Category: Feature Article

Introduction

Now that the 802.11n high-bandwidth wireless-network standard has been declared a final standard, the price of 802.11n-compatible wireless-network hardware will come down to more affordable levels. This will lead to you considering upgrading your wireless network to 802.11n whenever the time is right to renew your home-network IT hardware.

The 802.11n access point

This works in a different manner to the 802.11a/b/g access points we are so used to. Basically, these units use a “multiple in, multiple out” methodology with “front-end diversity”. They will typically have two or three aerials with each aerial serving a particular transceiver. Some units may have an aerial serving a receiver as well as the two aerials serving two transceivers. It is totally different from “antenna diversity” which is used on most 802.11b/g routers and access points, where one transceiver works with two aerials, choosing whichever has the best signal strength.

These access points and the network client devices that connect to them also make use of “constructive multipath” to improve their quality of reception.This is different from the “destructive multipath” often experienced with FM radio and analogue television. Here, signals picked up as reflected signals are mixed with signals received by line-of-sight and “worked out” as a data stream.

The premium-priced 802.11n access points will be typically dual-band in which they can work on the existing 2.4GHz band or the newer 5GHz band. Some of this equipment may be able to work on both bands, as though there are two access points in one box.

Access Point Types

Single Band

These access points use a single access point that is set up to work on one band, typically 2.4GHz, but some of them work on 5GHz as an “add-on” access point.

Dual Band, Single Radio

These access points are like a single-band access point but can be set by the user to work on either 2.4GHz or 5GHz, but not both of the bands.

Dual Band, Dual Radio

These access points, sometimes described as “simultaneous dual-band”, are effectively two 802.11n access points in one box with one working on 2.4GHz and the other working on 5GHz.

Access Point Operating Modes

Primary Operating Modes

A typical 802.11n access point can be configured to work in one of two primary operating modes – a “compatibility” mode or an “N-only” mode.

Compatibility Mode

This mode, known as Mixed Mode or G-compatible mode allows 802.11g wireless network hardware to work from the same access point alongside 802.11n equipment. The limitation with this mode is that the wireless network works to a “worst-case” scenario with throughput that doesn’t hit the standards for an 802.11n segment. You will still have the larger coverage and service reliability with the 802.11n equipment and this benefit may pass through to 802.11g equipment

N-only Mode

This mode allows the access point to work only with 802.11n equipment and gives the equipment full wireless throughput as well as the full reliability of the standard.

Wideband vs Standard Channels

802.11n access points can run their channels as either “standard” 20MHz channels or 40MHz wideband channels which can yield higher throughput. The wideband channels also make use of a “standard” channel as a “base” channel for the double-width channel.

The preferred method of operation is that a 2.4GHz access point works on “standard” channels and most such access points will be set to have this kind of behaviour by default. But you can run these access points on the wideband channels with the limitation of poorer compatibility with 802.11g devices. If you are running a 2,4GHz access point in a manner to be compatible with regular 802.11g devices, it would be a good idea to stick to “standard” channels. If you are running 5GHz access points, you can get away with using the wideband channels and I would prefer setting up a 5GHz 802.11n extended-service-set to work this way.

The number of streams a device can handle

An 802.11n wireless device will typically be rated as being a single-stream, dual-stream or multiple-stream device. This relates to how many streams of data the wireless device can handle. All Wireless-N (802.11n) access points and routers will typically be either a dual-stream type or a multiple-stream type in the case of premium devices. Similarly, laptops with integrated Wireless-N capability; and add-on Wireless-N products will typically be dual-stream devices.

The main class of devices that will handle only one stream will be primarily-battery-powered devices like smartphones, WiFi VoIP phones, and WiFi-enabled digital cameras / portable media players because the single-stream ability won’t be intensive on these devices’ internal battery resources. Similarly, the idea of a single-stream Wireless-N network interface will also appeal to applications where size or cost do matter.

Other points to know

Best practice with dual-band equipment

If you are running dual-band equipment, especially dual-band dual-radio equipment, it would be a good idea to use the 5GHz band as N-only mode, while 2.4GHz works as compatibility mode. If you are running dual-band single-radio equipment, you will need to use older 2.4GHz equipment to run an 802.11g service set with the dual-band single-radio equipment on 5GHz N-only mode.

Use of aftermarket antennas

You can use external aftermarket antennas (aerials) with 802.11n equipment as long as all of the antennas are of the same type. This may work well if you replace the omnidirectional whip aerials with stronger omnidirectional ones. Then you may have to space the aerials further apart for the front-end diversity to work properly The main difficulty you will have is using directional aerials, in which case you may need to look for directional aerials optimised for 802.11n setups.

As well, if you are running dual-band dual-radio equipment, you will have to use antennas that can work on the 2.4GHz and 5GHz bands rather than antennas optimised for the 2.4GHz bands.

Shaping your 802.11n wireless network – the ideal upgrade path for your wireless network

I will be talking of WiFi networks that work on a particular technology and with a unique SSID and security parameter set as an “extended-service-set”. This allows me to cover setups where there are multiple access points working with a particular configuration.

You may be tempted to construct a multiple-access-point extended-service-set with an 802.11g access point and an 802.11n access point working in “compatibility mode” connected by an Ethernet or HomePlug wired backbone. The simple answer is "don’t”. You will end up with your wireless network having reliability problems especially as devices roam between the different access points and switch operating modes.

The simple answer would be to run different extended-service-sets with at least one access point for each WiFi technology. They are set up with different ESSIDs (such as SSID for the G cloud and SSID-N for the N cloud) with the wireless stations choosing between the different ESSIDs. The only thing they can have that is common is the WPA security parameters, and a common wired backbone which can be Gigabit Ethernet or HomePlug AV.

This could be achieved through deploying an existing 802.11g router that is set up as an access point and working on “SSID-G” and one channel while a newer 802.11n router working as the Internet “edge” is set to “N-only: or “compatibility” mode in the case of a single-band 2.4GHz unit, and set to “SSID-N” and a different channel.

As you evolve your wireless network, you may want to work towards establishing a 2.4GHz 802.11n “compatibility-mode” extended-service-set and a 5GHz N-only extended-service-set. You then upgrade your portable computers to work with dual-band 802.11n network interfaces or add dual-band 802.11n network adaptors to your existing equipment. The 5GHz extended-service-set will come in handy for high-throughput activity like video streaming and related applications while the 2.4GHz extended service set can work well with voice applications, smartphones, Internet radio and similar applications where throughput doesn’t matter.

If you are upgrading a wireless hotspot to 802.11n, it would be preferable to make sure your hotspot’s extended-service-set is on the 2.4GHz band and operating in “compatibility” mode so that customers can still use their existing 802.11g hardware on the wireless hotspot.

Some issues may occur with dual-band networks where the 5GHz extended-service-set may not cover the same area as the 2.4GHz extended-service-set. This is because the 5GHz band is of a higher frequency and shorter wavelength than the 2.4GHz band and is best demonstrated by AM radio stations being receivable at a longer distance compared to FM radio stations. It can be rectified by deploying a dual-band single-radio access point working on the 5GHz band in to the 5GHz extended-service-set as an infill access point.

Conclusion

Once you understand the 802.11n wireless standard and what it can and cannot do, you can make sure that you get the best out of the new standard while gaining the maximum mileage out of the existing wireless-network hardware.

Facebook | Fighting the Battle Against Money Scams

My comments and further explanation on this topic

This article in Facebook’s blog touches on a very common risk that can affect any social-networking site and user community. It mainly talks of the “money scam” which is really similar to the common “Nigerian” or “419” scam that many of us have encountered through the spam that comes in our mailboxes.

In the social-network version, a fraudster “sets up shop” on a Facebook or similar site and takes over a user’s account. They will then message the user’s social-network friends claiming that they are in another land and out of money. This will be via a message on the Wall or a direct message via the Inbox or a Chat session. They will typically require the friends to wire a huge amount of money to the scammer.

If you do receive one of these kinds of contacts from your friends via a social-networking Website, make a call by regular telephone to the number that you know the friend (or a person that you are sure knows them well such as their spouse / partner, child or employer) can answer such as their home or mobile number. Here, I would prefer to make a voice call rather than use text messaging. Then you can ascertain whether it is the friend who is in need or simply a scam taking place. As well, confirm the situation with mutual contacts. If the friend’s account is being compromised, tell them to change the account’s password immediately. Sometimes, companies like Facebook can lock down a compromised account and e-mail the account holder about what is going on. Then they advise the account holder to change their password immediately.

As well, know what resources do exist in your social-networking service for reporting compromised user accounts and be ready to identify “out-of-character” messages, links or pictures posted up on these services by your friends. For Facebook users, the link is http://www.facebook.com/help.php?page=420 .

Beethoven ….. Mozart ……. Schubert ……. Wagner ……… Handel …….. Vivaldi ……. How can you have them in your online music collection?

You may already have established a music collection centred around classical music and / or opera; with at least a few of those Deutsche Grammophon recordings or are just cottoning on to the Great Classics as a break from the regular popular music. Yet you want to add the music in to your digital collection for use on your iPod / portable MP3 player or to play through your DLNA-based home media network. The main problem you will end up with is how to locate a specific work or movement / aria / chorus in your collection; or material by a specific composer.

It may not appeal to those of you who prefer to listen to classical music from an LP or CD through very fine equipment, especially from audiophile-quality recordings or boutique labels; but those of you who are used to and don’t mind listening to classical music from the radio or cassettes or or play classical LPs and CDs through commonly-available equipment may be accepting of this practice.

Most music-management software pitched at classical-music enthusiasts works on a presumption that the music collection is exclusively focused to this genre. But the reality for most music collections is that there is a mixture of the classical-music genre as well as jazz and popular music existing in the collections. It also includes situations where there are recordings that feature a performer performing a collection of classical and other pieces, recordings featuring highlighted works by a particular composer or “themed” classical-music albums with pieces based on a common theme like a “Most Favourite Selection”; music mood or composition era.

How will you be integrating classical music in to your digital music collection

You may buy the music as MP3 files from an online music download service like what is currently being offered by Deutsche Grammophon or may simply buy classical-music CDs and “rip” them to your computer’s hard disk. In some cases, you may copy music you have on legacy analogue media like LPs to your hard disk.

What standards to implement

Unlike most contemporary popular music, this kind of music demands high quality recording and playback and is more so if you take this genre more seriously. The preferred order for storing the music in your master collection when you “rip” from CD or record from analogue media would be:

1. FLAC or similar lossless codec at best bitrate available
   This may have compatibility problems with most of the portable media players on the market, because they don’t have native support for this codec. Some DLNA-based media-player components, usually those hifi components made by companies who make equipment for discerning listeners may support this codec natively. If you wish to work with this codec, make sure that the media server or “jukebox” program that you use can transcode from this format to LPCM for DLNA applications or MP3 at 320kbps, AAC at 200kbps or WMA at 192kbps for portable media player applications. Most such programs that rip to these codecs can support these transcoding requirements
2. AAC at 200kbps or WMA at 192kbps
   These offer a tradeoff between good quality sound and storage efficiency and most devices on the market do support either of these codecs natively. It may still be worth it to check if the media server or “jukebox” program can transcode as mentioned above.
3. MP3 at 320kbps
   This is the codec that is often used for digital media but the only problem with it is that it is not efficient. It is also the preferred codec that is used when you download music via an online store.

The metadata issue

How does a person refer to a particular piece of classical music?

The works can be further differentiated by the performers who had a part in performing the work, such as a solo performer, orchestra (with a particular conductor), opera company or theatre.

Organising the Metadata

This is made more difficult because most music metadata is organised based on most popular music where the concept of an album is a collection of songs by one or more artists.

You will have to organise the metadata manually whenever you add a recording of a complete work to the music collection. This is more so where you buy a recording with multiple multi-movement works like nearly all concerto and sonata CDs and an increasing number of symphony CDs. Some of these recordings may have a multi-movement work plus a few single-movement works rather than two or more multi-movement works. This may not be of issue when you have recordings which are a selection of single pieces and/or key movements, arias and choruses from larger works.

You could give each work its own “album” name and make sure each movement in the work is given a track number that is consecutive to how the movements are meant to be performed. Another good practice would be to change the movement’s or part’s  “title” field to <<movement number>>-<<movement’s full name within work>>. There are some works that have a highlighted part within one of the movements, such as the 4th movement in Beethoven’s 9th Symphony. Here, the “Ode To Joy” chorus will typically be its own track and may be numbered “5” in the album track order, even though it is part of the 4th movement. You may still have to have this part being numbered as “5” in the album track order and the title’s movement number being “4a” so as to properly place it as part of its parent movement.

Also, if you are dealing with a suite of multi-movement works like Vivaldi’s “Four Seasons”, you may have to have each work, such as the “Spring” concerto as its own album. Similarly, long-form musical-theatre works like operas and ballets that are performed over multiple acts may need to have each act as its own album.

As well, you will need access to the “Composer” field for modifying and searching so you can integrate the composer as a key domain. This should be kept consistent in respect to the name of the composer. Try to avoid using name variations across different works by the same composer; and especially avoid referring to a composer by surname only. This can be more of an issue with works by Johann Sebastian Bach who was a very prolific composer; as well as the works composed by his sons such as that popular “Musette” piano piece. As for genres, the music should be listed under the “Classical” genre or similar genres.

Searching for the music

You may have to search amongst the “Album” metadata in the “Classical” genre to find works. As well, you should have access to the “Composer” metadata field – Windows Media Connect, Twonkymedia, Asset UPnP and other good servers provide for this. Musical theatre works like opera could have each act as its own work e.g. “La Traviata Act 1”, “La Traviata Act 2”.

You may need to search based on composer then work methodology if you are after a particular work. If you want to run a sequence of works, you will need to add the works to a “now playing” queue in your DLNA media player or controller. A good idea is to use playlists for keeping suites of multi-movement works like Vivaldi’s “Four Seasons”, or particular musical-theatre works together for sequential playback.

What needs to be done for music metadata management to cater for classical music

Data structures and fields in the databases need to exist to encompass the structure of classical music; primarily works, parts of long-form works (acts, etc) and suites of works. There also need to be data views that work commensurately with classical music’s structure i.e. to support “composer, works group, work, movement, performer(s)”. As well, music-management programs, including portable-media-player firmware and music metadata reference sites like Gracenote need to apply the different data structures and views when they are handling classical music. This can be made easier by detecting if a recording is identified as being part of the “classical music” super-genre; as well as providing a view structure for all classical-music recordings based on the “composer, works group, work, movement”; as well as the conventional “album-based” view for classical-music recordings so as to cater for “collection” recordings.

Summary

Once you can get your hands on the music metadata by editing it manually, you can safely integrate your classical music into your online music library while being sure you can locate that favourite work or movement.

Please feel free to leave any comments on how you had gone about integrating your classical music in to your online music library.

You might be thinking of using video conferencing as a way of talking with distant relatives or friends. Infact, there was an article on TV Channel 7 News (Melbourne, Australia) on 4 December 2008 regarding the use of this technology to allow families to communicate with elderly relatives who are in nursing homes that are a significant distance from the family.

Is your network ready?

You shoud make sure that you have a broadband service of at least 512kbps ADSL or standard cable specification. As far as your router is concerned, it needs to support UPnP IGD / NAT traversal behaviour. This may be easier with most home-use and SOHO / small-business routers bought from retailers. But you may have to be careful about routers supplied by Internet service providrs, especially if the equipment is not available for general retail sale.

Also check that you are getting good WiFi reception if the computer you intend to use is to be connected to the network via WiFi wireless. This may include making sure that the aerial(s) on the wireless router is upright and, perhaps, considering setting up a wireless network with two or more access points. This has been talked about in my feature article on multple-access-point wireless networks. If the computer is a desktop unit located far from ther router, such as a home theatre computer, and you don’t want to pull Ethernet cable out to it, it may be worth considering a HomePlug powerline network kit. This kit uses the AC wires in the home as a network segment and still provides Ethernet stability in a “plug and play” manner.

What hardware to use

Computer with properly-performing video and audio subsystem and and a decent-quality webcam like a Logitech or Microsoft unit. Most recent laptops have a webcam built in to them for this kind of activity. If you don’t have a microphone attached to your desktop computer, the microphone that is part of a decent-standard webcam can do the job for picking up the voices.

What software to use

There are three different platforms to work with for video conferencing. One is the Skype platform which has existed mainly as an international free-telephony platform. But now it has become more popular as a video-conferencing platform. This one is available for the common computing platforms such as Windows, MacOS X and UNIX / Linux as well as some devices like the Sony PSP and would be the preferred choice if you want to be sure of accessibility.

The other two are the Yahoo Messenger and Windows Live Messenger. Both of these are popular instant-message platfrms but have voice and video telephony built in to them. The main problem with them is that they work only with the Windows platform and the MacOS X platform, which may preclude UNIX / Linux users from using them. Windows Live Messenger is at the moment being rolled out to the XBox 360, mainly as a text chat system but could be rolled out for full video chat.

Going about it.

You will have to complete the setup wizard for the conference program and this will typically require you to use your e-mail address as your identifier.

As well, you will need to complete an audio-video check which allows you to make sure that the microphone is going to pick up the sounds and that the speaker is loud enough without causing unnecessary echo or feedback “howl”. This test simply requires you to set the microphone gain to a proper level by you saying a test passage in to the system at your normal voice and checking a level meter on the user interface. It also requires you to set the speaker volum by you hearing an audio test signal and adjusting the volume for personal comfort. At this point, the system sets itself to avoid the echo or feedback “howl”.

There will usually be a “video” test to make sure that the webcam is working properly and can see you. This will typically be a “mirror image” showing up on your screen of what the camera can see, so you can focus the camera and determine how much lighting you may need for proper visibility.

Then you exchange your video-conference ID with your family and friends who are running the same software. Typically, when a user adds a contact to one of these programs, the program sends a message to the contact asking for permission to add them to the list. This is to protect the contact’s privacy and make sure they are dealing with the right people.

Other issues to consider

If you are planning to engage in “group” video conferencing such as when your family is talking to a distant relative, it may be worth using the large-screen TV set for this purpose. Such a TV set should have a VGA connector or HDMI connector and can be connected to the computer via the VGA socket or a DVI or HDMI socket. If you are not using HDMI as the connector or your computer doesn’t pass audio through the HDMI connector, the sound should just be connected to the TV set or home-theatre receiver via a standard audio lead. Most older CRT-based sets can only be connected to a computer via a composite or S-video cable and the video driver set up for work with the composite / S-video output.

As well, you will have to make sure the webcan stays on top of the TV set. This may involve the use of a USB extension lead to connect the camera to the computer and the use of Blu-Tack or double-sided tape to keep the camera from falling off the set. This issue is more real with flat-screen sets which don’t have much space on top of them

If you are concerned about your privacy and security, you may need to keep the webcam disconnected while you are not involved in video conferencing so that rogue software doesn’t “open” the camera up.