HDTV:
HDTV news, reviews, sports and videos in Home entertainment
Explore, discover, enjoy!
Value Flowers UK.
Website construction:
Beaufort Web Design UK.
HDTV: Going Wireless
Back in the early days of radio it was apparently quite common for a non-technical person on seeing all the wires inside a set to ask why it was called a “wireless”. A wireless network lives up to its name rather better than the early radio sets. There might be a short lead from the back of a PC to a box of electronics on the top, but many wi-fi setups have no wiring worth mentioning. For many users this is really the only advantage of the wi-fi approach, but for most it is a major plus point. A short lead from a computer to a router or other piece of networking equipment is not difficult to implement, particularly if the two pieces of equipment are on the same desk. No do-it-yourself skills are likely to be required. The situation is very different when the items to be linked are on opposite sides of the room. An “off the shelf” lead is all that is needed to connect the two pieces of equipment, but keeping the lead tucked away discretely out of sight is more difficult. This is not just a matter of making things look pretty, and there is the safety aspect to consider. A lead placed where people keep tripping over is obviously unsafe, although in practice it is probably the networking equipment that is most likely to suffer. It becomes increasing difficult to keep things neat and safe as more equipment is added to the network. A certain amount of do-it-yourself ability is needed in order to install the wiring properly, but it is not too difficult to make a good job of it. Installing the wiring becomes much more difficult when leads have to be run from one room to another. This type of thing is still within the abilities of the average handyman with an electric drill, but it is not everyone´s “cup of tea”. Also, it is not a practical proposition unless you are prepared to have holes for the cables drilled in the walls, floors, and ceilings. Apart from aesthetic considerations, having a house entwined with various networking cables could adversely affect its resale value. In the case of a listed building, it is unlikely that permission to install the wiring would be obtained. It is usually possible to use ready-made cables, but this could mean having to use some standard lengths that are substantially longer than you require. You then have to hide a few metres of cable safely out of the way where no one will trip over it. The bits and pieces needed to make your own custom cables are readily available, but this is a more difficult approach. Surprisingly perhaps, making your own cables can be relatively expensive when all the costs are taken into account.
Having the longer links provided by wi-fi equipment has a huge advantage for most network users, but there are a few disadvantages to take into account when considering the wi-fi option. The obvious one is the higher cost, although as technology becomes cheaper this becomes a less significant drawback. Now the additional cost is still significant, although for slower wi-fi equipment it is becoming much less of an issue. It is a matter of pricing the various options and making your own subjective assessment with the prices prevailing at the time. With a typical home or small business network there will often be just one or two links that could really benefit from a wireless connection, which should help to keep the additional cost well within reason. The relatively slow speed of wireless systems is another potential drawback. Although a wired network has a notional speed of 10 or 100 megabits per second, in the real world any equipment you use will support the higher rate. A modern Ethernet system therefore works at 100 megabits per second and you can forget the lower rate. You will never use it. Wi-fi systems normally operate at 11 or 54 megabits per second. In practice, even a transfer rate of 11 megabits per second could be perfectly adequate. For many users, the point of networking a system is to share a broadband Internet connection. A standard ADSL connection operates with a download rate of 512 kilobits (0.512 megabits) per second, with an upload rate of just half that figure. Even allowing for inefficiencies in the systems, both types of wi-fi link can easily handle the sharing of an ADSL broadband Internet connection. Some broadband connections operate at higher rates of one or two megabits per second, but this is still well within the capabilities of wi-fi equipment. Wi-fi connections are also perfectly adequate for some types of file sharing. It is popular to use a home network to permit music files stored on one computer to be played on another PC in the system. Music files generally operate at about 64 to 256 kilobits per second, with a few operating at up to about 512k per second. This is again well within the capabilities of a wi-fi connection. Many of the videos played on PCs use a similar bit rate, but high quality video requires higher rates that could stretch a wi-fi system. This is not of significance to most home and small business users though. The speed of a wi-fi system is likely to be sluggish when transferring large files or large numbers of files from one PC to another. In theory it is possible for a system operating at 11 megabits per second to transfer more than one megabyte of data a second, but in practice the transfer rate could be little more than half this rate. To transfer 500 megabytes of data would therefore take at least eight minutes, and could well take closer to 15 minutes. For this type of thing transfers at 54 megabits per second are preferable, enabling 500 megabytes of data to be transferred in around one and a half to three minutes. A wired network would complete the task in little more than half the time, but would still be something less than instant.
Although, on the face of it, a wi-fi link is more than adequate for most users, there is a “fly in the ointment” that should not be overlooked. The quoted speeds for wi-fi equipment are the highest that can be achieved, and they require strong signal levels. Do not be misled by the ranges quoted for wi-fi equipment, which are often something like 100 metres, and in some cases much higher figures are quoted. A useable signal may be obtained at a range as large as 100 metres, but only with clear air between the aerials. Where longer ranges are quoted, these are usually for operation at speeds well below the maximum transfer rate. When using a wi-fi link from one room to another there will inevitably be walls, floors, ceilings, and all-manner of obstructions between the aerials. How much (or little) effect these have on the signal strength is not totally predictable, and the only way to find out is to use a “suck it and see” approach. Buildings that have large amounts of metal in their structure can be problematic, but a reasonable operating range should otherwise be obtained. A range of 10 or 20 metres is usually possible, but at longer ranges the transfer rate is likely to be significantly less than notional 11 or 54 megabits per second. When reduced speed is obtained, results should still be adequate for sharing a broadband Internet connection, audio files, etc., but a wired network would probably be a better choice for transferring large amounts of data. An unfortunate truism is that wi-fi equipment performs the worst in situations where it would be by far the most convenient solution. With a large distance plus walls and floors between the two units to be linked, using a connecting cable is very difficult. In this situation a wi-fi link is a much easier option that avoids the awkward wiring, but getting a strong signal is likely to prove difficult. In practice it is likely that many users will be prepared to put up with reduced speed in order to avoid the inconveniences of installing wiring.
Computer security has become a major issue in recent years. There seems to be a significant number of criminals continually thinking up new scams of finding ways of reworking old ones. The early viruses were produced by individuals who were really just showing off, and trying to show how clever they were. It has now become rather more sinister, with people trying to find ways of extracting money from companies or private individuals using what we now know as cyber crime. All Internet users now have to take security very seriously, but it is particularly important to the growing band of users that have a broadband connection. You do not have to be a computer genius to see that using wi-fi links has the potential to let hackers ”eavesdrop” on your network or even gain access to it. At the most basic level, anyone operating a wi-fi equipped PC within the range of your system could have free Internet access by way of your network and Internet connection. This would probably not matter a great deal if you have an unlimited broadband connection. The unwanted guest would effectively reduce the bandwidth of the Internet connection, but probably not to a significant degree. Someone using your Internet connection could prove costly if you have capped access, where extra has to be paid if more than a certain amount is downloaded each month. Either way, are you really unconcerned about others gaining access to your network for a bit of freeloading? Most of us value our privacy and would prefer to keep the network totally closed to outsiders, even if they have no really sinister intent. O course, some hackers trying to enter the network night have a sinister motive. With no security measures in use, someone could potentially hack into your network and gain personal information stored on the system, or even steal passwords or other sensitive information. Unless the network is used for purely unimportant applications such as games or entertainment, it is essential to take steps to keep it secure. Even if the system is only used for trivia, you would presumably still prefer not to have strangers using your Internet connection and accessing your PC. It is worth making the point here that much wi-fi equipment will install very easily. Indeed, in some cases it requires no setup information at all from the user. However, equipment of this type is installed without any of the built-in security measures being implemented. There is a temptation to simply “let well alone”, and not bother with implementing the security measures. With the network working well, why risk messing up the installation? Taking this attitude is definitely a mistake though, and it is a good idea to read the instruction manuals and get everything set up properly as soon as possible. Setting up a network to make it secure is quite simple and does not take long.
The range of frequencies available for use with wi-fi networks is quite narrow, but then allocation is broad enough to permit a number of channels to be accommodated. As will be explained later, there are actually two bands available for this type of equipment, and these are at frequencies near 2.4GHz and 5GHz. At present the vast majority of wi-fi devices operate in the 2.4GHz band, and this book is primarily about this type of wi-fi equipment. Even though there are several channels, congestion is still a potential problem. This depends on where you live, and to some extent it is a matter of luck. Although the short range of this equipment is normally considered to be a drawback, in this context it is definitely an advantage. In fact a range of a few miles would render wi-fi networks unusable as in many areas interference from other networks would render most systems useless. The short operating range largely avoids this problem in suburban and rural areas, but if you operate a wi-fi network in a town it is quite likely that you will find that you are not alone. Switching away from the default channel should avoid any major problems with interference from other systems. As wi-fi becomes more popular it could be difficult to find a totally clear channel in heavily built-up areas, giving a more limited operating range. Also, bear in mind that having several systems nearby could reduce the range somewhat even if they are not operating on the same channel as your system. Many wi-fi users are probably under the impression that a band has been set aside specifically for wireless networking. Unfortunately, this is not the case, and wi-fi shares the 2.4GHz band with several other types of equipment. These include such things as some cordless phone systems, baby monitors, Bluetooth devices, video senders, cordless headphones, and even microwave ovens. These devices all add to the congestion, and can potentially block some channels completely. They also add to the general noise on the band and tend to limit the maximum operating range. Again, in suburban and rural areas any problems should be minimal, but performance could be seriously compromised in some parts of towns.
The lack of wires to connect the system together is the main reason for using a wi-fi setup, but it does have one or two additional advantages that should not be overlooked. If the system includes any laptop or other portable computers it would be normal to equip each of them with some form of wi-fi adapter. Apart from avoiding the need to fiddle with wires each time a portable devices is connected to or removed from the network, a wi-fi connection makes it possible to access the network from just about anywhere in the building. In fact it should be possible to connect to the network from the garden, or possibly even the shed or summerhouse at the bottom of the garden. You can therefore surf the Internet while outside in the garden on a fine summer evening. In order to access the Internet it is not even necessary to return home, since wireless hotspots offer Internet access in numerous locations around the world. A wireless hotspot is a wireless access point (WAP) that connects to some form of Internet service. This will typically be a 512k ADSL broadband connection, but it could be some other type of broadband service. It should certainly be something much faster than an ordinary dialup connection, but bear in mind that you night have to share the service with other users, which could noticeably slow things down. The idea is to have hotspots in restaurants, cafes, motorway service stations, hotels, trains, airports, or anywhere convenient for potential users. As one would expect, these services are not usually free, and the hourly connection rates are quite high. Even so, this method can be cost-effective for those requiring Internet access on the move. The speed of the connection is also likely to be much faster than the alternatives, which are unlikely to be significantly cheaper. Some hotspots are provided free of charge, so you might get lucky from time to time and obtain free Internet access. Hotspots are aptly named, and due to their very limited area of coverage it is important to be in the right place in order to access one. Simply being in the right general area is unlikely to be good enough. The number of hotspots is increasing all the time, and this there are well over one thousand of them in the A search for any access points in Southend on Sea produced six results, with no less than five of these being part of the BT Openzone network. Four sites in the list are at cafes and restaurants, two are at payphones, and one is at a store owned by a well-known computer chain. The train and bus stations are conspicuously absent from the list, and as yet neither of these seem to be used much for wireless hotspots in the The first of these is owned by Intel, and using it to search for hotspots in the Southend on Sea area produced an impressive 22 results. However, it actually searched a much wider area than the wifi411 search engine, and most of the sites listed were actually in nearby towns. The second site is owned by BT, and it is necessary to go through a free registration process in order to reach the search engine. A conventional search engine is available in the left-hand section of the window, or you can use the maps to the right of this. Left-clicking the
You will probably encounter the term “roaming” when dealing with wireless hotspots. This can simply be a reference to the fact that you can literally roam with your laptop and still stay connected to the Internet, but remember that you can not roam far. At best you can only be about 100 metres from the hotspot´s aerial, and the maximum range could well be much less than that. More normally, this term refers to agreements between rival service providers that permit users of one service to go online using the equipment of another hotspot provider. Given the patchy coverage at present, this type of thing can make life much easier for users. However, the added convenience of roaming is likely to cost extra, where it is an option at all. At some locations it is possible to gain instant access to the hotspot by purchasing a voucher over-the-counter at the location. In other cases it is possible tom sign up and pay online using a credit or debit card.
Computer standards have tended to be something of a joke in the past. Standards have not only been a problem in the world of computing. The electronics industry in general has experienced problems with competing standards, which inevitably results in many people buying gadgets that soon become obsolete. In fact competing standards can ultimately kill the product, producing a situation where there are no winners and plenty of losers. An additional problem with computer standards is that manufacturers have tended to “do their own thing” rather than rigidly adhering to agreed standards. It is difficult to understand why a manufacturer would release a product that does not strictly adhere to the rules, but this was quite common in the past. Possibly it was the result of cost cutting, or perhaps it was just poor design work that was to blame. Anyway, even something as basic as trying to get a printer to work properly with a serial or parallel port used to be very difficult. Although “off the shelf” leads were usually available, ready-made leads often proved to be inadequate. Fortunately, the situation has improved somewhat over the years, and wi-fi is certainly free from many of the problems associated with wired interfaces. Inevitably though, there is more than one standard to contend with. The wireless networking equipment in common use conforms to the standards laid down by the
The differences between the three 802.11 standards STANDARD 802.11a 802.11b 802.11g Maximum speed 54Mbits/s 11Mbits/s 54Mbits/s Real-world speed 20Mbits/s 4.5Mbits/s 20Mbits/s Range (outdoors) 30 metres 120 metres 50 metres Range (indoors) 12 metres 60 metres 20 metres Band 5GHz 2.4GHz 2.4GHz Users 64 32 32 Total Separate channels 8 3 3 Compatibility - 802.11g 802.11b Wi-fi certified Yes Yes Yes
The ranges quoted here are theoretical, and would probably not be obtained in practice. These are the maximum ranges at the maximum operating speed, and longer ranges can be achieved at lower speeds. Bear in mind that ranges quoted for operation outdoors assume that there is clear air between the aerials. Walls, fences, and other solid objects between the aerials, particularly if they are made from metal, will substantially reduce the range. The only way to find the maximum usable operating range is to try it and see, but slightly pessimistic forecasts are usually the most accurate. As already explained, the maximum range indoors is heavily dependent on type and number of obstructions between the two aerials. A couple of plasterboard walls are unlikely to have much effect on the range, but a few substantial brick walls could massively reduce it. A large metal radiator in the wrong place could totally block the signal. In difficult surroundings, 802.11b equipment probably offers the greatest chance of providing useable results.
802.11a equipment has the advantage of not operating in the overused 2.4GHz band, and it also permits twice as many users per access point. However, for a home or small business network it is unlike that more than 32 users will need to use an access point. There are some drawbacks to 802.11a equipment, and probably the most important one for most potential users is that the cost is much higher than for equivalent 802.11b and 802.11g equipment. The economics of networking are at least as capricious as those for other aspects of computing, but opting for 802.11a equipment means paying more than twice as much for the privilege. Another important factor to bear in mind is that there is relatively little 802.11a equipment available, although choice and availability should improve in due course. Because 802.11a equipment operates on a different band, it is totally incompatible with the other two standards. 802.11b and 802.11g equipment can be freely mixed, but transfers will obviously be at the lower rate if one unit in a link is of the 802.11b variety. Note that it is possible to obtain 802.11a equipment that is compatible with the other two standards. However, this compatibility is presumably obtained by combining 802.11a and 802.11g gadgets in a single box. As one would expect, the extra hardware required tends to make these units relatively expensive. They are extremely versatile though.
On the face of it, the 802.11 a standard provides fewer channels than the other two standards. In reality it is actually better, since its eight channels do not overlap, and they are genuine channels. The 13 channels of the other two systems overlap to some extent, so significant interference between units operating on adjacent channels is quite possible. In fact the channel overlap problem is so great that it is only possible to have three totally separate channels. Together with its operation on the 5GHz band, this makes 802.11a equipment a safer choice in areas where there is severe congestion.
In theory, equipment manufactured to conform to one of the three IEEE standards work perfectly with any other equipment designed to meet the same standard (or a compatible one). In reality it is never as simple as this with such complex technology, and there have been incompatibility issues in the past. In some cases the level of performance obtained was below expectations, and in extreme cases no useable link was obtained. The wi-fi Is it essential to obtain equipment that has wi-fi certification? In theory it is safer to do so, but the fact that a unit lacks certification does not necessarily mean that it lacks full compatibility with the relevant standard. In fact, such equipment is likely to be perfectly usable. The wi-fi badge of approval is not as common as one might expect, and there is plenty of good quality equipment available that does not sport the wi-fi logo. On checking a mixture of “big name” and generic wi-fi units very few had the badge of approval. The cost of gaining approval has certainly deterred some manufacturers from seeking certification for their products. Added costs are obviously unwelcome when making any products, but they are particularly unhelpful when producing cheap generic devices. There is little chance of obtaining approved products if you take the cheap generic route, and customer support is often poor or nonexistent with these units. On the plus side, generic products are almost certain to be based on exactly the same chips as equivalents from the well-known companies. For those with limited experience of dealing with computer hardware it is probably better to opt for equipment from one of the well-known manufacturers such as Netgear, | 
HDTV: Search HDTV:
HDTV: ALL Wi-Fi & VoIP
|