HOW TO INCREASE UR BATERY LIFE.,.,.,.,.,.

How to Increase Mobile Phone Battery Life

05 august 10<!–Chad Upton–>

By Akash Khadke

Sometimes, you’re far from your charger and won’t be back anytime soon. Here are some tips to extend your battery when it’s running low.

Not all of these tips will apply to all phones, so use the ones that match the features on your phone. If your phone, camera or other gadgets frequently run out of power while you’re away from an outlet, consider an economical backup battery charger.

Turn Off 3G and Data

Most data capable phones can operate in different modes. If you turn off the high-speed wireless data mode, such as 3G, you will significantly reduce the power your phone consumes. This is the single biggest thing I find affects battery consumption.

Dim the Screen

The screen’s backlight uses a lot of power, keeping it off as much as possible will extend battery life. On the iPhone, press the top button, on many BlackBerrys, press ALT + ENTER to lock the keyboard and shutoff the screen. If your phone has an option to adjust the brightness, dim it. If it has auto-brightness, enable it. If you can set an “auto off” time then set it to the shortest time allowed.

Text Message Instead of Calling

If you can get away with communicating by text message, this can save power too. Although, it does require your screen, so short messages are better. These messages are embedded in the signals that your phone is already sending and receiving to normally communicate with the mobile network, even when you’re not using the phone, so it’s a very efficient way to communicate.

Turn Wifi and Bluetooth Off

Wifi and Bluetooth are great conveniences, but when you’re away from your charger and worried about losing phone capabilities, they’re a luxury that can go. Most phones with these features, have an option to disable them.

Don’t Play Games or Music

Well designed mobile phone processors have a low power mode that sips power when the phone is waiting for incoming calls in standby mode. Playing games requires the processor to work at its limit, which requires a lot more energy than standby mode. The same goes for playing music, especially if they’re compressed, high bit-rate or encrypted or drm protected music files — extra processing is needed to process these files and power the headphones or internal speaker.

Stop Background Apps

Some background apps use more power than others, it really comes down to the hardware in the phone the app is using (ex GPS) and how processor intensive the activity is.

Generally, if you’re trying to save power, closing the apps you don’t need can save power. This mostly applies to BlackBerry, Android and Windows Mobile devices.

It isn’t as important on iPhone since background apps aren’t true background apps, they have limited capabilities and therefore don’t consume a significant amount of battery power. That said, if you have a GPS tracking, VOIP or a music playing app running in the background, it could use significant amounts of power over long periods of time and it should be closed.

” 4G Mobile Technology ”

PREFACE:

In response to ever increasing demand for fast communication mobile phone where invented .

The desire of consumer to get hands on latest technology has pushed mobile technology to its limit .

Expanding  the technological bubble more and more.

Mobiles are best mode for clubbing communication, entertainment ,web together making its user to be virtually omnipresent

 

  Mobiles came into with a sole purpose of communication but today it has taken over us in every walk of life transferring data faster than light.

Already 3rd generation communication technology has enthralled us ,and world is just getting glimpse of 4th generation technology

In this presentation a sincere effort has been made to provide knowledge about’ 4th generation mobile technology’ 

 Despite of our best effort its possible that some unintentional error might have escaped our attention .We would gratefully acknowledge if any of these is pointed out

ACKNOWLEDGEMENT

We have great pleasure in presenting this report on “BLUETOOTH”. We’ll express our regards to those offered their valuable guidance in our work.

We take this opportunity to convey Our earnest gratitude to all the teachers of computer department and for guiding and helping us during the testing and assembly of our project and thus making our project a complete success.

We also wish to convey special thanks to our project guide Mr. Mayur, HOD Mr. Bhosle  who helped  and encouraged us during the making of our project to head towards the right direction.

 

SUMMARY:

The ever-increasing growth of user demand, the limitations of the third generation of wireless mobile communication systems, and the emergence of new mobile broadband technologies on the market have brought researchers and industries to a thorough reflection on the fourth generation. Many prophetic visions have appeared in the literature presenting 4G as the ultimate boundary of wireless mobile communication without any limit to its potential, but in practical terms not giving any design rules and thus any definition of it. In this article we give a pragmatic definition of 4G derived from a new user-centric methodology that considers the user as the “cornerstone” of the design. In this way, we devise fundamental user scenarios that implicitly reveal the key features of 4G, which are then expressed explicitly in a new framework – the “user-centric” system – that describes the various level of interdependency among them. This approach consequently contributes to the identification of the real technical step-up of 4G with respect to 3G.

 

 

INTRODUCTION:

 

 

In a world of increasing technological needs, the mobile Internet can play a significant role resolving the user’s capacity and connectivity needs. There is lots of research and suggestions around the 4G concept, where vendors and operators are trying to define it based on their preferred technology and strategic planning.

At the end of 2007, the total mobile subscribers were 3 billion, with GSM based users to grow over 2 billion. Several research reports are predicting that the WiMAX will commercially be deployed by 2009 and the LTE (Long Term Evolution) by 2015. However, the standards battle towards the 4G establishment is a major concern. ITU and IEEE are trying to secure a smooth transition into the new technology. (Figure 1)

There is no formal definition for 4G. It is a term used to describe the next step in wireless

communication. Several terms are also describing the concept, such as “Super 3G” or “Next Generation Wireless”. ITU is committed to announce the 4G definition during 2008, but certainly we are looking for a new converged system that will provide at least 100Mbps connectivity to the broadband users. 4G is expected

to offer data rates of 100 Mbps for mobile applications and 1 Gbps for nomadic applications and should be achievable by the year 2010.

Figure 1: 4G evolution into convergence [1],[2],[3]

 

 

 

The current defined objectives for 4G include [1],[2], [3],[4],[5]:

  • • Fully integrated IP solution
  • • “Anytime, Anywhere”
  • • Seamless connectivity- wireless and wireline
  • • Global access and interconnection
  • • Interoperability
  • • Data rates of at least 100Mbps
  • • Spectrally efficient system

 

There are several applications that could be supported and leveraged in the 4G due to the advanced

environment. These include mobile commerce with a dimension to mobile banking, peer-to-peer

networking and full usage of the advanced Internet services in the converged cloud. This cloud be

defined as a communications technology ecosystem (Figure 2) with a plethora of different services that

will give users a more convenient and easy lifestyle.

Figure 2: A suggested heterogeneous digital ecosystem [5]

 

Since 4G is not well defined yet, there is no demand or markets shaped yet. Therefore we are lacking forecasts or precise predictions that could help us to strategically plan for the market in an estimated time table. An interesting approach is to evaluate each country’s readiness to deploy 4G based on different criteria such as technological, business, legal, and policy.

The 3G in most cases and countries has not paid off yet and will not for the next 5 years. However, the operators are trying to decide on the best standard to invest in the long run and will cover their future needs ending up debating between the WiMAX and the LTE.

In this paper we describe an approach to study and evaluate the 4G readiness at a national level and answering the following research questions: Which countries are closer to 4G adoption? Since the markets are still shaping up, how can we forecast from the operators perspective, using the operators and vendors current trials and knowledge?

Our study aims to describe the new “4G readiness” concept, building upon the literature and the ereadiness concept [14] as well as the non-market factors as described in [16].

Along the same lines, we expect that a country’s 4G high ranking could be more an outcome and

indicator of innovation, supported with an advanced digital environment rather than a natural path of technological evolution.

This paper is organized as following: the first section describes the problem, section 2 gives an

overview of 4G current issues and technologies, section 3 describes the drivers and challenges for 4G,section 4 describes the suggested study and we close with section 5 as the conclusions.

 

 

 

 

 

                                                                 HISTORY
The history and evolution of mobile service from the 1G (first generation) to fourth generation are discussed in this section. Table 1 presents a short history of mobile telephone technologies.

This process began with the designs in the 1970s that have become known as 1G. The earliest systems were implemented based on analog technology and the basic cellular structure of mobile communication. Many fundamental problems were solved by these early systems. Numerous incompatible analog systems were placed in service around the world during the 1980s.

The 2G (second generation) systems designed in the 1980s were still used mainly for voice applications but were based on digital technology, including digital signal processing techniques. These 2G systems provided circuit-switched data communication services at a low speed. The competitive rush to design and implement digital systems led again to a variety of different and incompatible standards such as GSM (global system mobile), mainly in Europe; TDMA (time division multiple access) (IS-54/IS-136) in the U.S.; PDC (personal digital cellular) in Japan; and CDMA (code division multiple access) (IS-95), another U.S. system. These systems operate nationwide or internationally and are today’s mainstream systems, although the data rate for users in
these system is very limited. 

During the 1990s, two organizations worked to define the next, or 3G, mobile system, which would eliminate previous incompatibilities and become a truly global system. The 3G system would have higher quality voice channels, as well as broadband data capabilities, up to 2 Mbps. Unfortunately, the two groups could not reconcile their differences, and this decade will see the introduction of two mobile standards for 3G. In addition, China is on the verge of implementing a third 3G system. 

An interim step is being taken between 2G and 3G, the 2.5G. It is basically an enhancement of the two major 2G technologies to provide increased capacity on the 2G RF (radio frequency) channels and to introduce higher throughput for data service, up to 384 kbps. A very important aspect of 2.5G is that the data channels are optimized for packet data, which introduces access to the Internet from mobile devices, whether telephone, PDA (personal digital assistant), or laptop. 

However, the demand for higher access speed multimedia communication in today’s society, which greatly depends on computer communication in digital format, seems unlimited. According to the historical indication of a generation revolution occurring once a decade, the present appears to be the right time to begin the research on a 4G mobile communication system. 

4G
This new generation of wireless is intended to complement and replace the 3G systems, perhaps in 5 to 10 years. Accessing information anywhere, anytime, with a seamless connection to a wide range of information and services, and receiving a large volume of information, data, pictures, video, and so on, are the keys of the 4G infrastructures. The future 4G infrastructures will consist of a set of various networks using IP (Internet protocol) as a
common protocol so that users are in control because they will be able to choose every application and environment. 

Based on the developing trends of mobile communication, 4G will have broader bandwidth, higher data rate, and smoother and quicker handoff and will focus on ensuring seamless service across a multitude of wireless systems and networks. The key concept is integrating the 4G capabilities with all of the existing mobile technologies through advanced technologies. 

Application adaptability and being highly dynamic are the main features of 4G services of interest to users. 

These features mean services can be delivered and be available to the personal preference of different users and support the users’ traffic, air interfaces, radio environment, and quality of service. Connection with the network applications can be transferred into various forms and levels correctly and efficiently. The dominant methods of access to this pool of information will be the mobile telephone, PDA, and laptop to seamlessly access the voice communication, high-speed information services, and entertainment broadcast services. Figure 1 illustrates elements and techniques to support the adaptability of the 4G domain. 

The fourth generation will encompass all systems from various networks, public to private; operator-driven broadband networks to personal areas; and ad hoc networks. The 4G systems will interoperate with 2G and 3G systems, as well as with digital (broadband) broadcasting systems. In addition, 4G systems will be fully IP-based wireless Internet. 

This all-encompassing integrated perspective shows the broad range of systems that the fourth generation intends to integrate, from satellite broadband to high altitude platform to cellular 3G and 3G systems to WLL (wireless local loop) and FWA (fixed wireless access) to WLAN (wireless local area network) and PAN (personal area network), all with IP as the integrating mechanism. 

With 4G, a range of new services and models will be available. These services and models need to be further examined for their interface with the design of 4G systems. Figures 2 and 3 demonstrate the key elements and the seamless connectivity of the networks. 

ABOUT  THE  TOPIC

4G (also known as Beyond 3G), an abbreviation for Fourth-Generation, is a term used to describe the next complete evolution in wireless communications. A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an “Anytime, Anywhere” basis, and at higher data rates than previous generations.

As the second generation was a total replacement of the first generation networks and handsets; and the third generation was a total replacement of second generation networks and handsets; so too the fourth generation cannot be an incremental evolution of current 3G technologies, but rather the total replacement of the current 3G networks and handsets

 

 

 

 

 

Objectives

4G is being developed to accommodate the quality of service (QoS) and rate requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB), minimal service like voice and data, and other streaming services for “anytime-anywhere”. The 4G working group has defined the following as objectives of the 4G wireless communication standard:

Ø A spectrally efficient system (in bits/s/Hz and bits/s/Hz/site),[2]

Ø High network capacity: more simultaneous users per cell,[3]

Ø A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R,[1]

Ø A data rate of at least 100 Mbit/s between any two points in the world,[1]

Ø Smooth handoff across heterogeneous networks,[4]

Ø Seamless connectivity and global roaming across multiple networks,[5]

Ø High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)[5]

Ø Interoperability with existing wireless standards,[6] and

Ø An all IP, packet switched network.[5]

Ø In summary, the 4G system should dynamically share and utilise network resources to meet the minimal requirements of all the 4G enabled users

 

 

 

 

 

 

 DESCRIPTION

 

 

 

Motivation for 4G Research Before 3G Has Not Been Deployed?

  • 3G performance may not be sufficient to meet needs of future high-performance applications like multi-media, full-motion video, wireless teleconferencing. We need a network technology that extends 3G capacity  by an order of magnitude. 
  • There are multiple standards for 3G making it difficult to roam and interoperate across networks. we need global mobility and service portability
  • 3G is based on primarily a wide-area concept. We need hybrid networks that utilize both wireless LAN (hot spot) concept and cell or base-station wide area network design. 
  • We need wider bandwidth
  • Researchers have come up with spectrally more efficient modulation schemes that can not be retrofitted into 3G infrastructure
  • We need all digital packet network that utilizes IP in its fullest form with converged voice and data capability.

 

Hence Mobile technology developments will not simply end with deployment of 3G networks. Need for improvement motivates further development. Large mobile revenues are fueling funding for that development. As a result, R&D for 4G is already under way. 4G networks promise to offer bandwidth that’s comparable to that of landline networks, with mobility comparable to that of existing cellular services.

Already, a key controversy is emerging about whether 4G will be an evolutionary or a revolutionary development. Some people believe that 4G will simply constitute an evolutionary technology that will emerge in ten years or so. Such people point out that 3G development started many years before 3G deployment. Other people believe that 4G development must accelerate because 3G is a disappointment. Notably, users increasingly expect multi-megabit-per-second performance from their landline and Wi-Fi networks—but typical users of 3G services may never experience the 2-Mbit/s performance originally promised by industry. Business users and governments that are disappointed with 3G hope that 4G will yield revolutionary developments—not evolutionary ones. They hope that 4G deployments will occur on an accelerated timetable—before 2010, rather than in ten years.

New technologies do indeed promise to provide improved performance—even with limited spectrum availability. Existing technologies, including 3G, do not maximize the bit-carrying capacity of available spectrum. Improved capacity means ability to serve more customers with the same amount of resources. Thus, improved capacity promises lower capital and operating expenses per customer. Such benefits can result from technologies such as orthogonal frequency-division multiplexing (OFDM) and smart antennae.
Users and industries also hope that next-generation networks will deliver improved interoperability among networks and devices. One way to improve interoperability will be via software-defined radio. This report provides insight about how these technologies will fit into future 4G services. In addition, the report provides insight into the outlook for spectrum availability, all-IP networks, centralized versus decentralized networks, and other issues of interest to providers of wireless technologies and servicesThere is no formal definition for what 4G is; however, there are certain objectives that are projected for 4G. These objectives include: that 4G will be a fully IP-based integrated system. 4G will be capable of providing between 100 Mbit/s and 1 Gbit/s speeds both indoors and outdoors, with premium quality and high security.

Comparing Key Parameters of 4G with 3G

 

 

3G (including 2.5G, sub3G)

4G

Major Requirement Driving Architecture 

Predominantly voice driven – data was always add on

Converged data and voice over IP

Network Architecture

Wide area cell-based

Hybrid – Integration of Wireless LAN (WiFi, Bluetooth) and wide area

Speeds

384 Kbps to 2 Mbps

20 to 100 Mbps in mobile mode

Frequency Band

Dependent on country or continent (1800-2400 MHz)

Higher frequency bands (2-8 GHz)

Bandwidth

5-20 MHz

100 MHz (or more)

Switching Design Basis

Circuit and Packet

All digital with packetized voice

Access Technologies

W-CDMA, 1xRTT, Edge

OFDM and MC-CDMA (Multi Carrier CDMA)

Forward Error Correction

Convolutional rate 1/2, 1/3

Concatenated coding scheme

Component Design

Optimized antenna design, multi-band adapters 

Smarter Antennas, software multiband and wideband radios

IP 

A number of air link protocols, including IP 5.0 

All IP (IP6.0)

 

 

 

#

Voice was the driver for second-generation mobile and has been a considerable

success. Today, video and TV services are driving forward third generation (3G) deployment. And in the future, low cost, high speed data will drive

forward the fourth generation (4G) as short-range communication emerges. Service and application ubiquity, with a high degree of personalization and synchronization

between various user appliances, will be another driver. At the same time, it is probable that the radio access network will evolve from a centralized architecture to a distributed one.

Service Evolution

The evolution from 3G to 4G will be driven by services that offer better quality

(e.g. video and sound) thanks to greater bandwidth, more sophistication

in the association of a large quantity of information, and improved personalization.

Convergence with other network (enterprise, fixed) services will come

about through the high session data rate. It will require an always-on connection

and a revenue model based on a fixed monthly fee. The impact on network

capacity is expected to be significant. Machine-to-machine transmission

will involve two basic equipment types: sensors (which measure parameters)

and tags (which are generally read/write equipment). It is expected that users will

require high data rates, similar to those on fixed networks, for data and streaming

applications. Mobile terminal usage (laptops, Personal digital assistants, handhelds) is expected to grow rapidly as they become more user friendly. Fluid

high quality video and network reactivity are imporuser requirements.

Key infrastructure design requirements include: fast response, high session rate, high capacity, low user charges, rapid return on investment for operators, investment that is in line with the growth in demand, and simple autonomous terminals. The infrastructure will be much more distributed than in current deployments, facilitating the introduction of a new source of local traffic: machine-tomachine. Figure 1 shows one vision of how services are likely to evolve; most such visions are similar.

Multi-technology Approach

Many technologies are competing on the road to 4G, as can be seen in Figure 3.Three paths are possible, even if they are more or less specialized. The first is the

3G-centric path, in which Code Division Multiple Access (CDMA) will be progressively pushed to the point at which terminal manufacturers will give up. When this point is reached, another technology will be needed to realize the required increases in capacity andata rates.

The second path is the radio LAN one. Widespread deployment of WiFi is

expected to start in 2005 for PCs, laptops and PDAs. In enterprises, voice may start to be carried by Voice over Wireless LAN (VoWLAN). However, it is not clear

what the next successful technology will be. Reaching a consensus on a 200

Mbit/s (and more) technology will be a lengthy task, with too many proprietary

solutions on offer.

A third path is IEEE 802.16e and 802.20, which are simpler than 3G for the equivalent performance. A core network evolution towards a broadband Next Generation Network (NGN) will facilitate the introduction of new access network technologies through standard access gateways, based on ETSI-TISPAN, ITU-T, 3GPP, China Communication StandardsAssociation (CCSA) and other standards.

How can an operator provide a large  number of users with high session data rates using its existing infrastructure? At least two technologies are needed. The  irst (called “parent coverage”) is dedicated

to large coverage and real-time services. Legacy technologies, such as

2G/3G and their evolutions will be complemented by WiFi and WiMAX. A second

set of technologies is needed to increase.

capacity, and can be designed without anyconstraints on coverage continuity. Thisis known as pico-cell coverage. Only theuse of both technologies can achieveboth targets (Figure 4). Handoverbetween parent coverage and pico cellcoverage is different from a classicalroaming process, but similar to classicalhandover. Parent coverage can also beused as a back-up when service deliveryin the pico cell becomes too difficult.

 

 

Key 4G Technologies

Some of the key technologies required for 4G are briefly described below:

 

Software defined radio

Software Defined Radio (SDR) benefits from today’s high processing power

to develop multi-band, multi-standard base stations and terminals. Although

in future the terminals will adapt the air interface to the available radio

access technology, at present this is done by the infrastructure. Several infrastructure gains are expected from SDR. For example, to increase network capacity at a specific time (e.g. during a sports event),

an operator will reconfigure its network  adding several

modems at a given Base Transceiver Station (BTS). SDR makes this

reconfiguration easy. In the context of 4G systems, SDR will become an enabler for the aggregation of multi-standard pico/micro cells.

For a manufacturer, this can be a powerful aid to providing multi-standard,

multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing.

 

 

Handover and mobility

Handover technologies based on mobile IP technology have been considered for

data and voice. Mobile IP techniques are slow but can be accelerated with classical

methods (hierarchical, fast mobile IP). These methods are applicable to data

and probably also voice. In single-frequency niques can be used when the carrier to

interference ratio is negative (e.g. VSFOFDM, bit repetition), but the drawback

of these techniques is capacity. In OFDM, the same alternative exists as in CDMA,

which is to use macro-diversity. In the case of OFDM, MIMO allows macro-diversity processing with performance gains. However, the implementation of macro-diversity implies that MIMO processing is centralized and transmissions are synchronous. This is not as complex as in CDMA, but such a technique should

only be used in situations where spectrum is very scarce  networks, it is necessary to reconsider the handover methods. Several tech-

Integration a Broadband NGN                                                                     The focus is now on deploying architecture                   

realizing convergence between

the fixed andmobile networks 

ITU-T Broadband NGN and ETSI- TISPAN).

 This generic architecture integrates all

service enablers (e.g. IMS, network selection,

middleware for applications providers),

and offers a unique interfaceto application

service providers.

2. Fourth generation wireless: an overview

2.1 Technological feasibility

There are several technologies suggested to deploy in the 4G and these may include:

􀂃 Software Defined Radio (SDR): is a radio communication system where components that have typically been implemented in hardware (i.e. mixers, filters, amplifiers, modulators/demodulators, detectors. etc.) are instead implemented using software on a personal computer or other embedded computing devices.

􀂃

Orthogonal frequency-division multiplexing (OFDM): is a frequency-division

multiplexing (FDM) scheme utilized as a digital multi-carrier modulation method

􀂃 Multiple-input and multiple-output, or MIMO), is the use of multiple antennas at both the transmitter and receiver to improve communication performance.

Universal Mobile Telecommunications System (UMTS), standardized by 3GPP Time Division-Synchronous Code Division Multiple Access, or TD-SCDMA, is a 3G mobile telecommunications standard, being pursued in the People’s Republic of China by the Chinese Academy of Telecommunications Technology

All these technologies are typified by high rates of data transmission and packet-switched transmission protocols. 3G technologies, by contrast, are a mix of packet and circuit-switched networks.

2.2 WiMAX vs. LTE

 

The LTE technology that Nokia and the Third Generation Partnership Project (3GPP) are pushing is an upgrade to existing GSM networks, a fact that makes even the CDMA operator Verizon Wireless to join the 3GPP trials. It is also a strategic decision, in order to be compatible with its European, GSMbased

parent company, Vodafone. LTE looks like it can heal the GSM/CDMA rift that has divided the industry, as no major carrier has yet signed on with obvious CMDA 4G upgrade technology, Ultramobile Broadband (UMB).

4 LTE will have the following advantages:

  • • Fast, with peak data rates of 100 Mbps download and 50 Mbps upload
  • • It makes CDMA and GSM debates moot
  • • It offers both FDD and TDD duplexing, which means the upload and download speeds don’t have to be synchronous, so operators can better optimize their networks to use more upload channels
  • • LTE will have lower latency, which makes real-time interaction on high band-width applications using mobiles possible 3GPP LTE, one of the most advanced mobile communication technologies to date, is currently undergoing 4G technology standardization by the 3GPP. This is the most likely technology to become he 4G standard, as many of the world’s major operators and telecommunications companies are members of LTE/SAE (Long Term Evolution/System Architecture Evolution) Trial Initiative (LSTI).

These companies include operators, such as Vodafone, Orange, T-Mobile, NTT DoCoMo, China Mobile and Telecom Italia and vendors, Ericsson, Nortel, Alcatel-Lucent, Nokia Siemens and LG Electronics. These are also the companies that will be considered to have the advantage in deploying first the 4G services.

WiMAX has certain advantages mainly over the Fiber to the home (FTTH) technology. When bundled with broadband internet access and IPTV, a WiMAX triple play becomes very attractive to residential subscribers. Given the QoS, security and reliability mechanisms built into WiMAX, the users will find

WiMAX VoIP as good as or even better than voice services from the telephone company. It also offers a cost effective infrastructure with efficient use of spectrum. Currently, the average cost of WiMAX  802.16-2004 baseband has decreased from $35 to almost $20 today per subscriber [8]. 4G proponents will serve as complements or upgrades to advance the 3G limitation to deliver video/TV and high speed Internet access. For WiMAX, there is a limitation of wireless bandwidth. For use in high density areas, it is possible that the bandwidth may not be sufficient to cater to the needs of a large clientele, driving potentially the costs high. But the main competitor for WiMAX today is the fiber and

the wireline network that especially in the US is a real challenge for the residential users as the operators are deploying and growing really fast.

 

3. 4G drivers and scenarios

 

The rise of mobile subscribers by 2011 estimating over 4 billion in a combination with the converged systems and application are the main contributors of the 4G evolution.[17]

The new mobile user’s lifestyle is increasing needs capacity, although the ‘walled garden’ might still be a limitation restricting the customer’s experience. The users are changed from consumers into producers of content such as photos, videos etc. Several applications will drive the mobile broadband market globally, including:

  • • Web 2.0,
  • • Online blogs,
  • • Mobile music,
  • • Location Based Services (LBS),
  • • Multimedia messaging,
  • • Gambling and
  • • Mobile TV.

There are a few scenarios discussed in [3] including WiBro and [10], which all agree that 4G will

evolve during 2010 and 2015 and attempting to cover different markets as of restructuring and

transition into 4G. For the next 5 years Verizon needs will evolve into 28Mbps download speed, raising a really early 4G LTE adoption compared to Vodafone [11].

These scenarios could be summarized as following:

1. Independent 4G system with one standard, the 3GPP LTE

2. Transition from 3G into 4G with existing (3GPP LTE) or new service providers

WiMAX and WiBro

3. Co-existence of different standards

4. Spread of open transmission

To explain the above cases, we claim that history matters and the path dependent concept can really explain the long-term outcome based on initial conditions, as in our case. The 4G development depends 6 on the initial conditions as shaped from 3G in most of the cases. Based on the ‘Increasing Returns’ [13], and ‘Path Dependency’ [14], [15] where alternatives are possible, and regarding the standards, “the one selected and heavily invested is ‘good enough’ or even optimal and remains in use because it becomes established in use”. This theory is matching the scenario of different standards co-existence that will interact in the ecosystem and complement each other referring to an LTE+ and WiMAX that will be established and standardized as 802.16e that offers advanced mobility. This is what usually occurs in technological development scenarios.

 

 

4. 4G wireless – suggested study

  4.1. 4G readiness theory

The need for strategic planning and new services has led new studies that could give us an idea of the mcurrent 4G status of the countries and towards the future 4G deployment.

The 4G readiness concept is a new term defined in this proposed study deriving from the e-readiness. “E-readiness is a measure of the quality of a country’s information and communications technology (ICT) infrastructure and the ability of its consumers, businesses and governments to use ICT to their benefit. The measure of a country’s ability to leverage digital channels for communication, commerce and government in order to further economic and social development” Based on the above definition, we develop the 4G readiness concept. Consequently, the 4G readiness is the “state of play” of a country’s mobile wireless 4G preparation status, and the ability of its potential and existing consumers, businesses and governments to use in the future the mobile wireless to their benefit. Based on the 4G readiness criteria we will rank the countries and estimate how soon they will close the gap to new 4G technological environment. Also to describe our study we are going to use a theory, to measure each country’s innovation using the Motivation/Ability framework (Figure 3). In this framework, we are describing the 4 different sections and how they are adjusted into our problem. The Motivation means that the 4G including the digital convergence should be the pot of gold and the new opportunity waiting for the winners, the first movers. The Ability describes the resources needed to develop 4G and craft them into business models for new products and services.

In the “Looking for a target” section, the operators are still undecided regarding the more beneficial choice or are lacking the spectrum to develop a new market. This hesitation also can derive from the “Looking for the Money” section, since the players are still expecting the 3G to pay off before they move into a new investment or wait for the LTE+, in order to upgrade the GSM networks that might also include smaller cost, much less than developing a WiMAX solution. “The Dilemma” is what we can quantify using our 4G readiness metric and estimate it per country, assuming basic innovation and ability. Finally “The Hotbed” is addressing all the innovative countries that feel confident and in the right path for the 4G adoption in the near future.

Other important non-market factors for 4G based on the framework development are:

  • • Industry standards
  • • Cultural norms
  • • State of technological development
  • • Government regulation
  • • Country’s intellectual property infrastructure

We are applying non-market metrics and factors, because there are no markets structured shaped yet and even and the current 3G markets provide very little knowledge to support the new landscape for 10 years from today.

 

 

 

 

 

Conclusions

This study provided an overview of the 4G evolution and technologies. It also described the ereadiness ranking and the approach adopted in this study to adopt e-readiness for 4G readiness.

This type of studies and the expected results will shed light into the current operators’ strategies and market str ucturing at a national level. The ranking at country level will help us identify if the biggest players in these countries play a significant role and having an impact as leaders in 4G. The study will reveal which countries have a competitive advantage towards the 4G, the weak countries that might be strong in the digital part but weak in the mobile wireless area and the reasons. Finally we will pay special attention into the strong countries and perhaps identify the path and the strategies that will shape the 4G markets faster and accumulate more capital ands investments

 As the history of mobile communications shows, attempts have been made to reduce a number of technologies to a single global standard. Projected 4G
systems offer this promise of a standard that can be embraced worldwide through its key concept of integration. 

Future wireless networks will need to support diverse IP multimedia applications to allow sharing of resources among multiple users. There must be a low complexity of implementation and an efficient means of negotiation between the end users and the wireless infrastructure. The fourth generation promises to fulfill the goal of PCC (personal computing and communication)—a vision that affordably provides high data rates everywhere over a wireless network.

 

References:

 

1. “4G Mobile Networks – Technology beyond 2.5G and 3G”, Jun-Seok Hwang et.al, PCT’07

Proceedings

2.www.alcatel.com/atr

3. www.m-indya.com/4g/

 

 

 

 

 

 

 

 

 

 

 

 

GLOSSARY

1) IEEE: Institute of Electronic and Electrical Engineering.

2) LAN: Local Area Network. 

3) GAP: Generic Access Profile. This profile describes the mechanism by which one device discovers and accesses another device when they do not share a common application.

4)GIAC: General Inquire Access Code. The default inquiry code which is used to discover all devices in range.
 

5) GM: Group Management.

 

Voice Over IP

 

                 PROJECT ON

 

 

 

                          “ Voice Over Internet Protocol Version-4.”

 

 

 

 

                                                            By,

 

  1. 1.     Akash Khadke

 

                            M.G.M College Of Engineering & Technology .

               Kamothe , Navi Mumbai.

PIN- 410209.

1                            Introduction to VOIP

 

Applications involving voice over internet protocol technology:

 

Ä   Internet Voice Telephony.

Ä   Intranet & Enterprise network voice telephony.

Ä   Internet fax service.

Ä   Multimedia internet collaboration.

Ä   Internet call centers

Ä   PBX intercommunications.

Approaches to deploy Voice Over internet Protocol Network:

 

Ä   Desktop Approach.

Ä   Shared Approach.

Desktop Approach:

Each individual purchases VOIP enabled terminals used to support remote communications.

Shared Approach:

VOIP capabilities are developed in an industrial strength mode using shared , network-resident servers.

 

 

 

 

General of VOIP:

Voice signaling protocols have evolved, keeping with the prevalent move from circuit to packet switched networks.

In past, voice analysis & synthesis using a vocoder technology produced a robotic sounding voice, but has changed dramatically during 1990’s.a lot of work is gone into all objective testing of the voice to determine how good the proposed algorithms are. The most frequently used test in  International Telecommunications Union (ITU-T) SG12 is the “Absolute Category Rating”(ACR)test.

Subjects listen to about 8 to 10’s of speech material & are asked to rate the quality of what they heard. Usually 5 point scale is used to represent the quality rating.

Example:

5= Excellent,

1= Bad.

By assigning the corresponding numerical values to each rating, a Mean Opinion Score(MOS) can be computed by each coder by averaging these scores.

Developers & planners are looking at VIOP for intranet & Enterprise Network Applications & enterprise network applications and at VOIP for geographically dispersed applications.

Products  for VOIP are emerging because organizations have significant investments in private data facilities that have the capacity available to carry additional on net traffic what is perceived to be little initial incremental expense.

 

Requirements of VOIP over data applications:

Ä   Compression.

Ä   Silence suppression.

Ä   Quality Of Service.

Ä   Signaling for voice traffic.

Ä   Echo control.

Ä   Voice switching.

 

Compression:

 Compression significantly reduces the amount of bandwidth used by a voice conversation, while maintaining high quality.

Silence suppression:

The ability to recover bandwidth  during periods of silence in a conversation makes the bandwidth available for other user of the network.

Quality Of Service : 

Assuring  priority for voice transmission is critical..

Signaling for voice traffic :

Support of traditional PBX’s and the associated signaling is critical.

Echo Control :

Echo in annoying & descriptive control is key

Voice Switching:

 Data network equipment can generally support on net applications off net is also critical. At the very least the adjunct equipment must

 decide whether to route a call over the internal data network or route it to PSTN. 

 

 

 

 

 

 

 

Advantages of VOIP:

 

Ä   Long Distance cost savings :

By integrating voice, data & fax over an Internet Protocol Enterprise network, a company can reduce long distance charges for intra-company calls. By reducing the number of access lines, the organization can also reduce the fee charges.

Ä   Reduced Equipment Investment :

Companies generally lease/ purchase separate equipments and facilities for voice support. With VOIP the cost of securing & securing equipments is reduced, because all the intra-company traffic or voice and data is delivered over the  same network.

The different types Protocols used for Voice over IP are as follows :

Ä   MGCP and MEGACO/H.248

Ä   H.232

Ä   SIP (Session Initiation Protocol)

 

 

 

 

 

 

 

 

 

 

Introduction to H.323 standard

 

 

Definition:

H.323 is a standard that specifies the components, protocols and procedures that provide multimedia communication services – real-time audio, video and data communications- over packet switched networks including Internet Protocol(IP)- based networks. H.323 is a part of a family of ITU-T recommendations called H.32X that provides multimedia communication services over a variety of networks.

                               Terminals on the packet Network

What is  H.323 ?

The H.323 standard is a cornerstone technology for the transmission of real-time audio, video and data communications over packet-based networks. It specifies the components, protocols and procedures providing multimedia communication over packet-based networks

H.323 can be applied in a variety of mechanisms

Ä   Audio only (IP telephony),

Ä   Audio and Video (Video telephony),

Ä   Audio, Video, Data.

H.323 can also be applied to multipoint-multimedia communications. H.323 provides myriad services and therefore can be applied in a wide variety of areas : Consumer, Business and Entertainment.

H.323 Versions:

Version 1 of the H.323 standard does not provide guaranteed  Quality of Service(QoS). The emergence of voice over IP (VOIP) applications and IP telephony has paved the way for a revision of the H.323 specification. The absence of a standard for voice over IP resulted in products that were incompatible. With the development of VOIP, new requirements emerged such as :

Ä   providing communication between a PL-based phone on a traditional Switched Circuit Network (SCN).

Such requirements forced the need for a standard for IP-telephony.

Version 2 of H.323 – packet based multimedia communications system- was defined to accommodate these additional requirements and was accepted in Jan 1998.

New features are being added to the H.323 standard, which will evolve to Version 3 shortly.

The features being added include:

Ä   Fax- over-packet networks,

Ä   Gatekeeper-Gatekeeper communications and

Ä   Fast- connection mechanism.

The H.323 standard is part of the H.32X family of recommendations specified by ITU-T.

The H.323 Protocol Stack

 

 

 

 

 H.323 Components

H.323 Components :

The H.323 standard specifies 4 kinds of components, which when networked together, provide the point–to-point and point-to-point-to-multipoint multimedia – communication services :

Ä   Terminals

Ä   Gateways,

Ä   Gatekeepers,

Ä   Multipoint Control Units (MCU’s).

Terminals:

Used for real-time bidirectional multimedia communications, an H.323 terminal can either be a personal computer (PC) or a stand-alone device, running an H.323 & the multimedia applications. It supports audio communication and can optionally support video or data communications. As the basic service provided by an H.323 terminal is audio communications, an H.323 terminal plays a key role in IP-telephony services.

H.323 terminals are the client endpoints on the LAN that provide real-time, two-way communication. They can be realized either as SW-Clients running on a PC or workstation or as a dedicated HW-devices. All terminals must support voice communication; video and are optional.  

Function of the Terminal:

The terminal is the user or the end point.

Ä   Provides real-time 2 way communication.

Ä   Optional : Video & data streaming.

Ä   Mandatory voice streaming.

Protocols Supported by the Terminal

Ä   H.232

Ä   H.245 (Control channel usage & capabilities)

Ä   sQ.931 (Call setup & signaling )

Ä   RAS (for use with Gatekeepers/Registration/ Admission/Status)

Ä   RTC/RTCP (sequence Audio & status video packets)

Gateways :

A gateway connects two dissimilar networks. An H.323 gateway provides connectivity between an H.323 network and a non-H.323 network. For example, a gateway can connect and provide communication between an H.323 terminal and SCN networks (SCN networks includes all switched telephony networks, e.g. public switched telephone network [PSTN] ).

This connectivity of dissimilar networks is achieved by translating protocols for call setup and release, converting media between different networks, and transferring information between the networks connected by the gateway. A gateway is not required, however, for communication between two terminals on an H.323 network.

The Gateway also translates between audio and video codec’s and performs call setup and clearing on both the LAN side and the PSTN side.  

The Functions of the gateway can be stated as follows:

Ä   Task-translation.

Ä   Audio Codec

Ä   Video codec

Ä   H.245 à H.221 (ISDN Conference)

H.245 à H.242 (Audio-Visual terminals)

Gatekeepers :

A gatekeeper can be considered the brain of the H.323 network. It is the most important component of an H.323 enabled network.

It is the focal point for all calls within the H.323 network.

Although they are not required, gatekeepers provide important services such as addressing, authorization and authentication of terminals and gateways; bandwidth management; accounting; billing; and charging. Gatekeepers may also provide call-routing service.

The Functions of the Gatekeeper can be stated as follows :

Ä   Task: user information / “name server”

Ä   Gatekeeper is optional but essential.

Ä   Managing communications.

Ä   Address translation.

Ä   Call Control.

Ä   Routing services.

Ä   System management.

Ä   Security policies.

Multipoint Control Unit:

MCU’s  provide support for conferences of three or more H.323 terminals. All terminals participating in the conference establish a connection with the MCU.

 The MCU manages conference resources, negotiates between terminals for the purpose of determining the audio or video coder/decoder (CODEC) to use, and may handle the media stream.

The gatekeepers, gateways and MCU’s are logically separate components of the H.323 standard  but can be implemented as a single physical device.

The functions of the MCU can be stated as follows:

Ä   Task : maintain all audio, video data & control streams mandatory for conferences. 

An MCU is usually splitted into 2 devices :

Ä   MC (Multipoint Controller)

Ä   MP (Multipoint Processor)

Usually they are located inside a Gateway or a Gatekeeper.

H.323 Zone:

An H.323 zone is a collection of all terminals, gateways and MCU’s managed by a single gatekeeper. A zone includes at least one terminal and may include gateways or MCU’s. A zone has only one gatekeeper.

 A zone may be independent of network topology and may be comprised of multiple network segments that are connected using routers or other devices.

           An H.323 Zone

Zone Management:

The gatekeeper provides the above functions :

Ä   Address translation.

Ä   Admission control

Ä   Bandwidth Control.

For terminals, gateways and MCU’s located within the Zone control.

Zone managed by Gatekeepers

Protocols Specified by H.323:

The protocols specified by h.323 are listed below.H.323 is independent of the packet network and the transport protocol over which it runs and does not specify them:

Ä   Audio Codec’s

Ä   Video Codec’s

Ä   H.225 RAS

Ä   H.225 Call Signaling

Ä   H.245 Control Signaling

Ä   Real-time Transport Protocol (RTP)

Ä   Real-time Transport Control Protocol (RTCP)

 

Terminal Side Protocol Stack

Audio CODEC:

An audio CODEC encodes the audio signal from the microphone for transmission on the transmitting h.323 terminal and decodes the received audio code that is sent to the speaker on the receiving h.323 terminal. As audio is the minimum service provided by the H.323 standard, all H.323 terminals must have at least one audio CODEC support.

Video CODEC:

A Video CODEC encodes video from the camera for transmission on the transmitting h.323 terminal and decodes the received video code that is send to the video code that is send to the video display on the receiving H.323 terminal. As H.323 specifies support of video is optional, the support of video Codec’s is optional as well. However , any H.323 terminal providing video communication must support video encoding and decoding as specified in the ITU-T  H.261 recommendation.

Registration Admission And Status:

Registration, Admission and Status(RAS), is the protocol between end points (Terminals & Gateways ) and gatekeepers. The RAS is used to perform registration, admission control, Bandwidth changes, status and disengaged procedures between end points and Gatekeepers.

An RAS channel is used to exchange RAS messages. This signaling channel is opened between an end point and a gatekeeper prior to the establishment of any other channels.

H.225 Call Signaling:

H.225 call signaling is used to establish a connection between 2, H.323 end points. This is achieved by exchanging H.225 protocol messages on the call signaling channel. The call signaling channel is opened bet 2, H.323 end points or between an end point and the gatekeeper.

H.245 Control Signaling:

H.245 control signaling is used to exchange end-to- end control messages governing the operation of the H.323 end point. These control messages carry information related to the following:

Ä   Capabilities Exchange.

Ä   Opening and closing of logical channels used to carry media streams.

Ä   Flow- Control messages.

Ä   General commands and indications.

Real-time Transport Protocol:

Real-time Transport Protocol (RTP) provides end-to-end delivery services of real-time audio and video. Whereas , H.323 is used to transport data over IP-based networks, RTP is typically used to transport data via the User Datagram Protocol (UDP). RTP,  together with UDP, provides transport-protocol functionality. RTP provides payload-type identification, sequence numbering, time-stamping and delivery monitoring. UDP provides multiplexing and checksum services. RTP can also be used with other transport protocols.

Real-time Transport Control Protocol:

Real-time Transport Control Protocol (RTCP) is the counter part of RTP that provides control services. The primary function of RTCP is to provide feedback on the quality of the data distribution. Other RTCP functions include carrying a transport-level identifier for an RTP  source, called a canonical name , which is used by receivers to synchronize audio and video.

Terminal Characteristics:

H.323 terminals must support the following :

Ä   H.245 for exchanging terminals capabilities and creation of media channels.

Ä   H.225 for call signaling and call setup.

Ä   RAS for registration and other admission control with a Gatekeeper.

Ä   RTP/RTCP for sequencing audio and video packets.

H.323 terminals must also support the G.711 Audio CODEC. Optional components in an H.323 terminal are Video Codec’s, T.210 data-conferencing  protocols and MCU capabilities.

Gateway and Gatekeeper Characteristics:

Gateway characteristics:

A gateway provides translation of protocols for call-setup and release, conversion of media formats between different networks, and the transfer of informati0on between H.323 and non-H.323 networks. An application of the H.323 Gateway is in IP- telephony, where the H.323 gateway connects an IP- network and SCN network(example : ISDN network).

On the H.323 side, a Gateway runs H.245 control signaling for exchanging capabilities, H.225 call signaling for call set-up and release, and H.225 registration, admission and status (RAS) for registration with the Gatekeeper. On the SCN side, a Gateway runs SCN-specific protocol(e.g.: ISDN and Signaling System number 7 (SS7) protocols).

                                                 Gateway Protocol Stack

Terminals communicate with Gateways using the H.245 control-signaling protocol and H.225 call-signaling protocol. The Gateway translates these protocols in the transparent fashion to the respective counter parts on the non-H.323 network and vice versa. The Gateway also performs call-set-up & clearing on both the H.323-network side and the non-H.323-network side. Translation between audio, video and data formats may also be performed by the Gateway. Audio and video translation may not be required if both terminal types find a common communication mode.

Gatekeepers are aware of which end points are Gateways because this is indicated when the terminals and Gateways register with the Gatekeeper. A Gateway may be able to support several simultaneous calls between the H.323 and non-H.323 networks.

Gatekeeper Characteristics:     

Gatekeepers provide call-control services for H.323 end points such as address translation and bandwidth management  as defined within RAS. Gatekeepers in H.323 networks are optional. If they are present in a network, however, terminals and Gateways must use their services. The H.323 standard both define mandatory services that the gatekeeper must provide and specify other optional functionality that it can provide.

An optional feature of a Gatekeeper  is called signaling routine. End points send call-signaling  messages to the Gatekeeper, which the Gatekeeper routes to the destination end points. Routing calls through Gatekeepers provides better performance in the network, as the Gatekeeper can make routing decisions based on a variety of factors, for example, load balancing among Gateways.

The services offered by a Gatekeeper are defined by RAS and include address translation, admissions control bandwidth control and zone management. H.323 networks that do not have Gatekeepers may not have these capabilities, but H.323 networks that contain IP-telephony, Gateways should also contain a Gatekeeper to translate incoming E.164 telephone addresses into transport address. A gatekeeper is a logical component of H.323, but can be implemented as a part of a Gateway or MCU.

Gatekeeper Components

Mandatory Gatekeeper functions :

Address Translation:

Calls originating within an H.323 network may use an alias to address the destination terminal. Calls originating outside the H.323 network and received by a Gateway may use an E.164 telephone Number (e.g. 310-442-9222) to address the destination terminal. The gatekeeper translates this E.164 telephone number or the alias into the network address(e.g. 204.252.32:456 for an IP-based network) for the destination terminal. The destination end point can be reached using the network address on the H.323 network.

Admission control:

The Gatekeeper can control the admission of the endpoints into the H.323 network. It uses RAS messages, admission request(ARQ), confirm(AFC) and reject(ARJ) to achieve this.

Bandwidth Control:

The gatekeeper provides the support for bandwidth control by using the RAS message, bandwidth request(BRQ) , confirm(BCF) and reject (BRJ). The result is to limit the total allocated bandwidth to some fraction of the total available, remaining bandwidth for data applications. Bandwidth control may also be a null function that accepts all requests for bandwidth changes.

Optional gatekeeper functions:

Call-control Signaling:

 The gatekeeper can route call signal messages between H.323 end points. In a point-to-point conference, the gatekeeper may process H.225 call- signaling messages. Alternatively, the gatekeeper may allow the end points to send H.225 call-signaling messages directly to each other.

Call Authorization:

When an end point sends call-signaling messages to the gatekeeper, the gatekeeper may accept or reject the call, according to the H.225 specification. The reasons for rejection may include access-based or time-based restrictions, to and from particular terminals or gateways.

Call Management:

The gatekeeper may maintain information about all active H.323 calls so that it can control its zone by providing the maintained information to the bandwidth-management functions or by re-routing the calls to different endpoints to achieve load balancing.

Registration, Admission and Status

The H.225 RAS is used between H.323 endpoints ( terminals and gateways) and gatekeepers for the following:

Ä   Gatekeeper Discovery (GRQ)

Ä   End point registration

Ä   End point location

Ä   Access tokens

The RAS messages are carried on a RAS channel that is unreliable. Hence, RAS message exchange may be associated with timeouts and retry counts.

Gatekeeper discovery:

The gatekeeper discovery process is used by the H.323 endpoints to determine the gatekeepers which the endpoint must register. The gatekeeper discovery can be done statically or dynamically.

In static discovery, the end point knows the transport address of its gatekeeper a priori.

In the dynamic method of gatekeeper discovery, the send point multicasts a GRQ message on a gatekeepers discovery multicast address: “Who is my Gatekeeper?” one or more Gatekeepers may respond with a GCF message: “ I can be your Gatekeeper.”

End point registration:

Registration is a process used by the endpoints to join a zone and inform the gatekeepers of the zones transport and alias addresses. All end points register with a gatekeeper as part of their configuration.

Endpoint location:

Endpoint location is a process by which the transport address of an endpoint is determined and given its alias name or E.164 address.

Other Control:

The RAS channel is used for other kinds of control mechanisms, such as admission control, to restrict the entry of an endpoints into a zone, bandwidth control, and disengagement control, where an endpoint is disassociated from a gatekeeper and its zone.

H.225 Call Signaling and H.245 Control Signaling

H.225 Call Signaling:

H.225 Call signaling is used to set up connections between H.323 endpoints (terminals and Gateways), over which the real-time data can be transported. Call signaling involves the exchange of H.225 Protocol messages over a reliable call-signaling channel.

H.225 messages are exchanged between the endpoints if there is no gatekeeper in H.323 network. When a gatekeeper exists in the network, the H.225 messages are exchanged either directly between the end points or between the end-points after being routed through the gatekeeper. The method chosen is decided by the gatekeeper during RAS-admission message exchange.

Gatekeeper-Routed Call Signaling:

 The admission messages are exchanges between endpoints and the gatekeeper on RAS channels. The gatekeeper receives the Call-signaling messages on the call-signaling channel from 1 endpoint and routes them to the other endpoint on the call-signaling channel of the other endpoint.

Direct Call-Signaling:

During the admission confirmation, the gatekeeper indicates that the endpoints can exchange call-signaling messages directly. The endpoints exchange the call-signaling on the call-signaling channel.

H.245 Control Signaling:

The H.245 control Channel is the logical channel 0 and is permanently open, unlike the media channels.

Connection Procedures:

The Following example describes the steps involved in creating an H.323 call, establishing media communication and releasing the call. The example network contains 2, H.323 terminals (T1 and T2) connected to a gatekeeper. Direct call signaling is assumed. It is also assumed that the media stream uses RTP encapsulation. The below diagram illustrates the Call- establishment:

                                                            H.323 Call Signaling

 

The steps can be listed as:

  1. T1 sends the RAS ARQ message on the RAS channel to the gatekeeper for registration. T1 requests the use of direct call signaling.
  2. The gatekeeper confirms the admission of T1 by sending ACF to T1. The gatekeeper indicates in ACF that T1 can use direct call signaling.
  3. T1 sends an H.225 call signaling setup message to T2 requesting a connection.
  4. T2 responds with an H.225 cal proceeding message to T1.
  5. Now T2 has to register with the gatekeeper. It sends an RAS ARQ message to the gatekeeper on the RAS channel.
  6. The gatekeeper confirms the registration by sending an RAS ACF message to T2.
  7. T2 alerts T1 of the connection establishment by sending an H.225 alerting message.
  8. Then T2 confirms the connection establishment by sending an H.255 connect message to T1, and the call is established. The below figure denotes the H.323

                                        

H.323 Control Signaling Flows

 

 

  1. The H.245 control channels is established between T1 and T2. T1 sends an H.245 TerminalCapabilitySet message to T2 to exchange its capabilities.
  2. T2 acknowledges T1’s capabilities by sending an H.245 TerminalCapabilitySetAck message.
  3. T2 exchanges its capabilities with T1 by sending an H.245 TerminalCapabilitySet message.
  4. T1 acknowledges T2’s capabilities by sending an H.245 TerminalCapabilitySetAck message.
  5. T1 opens a media channel with T2 by sending an H.245 OpenLogicalChannel message. The transport address of the RTCP channel is included in the message.
  6. T2 acknowledges the establishment of the unidirectional logical channel from T1 to T2 by sending an H.245 OpenLogicalChannelAck message. Included in the acknowledge message are the RTP transport address allocated by T2 to be used by the T1 for sending the RTP media stream and the RTCP address received from T1 earlier.
  7. Then, T2 opens a media channel with T1 by sending an H.245 OpenLogicalChannel message. The transport address of the RTCP channel is included in the message.
  8. T1 acknowledges the establishment of the unidirectional logical channel from T2 to T1 by sending an H.245 OpenLogicalChannelAck message. Included in the acknowledging message are the RTP transport address allocated by T1 to be used by T2 for sending the RTP media stream and the RTCP address received from T2 earlier. Now the bidirectional media stream communication is established.

 

 

                H.323 Media Stream & media Control Flows

  1. T1 sends the RTP encapsulated media stream to T2.
  2. T2 sends the encapsulated media stream to T1.
  3. T1 sends the RTCP message to T2.
  4. T2 sends the RTCP message to T1.

 

  1. T2 initiates the call release. It sends an H.245 EndSessionCommand message toT1.
  2. T1 releases the call endpoint and confirms the release by sending an H.245 EndSessionCommand message to T2.
  3. T2 completes the call release by sending an H.225 release complete message to T1.
  4. T1 and T2 disengage with the gatekeeper by sending an RAS DRQ message to the Gatekeeper.
  5. The gatekeeper disengages T1 and T2 and confirms by sending DCF messages to T1 and T2.     

 

 

 

 

                                                 H.323 Call Release

      An example for H.323 call signaling.

An Example network can be represented as follows:

 

An Introduction to Session Initiation Protocol (SIP)

 

      Ancestors of SIP

Ä   HTTP (basic request/ response format, status codes, etc)

Ä   Email/SMTP (Address style)

Ä   URL (addresses)

Ä     Transfer control protocol / user datagram protocol (TCP/UDP) (message transport)

Ä   Real Time Protocol(RTP) (voice session)

         The clients for SIP:

Ä   Terminal act as UserAgentServer(UAS)  or UserAgentClient (UAC) could be soft phones or IP-phones. 

Ä   Gateways  primary task: translation. 

        The Server for SIP:

Ä    Proxy server  receives SIP messages and forward them to the next server in the network.

Ä   Redirect Server provides information against the next hop. 

Ä   Registrar Server requests current location for UAC registration; they are often co-located with a redirect or proxy server. 

An example of the SIP network

 

An example of SIP messages :

The commands the SIP uses are called “methods”

SIP method            Description.

INVITE                 Invites a user to call.

ACK                      Used to facilitate reliable message exchange for INVITE’s

BYE                      Terminates the connection between users/ declines a call

CANCEL              Terminates a request or search for a user

OPTIONS              Requests Information about the server capabilities.

REGISTER           Registers the users current location.

INFO                     Used for mid session signaling.

The Server Responses

1xx             Information

2xx                        Successful

3xx                        Redirection

4xx                        Request failure

5xx                        Server failure

6xx                        Global failure.

A SIP call example

                              Comparison between SIP and  H.323

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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