We are urgently looking for a VAS Customer System Integration Manager to support our client based in the Middle-East.
Please not that we will give preferences to candidates with a PMP certification, and able to communicate in Arabic.
CSI Systems Integration
MAIN PURPOSE OF THE ROLE AND KEY RESPONSIBILITIES:
Being part of the CSI VAS project Implementation team the CSI Customer Project Manager manages the delivery of the VAS projects. Facilitates, develops and ensures execution of the project activities according to the project plan together with all relevant stakeholders in work streams, sub region and Project management office.
•Defines project scope targets to meet the execution of the allocated VAS Project needs.
•Plans and manages project deliverables, costs, time schedules and milestones.
•Works effectively with all the project stakeholders. Leads, manages and coaches Specialists & Engineers assigned to the project.
•Manages processes within defined project management methodology.
•Systematically and proactively manages project risks together with key project stakeholders.
•Identifies and re-uses best practices and applies lessons learned and uses project tools.
•Ensures that projects will get delivered efficiently and with high quality within the approved, budget, schedule and scope
REQUIREMENTS:
Degree level in Telecom, engineering, PMP certified is preferable.
• Typically 5-10 years of relevant project management experience
• Extensive experience in project management and/or change management programs
• Experience in working in a multi-cultural environment is preferred.
• Experience in managing IN projects is essential
PERSONAL ATTRIBUTES:
• Project management skills
• Change management skills
• Strong capability to plan and organize work
• Solution orientation to drive topics to meet plans
• Strong team player
• Excellent written and oral communication skills
• Ability to work with various cultures & Background
If you are interested in this role please send your CV to mbouhadouf@firstpointgroup.com
Tuesday, March 16, 2010
Needed Network Engineer in Singapore - CCNP must
Adecco Personnel Pte Ltd is hiring Network Controller with one of the Leading Telecom company in Singapore.
For full details, please see the job description below.
RESPONSIBILITIES:
- Proactively manage and monitor network performance on customers network round the clock(7x24) to meet customers' Service Level expectations
Act as Tier2/Levle2 for Network Fault incidents
- Work closely with T1.5 & T3 Teams during engagement and Network outage resolution process
- To systematically analyze and diagnose network faults
- Suggest improvement plan as part of preventive measure per case basis
- To effectively manage service providers and equipment vendors
REQUIREMENTS:
Qualification:
- Diploma holder with more than 4 years' related experience in telecommunications industry
SkillSet:
- Strong Hands-on experience in managing WAN networks and Cisco routers.
- Strong technical knowledge in WAN/LAN networking
- Strong technical knowledge of telecommunication products and services (eg. Private Leased line, MPLS, Frame Relay, Broadband and ISDN)
- Good understanding of network protocols such as TCP/IP, SNMP and VOIP.
- Working knowledge of network Element Management System (eg. SMARTS, VitalNet and Concord)
- Knowledge of UNIX and Remedy Ticketing System will be an advantage.
Independent, self-driven and highly customer focused
- Candidates with past ¡°Service Provider experience¡± will be preferred
- A strong team player who seeks a long term career in customer service
- A good Observer with strong analytical skills
Certification Required:
- CCNP is required
Please furnish your latest CV in word format to harsha.gohil@adecco-asia.com
Regards,
Harsha Gohil
Adecco Personnel Pte Ltd
+65-62359775
For full details, please see the job description below.
RESPONSIBILITIES:
- Proactively manage and monitor network performance on customers network round the clock(7x24) to meet customers' Service Level expectations
Act as Tier2/Levle2 for Network Fault incidents
- Work closely with T1.5 & T3 Teams during engagement and Network outage resolution process
- To systematically analyze and diagnose network faults
- Suggest improvement plan as part of preventive measure per case basis
- To effectively manage service providers and equipment vendors
REQUIREMENTS:
Qualification:
- Diploma holder with more than 4 years' related experience in telecommunications industry
SkillSet:
- Strong Hands-on experience in managing WAN networks and Cisco routers.
- Strong technical knowledge in WAN/LAN networking
- Strong technical knowledge of telecommunication products and services (eg. Private Leased line, MPLS, Frame Relay, Broadband and ISDN)
- Good understanding of network protocols such as TCP/IP, SNMP and VOIP.
- Working knowledge of network Element Management System (eg. SMARTS, VitalNet and Concord)
- Knowledge of UNIX and Remedy Ticketing System will be an advantage.
Independent, self-driven and highly customer focused
- Candidates with past ¡°Service Provider experience¡± will be preferred
- A strong team player who seeks a long term career in customer service
- A good Observer with strong analytical skills
Certification Required:
- CCNP is required
Please furnish your latest CV in word format to harsha.gohil@adecco-asia.com
Regards,
Harsha Gohil
Adecco Personnel Pte Ltd
+65-62359775
DMR Digital Mobile Radio
- a summary or overview about the basics of DMR, Digital Mobile Radio technology, the digital radio communications alternative to analogue PMR, professional mobile radio.
Digital Mobile Radio, DMR, is a new standard that has been developed by ETSI defining digital standard for PMR. PMR, an acronym for Professional, Personal, or Private mobile radio is recognised as the term covering radio communications other than mobile telephones.
With the growing need to improve the efficiency of radio communications systems and add new facilities, the move to a digital system is of great importance. Accordingly the new Digital Mobile Radio communications system has been developed to provide affordable digital systems with low complexity with facilities for voice, data and other supplementary services.
Although the Digital Mobile Radio communications system has been defined by ETSI, a European organisation, it is being developed as a worldwide standard which will have a similar take-up to previous analogue radio communications systems such as MPT 1327.
The resulting Digital Mobile Radio technology has been designed to deliver a cost-effective, highly functional communication system for professional mobile radio users, along with an easy upgrade path and multi-vendor interoperability and flexibility. It has been designed to operate within the existing 12.5 kHz channel spacing that is standard for PMR applications. It ahs also been designed to meet the future 6.25 kHz channel equivalence. The DMR standard is designed to operate within the existing 12.5kHz channel spacing used in licensed land mobile frequency bands globally and to meet future regulatory requirements for 6.25kHz channel equivalence.
DMR Digital Mobile Radio basics
The Digital Mobile Radio communications standard has been developed to meet the requirements of many different classes of users. Those developing the standards have looked at the users of existing PMR radio communications systems. They concluded that these users fell broadly into three different categories:
* Domestic and short range industrial users. These users typically need fast, convenient and low cost communications over a limited range. Typically simple low power low cost radios meet their needs admirably.
* Professional users for which radio communications are critical. These applications can be found in organisations that need to communicate with a mobile workforce. They include business sectors such as transportation, construction, manufacturing, energy and utilities. The communications needs vary considerably but they may need to communicate over a restricted area, of they may require communications across a variety of sites or over a much larger region.
* Emergency services for which radio communications are vital. These applications require top reliability communications which need also to be secure. They may also need to be available over a wide area, and may need to be customised to the specific needs of the user. These radio communications networks are costly, but a necessary requirement for these organisations.
In order to meet these needs the ETSI standard for Digital Mobile Radio provides for three different tiers of radio communications systems.
* Tier 1: This is a basic licence free form of digital radio communications system. Its aim is to fill the same slot that is addressed by PMR466.
* Tier 2: This form of the Digital Mobile Radio communications system requires licensed operation and it offers high power levels, peer to peer operation as well as a repeater mode to provide greater coverage.
* Tier 3: This tier of the Digital Mobile Radio communications standard again requires a licence and provides for trunked operation, thereby providing a digital form of the widely used MPT1327 standard.
The Digital Mobile Radio standard provides operation within the existing channel spacing used within the land mobile radio frequency allocations. It thereby provides an easy upgrade path for current users of analogue mobile radio technology.
Digital Mobile Radio and other technologies
It may appear that Digital Mobile radio directly competes with other technologies and therefore may be redundant. However it has been designed to offer unique advantages and fill a market requirement that is not being addressed by other services.
* Unlicensed PMR: This sector of the market requires low cost solutions. The main driver is for improved use of the spectrum which will be provided by the Tier 1 Digital Mobile Radio technology. This will ultimately need to take over from the existing analogue solutions.
* TETRA and Project 25 (P25) : These standards are typically aimed at the market where mission criticality is key and where a variety of different facilities are required. TETRA (Terrestrial Trunked Radio) the standards for which are under ETSI control uses 25 kHz channels and supports many facilities including multiple talk groups on multiple frequencies, including one-to-one, one-to-many and many-to-many calls.
In North America the Telecommunications Industry Association, TIA has developed a system with the name Project 25 (P25) which has similar capabilities to TETRA but uses 12.5 kHz channel spacing with FDMA for Phase I although Phase II will use a two slot TDMA system for digital trunked radio
Both these systems are very sophisticated and require a complex infrastructure which enable them to provide a highly reliable service. Digital Mobile Radio is able to offer a lower cost alternative that will be more applicable to lower end applications.
* MPT1327 and dPMR : The majority of the PMR business is seen in between the low end domestic and small business short range communications and the high end mission critical region. In this arena, cost is a critical element and all the facilities offered by TETRA and P25 are not needed. Digital Mobile Radio is seen as offering a key improvement in this area. It provides increased capacity and spectrum efficiency usage along with improved facilities and reliability. While analogue radios and MPT1327 for trunked radio have provided very fgood services there is a need to move to more efficient digital radio options. Accordingly Digital Mobile Radio technology is seen as providing the solution for new users and those needing to upgrade.
DMR Association
The foundations for the DMR Association were laid in 2005 when a group of companies that were potential suppliers of DMR equipment signed a Memorandum of Understanding to support ETSI in the establishment of Digital Mobile Radio as an open standard. These suppliers included: Fylde Micro, Icom, Kenwood, Motorola, Selex, Tait, and Vertex Standard.
The standardisation work was undertaken such that the DMR standards were overseen by ETSI and the standards and themselves were issued by them.
Then in 2009, the original signatories of the original MOU set up the DMR Association (www.dmrassociation.org) with its aims to provide interoperability between Digital Mobile Radio vendors equipment and to provide information about the DMR standard.
ETSI Digital Mobile Radio standards
Digital Mobile Radio technology is defined under the relevant ETSI standards. These include the following:
* TR 102 398 : This technical report provides an introduction to Digital Mobile Radio technology
* TS 102 362 parts 1 to 3: These technical specifications define Digital Mobile Radio protocol conformance testing and test suites
* TS 102 490: This technical specification defines the narrow-band or 'digital PMR' protocol.
* Technical Report TR 102 335-1: Digital Mobile Radio System Reference document for Tier 1 DMR.
* TR 102 335-2: Digital Mobile Radio System Reference document for Tier 2 DMR (licensed).
Digital Mobile Radio Summary
Digital Mobile Radio technology offers users of Professional Mobile Radio systems the opportunity to upgrade their PMR systems from analogue to digital technology. As the DMR standard has been developed to facilitate the easy migration from analogue to digital, Digital Mobile Radio provides an ideal platform for many users.
Digital Mobile Radio, DMR, is a new standard that has been developed by ETSI defining digital standard for PMR. PMR, an acronym for Professional, Personal, or Private mobile radio is recognised as the term covering radio communications other than mobile telephones.
With the growing need to improve the efficiency of radio communications systems and add new facilities, the move to a digital system is of great importance. Accordingly the new Digital Mobile Radio communications system has been developed to provide affordable digital systems with low complexity with facilities for voice, data and other supplementary services.
Although the Digital Mobile Radio communications system has been defined by ETSI, a European organisation, it is being developed as a worldwide standard which will have a similar take-up to previous analogue radio communications systems such as MPT 1327.
The resulting Digital Mobile Radio technology has been designed to deliver a cost-effective, highly functional communication system for professional mobile radio users, along with an easy upgrade path and multi-vendor interoperability and flexibility. It has been designed to operate within the existing 12.5 kHz channel spacing that is standard for PMR applications. It ahs also been designed to meet the future 6.25 kHz channel equivalence. The DMR standard is designed to operate within the existing 12.5kHz channel spacing used in licensed land mobile frequency bands globally and to meet future regulatory requirements for 6.25kHz channel equivalence.
DMR Digital Mobile Radio basics
The Digital Mobile Radio communications standard has been developed to meet the requirements of many different classes of users. Those developing the standards have looked at the users of existing PMR radio communications systems. They concluded that these users fell broadly into three different categories:
* Domestic and short range industrial users. These users typically need fast, convenient and low cost communications over a limited range. Typically simple low power low cost radios meet their needs admirably.
* Professional users for which radio communications are critical. These applications can be found in organisations that need to communicate with a mobile workforce. They include business sectors such as transportation, construction, manufacturing, energy and utilities. The communications needs vary considerably but they may need to communicate over a restricted area, of they may require communications across a variety of sites or over a much larger region.
* Emergency services for which radio communications are vital. These applications require top reliability communications which need also to be secure. They may also need to be available over a wide area, and may need to be customised to the specific needs of the user. These radio communications networks are costly, but a necessary requirement for these organisations.
In order to meet these needs the ETSI standard for Digital Mobile Radio provides for three different tiers of radio communications systems.
* Tier 1: This is a basic licence free form of digital radio communications system. Its aim is to fill the same slot that is addressed by PMR466.
* Tier 2: This form of the Digital Mobile Radio communications system requires licensed operation and it offers high power levels, peer to peer operation as well as a repeater mode to provide greater coverage.
* Tier 3: This tier of the Digital Mobile Radio communications standard again requires a licence and provides for trunked operation, thereby providing a digital form of the widely used MPT1327 standard.
The Digital Mobile Radio standard provides operation within the existing channel spacing used within the land mobile radio frequency allocations. It thereby provides an easy upgrade path for current users of analogue mobile radio technology.
Digital Mobile Radio and other technologies
It may appear that Digital Mobile radio directly competes with other technologies and therefore may be redundant. However it has been designed to offer unique advantages and fill a market requirement that is not being addressed by other services.
* Unlicensed PMR: This sector of the market requires low cost solutions. The main driver is for improved use of the spectrum which will be provided by the Tier 1 Digital Mobile Radio technology. This will ultimately need to take over from the existing analogue solutions.
* TETRA and Project 25 (P25) : These standards are typically aimed at the market where mission criticality is key and where a variety of different facilities are required. TETRA (Terrestrial Trunked Radio) the standards for which are under ETSI control uses 25 kHz channels and supports many facilities including multiple talk groups on multiple frequencies, including one-to-one, one-to-many and many-to-many calls.
In North America the Telecommunications Industry Association, TIA has developed a system with the name Project 25 (P25) which has similar capabilities to TETRA but uses 12.5 kHz channel spacing with FDMA for Phase I although Phase II will use a two slot TDMA system for digital trunked radio
Both these systems are very sophisticated and require a complex infrastructure which enable them to provide a highly reliable service. Digital Mobile Radio is able to offer a lower cost alternative that will be more applicable to lower end applications.
* MPT1327 and dPMR : The majority of the PMR business is seen in between the low end domestic and small business short range communications and the high end mission critical region. In this arena, cost is a critical element and all the facilities offered by TETRA and P25 are not needed. Digital Mobile Radio is seen as offering a key improvement in this area. It provides increased capacity and spectrum efficiency usage along with improved facilities and reliability. While analogue radios and MPT1327 for trunked radio have provided very fgood services there is a need to move to more efficient digital radio options. Accordingly Digital Mobile Radio technology is seen as providing the solution for new users and those needing to upgrade.
DMR Association
The foundations for the DMR Association were laid in 2005 when a group of companies that were potential suppliers of DMR equipment signed a Memorandum of Understanding to support ETSI in the establishment of Digital Mobile Radio as an open standard. These suppliers included: Fylde Micro, Icom, Kenwood, Motorola, Selex, Tait, and Vertex Standard.
The standardisation work was undertaken such that the DMR standards were overseen by ETSI and the standards and themselves were issued by them.
Then in 2009, the original signatories of the original MOU set up the DMR Association (www.dmrassociation.org) with its aims to provide interoperability between Digital Mobile Radio vendors equipment and to provide information about the DMR standard.
ETSI Digital Mobile Radio standards
Digital Mobile Radio technology is defined under the relevant ETSI standards. These include the following:
* TR 102 398 : This technical report provides an introduction to Digital Mobile Radio technology
* TS 102 362 parts 1 to 3: These technical specifications define Digital Mobile Radio protocol conformance testing and test suites
* TS 102 490: This technical specification defines the narrow-band or 'digital PMR' protocol.
* Technical Report TR 102 335-1: Digital Mobile Radio System Reference document for Tier 1 DMR.
* TR 102 335-2: Digital Mobile Radio System Reference document for Tier 2 DMR (licensed).
Digital Mobile Radio Summary
Digital Mobile Radio technology offers users of Professional Mobile Radio systems the opportunity to upgrade their PMR systems from analogue to digital technology. As the DMR standard has been developed to facilitate the easy migration from analogue to digital, Digital Mobile Radio provides an ideal platform for many users.
Radio Broadcast Technology
- radio broadcast technology and radio broadcasting including analogue radio digital radio, analogue television and the many forms of digital television for terrestrial television, satellite television and mobile or handheld television.
Radio broadcasting is an established use of radio technology. The first organised broadcasts taking place in the 1920s. Now there are many radio stations broadcasting all over the world using a variety of differernt types of transmission. Today, radio broadcast equipment from transmitters and receivers to antennas, studios and relay links are widely available, although with the new standards for transmission including DAB Digital Radio and DRM, new equipment is required. Nevertheless AM as well as FM with its RDS capability are still the most widely used.
AM broadcasting
C-QUAM system for broadcasting AM stereo
VHF FM broadcasting
VHF FM is the most widely used form of broadcasting in areas of the world where the population is relatively high. Its bandwidth enables it to carry high quality transmissions, stereo, and other services such as RDS.
Broadcast VHF FM
RDS - Radio Data Service
Digital Radio Broadcasting)
DAB digital radio is now widely deployed in many countries around the globe, and now that the cost of radios has fallen, listener figures are rising. Although not available in many countries, it is certainly making a significant impact where it has been deployed, adding more flexibility and the possibility of near CD quality.
What is DAB, Digital Audio Broadcasting
DAB digital radio Band III channel numbers and frequencies
HD Radio - the new digital radio system for the USA
Digital Radio Mondiale (DRM) - the new standard to replace AM broadcasting
Television
There are many way in which television can be distributed these days. From the old analogue television radio broadcasts, through the new digital methods of radio delivery to IP based delivery over wired networks such as the Internet.
What is DVB - Digital Video Broadcasting - an overview or tutorial about the basics of DVB
DVB-T - the standard for terrestrial digital television
DVB-T2 - the second generation standard for terrestrial television
DVB-SH for satellite services to handheld devices
DVB-RCS
IPTV - Internet Protocol Television
Radio broadcasting is an established use of radio technology. The first organised broadcasts taking place in the 1920s. Now there are many radio stations broadcasting all over the world using a variety of differernt types of transmission. Today, radio broadcast equipment from transmitters and receivers to antennas, studios and relay links are widely available, although with the new standards for transmission including DAB Digital Radio and DRM, new equipment is required. Nevertheless AM as well as FM with its RDS capability are still the most widely used.
AM broadcasting
C-QUAM system for broadcasting AM stereo
VHF FM broadcasting
VHF FM is the most widely used form of broadcasting in areas of the world where the population is relatively high. Its bandwidth enables it to carry high quality transmissions, stereo, and other services such as RDS.
Broadcast VHF FM
RDS - Radio Data Service
Digital Radio Broadcasting)
DAB digital radio is now widely deployed in many countries around the globe, and now that the cost of radios has fallen, listener figures are rising. Although not available in many countries, it is certainly making a significant impact where it has been deployed, adding more flexibility and the possibility of near CD quality.
What is DAB, Digital Audio Broadcasting
DAB digital radio Band III channel numbers and frequencies
HD Radio - the new digital radio system for the USA
Digital Radio Mondiale (DRM) - the new standard to replace AM broadcasting
Television
There are many way in which television can be distributed these days. From the old analogue television radio broadcasts, through the new digital methods of radio delivery to IP based delivery over wired networks such as the Internet.
What is DVB - Digital Video Broadcasting - an overview or tutorial about the basics of DVB
DVB-T - the standard for terrestrial digital television
DVB-T2 - the second generation standard for terrestrial television
DVB-SH for satellite services to handheld devices
DVB-RCS
IPTV - Internet Protocol Television
USB tutorial
- a tutorial giving the essential technical details about USB, the Universal Serial Bus a widely used computer interface.
USB, or the Universal Serial Bus Interface is now well established as an interface for computer communications. In many areas it has completely overtaken RS232 and the parallel or Centronics interface for printers, and it is also widely used for memory sticks, computer mice, keyboards and for many other functions. One of the advantages of USB is its flexibility: another is the speed that USB provides.
USB provides a sufficiently fast serial data transfer mechanism for data communications, however it is also possible to obtain power through the connector and this has further added to the popularity of USB as many small computer peripherals may be powered via this. From memory and disk drives to other applications such as small fans and coffee cup warmers, the USB port on computers can be used for a variety of tasks.
USB evolution
The USB interface was developed as a result of the need for a communications interface that was convenient to use and one that would support the higher data rates being required within the computer and peripherals industries.
The first proper release of a USB specification was Version 0.7 of the specification. This occurred in November 1994. This was followed in January 1996 by USB 1.0. USB 1.0 was widely adopted and became the standard on many PCs as well as many printers using the standard. In addition to this a variety of other peripherals adopted the USB interface, with small memory sticks starting to appear as a convenient way for transferring or temporarily storing data.
With USB 1.0 well established, faster data transfer rates were required, and accordingly a new specification, USB 2 was released. Wit the importance of USB already established it did not take long for the new standard to be adopted.
With USB defining its place in the market, other developments of the standard were investigated. With the need for mobility in many areas of the electronics industry taking off, the next obvious move for USB was to adopt a wireless interface. In doing this wireless USB would need to retain the same flexible approach that provided the success for the wired interface. In addition to this the wireless USB interface needs to be able to transfer data at rates which will be higher than those currently attainable with the wired USB 2 connections. To achieve this ultra-wideband UWB technology is used.
USB capabilities
The basic concept of USB was for an interface that would be able to connect a variety of computer peripheral devices, such as keyboards and mice, to PCs. However, since its introduction, the applications for USB have widened and it has been used for many other purposes including, including measurement and automation.
In terms of performance, USB 1.1 enabled a maximum throughput of 12 Mbps, but with the introduction of USB 2.0 the maximum speed is 480 Mbps.
In operation, the USB host automatically detects when a new device has been added. It then requests identification from the device and appropriately configures the drivers. The bus topology allows up to 127 devices to run concurrently on one port. Conversely, the classic serial port supports a single device on each port. By adding hubs, more ports can be added to a USB host, creating connections for more peripherals.
USB Standards
USB is a standard that is being updated. Since its first introduction, the standard has been improved to meet the increasing needs of the user community. As a result there are a number of different USB standards, but fortunately these are backwards compatible.
1. USB1.1: This was the original version of the USB, Universal Serial Bus and was released in September 1998 after a few problems with the USB 1.0 specification released in January 1996 were resolved.. It provided a Master / Slave interface and a tiered star topology which was capable of supporting up to 127 devices and a maximum of six tiers or hubs. The master or "Host" device is normally a PC with the slaves or "Devices" linked via the cable.
One of the aims of the USB standard was to minimise the complexity within the Device by enabling the Host to perform the processing. This meant that devices would be cheap and readily accessible.
The data transfer rates of USB 1.1 are defined as:
* Low speed: 1.5 Mbps
* Full speed: 12 Mbps
The cable length for USB 1.1 is limited to 5 metres, and the power consumption specification allows each device to take up to 500mA, although this is limited to 100mA during start-up.
USB 1.1 does not allow extension cables or the inclusion of pass-through monitors (due to timing and power limitations).
2. USB 2.0: The USB 2.0 standard is a development of USB 1.1 which was released in April 2000. The main difference when compared to USB 1.1 was the data transfer speed increase up to a "High Speed" rate of 480 Mbps. However it should be noted that even though devices are labelled USB 2.0, they may not be able to meet the full transfer speed.
3. USB 3.0 : This improved USB standard which was first demonstrated at the Intel Developer Forum in September 2007. The major feature is what is termed the SuperSpeed bus, which provides a fourth transfer mode which gives data transfer rates of 4.8 Gbit/s. Although the raw throughput is 4 Gbit/s, data transfer rates of 3.2 Gbit/s, i.e.0.4 GByte/s more after protocol overhead are deemed acceptable within the standard. The standard is also backwards compatible with USB 2.0
USB connections and cables
The USB connector is remarkably simple having just four main connections for the data and power. In addition to this it is also possible to use extender cables. The maximum allowable length for an individual cable is 5 metres (3 metres for slow devices) and this allows the USB data acquisition module to be located remotely from the computer.
A USB cable has two forms of connector. These are designated the "A" and "B" connectors. The connections to the connectors are given below:
Pin Function
1 Vbus 4.75 - 5.25 V
2 Data -
3 Data +
4 Ground
Shell Screen
USB cable pin assignments
The connectors used for USB are designed to enable the power and ground connections to be made first applying power to the device before the signal lines are connected.
USB tutorial summary
With USB in almost universal use in new computers, a host of peripherals using the USB standard, its use is set to continue for many years to come. With the USB standard being updated to enable it to keep pace with technology, it could run like a similar story to Ethernet, where it will be in use for many years, but still at the forefront of technology..
USB, or the Universal Serial Bus Interface is now well established as an interface for computer communications. In many areas it has completely overtaken RS232 and the parallel or Centronics interface for printers, and it is also widely used for memory sticks, computer mice, keyboards and for many other functions. One of the advantages of USB is its flexibility: another is the speed that USB provides.
USB provides a sufficiently fast serial data transfer mechanism for data communications, however it is also possible to obtain power through the connector and this has further added to the popularity of USB as many small computer peripherals may be powered via this. From memory and disk drives to other applications such as small fans and coffee cup warmers, the USB port on computers can be used for a variety of tasks.
USB evolution
The USB interface was developed as a result of the need for a communications interface that was convenient to use and one that would support the higher data rates being required within the computer and peripherals industries.
The first proper release of a USB specification was Version 0.7 of the specification. This occurred in November 1994. This was followed in January 1996 by USB 1.0. USB 1.0 was widely adopted and became the standard on many PCs as well as many printers using the standard. In addition to this a variety of other peripherals adopted the USB interface, with small memory sticks starting to appear as a convenient way for transferring or temporarily storing data.
With USB 1.0 well established, faster data transfer rates were required, and accordingly a new specification, USB 2 was released. Wit the importance of USB already established it did not take long for the new standard to be adopted.
With USB defining its place in the market, other developments of the standard were investigated. With the need for mobility in many areas of the electronics industry taking off, the next obvious move for USB was to adopt a wireless interface. In doing this wireless USB would need to retain the same flexible approach that provided the success for the wired interface. In addition to this the wireless USB interface needs to be able to transfer data at rates which will be higher than those currently attainable with the wired USB 2 connections. To achieve this ultra-wideband UWB technology is used.
USB capabilities
The basic concept of USB was for an interface that would be able to connect a variety of computer peripheral devices, such as keyboards and mice, to PCs. However, since its introduction, the applications for USB have widened and it has been used for many other purposes including, including measurement and automation.
In terms of performance, USB 1.1 enabled a maximum throughput of 12 Mbps, but with the introduction of USB 2.0 the maximum speed is 480 Mbps.
In operation, the USB host automatically detects when a new device has been added. It then requests identification from the device and appropriately configures the drivers. The bus topology allows up to 127 devices to run concurrently on one port. Conversely, the classic serial port supports a single device on each port. By adding hubs, more ports can be added to a USB host, creating connections for more peripherals.
USB Standards
USB is a standard that is being updated. Since its first introduction, the standard has been improved to meet the increasing needs of the user community. As a result there are a number of different USB standards, but fortunately these are backwards compatible.
1. USB1.1: This was the original version of the USB, Universal Serial Bus and was released in September 1998 after a few problems with the USB 1.0 specification released in January 1996 were resolved.. It provided a Master / Slave interface and a tiered star topology which was capable of supporting up to 127 devices and a maximum of six tiers or hubs. The master or "Host" device is normally a PC with the slaves or "Devices" linked via the cable.
One of the aims of the USB standard was to minimise the complexity within the Device by enabling the Host to perform the processing. This meant that devices would be cheap and readily accessible.
The data transfer rates of USB 1.1 are defined as:
* Low speed: 1.5 Mbps
* Full speed: 12 Mbps
The cable length for USB 1.1 is limited to 5 metres, and the power consumption specification allows each device to take up to 500mA, although this is limited to 100mA during start-up.
USB 1.1 does not allow extension cables or the inclusion of pass-through monitors (due to timing and power limitations).
2. USB 2.0: The USB 2.0 standard is a development of USB 1.1 which was released in April 2000. The main difference when compared to USB 1.1 was the data transfer speed increase up to a "High Speed" rate of 480 Mbps. However it should be noted that even though devices are labelled USB 2.0, they may not be able to meet the full transfer speed.
3. USB 3.0 : This improved USB standard which was first demonstrated at the Intel Developer Forum in September 2007. The major feature is what is termed the SuperSpeed bus, which provides a fourth transfer mode which gives data transfer rates of 4.8 Gbit/s. Although the raw throughput is 4 Gbit/s, data transfer rates of 3.2 Gbit/s, i.e.0.4 GByte/s more after protocol overhead are deemed acceptable within the standard. The standard is also backwards compatible with USB 2.0
USB connections and cables
The USB connector is remarkably simple having just four main connections for the data and power. In addition to this it is also possible to use extender cables. The maximum allowable length for an individual cable is 5 metres (3 metres for slow devices) and this allows the USB data acquisition module to be located remotely from the computer.
A USB cable has two forms of connector. These are designated the "A" and "B" connectors. The connections to the connectors are given below:
Pin Function
1 Vbus 4.75 - 5.25 V
2 Data -
3 Data +
4 Ground
Shell Screen
USB cable pin assignments
The connectors used for USB are designed to enable the power and ground connections to be made first applying power to the device before the signal lines are connected.
USB tutorial summary
With USB in almost universal use in new computers, a host of peripherals using the USB standard, its use is set to continue for many years to come. With the USB standard being updated to enable it to keep pace with technology, it could run like a similar story to Ethernet, where it will be in use for many years, but still at the forefront of technology..
Mobile IP tutorial
- summary or tutorial about Mobile IP and its applications for mobility within fixed line and cellular telecommunications.
Mobile IP is becoming increasingly important. Mobile IP is required because high speed data and mobility are two key factors for today's wireless and telecommunications industry.
While high speed data is one issue, mobility is equally important. People need to take laptop computers with them use them anywhere as if they were working from their home network. While it is possible to make connections reasonably easily, improvements are being put in place to ensure full mobility and ease of use. Accordingly Mobile IP is a key element enabling this facility to become more robust and easier to use
As infrastructures and standards are already in place for data transfer it is necessary to adapt them to take account of mobility and introduce Mobile IP via an existing route rather than introducing completely new techniques. The most common services are the data services using the Internet Protocol (IP). When using this, a user which may be any form of node or computer is normally connected to a particular network or sub-network. Moving the computer from one network or sub-network to another creates problems because routing tables need to be updated to enable the data to reach the user at the new location.
Home operation
When connected to the base network, users are attached to their home network and all the routing tables needed to send the data to the required destination are set up for the computer in this locations. Using their home network IP address they can move anywhere within this particular network with no problem.
Mobile IP foreign agent and foreign networks
It is becoming increasingly common for computers to need to operate in networks other than their home network. The mobility of laptops has made this increasingly common. The network it connects to will not be its home network, but instead it will be what is termed a foreign network. Under these circumstances it needs a method of connecting back to the home network so that data packets sent to the home network can be forwarded to the new location and vice versa.
Mobile IP achieves this using what is called a Foreign Agent (FA). Each network has its own foreign agent to enable mobile data operation to be provided. It operates by advertising its presence and services on its network looking for any foreign users that may have attached to its network. Once a foreign user is found it communicates with them to establish the required information to link to the home network.
Similarly on the home network there is an equivalent agent and this is naturally called the "Home Agent" (HA). This Home Agent acts as what is termed a "proxy" for the mobile user. In other words it takes the place of the home IP location and routes data to the foreign agent, allowing communication with what is termed the "correspondent node" (CN).
In operation the foreign agent connects to the home agent when authentication is done and it uses what is termed an IP tunnel for communication. In this tunnel IP packets are packed within IP packets communicating the data. In this way the computer is able to move around freely using this Mobile IP, and communicate with data packets being routed via the home network.
Cell phone applications
With more data being transmitted over cellular networks there is a similar need for mobility within this arena as well, and accordingly mobile networks are also starting to employ Mobile IP. Work is well advanced on the CDMA2000 system used widely in North America, Asia and a number of other parts of the world. For UMTS, other areas of development are receiving the main focus of development and Mobile IP work is expected to follow on and be included in later releases of the standard.
The way in which IP is used on a cellular system is very similar to that employed using a dial up phone connection where a computer is to connect to the Internet. Here the user makes a connection using what is termed the Point to Point Protocol (PPP). As the connection is established the service provider assigns an IP address to the user. Once this has occurred then the data packets have an address to which they can be routed. While the connection is maintained all packets of data are routed to this IP address and others are obviously sourced from it.
The same happens when a mobile phone connects to the internet. A connection is established and an IP address is assigned to the phone or laptop. This works well while the phone is connected to the same base station or local switching centre. However when it needs to move away, a problem arises because each switching centre acts as a different sub-network. As when a mobile moves from one switching centre to the next the connection needs to be broken and a new one established using a new IP address. For CDMA2000 networks this is known as Simple IP. This is clearly not an efficient method of operating and considerably reduces the performance of the system because it breaks all the IP based connections made by applications running on the mobile node.
Accordingly the mobile phone system is treated as a network in the same way as it is for a wired LAN. Accordingly each switching centre has a foreign agent. This operates in the same way that it does for a wired LAN system. It communicates messages from a mobile operating that has moved away from its home switching centre, and in this way the IP connection is not broken.
By adopting this approach the foreign agents serving different switching centres are used, and the information updated with the home agent as the mobile moves from one switching centre to the next. Although this complicates the handover process, it enables a continuous connection to be maintained, despite the mobile moving its location and requiring to be served by different switching centres.
Summary
With the telecommunications scene changing rapidly, moving from a voice centred service to a data centred service and hybrid approaches being offered to provide the optimum service, Mobile IP is an important technique to be used to enable seamless transition from one area to the next, and one technology to the next.
Mobile IP is becoming increasingly important. Mobile IP is required because high speed data and mobility are two key factors for today's wireless and telecommunications industry.
While high speed data is one issue, mobility is equally important. People need to take laptop computers with them use them anywhere as if they were working from their home network. While it is possible to make connections reasonably easily, improvements are being put in place to ensure full mobility and ease of use. Accordingly Mobile IP is a key element enabling this facility to become more robust and easier to use
As infrastructures and standards are already in place for data transfer it is necessary to adapt them to take account of mobility and introduce Mobile IP via an existing route rather than introducing completely new techniques. The most common services are the data services using the Internet Protocol (IP). When using this, a user which may be any form of node or computer is normally connected to a particular network or sub-network. Moving the computer from one network or sub-network to another creates problems because routing tables need to be updated to enable the data to reach the user at the new location.
Home operation
When connected to the base network, users are attached to their home network and all the routing tables needed to send the data to the required destination are set up for the computer in this locations. Using their home network IP address they can move anywhere within this particular network with no problem.
Mobile IP foreign agent and foreign networks
It is becoming increasingly common for computers to need to operate in networks other than their home network. The mobility of laptops has made this increasingly common. The network it connects to will not be its home network, but instead it will be what is termed a foreign network. Under these circumstances it needs a method of connecting back to the home network so that data packets sent to the home network can be forwarded to the new location and vice versa.
Mobile IP achieves this using what is called a Foreign Agent (FA). Each network has its own foreign agent to enable mobile data operation to be provided. It operates by advertising its presence and services on its network looking for any foreign users that may have attached to its network. Once a foreign user is found it communicates with them to establish the required information to link to the home network.
Similarly on the home network there is an equivalent agent and this is naturally called the "Home Agent" (HA). This Home Agent acts as what is termed a "proxy" for the mobile user. In other words it takes the place of the home IP location and routes data to the foreign agent, allowing communication with what is termed the "correspondent node" (CN).
In operation the foreign agent connects to the home agent when authentication is done and it uses what is termed an IP tunnel for communication. In this tunnel IP packets are packed within IP packets communicating the data. In this way the computer is able to move around freely using this Mobile IP, and communicate with data packets being routed via the home network.
Cell phone applications
With more data being transmitted over cellular networks there is a similar need for mobility within this arena as well, and accordingly mobile networks are also starting to employ Mobile IP. Work is well advanced on the CDMA2000 system used widely in North America, Asia and a number of other parts of the world. For UMTS, other areas of development are receiving the main focus of development and Mobile IP work is expected to follow on and be included in later releases of the standard.
The way in which IP is used on a cellular system is very similar to that employed using a dial up phone connection where a computer is to connect to the Internet. Here the user makes a connection using what is termed the Point to Point Protocol (PPP). As the connection is established the service provider assigns an IP address to the user. Once this has occurred then the data packets have an address to which they can be routed. While the connection is maintained all packets of data are routed to this IP address and others are obviously sourced from it.
The same happens when a mobile phone connects to the internet. A connection is established and an IP address is assigned to the phone or laptop. This works well while the phone is connected to the same base station or local switching centre. However when it needs to move away, a problem arises because each switching centre acts as a different sub-network. As when a mobile moves from one switching centre to the next the connection needs to be broken and a new one established using a new IP address. For CDMA2000 networks this is known as Simple IP. This is clearly not an efficient method of operating and considerably reduces the performance of the system because it breaks all the IP based connections made by applications running on the mobile node.
Accordingly the mobile phone system is treated as a network in the same way as it is for a wired LAN. Accordingly each switching centre has a foreign agent. This operates in the same way that it does for a wired LAN system. It communicates messages from a mobile operating that has moved away from its home switching centre, and in this way the IP connection is not broken.
By adopting this approach the foreign agents serving different switching centres are used, and the information updated with the home agent as the mobile moves from one switching centre to the next. Although this complicates the handover process, it enables a continuous connection to be maintained, despite the mobile moving its location and requiring to be served by different switching centres.
Summary
With the telecommunications scene changing rapidly, moving from a voice centred service to a data centred service and hybrid approaches being offered to provide the optimum service, Mobile IP is an important technique to be used to enable seamless transition from one area to the next, and one technology to the next.
ISDN Tutorial
- summary, overview or tutorial about ISDN, Integrated Services Digital Network, and the services that ISDN can offer in the telcommunications arena.
ISDN or Integrated Services Digital Network is an international standard for end to end digital transmission of voice, data and signaling. It can operate over copper based systems and allows the transmission of digital data over the telecommunications networks, typically ordinary copper based systems and providing higher data speeds and better quality than analogue transmission. The ISDN specifications provide a set of protocols that enable the set up, maintenance and completion of calls.
ISDN, Integrated Services Digital Network, provides a number of significant advantages over analogue systems.
In is basic form it enables two simultaneous telephone calls to be made over the same line simultaneously.
Faster call connection. It typically takes a second to make connections rather than the much longer delays experienced using purely analogue based systems.
Data can be sent more reliably and faster than with the analogue systems.
Noise, distortion, echoes and crosstalk are virtually eliminated.
The digital stream can carry any form of data from voice to faxes and internet web pages to data files - this gives the name 'integrated services'
ISDN Usage
ISDN is in use around the world, but with the introduction of ADSL it is facing strong competition. The technology never gained much market share in the USA, although it used in other countries. In Japan it became reasonably popular in the late 1990s although it is now in decline with the advent of ADSL. The system was also introduced in Europe where providers such as BT, France Telecom and Deutsche Telekom introduced services.
ISDN Configurations
There are two types of channel that are found within ISDN. These are the 'B' and 'D' channels. The B or 'bearer' channels are used to carry the payload data which may be voice and / or data, and the d or 'Delta' channel is intended for signalling and control, although it may also be used for data under some circumstances.
Additionally there are two levels of ISDN access that may be provided. These are known as BRI and PRI.
BRI (Basic Rate Interface) - This consists of two B channels, eac of which provides a bandwidth of 64 kbps under most circumstances. One D channel with a bandwidth of 16 kbps is also provided. Together this configuration is often referred to as 2B+D.
The basic rate lines connect to the network using a standard twisted pair of copper wires. The data can then be transmitted simultaneously in both directions to provide full duplex operation. The data stream is carried as two B channesl as mentioned above, each of which carry 64 kbps (8 k bytes per second). This data is interleaved with the D channel data and this is used for call management: setting up, clearing down of calls, and some additional data to maintain synchronisation and monitoring of the line.
The network end of the line is referred to as the 'Line Termination' (LT) while the user end acts as a termination for the network and is referred to as the 'Network Termination' (NT). Within Europe and Australia, the NT physically exists as a small connection box usually attached to a wall etc, and it converts the two wire line (U interface) coming in from the network to four wires (S/T interface or S bus). The S/T interface allows up to eight items or 'terminal equipments' to be connected, although only two may be used at any time. The terminal equipments may be telephones, computers, etc, and they are connected in what is termed a point to point configuration. In Europe the ISDN line provides up to about 1 watt of power that enables the NT to be run, and also enables a basic ISDN phone to be used for emergency calls. In North America a slightly different approach may be adopted in that the terminal equipment may be directly connected to the network in a point to point configuration as this saves the cost of a network termination unit, but it restricts the flexibility. Additionally power is not normally provided.
PRI (Primary Rate Interface) - This configuration carries a greater number of channels than the Basic Rate Interface and has a D channel with a bandwidth of 64 kbps. The number of B channels varies according to the location. Within Europe and Australia a configuration of 30B+D has been adopted providing an aggregate data rate of 2.048 Mbps (E1). For North America and Japan, a configuration of 23B+1D has been adopted. This provides an aggregate data rate of 1.544 Mbps (T1).
The primary rate connections utilise four wires - a pair for each direction. They are normally 120 ohm balanced lines using twisted pair cable. Primary rate connections always use a point to point configuration.
Primary rate lines are widely used to conenct to Private Branch eXchanges (PBX) in an office etc. Typically this may be used to provide a number of POTS (Plain Old Telephone System) or basic rate ISDN lines to the users.
Summary
Although ISDN is has been overtaken by technologies such as ADSL it is nevertheless still widely used in many areas, particularly where existing services need to be maintained, or where compatibility needs to be guaranteed. As such it is still an important technology that will be encountered for many years to come.
ISDN or Integrated Services Digital Network is an international standard for end to end digital transmission of voice, data and signaling. It can operate over copper based systems and allows the transmission of digital data over the telecommunications networks, typically ordinary copper based systems and providing higher data speeds and better quality than analogue transmission. The ISDN specifications provide a set of protocols that enable the set up, maintenance and completion of calls.
ISDN, Integrated Services Digital Network, provides a number of significant advantages over analogue systems.
In is basic form it enables two simultaneous telephone calls to be made over the same line simultaneously.
Faster call connection. It typically takes a second to make connections rather than the much longer delays experienced using purely analogue based systems.
Data can be sent more reliably and faster than with the analogue systems.
Noise, distortion, echoes and crosstalk are virtually eliminated.
The digital stream can carry any form of data from voice to faxes and internet web pages to data files - this gives the name 'integrated services'
ISDN Usage
ISDN is in use around the world, but with the introduction of ADSL it is facing strong competition. The technology never gained much market share in the USA, although it used in other countries. In Japan it became reasonably popular in the late 1990s although it is now in decline with the advent of ADSL. The system was also introduced in Europe where providers such as BT, France Telecom and Deutsche Telekom introduced services.
ISDN Configurations
There are two types of channel that are found within ISDN. These are the 'B' and 'D' channels. The B or 'bearer' channels are used to carry the payload data which may be voice and / or data, and the d or 'Delta' channel is intended for signalling and control, although it may also be used for data under some circumstances.
Additionally there are two levels of ISDN access that may be provided. These are known as BRI and PRI.
BRI (Basic Rate Interface) - This consists of two B channels, eac of which provides a bandwidth of 64 kbps under most circumstances. One D channel with a bandwidth of 16 kbps is also provided. Together this configuration is often referred to as 2B+D.
The basic rate lines connect to the network using a standard twisted pair of copper wires. The data can then be transmitted simultaneously in both directions to provide full duplex operation. The data stream is carried as two B channesl as mentioned above, each of which carry 64 kbps (8 k bytes per second). This data is interleaved with the D channel data and this is used for call management: setting up, clearing down of calls, and some additional data to maintain synchronisation and monitoring of the line.
The network end of the line is referred to as the 'Line Termination' (LT) while the user end acts as a termination for the network and is referred to as the 'Network Termination' (NT). Within Europe and Australia, the NT physically exists as a small connection box usually attached to a wall etc, and it converts the two wire line (U interface) coming in from the network to four wires (S/T interface or S bus). The S/T interface allows up to eight items or 'terminal equipments' to be connected, although only two may be used at any time. The terminal equipments may be telephones, computers, etc, and they are connected in what is termed a point to point configuration. In Europe the ISDN line provides up to about 1 watt of power that enables the NT to be run, and also enables a basic ISDN phone to be used for emergency calls. In North America a slightly different approach may be adopted in that the terminal equipment may be directly connected to the network in a point to point configuration as this saves the cost of a network termination unit, but it restricts the flexibility. Additionally power is not normally provided.
PRI (Primary Rate Interface) - This configuration carries a greater number of channels than the Basic Rate Interface and has a D channel with a bandwidth of 64 kbps. The number of B channels varies according to the location. Within Europe and Australia a configuration of 30B+D has been adopted providing an aggregate data rate of 2.048 Mbps (E1). For North America and Japan, a configuration of 23B+1D has been adopted. This provides an aggregate data rate of 1.544 Mbps (T1).
The primary rate connections utilise four wires - a pair for each direction. They are normally 120 ohm balanced lines using twisted pair cable. Primary rate connections always use a point to point configuration.
Primary rate lines are widely used to conenct to Private Branch eXchanges (PBX) in an office etc. Typically this may be used to provide a number of POTS (Plain Old Telephone System) or basic rate ISDN lines to the users.
Summary
Although ISDN is has been overtaken by technologies such as ADSL it is nevertheless still widely used in many areas, particularly where existing services need to be maintained, or where compatibility needs to be guaranteed. As such it is still an important technology that will be encountered for many years to come.
IMS, IP Multimedia Subsystem tutorial
- a summary or tutorial of IMS, IP Multimedia Subsystem, providing the highlights of its operation and structure.
IMS, or IP Multimedia Subsystem is having a major impact on the telecommunications industry, both wired and wire-less. Although IMS was originally created for mobile applications by 3GPP and 3GPP2, its use is more widespread as fixed line providers are also being forced to find ways of integrating mobile or mobile associated technologies into their portfolios. As a result the use of IMS, IP multimedia subsystem is crossing the frontiers of mobile, wire-less and fixed line technologies. Indeed there is very little within IMS that is wireless or mobile specific, and as a result there are no barriers to its use in any telecommunications environment.
IMS, IP multimedia subsystem, itself is not a technology, but rather it is an architecture. It is based on Internet standards which are currently the major way to deliver services on new networks. However one of the key enablers for the architecture is the Session Initiation Protocol (SIP), a protocol that has been devised for establishing, managing and terminating sessions on IP networks. The overall IMS architecture uses a number of components to enable multimedia based sessions between two or more end devices.
One of the elements is a presence server that handles the user status, and this is a key element for applications such as Push to talk over Cellular (PoC) where the presence, or user status is key to enabling one user to be able to talk to another.
With users now needing to activate many sessions using different applications and often concurrently, IMS provides a common IP interface so that signalling, traffic, and application development are greatly simplified. In addition to this an IMS architecture means that subscribers can connect to a network using multiple mobile and fixed devices and technologies. With a variety of new applications from Push to talk over Cellular (PoC), gaming, video and more becoming available, it will be necessary to be able to integrate them seamlessly for users to be able to gain the most from these new applications.
It also has advantages for operators as well. Apart from enabling them to maximise their revenues, functions including billing, and "access approval" can be unified across the applications on the network, thereby considerably simplifying this area.
IMS, IP Multimedia Subsystem architecture
IMS provides a unified architecture which can be divided into three layers:
* Transport and Endpoint Layer
* Session Control Layer
* Application Server Layer
IMS Transport and Endpoint Layer
This layer initiates and terminates the SIP signalling, setting up sessions and providing bearer services including the conversion from analogue or digital formats to packets. It also provides the media gateways for converting the VoIP data to the PSTN TDM format.
IMS Session Control Layer
This layer contains what is termed the Call Session Control Function (CSCF) which provides the endpoints for the registration and routing for the SIP signalling messages, enabling them to be routed to the correct application servers. The CSCF also enables QoS to be guaranteed. It achieves this by communicating with the transport and endpoint layer.
The layer also includes other elements including the Home Subscriber Server (HSS) that maintains the user profiles including their registration details as well as preferences and the like. It includes the presence server essential to many interactive applications such as PoC. A further element of the session Control Layer is the Media Gateway Control.
Application Server Layer
The control of the end services required by the user is undertaken by the Application Server Layer. The IMS architecture and SIP signalling has been designed to be flexible and in this way it is possible to support a variety of telephony and non-telephony servers concurrently. Within this layer there is a wide variety of different servers that are supported. This includes a Telephony Application Server (TAS), IP Multimedia - Service Switching Function (IM-SSF), Supplemental Telephony Application Server, Non-Telephony Application Server, Open Service Access - Gateway (OSA-GW), etc.
Summary
The telecommunications industry as a whole is turning to IP based transport of data along with the introduction of new multimedia services. To enable this to be achieved telecommunications networks, whether fixed, cellular or wireless will need to be far more flexible and to achieve this it will be necessary to implement IMS, IP Multimedia Subsystem.
IMS, or IP Multimedia Subsystem is having a major impact on the telecommunications industry, both wired and wire-less. Although IMS was originally created for mobile applications by 3GPP and 3GPP2, its use is more widespread as fixed line providers are also being forced to find ways of integrating mobile or mobile associated technologies into their portfolios. As a result the use of IMS, IP multimedia subsystem is crossing the frontiers of mobile, wire-less and fixed line technologies. Indeed there is very little within IMS that is wireless or mobile specific, and as a result there are no barriers to its use in any telecommunications environment.
IMS, IP multimedia subsystem, itself is not a technology, but rather it is an architecture. It is based on Internet standards which are currently the major way to deliver services on new networks. However one of the key enablers for the architecture is the Session Initiation Protocol (SIP), a protocol that has been devised for establishing, managing and terminating sessions on IP networks. The overall IMS architecture uses a number of components to enable multimedia based sessions between two or more end devices.
One of the elements is a presence server that handles the user status, and this is a key element for applications such as Push to talk over Cellular (PoC) where the presence, or user status is key to enabling one user to be able to talk to another.
With users now needing to activate many sessions using different applications and often concurrently, IMS provides a common IP interface so that signalling, traffic, and application development are greatly simplified. In addition to this an IMS architecture means that subscribers can connect to a network using multiple mobile and fixed devices and technologies. With a variety of new applications from Push to talk over Cellular (PoC), gaming, video and more becoming available, it will be necessary to be able to integrate them seamlessly for users to be able to gain the most from these new applications.
It also has advantages for operators as well. Apart from enabling them to maximise their revenues, functions including billing, and "access approval" can be unified across the applications on the network, thereby considerably simplifying this area.
IMS, IP Multimedia Subsystem architecture
IMS provides a unified architecture which can be divided into three layers:
* Transport and Endpoint Layer
* Session Control Layer
* Application Server Layer
IMS Transport and Endpoint Layer
This layer initiates and terminates the SIP signalling, setting up sessions and providing bearer services including the conversion from analogue or digital formats to packets. It also provides the media gateways for converting the VoIP data to the PSTN TDM format.
IMS Session Control Layer
This layer contains what is termed the Call Session Control Function (CSCF) which provides the endpoints for the registration and routing for the SIP signalling messages, enabling them to be routed to the correct application servers. The CSCF also enables QoS to be guaranteed. It achieves this by communicating with the transport and endpoint layer.
The layer also includes other elements including the Home Subscriber Server (HSS) that maintains the user profiles including their registration details as well as preferences and the like. It includes the presence server essential to many interactive applications such as PoC. A further element of the session Control Layer is the Media Gateway Control.
Application Server Layer
The control of the end services required by the user is undertaken by the Application Server Layer. The IMS architecture and SIP signalling has been designed to be flexible and in this way it is possible to support a variety of telephony and non-telephony servers concurrently. Within this layer there is a wide variety of different servers that are supported. This includes a Telephony Application Server (TAS), IP Multimedia - Service Switching Function (IM-SSF), Supplemental Telephony Application Server, Non-Telephony Application Server, Open Service Access - Gateway (OSA-GW), etc.
Summary
The telecommunications industry as a whole is turning to IP based transport of data along with the introduction of new multimedia services. To enable this to be achieved telecommunications networks, whether fixed, cellular or wireless will need to be far more flexible and to achieve this it will be necessary to implement IMS, IP Multimedia Subsystem.
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