WiFi offloading, cell-phone battery drain, and dual-band access

Trends in mobile computing are merging, and will require robust cellular and wireless LAN infrastructures.

Jul 13th, 2011

by Scott Thompson, Oberon Inc.

Cell phones were originally designed for voice communications over the public cellular networks. Over time, Bluetooth wireless connectivity was added for convenience and connectivity to accessories. More recently WiFi has been integrated into some phones, and into most smartphones. The problem with WiFi is that the protocol itself was envisioned by the IEEE 802.11 wireless LAN architects as a convenient wireless replacement for cables in an Ethernet network, wherein the WiFi semiconductors could be powered by the PC's power supply or a laptop computer's large battery. Power efficiency was not a primary factor in the original WiFi architecture. So when WiFi chips designed for laptops are integrated into cell phones or smartphones they tend to draw an undesirable amount of power from the phone's small battery.

A report from UBM TechInsights looks at the progress of integration of WiFi into cell phones. While Bluetooth had achieved 100-percent adoption into handsets by 2010, WiFi had previously lagged. Since 2008, however, WiFi integration experienced explosive growth, and by 2010 had achieved a 92-percent adoption rate. This was largely fostered by the use of single-chip solutions (integrating WiFi and Bluetooth), which achieved 62-percent adoption by 2010. Although the availability of WiFi in standard handsets is still limited, the fastest growing segment of phones - the smartphones - all have WiFi integrated into them. With a smartphone, when WiFi is enabled there is a noticeable impact on battery life. Handset manufacturers and chipset designers have spent an enormous amount of design effort on conserving battery life while maintaining robust cellular communications utility of the phone. WiFi, on the other hand, has been an afterthought in handsets.

The current limitations of WiFi embedded into cell phones and smartphones will become more evident now as the cell-phone companies permit more mobile traffic to be unloaded onto available WiFi networks. The cell-phone companies recognize and impending deficit in available cellular spectrum. Spectrum availability is projected to cross a critical threshold at the end of 2012 according to a recent technical paper from the FCC, due to increased Web, data and video traffic. In order for their networks to continue to provide spectrum for essential voice communications, the cellular companies will more freely permit the mobile Web, data and video traffic to be unloaded onto public or private WiFi networks where available. And where will these WiFi networks be available? Homes, offices and public spaces. One study indicates that 62 percent of Internet-connected households have WiFi. and a growing number of businesses, schools, hospitals, government buildings and public spaces have a wireless LAN available. From the standpoint of spectrum conservation, throughput and availability, it behooves everyone to offload some of the traffic to available WiFi networks.

The aforementioned trends to increase WiFi usage, and limitations of WiFi in smartphones, have not gone unnoticed by the chipset manufacturers. In fact, the recent acquisition of leading wireless LAN chipset manufacturer Atheros by leading cellular chipset manufacturer Qualcomm, is positive affirmation of the need for the wireless LAN and cellular technologies to coexist and complement one another. As stated by Dr. Paul E. Jacobs, chairman and chief executive officer of Qualcomm, "It is Qualcomm's strategy to continually integrate additional technologies into mobile devices to make them the primary way that people communicate, computer and access content. This acquisition is a natural extension of that strategy into other types of devices. The combination of Qualcomm and Atheros is intended to accelerate this opportunity by utilizing best-in-class products for communications, computing and consumer electronics to broaden existing customer relationships and expand access to new partners and distribution channels. Said Steve Mollenkopf, executive vice president and group president of Qualcomm, "With this acquisition and our complementary products, Qualcomm will be in a strong position to take our successful mobile strategy of bringing the best technologies together into a systems solution and apply this to new opportunities. We see this strategy as central to helping our customers capitalize on the ubiquitous connectivity and seamless experiences that are developing across mobile phones, computing and consumer electronics."

From these statements, one would strongly suspect that the Atheros WiFi chipset technology is going to be more thoroughly integrated into the handset, especially with regard to conservation of battery power and improved mobile performance. I suspect that in the near future, smartphones and tablet computers will have "always-on" WiFi capability, without as noticeable an impact on battery life. Additionally, Atheros has been a leader in integrated 2.4-GHz and 5-GHz multiple-input multiple-output (MIMO) WiFi chipsets, exploiting the 500 MHz of bandwidth available at 5 GHz versus the 80 MHz of bandwidth available at 2.4 GHz. So, although smartphones possess 2.4-GHZ WiFi at this time, very soon they will possess both 2.4- and 5-GHz WiFi.

As I have indicated in several previous posts, wireless networking is not a matter of cellular or WiFi; it is both technologies acting in concert. And from the standpoint of building the wireless infrastructure, the designers needs to be cognizant of the fact that handsets, mobile computers and other devices, imminently, will anticipate the availability of a robust, mission-critical cellular network and dual-band WiFi wireless LAN.

Scott Thompson is president of Oberon Inc. You can email him at sdt@oberonwireless.com.

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