computer science

IEEE 802.20

IEEE 802.20 is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand IEEE 802.20 rather than just read about it. In short: IEEE 802.20 or Mobile Broadband Wireless Access (MBWA) was a specification by the standard association of the Institute of Electrical and Electronics Engineers (IEEE) for mobile broadband networks. The main standard was published in 2008.

Key takeaways

IEEE 802.20 belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IEEE 802.20 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IEEE 802.20 from memory before moving on to harder problems.

Reference excerpt

IEEE 802.20 or Mobile Broadband Wireless Access (MBWA) was a specification by the standard association of the Institute of Electrical and Electronics Engineers (IEEE) for mobile broadband networks. The main standard was published in 2008. MBWA is no longer being actively developed. This wireless broadband technology is also known and promoted as iBurst (or HC-SDMA, High Capacity Spatial Division Multiple Access). It was originally developed by ArrayComm and optimizes the use of its bandwidth with the help of smart antennas. Kyocera is the manufacturer of iBurst devices.

Description iBurst is a mobile broadband wireless access system that was first developed by ArrayComm, and announced with partner Sony in April 2000. It was adopted as the High Capacity – Spatial Division Multiple Access (HC-SDMA) radio interface standard (ATIS-0700004-2005) by the Alliance for Telecommunications Industry Solutions (ATIS). The standard was prepared by ATIS’ Wireless Technology and Systems Committee's Wireless Wideband Internet Access subcommittee and accepted as an American National Standard in 2005. HC-SDMA was announced as considered by ISO TC204 WG16 for the continuous communications standards architecture, known as Communications, Air-interface, Long and Medium range (CALM), which ISO is developing for intelligent transport systems (ITS). ITS may include applications for public safety, network congestion management during traffic incidents, automatic toll booths, and more. An official liaison was established between WTSC and ISO TC204 WG16 for this in 2005. The HC-SDMA interface provides wide-area broadband wireless data-connectivity for fixed, portable and mobile computing devices and appliances. The protocol is designed to be implemented with smart antenna array techniques (called MIMO for multiple-input multiple-output) to substantially improve the radio frequency (RF) coverage, capacity and performance for the system. In January 2006, the IEEE 802.20 Mobile Broadband Wireless Access Working Group adopted a technology proposal that included the use of the HC-SDMA standard for the 625kHz Multi-Carrier time-division duplex (TDD) mode of the standard. One Canadian vendor operates at 1.8 GHz.

Technical description The HC-SDMA interface operates on a similar premise as cellular phones, with hand-offs between HC-SDMA cells repeatedly providing the user with a seamless wireless Internet access even when moving at the speed of a car or train. The standard's proposed benefits:

IP roaming & handoff (at more than 1 Mbit/s) New MAC and PHY with IP and adaptive antennas Optimized for full mobility up to vehicular speeds of 250 km/h Operates in Licensed Bands (below 3.5 GHz) Uses Packet Architecture Low Latency Some technical details were:

Bandwidths of 5, 10, and 20 MHz. Peak data rates of 80 Mbit/s. Spectral efficiency above 1 bit/sec/Hz using multiple input/multiple output technology (MIMO). Layered frequency hopping allocates OFDM carriers to near, middle, and far-away handsets, improving SNR (works best for SISO handsets.) Supports low-bit rates efficiently, carrying up to 100 phone calls per MHz. Hybrid ARQ with up to 6 transmissions and several choices for interleaving. Basic slot period of 913 microseconds carrying 8 OFDM symbols. One of the first standards to support both TDM (FL, RL) and separate-frequency (FL, RL) deployments. The protocol:

specifies base station and client device RF characteristics, including output power levels, transmit frequencies and timing error, pulse shaping, in-band and out-of band spurious emissions, receiver sensitivity and selectivity; defines associated frame structures for the various burst types including standard uplink and downlink traffic, paging and broadcast burst types; specifies the modulation, forward error correction, interleaving and scrambling for various burst types; describes the various logical channels (broadcast, paging, random access, configuration and traffic channels) and their roles in establishing communication over the radio link; and specifies procedures for error recovery and retry. The protocol also supports Layer 3 (L3) mechanisms for creating and controlling logical connections (sessions) between client device and base including registration, stream start, power control, handover, link adaptation, and stream closure, as well as L3 mechanisms for client device authentication and secure transmission on the data links. Currently deployed iBurst systems allow connectivity up to 2 Mbit/s for each subscriber equipment. Apparently there will be future firmware upgrade possibilities to increase these speeds up to 5 Mbit/s, consistent with HC-SDMA protocol.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with IEEE 802.20

Start with the simplest possible case. Write down what IEEE 802.20 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to IEEE 802.20 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about IEEE 802.20 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of IEEE 802.20

In research: IEEE 802.20 appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses IEEE 802.20 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: IEEE 802.20 is common in secondary-school and first-year university syllabi. It links to neighbouring topics IEEE 802, Mobile broadband, Wireless networking standards, so understanding it makes those chapters shorter.
In everyday life: Look for IEEE 802.20 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study IEEE 802.20 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IEEE 802.20 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain IEEE 802.20 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IEEE 802.20 in simple terms?

Why does IEEE 802.20 matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study IEEE 802.20?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on IEEE 802.20.