Until recently our area of work was determined by the length of the cable connecting our computer to the network point. This was before Wi-fi became the norm in our lives.
Wi-Fi services provide staff and students with wireless connection to the US network. Unfortunately, with wi-fi, the expectation is created that it will always work perfectly and be accessible. Expectation and reality don’t necessarily correspond and this leads to frustration amongst users.
Realistically speaking Wi-fi is a best effort and various factors such as your physical distance from the wireless access point (WAP), WAPs influencing each other and structures in the way of the signal, play a large role.
Let’s look at the technical details –
Wi-fi networks have a limited range. The standard WAP uses 802.11b or 802.11g and with a standard antenna it will cover a range of 35 metres indoors and 100 metres outside. Reception can be improved by installing a higher gain antenna and adapting the antenna’s direction.
Due to the complex nature of radio propagation at typical wi-fi frequencies, especially the effect of signals bouncing off trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter.
Wi-fi connections can also be interrupted or slowed down due to other devices in the environment. Wi-fi pollution or too many access points can prevent access and interfere with other devices’ use of other access points. This is caused by overlapping channels on the 802.11g/b spectrum and can lead to a problem in densely populated areas or office buildings with many Wi-fi access points.
On our campuses the maximum connections to a hotspot (or WAP) are limited to 25 to 35 and the rest are denied access. The devices connected to a hotspot at a given moment have to share the output and the higher the number of devices, the less efficient the communications.
Other devices such as microwave ovens, ISM band devices, security cameras, cordless phones, baby monitors and amateur radios also use the 2.4 GHz band and this can cause significant interference.
Given all these factors, it is clear that Wi-fi isn’t always the best option for a stable, dependable network connection. If you are working from your office, rather plug your computer in at the network point and use Wi-fi only for emergencies or when you move around on campus.
If you want to register for use of Wi-fi on campus, contact the IT Service desk at +27 21 808 4367 or send an e-mail to help@sun.ac.za with the following information:
- Building
- Room number
- US number
- Username
- Asset number of device or description of the device
- Network card address (also known as the MAC address)
Access to Wi-fi services on campus take place via the Secure or MatiesWifi SSIDs. Devices with asset numbers are generally registered on Secure, where they have access to all network services. Other devices are registered on MatiesWifi with limited access to services. Both these SSIDs provide a speed of up to 54 Mbps.
For more information, contact the IT Service Desk or telecom@sun.ac.za
[SOURCE: www.wikipedia.org]
Tot nie te lank gelede nie was ons area van werk ingeperk deur die lengte van die kabel wat die netwerkpunt aan ons rekenaar verbind. Dit was voordat wi-fi `n gegewe in ons lewens geword het.
WI-FI op die US-kampus is ‘n kabellose verbinding aan die netwerk vir studente en personeel. Met wi-fi word die verwagting dikwels geskep dat dit oral 100% reg gaan werk en altyd beskikbaar sal wees. Wat verwag word en die werklike aanbod, stem ongelukkig nie ooreen nie en kan lei tot frustrasie by gebruikers.
Die realiteit is dat wi-fi `n beste poging is en faktore soos fisiese afstand vanaf die WAPs, WAPs wat mekaar beinvloed en fisiese strukture is in die pad van die sein is, speel `n groot rol.
Kom ons kyk na die tegniese details –
Wi-Fi netwerke het `n beperkte sendbereik. Die standaard WAP (wireless access point) gebruik 802.11b of 802.11g en met `n gewone antenna sal dit `n ontvangsgebied van 35 meter binneshuis en 100 meter buite kan dek. Ontvangs kan wel verbeter word met `n sterker antenna en deur die antenna-rigting aan te pas.
Weens die komplekse aard van radioverspreiding op tipiese Wi-fi frekwensies, veral die effek van seine wat weerkaats teen bome en geboue, kan algoritmes net `n beraamde seinsterkte voorspel vir `n area in verhouding tot `n sender.
Wi-Fi verbindings kan onderbreek word of die internet spoed verlaag word weens ander toestelle in die omgewing. Wi-fi besoedeling of `n oormatige hoeveelheid toegangspunte kan toegang belemmer en inmeng met ander toestelle se toegang. Dit word veroorsaak deur oorvleueling op die 802.11g/b spektrum en kan `n probleem word in digbevolkte areas soos groot woonstelblokke of kantoorgeboue met baie wi-fi toegangspunte.
Op ons kampus word die maksimum verbindings na `n “hotspot” beperk tot 25 tot 35 en die res word toegang geweier. Die hoeveelheid toestelle wat op een oomblik aan `n “hotspot” gekoppel word moet dus die deurset deel en verlaag effektiwiteit.
Boonop gebruik ander toestelle ook die 2.4 GHz band, insluitende mikrogolfoonde, ISM band toestelle, sekuriteitskameras, koordlose telefone, babamonitors en amateur-radios en dit kan beduidende steurings veroorsaak.
Met bogenoemde in ag geneem, is dit duidelik dat wi-fi nie altyd die beste opsie is vir `n stabiele, betroubare netwerkkonneksie nie. As jy in jou kantoor is, prop eerder jou rekenaar by die netwerkpunt in en gebruik wi-fi slegs vir noodgevalle of wanneer jy rondbeweeg op kampus.
As jy wil registreer vir die gebruik van wi-fi op kampus, kontak die IT Dienstoonbank by +27 21 808 4367 of stuur `n e-pos na help@sun.ac.za met die volgende informasie:
- Gebou
- Kamer
- US nommer
- Gebruikersnaam
- Batenommer van toestel of beskrywing van die toestel
- Netwerkkaartadres (of te wel die MAC-adres)
Toegang tot Wi-fi dienste op kampus kan verkry word deur die Secure of MatiesWifi SSIDs. Toestelle met batenommers word normaalweg op Secure geregistreer met toegang tot alle netwerkdienste, terwyl alle ander toestelle op MatiesWifi geregistreer word met beperkte toegang tot dienste. Beide hierdie wifi-verbindings gee `n spoed van tot 54 Mbps.
Vir verdere navrae kontak die IT Dienstoonbank of telecom@sun.ac.za
[BRON: www.wikipedia.org]
Another important factor is that if you have 10 devices connected to your WAP the bandwidth to ALL users is dictated to the wireless level of the slowest device. IOW, if you have 9 802.11G or N devices and one B device ALL will connect at B “speed”.