How many frequency bands are there

As different countries have different areas of available spectrum it has not been possible to have a high level of coordination from one country to the next and this has issues with roaming and the number of bans needed for handsets.

The LTE radio channels are also allocated numbers - these can be calculated from a simple defined formula. By having defined radio channels, they can be coordinated globally to facilitate roaming.

There is a large number of allocations or radio spectrum that has been reserved for FDD, frequency division duplex, LTE use. The bands also have a sufficient separation to enable the transmitted signals not to unduly impair the receiver performance. If the signals are too close then the receiver may be "blocked" and the sensitivity impaired. Re:Shannon's law: beaten severely Score: 2. Um, I don't think so. You might want to start with the ARRL [arrl. I do rember in one of my college classrooms a big poster saying who 'ownes' what band.

Propagation Score: 2. Radio waves diffract around things that are smaller then they are, and bounce off conductive flat things that are smaller then they are. So, Above 50GHz, we have millimeter microwave and beyond, which is blocked by rain, dense clouds, foliage, etc.

Lots of bandwidth, lousy range. Future expansion of indoor services will be in this area. Good for space-to-space communications, like Iridium inter-satellite links. In the low GHz range, where PCS type cell phones live, radio waves are under a foot long, reflect off buildings, get blocked by foliage, but get through clouds and fog. Your basic urban-services band. In the high MHz range, VHF, radio waves diffract around buildings, aren't bothered by foliage, but are blocked by the curvature of the earth.

TV and FM broadcast live here. In the low MHz range, HF, radio waves diffract around most ground features and sometimes bounce off the ionosphere, allowing long range radio communication. Broadcast AM radio lives here, extending below 1MHz. In the high KHz range, radio waves make it between continents, although interference is awful and bandwidth is limited. Radio Moscow and the Voice of America used to battle it out in this arena.

In the low KHz range, radio waves diffract around planets, go through oceans, and bandwidth is very limited. Re:Propagation Score: 2. Radio waves Correction: bigger. For Wireless communication we have always used geographic subdivision as well as frequency subdivision. First because we had so much geography and limited power for our radios. The cellular idea is just taking this natural existing situation and turning it into a planned scheme.

I see that we will continue to reduce the size of cells till we have a light infrastructure that allows direct connection from almost any location. Not jsut bandwidth Modulation methods are important, as well. Some spread spectum methods allow several users to share a band, although each users noise floor goes up. With good forward error correction this isn't too much of a problem. Error This is an ill-formed question.

Bandwidth in terms of communication is a function of signal-to-noise of the channel. In principle, on a perfectly noise free channel, you could communicate the entire sum of man's knowledge by taking the number represented by the concatenated digits and emitting a pulse of exactly that many whatevers volts, lumens, or Problem is that there is noise around, either in your receiver, or from someone else, or from the enviroment, that defeats this to a greater or lesser extent.

Currently, the way it's mostly done is companies get their little slice of the pie, and then fit as much data into that slice as they can, using whatever method protocol they see fit. This seems to produce a local optimum where the given frequency, being limited and expensive to expand upon, ends up being optimized and compressed to respectable levels.

However, this localized approach is probably suboptimal overall. The air's bandwidth Score: 2. This is a fascinating article. Effectively infinite Score: 2.

The carrying capacity of available frequencies is effectively infinite if properly handled. Promise of short-range optical wireless Score: 2. Ultimately, the RF spectrum offers of order 10 GBits per second shared among the whole population of a metropolitan area. Solar powered airplane repeaters Score: 2. Anyone have any more information about who was thinking about this? Satellite systems my biz use only BPSK 1 bit per symbol and QPSK 2 bits per symbol because A power is an extremely precious resource on a satellite, so you can't use the higher powered modulations, and B phase noise effectively smears that bit pattern around and makes it harder to discriminate -- and increasing power is the only way to push those blobs apart enough to where you can tell them apart.

Microwave systems, which are land-based and point to point, have virtually limitless power to draw on the local AC power grid , so they can run the fancier mods, even though they might be at exactly the same frequency range as satellite.

And they're taking a lot of good carbon out of the atmosphere, damn it! Next thing you know, we'll have global cooling! It's all natural. Wireless Bandwidth Score: 2.

The answer to either, however, is "a lot. But as we become able to transmit at lower and lower power levels, the amount of frequency reuse will go nowhere but up, providing us with quite a lot of bandwidth.

The only real problem is that there are upper and lower bounds to the usable frequency spectrum. Go too high, and you're talking about IR. Too low, and you're in the ultra low frequency band, where it takes a good deal of time just to get three letters across. With technologies like CDMA, one can get quite a lot out of a small chunk of spectrum, and by just changing the code used, avoid interference with other transmitters and recievers. Can't wait for it to take off for more than cellphones Earth has bandwidth-o-plenty Score: 2.

Assuming that frequencies are assigned semi-intelligently lack of wireless bandwidth will not be a problem Granted, these few things would help: 1. Radio and TV broadcasts will eventually be migrated from air to internet 2. Other remote communications tools will also be converted to a standard Wireless IP? An efficient Wireless IP protocol is implemented for Internet use. Doing that frees a substantial amount of bandwidth. But if lack of bandwidth were going to be a problem, I think we'd be hearing more about problems already existing in areas of high population density.

I fully expect, however, that more bandwidth would be available in less populated areas although it would have to be somewhat populated for the service to exist there in the first place. As for a total wireless conversion, I don't see that ever happening. Fiber is too fast of a medium to throw away. Every building will receive fiber eventually. Perhaps the high speed wireless would be propogated that way through very low power connections from building to building.

Your house will be a mini cell-tower Changing Questions and Answers. Score: 3. People misunderstand physics as "invalidating itself" more often than it does. Usually physics refines its assumptions. Most physical statements once confirmed by several experiments don't turn out to be false later, just narrower in implication than expected.

Share twitter facebook. Re:wrong Score: 3. PCS is a cellular system. Yes, SS is old tech, but new to the consumer Score: 3. Yes, you are right. But it has only been available for consumer use very recently. It was considered a military technology for a long time and even hams had to follow very strict regulations to use it, which only very recently have been relaxed. Re:High Frequencies Score: 3. The key is reuse, not carrying capacity.

Ultra-wide-band and limits. If atmospheric and obstruction effects cut off everything above, say, 30 GHz, and your wideband transmitter makes use of parts of the spectrum above the cutoff point, the received data will be garbled what will actually happen is that the pulses will smear out and start interfering with each other.

UWB is an interesting technology, but the data rate limits imposed by bandwidth limits are independent of the encoding of the data see my posts re.

Packing more bits per sample. While this is true, there are strong practical limits to how many bits per sample you can have. You also can't space these levels arbitrarily closely - noise from your electronics and fundamental limits to the certainty with which you can count the number of radio photons in your sample both limit your spacing.

As spacing grows exponentially with the number of bits, you soon reach a limit for any given power level. In principle, you can just increase the power to compensate, but the power required goes up exponentially once you hit your level spacing limit. In practice, you typically have only a handful of bits per sample to keep the power requirements sane. DC to daylight. And beyond Score: 3. Who knows? Some of what I just said might even be correct!

Re:Answers Score: 3. I was with you until the last paragraph. I'll assume that in your last paragraph you are refering to the frequencies allocated for PCS use ie digital cell phones. There are not 5 redundant bands, but one band in the Mhz range that has been defined for use with PCS. This band has then been split up into several different blocks that can be auctioned off individually to different operators. The reason you want to have several blocks available in the same band is to promote competition and to allow the "Mom and Pop" shops a chance to enter the market.

This is no different than how things are done for, say, GSM in the rest of the world. I'm not sure that I understand your comment about costs of cellular infrastrcuture though. Vendors are the ones that build the equipment usually called manufacturers , you are probably referring to operators here. Assuming you mean operators, why would they want to share the cost of the cellular infrastructure? They each have to build their own network in order to accomodate their own customers?

Why would I let a competitor use my base station? Most of the signalling and such that takes place on the ground is done using leased-lines, so the cost for that portion of the network is already shared anyway. As I already mentioned, they are already all using the same band, so that isn't a problem. And when usage increases, they do just as you suggest: add more cells. Adding more cells is possible for all operators using the blocks that they have licensed using frequency reuse patterns.

Disclaimer: I work for Ericsson, however these views are my own and have not been endorsed by my employer. Multiplexing Score: 3. I know the question already touched on this somewhat, but multiplexing is basically the way to go with this CDMA can already squeeze more than 12 times the bandwidth out of a frequency and it's bound to only get better. I'd say the only problem with this is that it makes the hardware more intricate and more expensive.

This means that your power has to be ramped as your distance from a cell changes and handshaking with new cells is more complex as well. I also think that there are a lot of bands which are currently allocated that should be scrapped for newer tech or at least re-appropriated Nextel, the wireless company, for example operates on what used to be a 2-way business radio band.

Because of this they're in almost every major market but didn't have to bother with licensing. At the same time, their frequencies aren't necessarily guaranteed either. I could definitely see a lot of the PDA stuff getting into this band if a standard's ever developed. Check out alt. There is a "global" FCC. It's homepage is here [itu. It's purpose is to develop and foster global standards for bandwidth usage, among other things.

Most modern countries have communications ministries or bureaus that abide by them the FCC for example. Bluetooth Allocation Problems Score: 3. Finding and common band is a real problem. Bluetooth just got a nasty shock.

The French military refuses to open up their portion of the 2. They could very well make it illeagal to have a bluetooth device in France. Imagine getting your laptop nicked at the airport because it has Bluetooth! The truth is, their is no universal chunk of bandwidth in the world and the death of Bluetooth is going to prove it.

Re:The potential has no true upper limit Score: 3. I wholeheartedly disagree Our understanding of physics may change Normally "limits" that are broken are NOT defined by physics but by other things Current day manafactuing technology is another. These are not physics. If you push something beyond the limit that current physical laws dictate it must have THAT is the very essence of science.

Couldn't you just look this up? Come on, there has to be a website out there that deals precisely with this question Ever heard of the ITU? There already is an organization, the Iternational Telecommunications Union ITU that administers international RF frequency allocation on a nation by nation basis, among other things.

It mostly deals with surface to space and long-range bands, and adjudicates international bandwidth disputes. It is then up to national governments to administer their spectrum as they see fit. Score: 4. IIRC, the carrying capacity of our atmosphere is about Is that an African Atmosphere or a European atmosphere?

How many frequency bands are there? Let's ask Mr. Owl : One How many parallel lines per inch can you draw? My post is overlong sorry , and has two parts: 1 Some people seem confused, so let me elaborate on netcurl's post.

I've probably forgotten something, but hope this helps. Cell phones part of solution Score: 5. Answers Score: 5. The radio spectrum is a natural resource, nobody owns it. Thanks Bruce K6BP. Some limits. Score: 5. While the upper frequency limit for radio transmission is pretty mushy, there are a few factors that give you diminishing returns as you move beyond single-digit gigahertz: Walls.

Penetration distance of radio waves through a non-conducting substance like concrete is proportional to the wavelength of the signal very roughly. This means that ordinary radio has no problem going trough walls and floors, but that things like cell phone signals in the GHz range are more easily blocked if there are a couple of buildings between you and the tower.

This problem will get much, much worse as frequency increases. Rain and smog. Radio of conventional wavelengths will pass through rain, smog, and clouds with little difficulty. Yes, I would like to receive weekly updates. Successfully Submitted! Our team will get back to you shortly. Submit Another Query. Full Name. Your Company. Your Email. Please wait Please provide valid credentials. Create an account Create an account on everything RF to get a range of benefits. Enter Name. Enter Company.

X-band radar frequency sub-bands are used in civil, military and government institutions for weather monitoring, air traffic control, maritime vessel traffic control, defence tracking and vehicle speed detection for law enforcement.

Used for satellite communications. In Europe, Ku-band downlink is used from Communications satellites, uplink in either the You have already liked this page, you can only like it once!