why Wi-Fi is better than Cellular January 10^th, 2011
• Preparing for the Age of Exabytes November 16^th, 2010
• Wireless LANs and distributed antenna systems (DAS) March 26^th 2010