802.16 is an emerging wireless networking standard set by the IEEE that is still under development even as it is being deployed. The term “WiMax” stands for “Worldwide Interoperability for Microwave Access” and refers to the 802.16 standard in general – much the same way that “WiFi” refers to 802.11 in all of its flavors (a, b, g, n, etc). WiMax has a relatively large range and offers users broadband speeds.
IEEE 802.11 Specifications
- Range – 30-mile (50-km) radius from base station
- Speed – 70 megabits per second
- Line-of-sight not needed between user and base station
- Frequency bands – 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)
- Defines both the MAC and PHY layers and allows multiple PHY-layer specifications
(From HowStuffWorks.com)
How Does WiMax Work?
Think of WiMax as a mix between Cellular technology and WiFi. Towers are setup throughout the area, much like cell phone towers. These towers have a range of about 4-6 mile radius to provide out-of-site connections – similar again to cell phone towers. (Line-of-site WiMax connections can have a 30 mile radius.)
These WiMax towers receive their internet access through either a wired connection (such as fiber or a T3 line) or through line-of-site microwave connection (more common in the rural deployments).
Receivers, such as a desktop modem or PCMCIA card (and soon to be integrated into Intel mobile architectures and mobile phones, etc) are specifically calibrated to communicate with WiMax towers.
Later releases of the 802.16 standard (such as the ‘e’ revision), allow for handshake trade off between towers as the user moves about – in very much the same way as cell phones.
How Does WiMax Differ From WiFi?
- Range – WiMax has a much greater signal range than WiFi. For example, only two towers are needed by the local WiMax service provider to cover the entire city of Rexburg. Conversely, there are dozens of WiFi access points on the campus of BYU-Idaho alone that still do not provide full saturation.
2. “In Wi-Fi the media access controller (MAC) uses contention access — all subscriber stations that wish to pass data through a wireless access point (AP) are competing for the AP’s attention on a random interrupt basis. This can cause subscriber stations distant from the AP to be repeatedly interrupted by closer stations, greatly reducing their throughput. This makes services such as Voice over IP (VoIP) or IPTV, which depend on an essentially-constant Quality of Service (QoS) depending on data rate and interruptibility, difficult to maintain for more than a few simultaneous users. In contrast, the 802.16 MAC uses a scheduling algorithm for which the subscriber station need compete once (for initial entry into the network). After that it is allocated an access slot by the base station. The time slot can enlarge and contract, but remains assigned to the subscriber station, which means that other subscribers cannot use it. In addition to being stable under overload and over-subscription (unlike 802.11), the 802.16 scheduling algorithm can also be more bandwidth efficient. The scheduling algorithm also allows the base station to control QoS parameters by balancing the time-slot assignments among the application needs of the subscriber stations.” (Quoted from Wikipedia.org)
What are the Practical Uses of WiMax?
- WiMax is a viable solution for closing in on the “last mile” routes. Particularly in rural areas – where broadband access is unavailable due to the prohibitively high cost of laying cable (vs. return on investment) – WiMax can be seen as a means of reaching people that have yet to have been reached.
- Mobile broadband – the mobile standard of WiMax (that handshakes, like a cell phone) is expected by Intel, Sprint, and others to fuel the use of internet on mobile devices in the US and abroad significantly in the coming years. Nokia and other handset manufacturers are set to introduce devices that integrate WiMax into the heart of the functionality. Not only cell phones, but a derivative type of device – dubbed “Mobile Internet Device” (or MID) – are set to be a sector of growth over the coming months and years.
- Internet connection at home – WiMax has proven to challenge the likes of cable and DSL in the residential market. Even for those who never plan to go mobile with their internet – the low price of deployment for the ISP allows the savings to be passed onto the consumer. This allows for an enticing, additional form of competition in the residential internet market.
- Look for WiMax is emerging markets as well. India, China, and many African nations are looking toward WiMax and similar long range wireless technologies for connectivity. India currently has a large scale deployment of WiMax via the Tata corporation.
(Sources: HowStuffWorks.com and Wikipedia.org)
