Fixed Mobile Convergence (FMC)

Following a long period of development, fixed mobile convergence (FMC) appears ready to arrive in the froms of real carrier services for enterprises.The concept of FMC-the ability to access multimedia application from a variety of end user device while roaming across a range of fixed line and mobile networks-has broad appeal.Enterprise see FMC as a way to improve employee efficiency which may also help reduce telecom costs.Carrier look to help them survive and grow in a world where profits from providing mere connectivity and transport for voice and data rapidly dwindling.

Industry analysts are projecting aggresive uptake of FMC services:global sales of dual mode mobile phones are expected to exceed 100 million units by 2010 (per ABI research).FMC revenues may reach US80 billion worldwide by 2009 (per pyramid research)

FMC promises to provide carriers and their partners with a range of new applications and srevices they can deliver to enterprises to drive revenue, profits and customer retention.The first managed services to offer true convergence will allow enterprises users to roam between cellular networks and voice enabled wireless LANs (WLANs),using dual mode handset equipped with 3G and Wi-Fi radios.Carriers considering their own FMC solutions can learn some important lessons from the innovative carriers who brought these services to market in 2006,such as the new functioanllity that WLANs deliver,making mobile voice practical within the enterprises campus

As with all fundamentally transformative processes,the FMC revolution-from our current collection of disjointed fixed and mobile carrier and enterprise network,toward seamlessly interoperating,converged multimedia applicaiton delivery platform-will take place in a series of incremental steps

Carriers and enterprises that anticipate the critical technology inflection points that accompany each major phase in the evolution toward FMC will be able to make smarter decisions on near-term network infrastructure investments


The Role of WLANs in FMC

One of the critical inflection points in the path to FMC is the advent of WLAN infrastructure capable of supporting mobile voice with sophisticated roaming capabilities.Early carrier rollouts of managed FMC services have identified certain limitations inherent in aging WLAN architectures that use independent access points ( so called "fat APs") or a centralized WLAN gateway (the WLAN switch with thin APs approach)

The WLAN component of managed FMC services will have to implement a third - generation architecture - one that leverages discrete,distributed handling of WLAN transport,control and management functions - in order to deliver the following critical features:

1. Definition and enforcement of very granular WLAN quality of service policies,tunable to broad range of application (notable voice and video),end device capabilities and other characteristic

2. A combination of centralized control and access point intellegence to optimize perfomance along the data path to ensure scalability and consistent perfomance.

3. Seamless roaming (handover) between WLAN access points on the same LAN segment and between WLAN access points on different IP subnets

4. Management tools to help carriers centrally monitor,troubleshoot, and maintain WLAN equioment across an FMC customer base that may extend to thousand of locations

5. Features to support an eventual migration to IP multimedia system, including session initiantion protocl (SIP) based VoIP signaling and other SIP-enabled applications and services

6. Access point features to automatically enable to connection of the broadest possible range of end user device and radio types without the need for any end user configuration work

7. The ablitiy to add WLAN capacity in cost effective increments and planning tools that help carriers anticipate and pre emptively address problems with enterprise WLAN congestion,radio frequency (RF) coverage and infrastructure resilency

8. Thigh integration and interoperation with the wired LAN and its bandwidth management,netwrok security and authentication/authorization/accounting (AAA) infrastructure

Carriers considering their first FMC offerings can benefit greatly from the experiences of FMC pioneers and their customers.Talking to vendor reference customers will provide useful insight into how their WLAN infrastructure choice helped or impeded the rollout of FMC services.
At a minimum,carriers should begin to more closely examine the implications of FMC on WLANs as they consider potential vendor alliances.Identifying a WLA solution that can meet FMC's requirement - for multimedia support,quality of service (QoS), perfomance, scalability, managemeability and security - may help carriers to avoid some potentially costly mistakes. Read More..

P2P (Point to Point)

Online video has emerged as the most badwidth hungry application.Some researches have state that video services ocupy 60% of P2P traffic,which each file averaging around 1GB.
Hence VOD and downloads use huge amounts of network bandwidth and this is exerbated if a video is particularly popular.A singel video report covering 9.11,for instance, had a click rate exceeding 100 million

P2P connects peoples in a network and users can communicate directly via the internet rather than though any intermediary.Its application enable users to directly exchange and share file instead of connecting to servers for file browses and downloads..Significanly P2P alters the reality that the internet is the dominant power core as P2P devolves power to users via decentralization, while greatly enhancing the value of online services

However,the wide range of P2P appplicaitons on the internet describes a trend for which it is complicated for carriers to strategize.Its advantages are fairly evident.Firstly,P2P creates new opportunities as it can attract more users to broadband networks that provide these applications.Secodnly,P2P technologies can be used to optimize existing services and networks to increases perfomance and decrease cost.P2P and online TV for example represent a good combination.

Based on existing services, carriers can explore new P2P operation and profit models to render these application managable and profitable, and allows them to develop in a constructive,sustaibale way that caters to user requirements

The most obviously negative aspect is that if P2P applications are all interconnected in parralel, network bandwidth increase tremendously.In extreme cases, this may result in network congestion and the perfomance degradation of other internet application.Moreover, P2P based voice communicaiton technologies such as Skype have direclly threatened carrier's traditional voice communicaiton services

Given these considerations,carriers are left with two broad strategies:Prevent the use of P2P or develop and guide sustainable usage.Since P2P represents an irreversible trend,logic dictates that usage guidance is the better long term option,despite the fact that the challenges currently outweigh the opportunities.Correct decision making and implementation will be the tool to heighten the potential benefits

Many carrier have in fact started developing solutions for P2P apllication.Carriers should prevent illegal network resource usage,while exploting P2P applications' inherent advantages and transform then into something useful

Three strategies can be followed to reach this goal.The first is to limit overall bandwidth.Traffic should be localized to reduce pressure on the backbone network.The second is to employ P2P technologies to reconstruct existing networks,thereby increasing perfomance and reducing cost.Thirdly,P2P technologies can be used as a platform to develop new services and increase income.Some carriers have already started expanding network bandwidth


Adjust MAN architecture


Both P2P software download such as Bit Torrent, and live broadcast P2P software including PPLive are executed via applicaiton layer duplcations between node.In the present MAN architecture,users exist in a dual layer separation mode in the acces network.

Application layer duplication between users can only occur through the core convergence layer of the MAN or the backbone network and the bandwidht consumed on the MAN core convergence is proprotionate to the numbers of users

The present MAN see data traffic passing the convergence swtiches and BRAS before arriving at the MAN egress.No fixed bandwidth is reserved for each users from the access layer to the MAN egress and whenever a large amount of traffic exists on the access layer,much bandwidth will occupied on the convergence layer or the backbone network.Moreover ADSL bandwidth in the access network is asymmetrical as uplink bandwidth is fast less than downlink bandwidth.If application layer duplications are implemented,uplink bandwidth demands are increased,which would exeed present access network capacities.

If P2P services become mainstream services over present network architecture,badwidth on the MAN core convergence netwrok will see the greatest bottleneck,while access layer bandwidth will be continously occupied.In terms of online TV applications, P2P duplications on the application layer are not cost effective in term of bandwidth usaged compared with multicast.Network access can only adjust MAN architecture so that it can adapt to the P2P application layer duplication model and reduce pressure on the MAN convergence layer's P2P derived bandwidth demands.

To make the MAN architecture suitable for P2P applications layer duplications, the following principles should be obsreved:

1. Selecting symmetrycal access equipment

DSLAM is continously used by carriers but possesses asymmetrical access equipment that cause significanly more downlink abdwidth than uplink. It is rather suitable for C/S model than P2P.Therefore a shift toward symmetrical access technologies such as LAN,ADSL2+ or EPON is recommended

2. Flattering the access network

The nature P2P traffic means that placing the layer 3 gateway closer to users will increase bandidth saving on the MAN core convergence layer

3. Building a full meshed structure at the core convergence layer

MAN currently adopts a dual start,tree structure.All traffic passing MAN must cross two routers at he MAN core.This is unsuitable for P2P traffic,adaptation to which necessitates the adoption of multi node architecture at the MAN core layer under which different nodes network via the full meshed Read More..

Building a secure network

The internet begans as an experiments in 1969 by ARPA of the US Departement of defence.ARPA's intention was to create a very reliable digital communications network that could be used in wartime, so communication could be maintain even if the stations or physical links were targetted during attacks.Early researches into this area adopted an innovative and powerfull idea - packet switching- to build the ARPANET.Subsequencely the new technology proved to be highly successful.In the following years, more research networks were created and the ARPANET evolved into the NSFNET, before finally becoming the Internet we know today.

The internet began into rouse the interests of the public during the 1990s, partly due to the wide applications of PC and WWW.Soon access to the internet became a popular services of the residential customers as well as enterprises and the number of internet users has increase exponentially over the years, so much so, that as of the end of 2006, the number of people using the internet has sky rocketed to 1 billion worlwide.

As a public communcaiton service, the internet access has to reliable.However the kind of reliability that ARPA was looking for was actually robustness,that is, the capability to function correcly under negative impacts, so commands can be delivered to the outposts to coordinate attacks, even after some stations had been destroyed.In comparasion, the kind of reliability that the public needs is high availability.That is the proportion of the time whe the service is available, which is this instance, should be most of the time

Accoring to the Infocomm Development authority of Singapore, the availability of internet service provide by major ISPs in Singapore about 99.99%.In other words, internet service is unavailable and cannot be accessed for a little than a hour each year
Since the most people use the internet for seding email, browsing news sites,searching for information,etc, and for basically nothing very critical, then most people are satisfied with the service.

The new millenium has withnessed the coming of network convergence.A fair portion of long haul calls had been packetisez nad routed to the internet and now ILECs are beginning to replace PSTN with IMS.Succesful deployments of IPTV by pioneer telecom operators have helped to showcase the revenue and profit potential and triple play service and triggered a new wave of expansion of IP networks globally.As a result, more and more enterprises are switching to IP VPN to replace the expensive frame relay ceoonections.As the telecommunication network is heading into an all IP era, the internet will become the common IP bearer network for all kinds of new services.

Glory is always accompanied by a heavier sense of responsibility.Telecom operators established the availability standarad for PSTN and leased circuits long ago, five 9s (99,999%) which translate into 5 minutes downtime per year.Cable operator have a similar availability satandard for cable TV.In order to bear the traffic multy-play or VPN services, the IP bearer network has to be revolutionized,hence,improving availability from four 9s, to five 9s

To make the task even harder,some services are session based such as voice service. If the call is broken then the call is dropped and customers have to dial again.To effectively deal with this issue,the IP bearer network has to provide a fast automatic oath swichover mechanism to re reroute the traffic,like,SDH or PSTN, which are able to provide 50 milliseconds automatic protection

Is summary, as the common IP bearer network in All-IP era, the IP bearer network needs to be able to provide four 9s for internet access, five 9s for voice,IPTV and VPN, as well as a fast path switchover mechanism for session based services Read More..

Next Generation Network (NGN) architecture

The converged world of next generation networks (NGN) brings with it the promise of voice,video and data over a single broadband netwrok.This transition from the traditional circuit switched to packet switched networks has been underway for many years and Voice Over IP (VoIP) is now leading the transition

One NGN architecture for VOIP with centralised call processing decomposes the functional elements of a traditional circuit switch into specialized componnect with open interfaces.
Following are the key logical element of this reconstruction are the following:

1. THe MG handle the media or beared, interface.It converts media from the format used in one network to the format required in the another network.For example it can terminate the TDM trunk from the PSTN,packetize and optionally compress the audio signals an then deliver the packet to the IP network using real time protocol (RTP)

2. The MGC (also known as a call agent) contains the call processing.In addition it manage the resource of the MGs that it controls.The MGC controls the MG using a control protocol to set up the RTP connections and control the analog or TDM end point in the MG

3. THe SG sits at the edge of an IP network and terminates circuit-switched network signaling such as SS7 or ISDN from the circuit switched network.It transport or backhauls, this signaling to the MGC or other IP based application endpoint

MGCP can also be used as a control protocol between an MGC MGCU (TG) and an MG. While MGCP is defined by an informational (versus standard track) RFC, it is commonly used in many product today because the specification was available before Megaco and H.248 were finished.Both MGCP and Megaco/H.248 assume that the call control intelligence is outside the MGs and that the MGC handles it

Closely related to the MGCP protocol are the Packet Cable protocol, network based call signaling (NCS) and PSTN gateway call signaling protocol (TGCP).These protocol provide functionality similat to MGCP for cable based network


Sigtran

The IETF SigTran working group was founded after a Bird of a Father (BOF) session which was held at he Chicagi 1998 IETF meeting, to discuss transport of telephony sigaling over packet networks.The SigTran working group define the framework architecture and perfomance require in RFC 2719(126).The framework include the conceptof the reconstructing the traditional circuit switch into MGC,MG nad SG elements, thereby separating the signal and the media control plane

The framework document identified three necessary components for the SigTran protocl stack:

1. A set of adaptation layes that support the primitice of SCN telephony signaling protocol

2.A common siganling transport protocol that meets the requirement of transporting telephony signaling

3.IP network protocol

The three layers of the protocol stacks are:

1.Adaptation layer

2.Common Transport protocol

3.Internet protocol (IP) Read More..

Mobile Station at GSM

GSM refers to the cellular handsets as MS.PCMCIA cards are also available for laptop to allow data transfer over GSM network, without the need for a voice-centric handset.
The MS consists of typical equipment that the subscriber uses to access a PLMN and a removable smart card, knows as the SIM to identify the subscriber.

GSM was uniqueto use the SIM card to break the subscriber ID apart from the equipment ID.The SIM card is fully portable between Mobile Equipment (ME) units.This allows many features that we take for granted usch as being able to swap MS simply by swapping our SIM car over.All functionally continues seamless, including billing and the telephone number remains the same

An MS has several associated identities including the International Mobile Equipment Identity (IMEI), the International Mobile Subscriber Identity (IMSI), the Temporary Mobile Subscriber Identity (TMSI) and the Mobile Station ISDN (MSISDN) number


IMEI

Each ME has a unique number known as the IMEI, stored on it permanently.The IMEI is not only a serial number, it is also indicates the manufacturer, the country in which it was produced and the type approval. It is assigned at the factory

The IMEI is used so actions can be taken againts stolen equipment or to reject equipment that it cannot accept for technical and/or safety reason.The IMEI allows tracing and prevention of fraudulent use and in some circumtances,special network handling of specific MS types

Structures of the IMEI:

1.TAC (type approval code)

2.FAC (Final assembly code)

3.SNR (Serial number)


IMSI

Each subscriber is assigned a unique number,which is known as the IMSI.The IMSI is the only absolute identity a subscriber has within GSM and such as it is stored on the SIM.The SIM is a credit size or quarter-credit card size smart card that containts the subscriber's subscription details and grants the subscriber service when placed into a piece of ME.Among other purpose it is used for subscriber billing, identification and authentication when roaming

The structure of IMSI are

1. MCC ( Mobile Country Code)

2.MNC (Mobile Network Code)

3.MSIN (Mobile Station Identification Number)


TMSI

A TMSI is an alias used by the VLR ( and the SGSN in GPRS) enabled networks) to protect subscriber confidentiality.It is temporaily used as a substitute for the IMSI to limit the number of times the IMSI is broadcast over the air interface because intruders could ise the IMSI to identify a GSM subscriber


MSISDN

MSISDN is the number the calling party dial to reach the called party-in other qords it is the mobile usbscriber's directory number.This parameters refer to one of the ISDN number that assigned to a mobile subscriber in accordance with ITU recommandation

The structures of MSISDN are:

1.NDC (National destination code)

2.CC (Country code)

3.SN (Serial number) Read More..

Message Transfer Part (MTP)

MTP acts as the carrier for all SS7 message, providing reliable transfer of message from one signaling point to another.This function include levels one, two and three. In addition to providing signaling point to signaling point communication, the MTP also provide error detection and correction

The methodology of MTP are very similar to those used in other bit oriented protocol (BOPs), such as X.25.Sequence numbering and error checking mechanism are very similar
The signal unit structure used in all SS7 message provides all the information required by MTP level two and three.Flow control is provided through the use of a special signal unit called the Link Status Signal Unit (LSSU)

MTP provides all functions of layers one,two and three.Level two of MTP provides error detection/correction, as well as error checking through the cjeck bit field.In addition to these two fundamental functions, the following is provided:

1.Signal unit delimitation
2.Signal unit alignment
3.Signal unit error detection
4.Signal unit error correction
5.Signal unit initial alignment
6.Signal unit error monitoring
7.Flow control


Structure of MTP level two


The backward sequence number and the forward sequence number are used for sequencing packet and are used by level two to ensure tha all transmitted packets are received.They are also used for positive and negative acknowledgements.The indicator bits are used to request a retransmission.The lenght indicator allows level two to determine the type of signal unit being sent and the cyclic redundancy check (CRC) field is used to detect data errors in the signal unit


Flag

flag is used to indicates the beggining of a signal and the end of a signal unit.The flag in US network is used to indicate both beginning of the signal unit and the end another.In some other networks there can be both an opennung and closing flag


Sequence numbering

The SS7 protocol used sequence numbering like many other layer two bit oriented protocols.The SS7 technique is just a little different from, say X.25 but the principle is the same.Both a forwars sequence number (FSN and a backward sequence number (BSN) are provided


Indicator bits

The indicator bits are used to request a retransmission.There are two indicator bits; a forward indicator and a backward indicator bit.During normal conditions, both indicator should be of the same value (0 or 1).When a retransmission is being requested, the signal unit being sent by the signal point requesting the restransmission will have an intervet backward indicator bit.The forward indicator bit retains its original value.This indicates to the distant signaling point that an error occured and retransmission must take place.


Length indicator

it is used by level two to determine which type of signal unit is being sent.The value of the length indicator can be:
1. 0 (Fill in signal unit)
2. 1 or 2 ( link status signal unit)
3. 3 or more (message signal unit)


Cyclic redundancy check (CRC)

it is the last field in the signal unit.This field is calculated using the fields immediatly following the flag, up to the chek bit field itself Read More..

Essential understaning of MAN

Deployments in DWDM have stimulated huge capaciti level in long haul backbones nad large scale ethernet in LAN applications bandwidth.The subsequent bandwidth bottlenecks in MAS (Metropolitan Area Network) and AN (access network) have become increasly problematic.IP based voice and video service usch as NGN and IPTV have placed higher demand on MAN and AN functions and perfomance,rendering the condition of these two networks a significant concern to carriers

The concenpt of MAN initially describes a computer network concept corresponding to LAN and now it has been applied intelecom networks as a publice multiservice bearer network that provides broadband data and multimedia services in cities or suburbs with no strict definition.According to the NGN hierarchical architeture recommended by ETSI and ITU-T,NGN comprises two basic strata:service and transport.The transport layer refers to the service-supporting bearer network

A bearer network can be devided into three horizontal constituent parts:backbone netwrok,MAN and AN.The key factor in selecting bearer netwrok techonolies is the features of the services to the borne and these should be reflected in the technical developments of MAN.MAN services can be currently characterized as follows:

1.Compicated services.In additionto traditional TDM and internet, MAN has to bear nascent service usch as IPTV,NGN,3G,P2P and internet broadband applicaiton

2.Mainstream IP services.Essential to a new-type MAN construction is efficeint IP service bearing capability and suitably high QoS and security features.

3. Service inovations.New innovation rich services have been rapidly hitting the market, meaning that it is more adn more difficulty to cater the user demands since MAN require to possess sufficient flexibility,expandability and responsiveness in order to adapt to constantly changing requirements

4.Bandwidht hungry services.THe number of service necessitating high bandwidth coupled with increased users has placed upon MAN considerable badwidth and service management pressures

5.P2P applicaiotions.Large scale P2P applicaitons have changed traditional network traffic structure

6.Traditional service.Including TDM,FR and ATM these still occupy a place in the market.PSTN servie will exist long term and NGN and 3G service developments still rely on certain TDM circuits.The financial adn political sectors have special QoS and securiy demands and currently stick to traditional dedicated line services since doubts remain about the integrity of IP networks

7.Cost.MAN features a short service transport distance compared with the backbones, so cost is of great importance.Carrier can adopt low cost phisical layer technologies to enable short distance transport including ethernet direct connection and CWDM

Traditional networking concept comprises relively independent transport and data networks that provide different functions and so different applications are not carried over the sam network.Traditional carrier's MAN network include metro SDH,metro IP and occasionally ATM,FR and DDN which are siin to be replaced

SDH previously supported PSTN and PLMN and offered physical layer circuits to data networks.The metro IP networks was mainly used to provide internet service but the increase incarrie class IP application requires MAN to offer high quality IP bearing services.SDH networks have consequently developed into MSTP (multi service transport platform) that offer ethernet service and an IP bearing functions.The metro IP netwrok has also been developed into a carrier class by using MPLS and optimized ethernet technologies.For additonal carriers most MAN network will soon include metro MSTP and metro IP network.These two type of network are mmuttualy compelemtary but do compere with each other.They should be deployed in different area according to the conditions of subsequent phases with varied services domains.The gradual decrease in TDM services and the rapid growth of IP services means that the SDH based MSTP will offer fewer functions,while metro IP networks and ethernet will offer more Read More..