2.5G and 3G Wireless Networks
Radio Router Technology
- Flash OFDM (Orthogonal Frequency-Division Multiplexing)
While CDMA and UMTS
increase the capacity and spectral efficiency viewpoints as compared
to 2G and 2.5G wireless networks, there are still issues with these
packet networks when applied to wireless data. Scientists are working
on improving upon the spectral efficiency of CDMA. Another inherent
problem with wireless data transactions is that information is not
always sent in high-speed bursts bi-directionally. Unlike packetised
voice, there is a constant protocol and conversational chit chat
between the sending and receiving software. There is an inherent
latency and propagation delay between the two end points.
network technology tries to address the needs of wireless data in an
innovative way. According to the vendor, Flarion system is the first
truly IP-based broadband cellular network designed for data, and it outperforms
3G in all critical areas of performance. For example, the system is
capable of sustaining 12 Mbps of throughput per cell in a 3
carrier, 3-sector configuration, peak user data rates up to 3 Mbps,
full cellular mobility, les than 20 milliseconds of latency, and full
QoS. Flarion claims to have successfully developed, tested and carried
out technical trials of the system in 2001, and is planning to
demonstrate in NY a market trial system.
technology uses a radio-transmission framework for packet- based,
broadband, IP wireless communications. Radio-router technology is
designed to make links in an IP network mobile. Proponents of
Flash-OFDM hope that since IP network technology is already well
developed and inexpensive, radio-router systems will be relatively
easy, quick, and economical to implement.
A radio-router network
can be built atop the existing IP infrastructure, rather than from the
ground up like a 3G network, said Rajiv Laroia, founder and chief
technology officer of Flarion Technologies, which develops
The technology uses
OFDM, in which a single channel is divided into several subchannels,
each at a different frequency. This boosts bandwidth by letting a
system carry several transmissions at the same time. Radio-router
systems offer a maximum throughput of 1.5 Mbits per second, about the
same as a T1 line. OFDM, unlike traditional FDM, uses signal
modulation and demodulation techniques, as well as the orthogonal
placement of adjacent channels, to minimize interference. There is
less emphasis on individual channels' quality.
"Radio router is
a data-focused technology, designed from a data perspective. But it
does support voice- packet-switched voice, not circuit-switched
voice," according to Flarion.
Radio routers, IP
routers with radio adjuncts, would handle packet traffic and serve as
the equivalent of cellular base stations. Consumers would connect with
Flash-OFDM networks via PC cards in their notebooks and via
flash-memory cards in handheld devices. .
Caution - An uphill
battle with the established cellular networks
technology's potential, AT&T's Henry says, "Radio routers
face an uphill fight against the entrenched cellular businesses."
Cellular providers are much bigger and better established companies,
he explained, and cellular service appears like a safer investment to
many managers. Radio-router technology, on the other hand, might seem
exotic and thus might not attract big infrastructure investments, he
Other caution is that
Flarion's air-link interface introduces yet another standard and it
will face usual battles and delays in getting components built to
match Flarion's reference designs.
Information - Go to Flarion's