- bandwidth and transmission rates of various media:
||Digital transmission rate (Mbps)
||Fiber to curb
- 2.4GHz Industrial Scientific Medical (ISM) band:
- is an unlicensed band worldwide
- shares airspace with:
- microwave ovens
- Home RF (max. 2Mbps)
- IEEE802.11 wireless standard (max. 2Mbps)
- IEEE802.11b wireless LAN standard (max. 11Mbps)
- Bluetooth v1.0 (max. 1Mbps)
- Bluetooth v2.0 (max. 10Mbps)
- various commercial data-transmission systems
- wireless telephones
- wireless medical systems
- Apple's AirPort wireless system
- penetrates most walls unless there is substantial metal such as
plumbing or heavy steel reinforced concrete
- depending on power of transmitter, and wall structures, transmission
is usually from 10-100m.
- depending on the protocol, data transmission rates can reach 11Mbps?
- data transmission rate up to 115Kbps
- GPRS is a packet-based network based on GSM. GPRS, like GSM will be pervasive in Europe and Asia Pacific.
- data transmission rate up to 2000Kbps
- 3G technologies include W-CDMA and CDMA 2000
- Cellular mobile telephony:
- a service area is broken into hexagonal geographic units called cells,
typically with diameters of 1km & each with its own base station
- frequency division multiple access (FDMA):
- base station assigns a pair of frequencies (one for sending and
one for receiving) to a user's phone & the phone automatically
shifts to those frequencies
- 1st generation of cellular phones
- time division multiple access (TDMA):
- base station assigns specific time slots to each calling phone in
the cell; each phone synchronises itself with the base station so
that the phone transmits & receives only when its assigned time
slots occur; slots are repeated at high frequency so caller is not
aware of any interruption
- a freq. channel in use in one cell can be simultaneously used in
many other cells without mutual interference, as long as the cells
are not immediately adjacent
- code division multiple access (CDMA):
- uses a "spread spectrum" technique in which each phone
in a cell uses a distinct code known to the base station to
- does not have the freq-resuse restrictions of TDMA
- Cellular Digital Packet Data (CDPD):
- is a packet switched communications network that operates as an
overlay on the AMPS cellular system.
- Packet networks, including the internet break a stream of data into
independent blocks of data, called packets. Each packet is transmitted
independently and carries its own destination and error-correction
information. Thus, packet networks perform extremely well in systems
with variable traffic and channel quality - both of which are found in
the wireless environment.
- CDPD provides an advantage over circuit-switched (dial-up) data, in
that you can connect to the network once and remain connected, similar
to your LAN connection.
- CDPD transfers data over the cellular network at a rate of
- Connectivity: via cellular phone
- CDPD is available in most metropolitan areas of the US, some parts
of Mexico and Canada, Israel, New Zealand and parts of China
- Wireless WAN's are inherently secure. Carriers provide wireless
network authentication via a unique Electronic Serial Number (ESN)
and Internet Protocol (IP) address assigned to each PC card. In
addition, messages are broken into packets and then sent over
multiple channels through an encrypted air link.
The only point of susceptibility is from the cellular base station
to the Enterprise LAN. Most IT managers do not want to open up the
firewall to enable access in and out of the LAN. So, the solution is
a Virtual Private Network (VPN), which provides an encrypted
"tunnel" through the corporate firewall for user access to
everything on the LAN.
- Future WAN technologies:
- 2.5G (115Kbps) and 3G (2Mbps) will enable users to access their files,
email and the internet up to 20 times faster than they do today over a
dial-up modem connection.
- GPRS is a 2.5G technology and is a packet-based network based on GSM.
GPRS, like GSM will be pervasive in Europe and Asia Pacific.
- 1XRTT is a packet-based version of the CDMA network. 1XRTT will be
pervasive in the US.
- 3G technologies include W-CDMA and CDMA 2000. Each will provide speeds
up to 2Mbps.
- Wireless LAN:
- uses wireless PC cards which transmit radio to base station which is
wired to the wired LAN
- A wireless LAN consists of two main components: an access point
and a WLAN card (PC card for notebook or PC card and a PCI adaptor
or USB devices for desktops). The access point is a bridge between
your "wired" network and your "wireless"
network. The access point then allows WLAN card to communicate with
your "wired" network, giving you the ability to walk
around the office campus and access whatever is on your LAN (email,
internet, files) as long as you are within proximity of the access
point. In the case of a desktop PC, a wireless LAN enables you to
get network access into conference rooms or hard to wire areas. To
set up file and print share information within an office is as easy
as a "wired" LAN. An alternative to the traditional access
point for a small network is the PCI card. If you already have a
desktop PC and adequate software, you can plug a PCI card into it
and essentially use the PC as your access point.
- Depending on how much noise is present in your environment and
your contact speed, the range, with both access points, will cover
80 feet up to 1750 feet.
- 802.11b is the worldwide standard for wireless LAN's in the 2.4GHz
spectrum developed by the Institute of Electrical and Electronic
It specifies a higher rate physical layer that operates at 11Mbps,
as opposed to previous technology standards such as 802.11 and Home
RF which were limited to 2Mbps. Future technology standards such as
802.11a and HiperLAN provide for data rates up to 54 Mbps in the
5GHz spectrum. These technologies are expected to hit the market by
2002/3. As costs for these technologies continue to drop and data
transmission speeds continue to approach those of wired Ethernet
connections, wireless LAN solutions will become a viable alternative
to the wired network.
- Wireless PAN:
- this refers to personal area network which is the short range
communication within a room or cubicle
- infra-red is available on most notebooks and many printers
- requires line of sight between transmitters
- Bluetooth technology:
- Bluetooth is the standard developed by the Bluetooth Special
Interest Group (SIG) for PAN's. It specifies a communications
standard for small-form factor, low-cost, short range radio
links between notebooks, PDA's, peripherals (i.e. printers,
scanners, digital cameras, mice, keyboards, projectors) and
mobile phones. Bluetooth replaces the need for serial cables and
IrDA that have been used in the past to link devices in a
Personal Area Network. The Bluetooth SIG is an industry group
consisting of leaders in the computing, telecommunications and
networking industries that are driving development of the
technology and helping bring it to market.
- Bluetooth operates in the 2.4GHz Industrial Scientific Medical
(ISM) band & uses frequency hop (FH) spread spectrum, which
divides the frequency band into a number of hop channels which
can be selected pseudorandonly during a connection.
- supports up to 8 devices in a piconet (2 or more Bluetooth
units sharing a channel)
- Bluetooth operates at less than 1Mbps, whereas 802.11b
wireless LAN solutions are now operating at 11Mbps.
- Bluetooth 1.0 RF signals are solid to about 10m, but by
increasing the transmit power, may be able to reach 100m &
will pass through most walls unless there is a lot of metal in
them such as plumbing or heavy steel reinforced concrete
- Bluetooth 1.0 will operate at about 700Kbps. The next
generation specification, Bluetooth 2.0 will operate at speeds
up to 10Mbps. Bluetooth 2.0 products will likely lag Bluetooth
1.0 products by about one year.
- Bluetooth is inherently secure. First, it is a Frequency
Hopping Spread Spectrum technology, which simply means that data
is sent via a random pattern that hops around from frequency to
frequency within a particular band. This makes it very difficult
for the average intruder to intercept. Secondly, Bluetooth users
can set up their own levels of authentication. You can choose to
set up your Bluetooth device to always communicate with another
Bluetooth device or to only talk to certain Bluetooth devices.
As the receiver of data, you can also choose to link with the
device that is wishing to communicate with you or not.Lastly,
once the communications link has been established, the data is
all encrypted using a 40-bit or 64-bit algorithm.
- Since Bluetooth and 802.11b wireless LAN solutions run at the
same frequency, they do have some conflicts when they are within
very close proximity of each other. As we believe the two
solutions will co-exist, we are working with our partners to
resolve these issues and driving towards solutions that will co-exist.