Selasa, 26 Januari 2010
Understanding of Roaming
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In wireless telecommunications, roaming is a general term that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. Roaming ensures that the wireless device keeps connected to the network, without losing the connection. The term "roaming" originates from the GSM (Global System for Mobile Communications) sphere; the term "roaming" can also be applied to the CDMA technology, see CDMA Roaming. Traditional GSM Roaming is defined (cf. GSM Association Permanent Reference Document AA.39) as the ability for a cellular customer to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when travelling outside the geographical coverage area of the home network, by means of using a visited network. This can be done by using a communication terminal or else just by using the subscriber identity in the visited network. Roaming is technically supported by mobility management, authentication, authorization and billing procedures.
Type Of Roaming
- Regional roaming:
This type of roaming refers to the ability of moving from one region to another region inside national coverage of the mobile operator. Initially, operators may have provide commercial offers restricted to a region (sometimes to a town). Due to the success of GSM and the decrease in cost, regional roaming is rarely offered to clients except in nations with wide geographic areas like the USA, Russia, India, etc., in which there are a number of regional operators.
- National roaming:
This type of roaming refers to the ability to move from one mobile operator to another in the same country. For example, a subscriber of T-Mobile USA who is allowed to roam on AT&T Mobility's service would have national roaming rights. For commercial and license reasons, this type of roaming is not allowed unless under very specific circumstances and under regulatory scrutiny. This has often taken place when a new company is assigned a mobile telephony license, to create a more competitive market by allowing the new entrant to offer coverage comparable to that of established operators (by requiring the existing operators to allow roaming while the new entrant has time to build up its own network). In a country like India, where the number of regional operators is high and the country is divided into circles, this type of roaming is common[citation needed].
- International roaming:
This type of roaming refers to the ability to move to a foreign service provider's network. It is, consequently, of particular interest to international tourists and business travellers.
Broadly speaking, international roaming is easiest using the GSM standard, as it is used by over 80% of the world's mobile operators. However, even then, there may be problems, since countries have allocated different frequency bands for GSM communications (there are two groups of countries: most GSM countries use 900/1800 MHz, but the United States and some other countries in the Americas have allocated 850/1900 MHz): for a phone to work in a country with a different frequency allocation, it must support one or both of that country's frequencies, and thus be tri or quad band.
- Inter-standards roaming:
This type of roaming refers to the ability to move seamlessly between mobile networks of different technologies.
Since mobile communication technologies have evolved independently across continents, there is significant challenge in achieving seamless roaming across these technologies. Typically, these technologies were implemented in accordance with technological standards laid down by different industry bodies and hence the name.
A number of the standards making industry bodies have come together to define and achieve interoperability between the technologies as a means to achieve inter-standards roaming. This is currently an ongoing effort.
The concept of Mobile signature Roaming is: an access point should be able to get a Mobile Signature from any end-user, even if the AP and the end-user have not contracted a commercial relationship with the same MSSP. Otherwise, an AP would have to build commercial terms with as many MSSPs as possible, and this might be a cost burden. This means that a Mobile Signature transaction issued by an Application Provider should be able to reach the appropriate MSSP, and this should be transparent for the AP(reference).
Network elements belonging to the same Operator but located in different areas (a typical situation where assignment of local licenses is a common practice)pair depends on the switch and its location.Hence, software changes and a greater processing capability are required, but furthermore this situation could introduce the fairly new concept of roaming on a per MSC basis instead of per Operator basis. But this is actually a burden, so it is avoided.
- Permanent Roaming:
This type of roaming refers to customers who purchase service with a mobile phone operator intending to permanently roaming, or be off-network. This becomes possible because of the increasing popularity and availability of "free roaming" service plan, where there is no cost difference between on and off network usage. The benefits of getting service from a mobile phone operator that isn't local to you can include cheaper rates, or features and phones that aren't available on your local mobile phone operator, or to get to a particular mobile phone operator's network to get free calls to other customers of that mobile phone operator through a free unlimited mobile to mobile feature. Accidentally become a permanent roaming customer does not usually happen. Most mobile phone operators will require the customer's living or billing address be inside their coverage area or less often inside the government issued radio frequency license of the mobile phone operator, this is usually determined by a computer estimate because it its impossible to guarantee coverage (see Dead zone (cell phone)). If a potential customer's address is not within the requirements of that mobile phone operator, they will be denied service. In order to permanently roam customers may use a false address and online billing, or a relative or friends address which is in the required area, and a 3rd party billing option.
Most mobile phone operator discourage or prohibit permanent roaming since they must pay per minute rates to the network operator their customer is roaming onto to[2], while they can not pass that extra cost onto customers ("free roaming").
- Trombone roaming:
Roaming calls within a local tariff area, when at least one of the phones belong outside that area. Usually implemented with trombone routing[3] also known as tromboning[4]
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