science

Opportunity-Driven Multiple Access

Opportunity-Driven Multiple Access is a 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 Opportunity-Driven Multiple Access rather than just read about it. In short: Opportunity-Driven Multiple Access (ODMA) is a UMTS communications relaying protocol standard first introduced by the European Telecommunication Standards Institute (ETSI) in 1996. ODMA has been adopted by the 3rd-Generation Partnership Project, 3GPP to improve the efficiency of UMTS networks using the TDD mode.

Key takeaways

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

Reference excerpt

Opportunity-Driven Multiple Access (ODMA) is a UMTS communications relaying protocol standard first introduced by the European Telecommunication Standards Institute (ETSI) in 1996. ODMA has been adopted by the 3rd-Generation Partnership Project, 3GPP to improve the efficiency of UMTS networks using the TDD mode. One of the objectives of ODMA is to enhance the capacity and the coverage of radio transmissions towards the boundaries of the cell. While mobile stations under the cell coverage area can communicate directly with the base station, mobile stations outside the cell boundary can still access the network and communicating with the base station via multihop transmission. Mobile stations with high data rate inside the cell are used as multihop relays. The initial concept of Opportunity Driven Multiple Access (ODMA) was conceived and patented in South Africa by David Larsen and James Larsen of SRD Pty Ltd in 1978 [1] The ODMA standard was tabled by the 3GPP committee in 1999 due to complexity issues. The technology continues to be developed and enhanced by IWICS who holds the key patents describing the methods employed in ODMA to effect opportunity driven communications.

ODMA Technology Basic Concepts With the explosion of cellular phone use and Internet multi-media services, wireless networks are becoming increasingly congested. The increased demand has raised our expectations, while creating capacity problems and a need for greater bandwidth. However, if the transmitted power of wireless units is significantly reduced, then there is a potential solution. This implies a signal-to-noise ratio improvement: the ratio is affected by numerous parameters, including radio frequency and path. Opportunity Driven Multiple Access (ODMA) continually determines optimal points along that path to support each transmission. Adaptation ODMA uses many adaptation techniques to optimize communications, but one of the most powerful is path diversity. From origin to destination, ODMA stations relay the transmissions in an intelligent and efficient manner.

Each Subscriber Builds the Network The available optimal paths will increase as subscribers join the network, supporting a fundamental aspect of the ODMA philosophy: Communications are dynamic and local, best controlled at the station level, rather than from some centralized source. Each ODMA-network station is an intelligent burst-mode radio, which can use all the available bandwidth some of the time. However, as with any technology, weather or general network conditions can affect transmissions.

Efficiency with Sub-Bands Like cellular networks, the ODMA-network stations operate in the same wide frequency band, but frequency hopping, at lower data rates, introduces sub-bands. Because transmission is packet based and connectionless, stations relay packets from neighbor stations. For each packet, a station optimizes the transmission by adapting the route, power, data rate, packet length, frequency, time window and data quality over a wide range. Each station has responsibility and much autonomy for routing and service-enhancing adaptation to the current environment. For security, stations accept the authority of a network supervisor.

See also 3G 3GPP: the body that manages the UMTS standards CDMA: Code-division multiple access TDMA: Time-division multiple access FDMA: Frequency-division multiple access

References Lee, William (2006). Wireless and Cellular Telecommunications (3rd ed.). McGraw-Hill. p. 722. ISBN 0071436863.

External links http://www.3gpp.org/ftp/Specs/archive/25_series/25.924/25924-100.zip http://www.iwics.com

Illustrations

Opportunity-Driven Multiple Access: ODMA Routing — ODMA Routing

Worked examples

Example 1 — a first encounter with Opportunity-Driven Multiple Access

Start with the simplest possible case. Write down what Opportunity-Driven Multiple Access claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Opportunity-Driven Multiple Access 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 Opportunity-Driven Multiple Access 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 Opportunity-Driven Multiple Access

In research: Opportunity-Driven Multiple Access appears in 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 Opportunity-Driven Multiple Access 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: Opportunity-Driven Multiple Access is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3GPP standards, Mobile telecommunications standards, UMTS, so understanding it makes those chapters shorter.
In everyday life: Look for Opportunity-Driven Multiple Access 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 Opportunity-Driven Multiple Access in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Opportunity-Driven Multiple Access 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 Opportunity-Driven Multiple Access out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Opportunity-Driven Multiple Access in simple terms?

Why does Opportunity-Driven Multiple Access matter?

Because it connects several 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 Opportunity-Driven Multiple Access?

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 Opportunity-Driven Multiple Access.