Very simply, a WLAN is a Local Area Network that transmits data from one device to another using radio frequency communication links. Most WLANs are an extension of a larger wired network, however, in some applications such as ad-hoc networks there are no wired components. Generally the WLAN networks that are most commonly used are based on the IEEE 802.11 protocol suite but can also consist of other IEEE standards (such as Bluetooth or WiMax) or even proprietary communication protocols.
All products that conform to a specific task group of the IEEE 802.11 standards maintain some interoperability. However, because different vendors can implement the standards differently, the Wi-Fi Alliance created a vendor-neutral certification based strictly on interoperability of products regardless of the manufacturer. Products that carry the Wi-Fi certification are tested to ensure a base level of interoperability.
Wi-Fi is a trademark and certification of the Wi-Fi Alliance. The alliance is a global non-profit association focused on a will defined interpretation of the IEEE wireless standards and ensuring interoperability between hardware manufacturers. The term Wi-Fi is generally used synonymously with 802.11a/b/g/n protocols but is actually the certification stamp that ensures the standards have been implemented consistently with all other Wi-Fi certified devices.
An SSID is the identifier for a particular wireless network, often called the wireless network name. The SSID is advertised by an access point so all clients can identify the possible wireless connections that are available. A WLAN may have multiple SSIDs, each with different levels of security and bandwidth allocations.
WLAN’s have a wide range of security options available today that can make the data as secure as you want it to be. With strong data encryption algorithms such as AES, and authentication options using certificates or RADIUS credentials, there are many options based on what your security infrastructure will allow.
There are multiple parts to wireless security such as authentication, encryption and intrusion detection and prevention. Give SideBand a call to talk about your options.
WEP is an acronym for Wired Equivalent Privacy and is a set of security tools for wireless connections. It uses the RC4 encryption cipher to encrypt the data but when WEP was being designed, the cypher was not implemented properly because WEP always started the cypher at a known stating place when it was supposed to start with a random value. The flaw became widely publicized and WEP soon lost all credibility as a meaningful method of security. WEP was included in the original IEEE 802.11 standards and still remains an option in most products even though it is not recommended.
WPA stands for Wi-Fi Protected Access and is a set of security standards certified by the Wi-Fi alliance. The security standards are taken from the IEEE 802.11i task group but ensure interoperability of security standards between different manufacturers. WPA was quickly adopted because it was the first practical alternative to WEP which had been shown to be insecure. WPA2 introduces AES encryption algorithms to wireless security in the form of CCMP.
802.1x is an IEEE standard for defining port based access control that has been adopted for use in wireless networks. The protocol makes use of a RADIUS server, certificates and user database to provide authentication to wireless clients.
Data encryption over wireless networks makes data unreadable to anyone who does not possess the encryption key.
Authentication is the act of confirming identity.
Association is the process of establishing a connection to the network.
A wireless client is any device that transmits data to another client or network device without using wires to send the data.
In most scenarios all stationary clients devices (such as desktops and servers) remain on the wired network and devices that need mobility (laptops and handhelds) attach to the wireless network. There are some scenarios where all clients attach to the wireless network, such as those that are deployed in school dormitories or hotels.
An access point or AP is the infrastructure device that contains a wired network interface and one or more radio interfaces that bridges data between the air and the wire.
From a hardware perspective most APs support a minimum of 255 clients each. This question is really about how much bandwidth you require per user. Just like any other communications device the AP is usually oversubscribed to some degree as most of the time users won’t all be transmitting data at the same time.
A WLAN system can be designed to accommodate a huge number of clients but the bandwidth available in any given area is finite (dependant on modulation and channel availability.)
A wireless controller is the central piece of a highly scalable wireless architecture. The controller handles configurations and firmware distribution to its associated access points as well as RF optimization and client roaming.
Transmission range varies among products as most don’t push the maximum allowed power. Excess power is not desirable in most deployments as reducing the individual cell size creates the availability of more cells and thus more bandwidth. 2.4GHz will generally “go further” than 5GHz as the lower the frequency the better the propagation through objects. It is best practice to match the transmission range of the APs with the transmission range of the clients that are being supported.
This is dependent on your requirements and your facility. Once the application and operational requirements have been established a site survey is conducted to determine hardware needs.
A site survey is the process of creating a radio frequency (RF) and installation plan. This will be a blueprint for WLAN deployment.
Site surveys are necessary because no two environments are the same. For the precise radio planning that enables high end equipment to perform to their touted specifications an onsite survey is the only way to guarantee a successful deployment on the first try.
Many applications are trending WLAN requirements to the complex, but there are scenarios that have requirements that do not necessitate formal RF planning. Hotspot type coverage for a data application is one where a site survey would not typically be performed.
A site survey addresses fitting functional requirement to a particular environment.
The result of a site survey is a deployment plan that is guaranteed to perform. The survey documentation is typically handed off to a wiring contractor for data cabling to identify locations.
It is always recommended to perform a site survey with the same equipment that will be deployed. There are some instances where this is not an absolute requirement but it is always recommended to heavily evaluate before deploying equipment based on a dissimilar hardware survey.
Yes, the requirements are quite different. There are currently three main categories of design; data, voice and location. Density requirements are lowest with data and highest with location. We recommend that if there is a possibility in the future of need for one of the other applications that it is accounted for in the initial design as it is not easy to go from one design to the next.
I have a wireless management tool that can recommend AP locations. Can this be used in lieu of a formal site survey?
In general, and certainly for any critical applications, a site survey is required. These tools can be useful in gauging estimates for deployment but they do not substitute an actual survey. A site survey provides far more than how many APs are required to “cover” a facility.
My wireless management tool shows that I have full coverage but users complain about dead spots, how can that be?
These systems for coverage monitoring are not nearly as accurate as a survey performed by a WLAN engineer. They typically monitor AP to AP coverage rather than AP to client coverage. This gives a rough estimate only. If you have doubts about coverage a post deployment survey is recommended and will shed light on the situation in a hurry.
Many things can factor into performance degradation on wireless networks. SideBand Systems engineers can quickly and accurately analyze the conditions affecting your WLAN and form a plan for remediation.
In this situation a post deployment survey will provide the quickest path do a desirable state. If your current hardware needs a refresh a new survey should be conducted – this will also provide performance evaluation of the current infrastructure. This process is not service interrupting so your current WLAN will stay up during the process.
Lower performance and dropped connections are typical results of poor coverage. Any sources of interference will dramatically increase the visibility of poor coverage. Insufficient coverage is not always clear cut and it is necessary to determine what constitutes the proper coverage boundary for your client devices and applications.
You can absolutely have too many APs and this can actually be more troublesome than too few APs. When devices on the same channel are co-located without enough channel separation the result is wasted equipment and reduced performance.
Overlapping channels are akin to using hubs rather than switches. You gain no bandwidth by co-locating devices on the same channel – in fact you lose it. Each channel is a shared medium and must be separated to extract performance. Even neighbor networks share this bandwidth.
Any device that operates at 2.4GHz will interfere with 802.11b/g/n and devices that operate at 5GHz or 5.8GHz will impact your 802.11a/n and 802.11ac networks. Typical interferers are cordless phones, microwave ovens, security cameras, baby monitors and Bluetooth; however there are all kinds of devices that use this unlicensed spectrum.
Yes, since the wireless channel is a shared medium you share bandwidth with other WLANs and other devices using the same frequency. It is important for networks that abut outside networks to optimally channelize between these devices and your own.