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Designing an easy-to-use wireless router
for the SOHO market
By Rahul Patel
Sr. Product Line Manager
Wireless Networking
Business Unit
Broadcom Corp.
E-mail: [email protected]
Wireless LAN (WLAN) has
made possible the benefits of
“being connected” and “mobile” at the same time. In addition to providing fast and convenient network access, today’s
Wi-Fi products include robust
security features that alleviate
concerns about data protection
over open-air. The latest Wi-Fi
equipment is as functional and
cost-effective as wired equipment, making a stronger case
for the continuation of the dramatic growth of Wi-Fi nodes. In
fact, according to Forward Concepts, the number of Wi-Fi
nodes is expected to grow to
more than 180 million by 2006.
The two largest Wi-Fi market segments today are client
card solutions for PCs and
router products. As these markets continue to grow, designers are continually faced with
new and different challenges to
design efficient and cost-effective routers. This article discusses some of the challenges
of designing a router that will
successfully serve the needs of
the small office and home office (SOHO) markets, and address the scalability that will
enable WLAN equipment
manufacturers to overcome
these issues.
that supports hardware-accelerated Wi-Fi Protected Access
(WPA) and provides long-range
coverage of up to 76m.
WLAN-enabled solutions
As WLANs become more widespread, many routers or gateways now include both 802.11x
and Ethernet routing/switching capabilities by default. The
IEEE 802.11g standard has become the mainstream WLAN
technology, and majority of the
routers sold today support
802.11g.
Less than a year ago, a basic
Wi-Fi router consisted of five
ICs—CPU, five-port switch,
Ethernet PHY, 802.11g radio or
MAC/baseband and PHY—
along with f lash, DRAM and
other ancillary components.
The WLAN functionality is supported using a mini PCI or
Cardbus interfacing the CPU
via PCI or a PCI-like bus.
Most leading manufacturers
today, however, have integrated
at least some of the abovementioned functionality. The
1G SoC-based solution integrates the CPU, MAC, baseband
and PHY into a single chip. This
effectively reduces the number
of functional ICs to four (Figure 1). Some of the newer
router designs even support a
wireless-on-motherboard
implementation instead of the
mini PCI or cardbus solutions
that were used in legacy systems.
The 1G SoC solution has obvious advantages over the
legacy solutions—including
lower bill-of-materials, smaller
form factor, less system power
dissipation and less integration
of discrete functionality at system level. In general, the integrated solution is more compact and less expensive compared to the legacy systems.
As the need for security
grows for both wired and wireless networks, more routers are
beginning to support security
features, including WPA,
WPA2, 802.11i and VPN. Further, as USB becomes the de
facto interface for connecting
printers, storage and media devices, there is a growing need
for newer routers that support
USB host functionality and interfaces. These additional hardware functionalities require
two or more additional ICs. If
the 1G SoC routers are combined with these additional
chips, the result would be an
increasingly complex and expensive solution. The task of
system integration could be-
USB
Controller
SDRAM
RF circuit
Radio
CPU+
MAC/baseband
Flash
Increased adoption
Once considered a luxury, the
combination of broadband and
wireless connectivity is now becoming an integral part of the
home and office. The ability to
wirelessly share one broadband
connection among five to 10
users makes WLANs an increasingly popular and inexpensive
way to extend the data network
in a small office setting. Wi-Fi
connectivity can be deployed in
a variety of office devices, such
as laptops, desktop PCs, printers, storage equipment, VoIP
phones, digital cameras, projectors, media players and servers.
Since many SOHO users are
not highly technical and do not
have access to an IT department, they require network
equipment that is secured, easy
to set up, configure and use.
Also, these users are often costconscious consumers, operating businesses on a limited budget. Despite these limitations,
SOHO networks must offer adequate CPU processing capability to support Firewall, network
address translation (NAT), parental controls and management functions and at least five
10/100 Ethernet ports, with
support for management
features, such as VLAN
(IEEE802.1q) for multiple
subnet support, demilitarized
zone (DMZ) implementation
and network segregation and
QoS (IEEE802.1p) for guaranteed bandwidth applications.
All of these need to be achieved
without compromising on
wired speed routing.
Based on such requirements,
deploying a SOHO network
needs solutions that not only
offer the optimal cost/performance ratio, but also support a
secured wireless connection
with high throughput. This
would mean using a 54Mbps
(802.11g) or higher connection
Clock
VPN
Processor
5-port 10/10
Switch
Magnetics
RJ45
Magnetics
RJ45
Magnetics
RJ45
Magnetics
RJ45
4-Port 10/100 LAN
Figure 1: An SoC-based solution integrating CPU, MAC baseband and PHY into a single chip.
Magnetics
RJ45
10/100 WAN
come even more complicated in
terms of hardware design and
software implementation, especially if all these additional
chips were sourced from different suppliers.
One way to resolve this dilemma of providing a featurerich router would be to source
all the chips from the same supplier. However, this too would
be time consuming and pose
system integration challenges.
An example of an integrated
solution that addresses all of the
above requirements is Broadcom’s BCM5350. This chipset
integrates a high-performance
MIPS32 processor with an onchip memory management unit,
32bit processor bus, VPN coprocessor, IEEE 802.11g MAC/
baseband controller and fiveport 10/100 Ethernet switch
with integrated PHYs, USB host
controller and DRAM controller
that support both SDRAM and
DDRAM. The MIPS32 processor is capable of wire-speed
bridging and routing with advanced firewall protection. The
integrated Ethernet switch is
derived from the 6G of
Broadcom’s popular ROBOswitch family, which has shipped
over 100 million devices to date.
Its built-in WLAN capabilities
support IEEE 802.11g and
802.11a/g implementations.
Figure 2: A highly-integrated sytem-on-chip-based router reduces the entire chipset
to just two chips, including the radio device.
As shown in Figure 2, a
highly-integrated SoC-based
router reduces the entire router
chipset to just two chips, including the radio device. This
helps reduce the system bill-ofmaterials, form factor and
power consumption and makes
the entire system much less expensive. The richness of embedded features on this chipset
allows for scaling of the same
solution for both SOHO applications.
Market trends
Three major trends appear to be
emerging in the Wi-Fi router
marketplace today: time-tomarket pressure for new fea-
tures, constant cost pressure, as
well as ease-of-use and security
If WLANs are to become
ubiquitous in SOHO, then
equipment design has to become easy. This will motivate
chip vendors to provide systemlevel intellectual property and
manufacturing-ready quality
reference designs at lower costs.
Designs will have to use less external bill-of-material, including smaller flash and DRAM.
In addition to the trend toward simpler design methodologies, there is a growing need for
wireless products that are easy
for the average user to install
and enable security features.
Setting up security can be con-
fusing to typical home users that
have no previous knowledge of
networking terms and protocols. Hence, over 80 percent of
home Wi-Fi networks today are
not secured. To solve this problem, Broadcom, for instance,
has developed a setup wizard
called SecureEZSetup, which
simplifies WLAN configuration
and WPA security setup.
As high-speed applications
(such as multimedia streaming
over a wireless network) become more popular in the
home, there is a growing need
for high-speed wireless connectivity and guaranteed bandwidth requirements. Broadcom
supports a high-speed performance mode (125Mbps) that is
compatible with 802.11g. This
guaranteed bandwidth accompanied by QoS will be further
supported by IEEE’s upcoming
standard, 802.11e.
System developers expect
new WLAN-enabled technologies for the SOHO market to offer increased performance, security and ease-of-use at lower
costs. As Wi-Fi increasingly becomes a necessity in the home
and enterprise, highly-integrated router chipsets that address better coverage, throughput and security are expected
to become the next logical
platform.