biology

Personal Handy-phone System

Personal Handy-phone System is a biology 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 Personal Handy-phone System rather than just read about it. In short: The Personal Handy-phone System (PHS), also known as the Personal Communication Telephone (PCT) in Thailand, and the Personal Access System (PAS) and commercially branded as Xiaolingtong (Chinese: 小灵通) in China, was a mobile network system operating in the 1880–1930 MHz frequency band. In Japan, it was introduced as a low-cost wireless service with smaller coverage areas than standard cellular networks.

Key takeaways

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

Reference excerpt

The Personal Handy-phone System (PHS), also known as the Personal Communication Telephone (PCT) in Thailand, and the Personal Access System (PAS) and commercially branded as Xiaolingtong (Chinese: 小灵通) in China, was a mobile network system operating in the 1880–1930 MHz frequency band. In Japan, it was introduced as a low-cost wireless service with smaller coverage areas than standard cellular networks. Its affordability made it popular in China, Taiwan, and other parts of Asia, as both the handsets and network infrastructure were relatively inexpensive to maintain. Developed in the 1990s, PHS used a microcell architecture with low-power base stations covering 100 to 500 metres (330 to 1,640 ft). Unlike conventional cellular networks that relied on large cell sites for extensive coverage, PHS’s design was better suited for dense urban environments and reduced infrastructure costs. PHS was overtaken in the marketplace by GSM (2G) and UMTS (3G), with the last retail network decommissioned in 2021 and the last commercial network terminated in 2023.

Outline The name "Xiaolingtong" was adopted from the protagonist of Ye Yonglie's science fiction classic, Little Smarty Travels to the Future (Xiao Lingtong manyou weilai 小灵通漫游未来).

Technology

PHS is essentially a cordless telephone like DECT, with the capability to handover from one cell to another. PHS cells are small, with transmission power of base station a maximum of 500 mW and range typically measures in tens or at most hundreds of metres (some can range up to about 2 kilometres in line-of-sight), contrary to the multi-kilometre ranges of CDMA and GSM. This makes PHS suitable for dense urban areas, but impractical for rural areas, and the small cell size also makes it difficult if not impossible to make calls from rapidly moving vehicles. PHS uses TDMA/TDD for its radio channel access method, and 32 kbit/s ADPCM for its voice codec. Modern PHS phone can also support many value-added services such as high speed wireless data/Internet connection (64 kbit/s and higher), WWW access, e-mailing, and text messaging. PHS technology is also a popular option for providing a wireless local loop, where it is used for bridging the "last mile" gap between the POTS network and the subscriber's home. It was developed under the concept of providing a wireless front-end of an ISDN network. Thus a PHS base station is compatible with ISDN and is often connected directly to ISDN telephone exchange equipment e.g. a digital switch. In spite of its low-cost base station, micro-cellular system and "Dynamic Cell Assignment" system, PHS offers higher number-of-digits frequency use efficiency with lower cost (throughput per area basis), compared with typical 3G cellular telephone systems. It enables flat-rate wireless service such as AIR-EDGE, throughout Japan. The speed of an AIR-EDGE data connection is accelerated by combining lines, each of which basically is 32 kbit/s. The first version of AIR-EDGE, introduced in 2001, provided 32 kbit/s service. In 2002, 128 kbit/s service (AIR-EDGE 4×) started and in 2005, 256 kbit/s (8×) service started. In 2006, the speed of each line was also upgraded to 1.6 times with the introduction of "W-OAM" technology. The speed of AIR-EDGE 8× is up to 402 kbit/s with the latest "W-OAM" capable instrument. In April 2007, "W-OAM typeG" was introduced allowing data speeds of 512 kbit/s for AIR-EDGE 8x users. Furthermore, the "W-OAM typeG" 8× service was planned to be upgraded to a maximum throughput of 800 kbit/s, when the upgrading for access points (mainly switching lines from ISDN to fibre optic) in its system are completed. Thus it was expected to exceed the speeds of popular W-CDMA 3G service like NTT DoCoMo's FOMA in Japan.

Implementation

… excerpt ends here. Continue reading the full article.

Illustrations

ASTEL [ja]-brand PHS Base station in Tokyo, Japan

Worked examples

Example 1 — a first encounter with Personal Handy-phone System

Start with the simplest possible case. Write down what Personal Handy-phone System claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, 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 Personal Handy-phone System 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 Personal Handy-phone System 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 Personal Handy-phone System

In research: Personal Handy-phone System appears in biology 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 Personal Handy-phone System 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: Personal Handy-phone System is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1995 establishments in Japan, First generation mobile telecommunications, Japanese inventions, so understanding it makes those chapters shorter.
In everyday life: Look for Personal Handy-phone System 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 Personal Handy-phone System in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Personal Handy-phone System 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 Personal Handy-phone System out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Personal Handy-phone System in simple terms?

Why does Personal Handy-phone System matter?

Because it connects several biology 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 Personal Handy-phone System?

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 Personal Handy-phone System.