Planning for Tiers of Coverage
Planning for Tiers of Coverage
Sep. 23, 2003 03:53 PM
An important trend in the wireless sector that has for the most part gone
unnoticed has been the emergence of a new class of mobile devices that can
support multiple wireless air interfaces.
Dozens of handheld, smart phone, tablet, subnotebook (including ultrathin),
and notebook systems are shipping with built-in wireless radio modems. These
built-in radio modems typically support one of the primary interfaces, which
include Bluetooth, IEEE 802.11b, GPRS, and CDMA2000 1x. Devices with
dual-wireless interface support are also appearing on the market, but most
often as higher-end models in a particular mobile device product line.
This new trend is paving the way for tiers of wireless coverage that will
help to ensure that live data and/or voice is always available to mobile end
All commercial wireless air interfaces map to one of the wireless network
categories, which are: Wireless Wide-Area Networks (or WANs), Wireless Local
Area Networks (or WLANs), and Personal Area Networks (or PANs). These
categories are differentiated by key wireless attributes including: average
range of coverage or service area; the rate of data transmission; frequency
assignment and management; and support for voice (in addition to data).
As the wireless sector has matured, worldwide technology leaders have
also emerged in each category to now include GPRS, IEEE 802.11b, and
Bluetooth. That said, the world of wireless is quickly evolving, with
technologies such as CDMA2000 EV-DO, UMTS, and IEEE 802.11a starting to move
up the deployment curve.
Integrated Wireless Interfaces
As Table 1 shows, mobile devices of all types are shipping with one, and,
in the case of higher-end models, two or more integrated wireless air
interfaces. Examples of the higher-end systems that support dual interfaces
include the Hewlett Packard iPAQ Pocket PC h5550, the Symbian-based Sony
Ericcson P800, and the Apple PowerBook G4. All three devices have integrated
Bluetooth along with either Wi-Fi 802.11 or GPRS interfaces (typically one
interface will constitute a radio modem with several components, including a
digital signal processor or DSP and several RF filters). WANDA, a Pocket PC
device from Texas Instruments (see Figure 1) is in a special class of mobile
devices as it supports Bluetooth, IEEE 802.11b, and GPRS.
For mobile devices that include only a single integrated wireless
interface, an additional wireless network type (cellular data for example)
can be realized with a SD/IO, MMC, CF, or PCMCIA third-party expansion
cardslot option. Thus, tiers of coverage can be realized by selecting a
mobile device that includes at least one integrated wireless air interface
with an additional third-party wireless interface, or by selecting a
dual-interface model (if available).
Improved OS Level Support Improved device driver support and configuration capability (e.g.,
Window XP and Pocket PC 2003 zero-configuration for Bluetooth wireless
Enhanced connection management: Application Programming Interfaces (or
APIs) available to OS-level (including built-in applets) and third-party
Additional user interface controls and dialogs added to the mobile or
desktop operating system¹s built-in connection manager to support the
attributes of a particular air wireless interface (e.g., Bluetooth).
Although hardware availability for wireless interfaces is critical, it is
not the only factor in the coverage equation. New or enhanced support at the
operating system level is also a key contributing factor toward the
realization of mobile devices that can realize multitiered service coverage
areas. With the latest round of OS releases including Palm OS version 5,
Pocket PC 2003 (which is a variation of Windows CE .NET version 4.2),
Symbian version 7 (with Wideband CDMA support), and Windows XP, new features
have been either introduced or improved in each system to provide enhanced
support for the unique connection attributes of a given air interface. This
has particularly been the case for the Bluetooth, 802.11b, and GPRS wireless
interface. Improvements at the operating system level have spanned several
areas and have included the following:
IP Is the Common Denominator
Another key factor, particularly to application developers, is the nearly
ubiquitous support for Internet Protocol (IP) among all major wireless
interfaces including the Personal Area Network arena currently dominated by
Bluetooth. A primary function of the IP protocol is to provide network
addressing for all nodes on a given network segment. Other functions of IP
include datagram movement as well as fragmentation and reassembly of
packets. As shown in Table 2, IP support is available among all wireless air
interfaces including CDMA2000, GPRS, UMTS (which will bring true 3G wireless
service), IEEE 802.11b, and Bluetooth.
The complementary Transmission Control Protocol, or TCP, uses the
addressing services provided by the IP stack to format the data for
transmission between two or more (in the case of multicast) nodes.
The Future Is Mobile IP
Nearly all of the wireless interfaces noted above have been geared toward
either IP version 4 or, more recently, IP version 6. However, operating IP
sessions over wireless networks involves managing the challenges associated
with the dynamic conditions a wireless network offer presents. To address
this, the development of Mobile IP was initiated by leading vendors and
standards organizations within the wireless industry. Among the features
supported in Mobile IP is the ability of an IP session to transition from
subnetwork to subnetwork as a mobile device subscriber transitions across
several base stations or access points in a series of handoffs. This
technology will further facilitate coverage tiers by providing for more
robust wireless network connections, which will improve the capability of
devices to automatically transition across tiers (or wireless coverage
Planning for Tiers of Coverage
For most organizations deploying mobile devices and wireless technology,
truly effective coverage tiers are not easily realized. While coverage tiers
are possible through the integration of several key wireless technologies in
a device to improve the overall experience for the end user, realizing this
requires careful thought and planning. Developing your own set of criteria
will make the following planning stages, as well as the evaluation process,
go more smoothly:
1. Determine what areas of coverage are important for a particular user
group and/or application.
2. Identify one or more of the three types of wireless technology that
could provide the service area required. In the case of WWAN, this will
involve determining what carriers are available in the area. If commercial
WLAN hotspots are also feasible, then service plans will also apply here.
3. Match the mobile device possibilities including third-party hardware
interfaces to the type of wireless air interface available. Again, in some
cases the intended cellular coverage area may affect device selection.
4. Following a strategy of seeking out software solutions to fill in the
gaps left by hardware, OS and device driver shortcomings are recommended. In
particular, seek out applications that utilize built-in connection
management APIs and/or third-party utilities that automate connection
management for different wireless interfaces.
Coverage tiers are possible today, and they can be very effective, even
to the point of masking some of the deficiencies of a particular wireless
technology or carrier service. The key items to look for include integrated
wireless interfaces, strong OS support, and wireless-savvy applications.