The telecommunications industry’s lexicon is ever-changing and its acronyms and words sometimes have different meanings for different people. In no sector of communications is the vocabulary more dynamic than in the wireless space. So xchange is taking this, our first issue of 2007, as an opportunity to revisit the definitions of popular wireless terms and help you understand some of the new words flying around. So get your seat in the forward-and-upright position and we’ll let ’er rip.
2G
Old school wireless folks may remember good ’ole second-generation, a.k.a. 2G, wireless. These wireless networks fall into two camps: time-division multiple access/global system for mobile communications (TDMA/GSM) and code-division multiple access (CDMA). These low-speed circuits were designed and are used primarily for voice communications.
2.5G
As you may recall, shortly after 2G appeared, we started to hear about 3G, but the industry wasn’t ready for it quite yet, so it threw out the 2.5G stepping stone. 2.5G offers higher data rates than 2G, plus it enables the delivery of basic data services. It also allows for always-on communications rather than session-based calls, and can support IP traffic.
To make things muddier yet, there are a handful of 2.5G options. TDMA/GSM added general packet radio access (GPRS) as its 2.5G data component. Then came enhanced data rates for GSM (EDGE), which was slightly faster still. CDMA developed to CDMA2000 1x-RTT, which has speeds comparable to EDGE.
However, EDGE and CDMA2000 sometimes are considered early 3G technologies. So that leads us to ...
3G
Third-generation wireless networks are the latest generation of active mobile services. They provide better quality voice and high-speed data, support for packet applications and access to the Internet.
GSM 3G networks are based on UMTS/WCDMA and the faster HSDPA/HSUPA. The CDMA version of 3G is EV-DO and its subsequent revisions (more reading!).
4G
Surprise! Next is fourth-generation wireless networking. But, wait! Fourth-generation wireless networks are not expected to materialize until at least 2008. These 4G networks promise to support IP end-to-end, and to enable personalized, high-definition multimedia and video services. Some 4G technology candidates are mobile WiMAX, LTE and OFDM (all defined subsequently).
Sprint Nextel Corp. is working to pioneer 4G wireless. Check out the cover story I wrote about the company’s 4G strategy in the December issue of xchange (“Out of the Lab, Into the Real World”).
Beamforming
Beamforming is the process of delaying the outputs of the sensors in a radio array’s aperture and adding these together to reinforce the signal and lessen noise and other interference. Got that?
The technology will be included new in broadband wireless access points for WiMAX and Wi-Fi.
EV-DO
Well, actually, it’s CDMA2000 1xEV-DO. The EV-DO stands for evolution, data-optimized technology and is a direct evolution of the CDMA 3G standard. It enables high-speed wireless connectivity comparable to wired broadband. Its direct competitor is HSPDA/HSUPA.
Femtocell
No, this doesn’t have anything to do with Michael J. Fox. A femtocell is an ultra-low-cost 3G base station for use in a home or small office, to be used as an alternative to a Wi-Fi router.
HSDPA/HSUPA
Can you say that three times fast? High-speed downlink packet access and high-speed uplink packet access are the next evolution of the UMTS/WCDMA standard, and will enable high-speed wireless connectivity comparable to wired broadband. Its direct competitor is CDMA2000 1xEV-DO.
LTE
Long-term evolution will be a 4G technology that will follow HSDPA/HSUPA, optimized for IP-based traffic. LTE has a goal of achieving two-to-four times the spectral efficiency of 3G networks. This means LTE networks will be able to squeeze more bits of data into the same amount of spectrum as 3G, resulting in increased data speeds and/or increased capacity. It will be accompanied by development of the core architecture of mobile networks, called system architecture evolution (SAE).
MIMO
You’re probably familiar with this one. Multiple input/multiple output technology is found in the 802.11n version of the Wi-Fi standard and in new WiMAX equipment. There are multiple transmitters and receivers at the AP and the client. The completely independent radios operate on the same frequency channel, with the assumption that there are multiple paths a signal can take between AP and client due to reflections in the RF environment caused by doors, walls, furniture and the like. The paths are uncorrelated, so different transmissions take different pathways, and the signals don’t bump into each other. The result is a much more efficient, and redundant, transmission system.
OFDM
Orthogonal frequency division multiplexing is a transmission technique for RF signals that divides the data in a channel into several subchannels, each at a different frequency. This boosts bandwidth by letting a system carry several transmissions at the same time. Interference will degrade only a small portion of the signal and has no or little effect on the remainder of the frequency components. It is considered the basis of future 4G candidates.
OTA
Proving the theory that everything in communications requires an acronym, OTA was coined to stand for over-the-air, which simply means without hooking into a wired network. For instance, OTA song downloads are sent wirelessly directly to the handset, as opposed to requiring a user to plug into a PC to “sideload” the content.
Picocell
These adorable little fellas provide localized wireless coverage and normally are found inside buildings or other structures where coverage is poor or where there are a high number of users, such as airport terminals, train stations or shopping centers.
SDR
Not to be confused with an STD, the SDR is a software-defined radio, which consists of software modules running on a generic hardware platform. The end result is a radio that can be upgraded, patched or reconfigured (often remotely) using only software, translating into operational and capital efficiencies and increased flexibility for operators.
UMTS/WCDMA
The Universal Mobile Telecommunications Service is the 3G wireless standard being deployed by operators migrating from GSM-based 2G networks. Wideband CDMA is an effectively synonymous term for UMTS, used in the United States and Japan. Its direct competitor is CDMA2000.
ZigBee
It sounds fun, but can you define it? ZigBee, built on the 802.15.4 standard, is designed for home or industrial control applications, such as automatic light shutoff. It has low power consumption and low data speeds.
