Bluetooth - an inferior LAN concept?
Original Post: Bluetooth - a dead-born LAN concept (SIG
Forum) Date: 2000-06-22
The point has been made that Bluetooth
is technologically inferior to other proposed wireless networks, here we have
a supporting & opposing argument :
The case against Bluetooth:
Bluetooth is a Local Area Network (LAN) concept based
on spread-band radio communication in the free 2.4 GHz band. Although the
idea of using this frequency band for LAN is tempting (due to the fact that
it represents an international standard), there are several serious
drawbacks:
1. The available transport capacity in the 2.4 GHz band is rather
limited, compared with the amount of data supposed to be transported through
future LANs. LANs need transport capacities of the order of Gbps rather than
only of fractions of Mbps, if they should cope with the huge data amounts of
graphic information files transferred to display screens or to printers!
2. The 2.4 GHz radiation freely propagates through the atmosphere
and through dielectric materials (walls, windows). The mutual perturbation
(cross-talk) of corresponding office equipment within a same building will
thus be a serious problem; data transfer is not as compliant with bad
communication channels as are mobile phones!
3. The freely propagating 2.4 GHz signals of Bluetooth can be
intercepted even far from the application point with the help of
corresponding equipment (parabolic antenna, amplifiers). Even if the
frequency hopping scheme provides some level of security, confidentiality is
heavily compromised in view of the currently available decoder technology.
4. The internationally free 2.4 GHz band has already been tagged for
RFID applications (e.g. Intermec: Intellitag),
and is supposed to become an Industry Standard in this field. Bluetooth will
have to cope with all the interference's produced by the corresponding RFID
tag readers!
5. There are alternative technologies available for realising more
efficient LANs:
- Move to a higher frequency: e.g. to the 60 GHz band which is free
world-wide, due to the atmospheric attenuation of this frequency by the
omnipresent molecular oxygen's first rotational spectral absorption band.
This attenuation follows an exponential law in function of the distance,
such that a radiated signal is completely extinguished after about 50 to
100 meters. The 60 GHz band has thus no value for telecommunication
applications, nor for radar imaging; in contrary, it presents ideal
conditions for realizing a LAN: the limited propagation range protects from
cross-talk and assures confidentiality of the transmitted information; the
large bandwidth (of over 1 GHz) assures a reasonable data transfer rate.
- Use an optical (IR) communication link, which potentially can assure
transfer rates of several tens of Gbps.
In view of these drawbacks and of the available
alternative technologies, I do not really believe in the future of Bluetooth;
it seems to me what its name says: a bygone Viking king.
The case for Bluetooth (1)
You have many good points, and many things you said are
very true. However i believe your agruement is flawed:
1. Bluetooth is WPAN (Wireless Personal Area Network) not LAN. It is
proposed as a low cost, low profile, low power wireless link for the sake of
convenience (as IrDA replacement). It is not
intended to be a LAN replacement.
2. If your situations require large amount of file transfer, you
better use 802.11 or wired Ethernet, fast
Ethernet, gigabit Ethernet or even fiber. Nobody said BT is for large file
transfer. It is like carry big table with your motorcycle, nobody said
motorcycle is designed for that purpose. Again Bluetooth (and other wireless
device) are for convenience not for speed. Wireless will never be competitive
with wire type communication device (for cost, speed). But it brings us
mobility and convenience. Look at cellular phone, you should get my point.
3. The interference problem you mentioned is very true, no argument
about it, that's why we are moving toward higher and higher freq. If you have
lots of interference, then you need to find some other possible way to
counter it. But remember, how much interference is going to be in your house?
4. As for security problem, I think you underestimate it. There are
lots of security stuffs in any wireless device, it will be very difficult,
although not impossible, to intercept. Also, the range for BT is fairly
short, it is around 10meters so I assume no other people (except your
parents) can come that close to catch the transmission. BTW, will somebody be
that interested in intercepting my mp3 file transfer from my desktop to my
mp3 player? RFID doesn't have anything to do with BT since they are used in
different situations.
5. I totally disagree with your last statement. 60 GHz is a
potential way to go (and many people have been studying that for a while)
however, to make it cost effective and available to ordinary people, there is
still a long way to go (and maybe we will never get there). What you said
sounds very easy, but can you tell me how much a 60 GHz WLAN adapter gonna
cost (remember a BT node will cost under 5 dollars in the future)? How much
power is it gonna drain? How big it gonna be?
To me, you are suggesting using a Boeing 747-400 for
carrying 10 people from LAX to John Wayne. The invention of airplane doesn't
kill automotive industry since they can find areas to fit themselves in, I
think it will be true for BT (and other wireless device).
The case for Bluetooth (2)
I would agree with you if I really expected Bluetooth
to be a wireless LAN solution. However, that does not seem to be the case.
Bluetooth seems focused on short-range, personal, device-to-device
communication. I do know that some people are thinking of re-applying the
technology to create wireless LANs. But, as you made very clear, there are
better technologies available. As for IR, I'd personally rather allow by
devices to synch while they're in my pockets and bags rather than line them
up in parade formation for a big synch fest. I think that's what Bluetooth is
all about- personal choice
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