Tuesday, July 3, 2012

An Introduction to M2M Technology : It’s Applications & Prospects in Bangladesh

Md. Shahinur Rahman*

Today, mobile operators in developed markets are actively seeking new avenues for revenue generation since the traditional sources such as voice are getting saturated. M2M communication is considered as one such opportunity. It's now possible for your refrigerator to talk to your stove and your alarm system to your car, and you could control and run initial machines, systems all on one network. This is a new networking trend known as machine-to-machine, or M2M. M2M leverages wireless networking technologies like sensing and MANET (Missings Are Now Equally Treated) to much wider applications leveraging also the internet.


The origin of M2M communications is cloudy because of the many different possibilities of its inception. It began around the year 2000, possibly earlier, when cellular technology first began to learn to connect directly to other computer systems. The year 2009 was important to the development of M2M technology, both in the U.S., and in Europe. In the United States, AT&T and Jasper Wireless entered into an agreement to both support the creation of M2M devices jointly. In conjunction, they have stated that they will be trying to further connections between consumer electronics and M2M wireless networks, which would create a boost in speed, connectivity, and overall power of such devices.
M2M: What does it mean?
M2M stands for machine-to-machine, mobile-to-machine, or man-to-machine communication. Generally stated, M2M is the connection and communication among all aspects of the physical enterprise: knowledge workers, business applications, and remotely dispersed assets and equipment.
Machine-to-machine (M2M) refers to technologies that allow both wireless and wired systems to communicate with other devices of the same ability. M2M uses a device (such as a sensor or meter) to capture an event (such as temperature, inventory level, etc.), which is relayed through a network (wireless, wired or hybrid) to an application (software program), that translates the captured event into meaningful information (for example, items need to be restocked). Such communication was originally accomplished by having a remote network of machines relay information back to a central hub for analysis, which would then be rerouted into a system like a personal computer.
Simple Architecture of M2M
M2M communication is the data flow among people, devices, and systems. The data will be interpreted as information for remote control and monitoring. Three basic elements for M2M are:
  • Embedded Processor for storing data.
  • Communication Technology for transfer of data.
  • Management Applications for monitoring and control.
A machine can be defined as anything with mechanical, electrical, electronic, or environmental properties. Examples include manufacturing machinery, refrigeration systems, telecommunications equipment, server cabinets, data centers, HVAC systems, storage tanks, and security equipment. Industry-specific assets like utility equipment, natural gas compressors and pipelines, traffic management systems, and restaurant and convenience store equipment can also be considered machines in the context of M2M.

* Divisional Engineer Phones, Basabo, Khilgaon, BTCL, Dhaka.


Figure-1: Simple Architecture of M2M

Modern machines increasingly contain computers that stores information. They may also have inbuilt radios to transmit/retrieve information that helps efficient and safer automatic operation of home/industrial/business/medical processes. The information can important for operator to act on it accordingly. Even if machines do not contain computers, they can be attached with sensor radio devices to provide physical information. Moreover, the devices may happen to be out of range of each other and there will be a need to route the information i.e. both point to point and point to multi-point communication is necessary for M2M.
In recent years, SMS has become an increasingly important transmission mechanism for M2M communication, with the ubiquity of GSM and the relatively low cost of SMS being cited as advantages. Concerns have been raised over the reliability of SMS as an M2M channel, however the rise of direct Signaling System 7 (SS7) connected SMS gateways, which can offer increased reliability and the ability to confirm delivery, have allayed many of these fears.
M2M Value Network
Value generation for an M2M solution is only possible with the confluence of multiple industries and their respective players. Hence, a value network approach would enable us to capture the reality in an M2M business. Figure-2 provides an overview of all the roles involved in an M2M business. The roles are described as follows:

Figure-2: M2M value Network

The end-user for the M2M application can be either a business firm or a consumer. These roles don’t have a major influence on the value network as they are mainly involved in the consumption of the service. However, one possible way of their influencing the net is in terms of the demand. Changes in demand would lead to different configurations among other players in the network, in order to generate economically viable business
Service operator provides the basic M2M service to the end-user. The service operator works in tandem with the network operator to provide M2M services. The service operator has a direct relationship with the end-user.
•  Network operator provides the basic
Communication transport network service to the service operator.Application provider develops M2M value-added services for a service operator to be consumed by the end-user.
Equipment vendor:
Ø  End-user equipment vendor provides M2M-enabled equipments. A player having this role would typically work with the systems integrator.
Ø  Mobile equipment vendor provides the necessary mobile infrastructure such as GSM-based modules for M2M communications. A player having this role works in cooperation with the network operator.
System integrator plays a major role in providing an end-to-end M2M solution. A player with this role would work together with the network operator, end-user and equipment vendors.

A player can assume one or more of these roles according to the business model. Assuming more than one role could provide additional power in the value network. For instance, a network operator can act as a service operator and systems integrator in order to get greater control over the value network.
M2M in Everyday Life: The Internet is now staple in everyday consumer life, enabling people to connect and share information with other people, and to stay connected to the world. Web-enabled devices (cellular phones, PDA’s, mini-computers, etc.) and communications services are introduced everyday that go beyond people-to-people connections to connect businesses, healthcare providers and others with individual consumers. They aren’t simply connecting with people. They are providing “smart consumer services” that ultimately improve and enhance individual quality of life. They enable consumers to protect and better manage their homes, cars, and other personal effects. They help them improve and maintain the condition of their health. And they provide conveniences never before dreamed of.

M2M Applications:                                               

  • Improved tire safety via tire pressure monitoring (TPM) - information is transmitted from auto tires to the auto computer that alerts owner.
  • Improved auto performance via in-car computer reporting operating condition data that tracks performance that notifies and coordinate warranty services and routine maintenance.
  • Reduced loss of auto via global positioning systems (GPS) that enable smart consumer services such as Vehicle location via SMS/Web, Nearest vehicle trace, Engine status, Movement status (standby/running), Hijack Vehicle Detection and Anti-theft system.
  • Lifestyle conveniences such as keyless entry for locking/unlocking doors and trunks, remote engine ignition, and anti-frost systems, "NO-GO" area,,Speed violation alert,  Battery tamper alert
Healthcare & Sports
  • Decreased recovery time and lowered health care costs via remote patient monitoring and management outpatient services
  • Improved qualify of life via pacemaker, insulin pumps, heart-related monitors, medical alert pendants, hearing aids, and other health-critical monitoring devices and services that are not only tied to managed care services, but also to emergency alert and messaging services to notify of device failure and patient incapacity
  • Lifestyle conveniences such as wireless heart-rate monitors, time/distance/speed monitors and receivers that transmit sport and exercise performance data to manage on-going fitness programs
Home Automation & Control
  • Improved security via home security systems that monitor and detect dangerous conditions from fire and other hazards, and intruders
  • Preserve energy through lighting, thermostat, irrigation and utility systems that not only enable remote controls, but also monitor operating condition of A/C units, pools, water heaters, and more in real time to detect potential over-consumption of utilities as well as forewarning potential failure
  • Lifestyle conveniences that include wireless speakers, entertainment controls, computer devices such as wireless keyboards, mouse’s, headsets, wireless game controllers

M2M in Public Services

Public services organizations are implementing M2M solutions to help them offer services and works within the most effective and sustainable use of both their natural resources available and their services infrastructures. Original equipment manufacturers (OEMs) and solutions providers have begun providing wireless networking-enhanced products to public services organizations along with “smart services” to help them achieve their cost and resource conservation goals.

As a services provider, the pubic services organizations themselves have extended the M2M capabilities to their constituents and have begun providing “smart services” as well. Smart services offered by public services organizations ultimately improve and enhance individual quality of life while improving quality of life collectively for the communities they serve.

Water, Electricity, and Gas
  • Reduced overall costs and improved accuracy of collecting utility usage information for billing purposes through automatic meter reading (AMR) -- the remote collection of consumption data from electric, water and gas meters -- using wireless communications
  • Improved conservation via “time-of-use” metering / billing that ties pricing of power and water consumed based on time-of-day and adherence to usage allocations
Homeland security
  • Improved security in ports and transit systems via cargo container security systems and services that identify contents and monitor conditions of containers.
  • Secure public infrastructure (water, power and fuel supply chains) via asset tracking and monitoring using GPS / satellite and radio communications with ability for remote control monitor real-time conditions.

Prospects of M2M in Bangladesh:

At present, In our country the total number of Mobile Phone Active Subscribers has reached 89.457 million3 at the end of March 2012, the total number of PSTN Phone Subscribers has reached 1028.19 thousand3 at the end of May 2010 and the Internet subscribers has reached 31140.8043 thousand (mobile internet 29609.497 + PSTN 1208.000 + WiMAX 323.307) at the end of February 2012. However we stand on a low level of internet diffusion. The latest statistics revealed that internet penetration for PSTN is only 0.8 percent8 in Bangladesh. Though the PSTN internet penetration is very poor but the number of mobile internet subscribers is very high and we find one mobile phone in every two person9. So this huge number of mobile phones subscribers indicates a great opportunity for M2M Services in Bangladesh. We can also apply the services of M2M into our service type Organizations (like: DESA, DESCO, Railway, Telecom, BRTC, BIWTA, Port, Banks, WASA, TITAS, etc). Already some mobile operators & Financial Institutions are started a few M2M services like: Vehicle tracking, Buddy Tracker, e-bill (Electric Bill, Gas Bill etc), Railway Ticketing, e-care, Mobile banking, e-banking, electronic money transfer etc. So there is a huge prospect’s / opportunities both have in Public & Private sectors in Bangladesh.

Conclusion: Maturity in voice revenues and advancement in the mobile technologies have motivated operators to look at possibilities of providing value-added data services. In this regard, M2M services have attracted much attention recently from the mobile operators in Bangladesh. The current implementations are concentrated to individual users but it should be concentrated towards business users. They are as follows:
• Mobile operators need to interact and cooperate with industry players outside the mobile realm in order to provide innovative, cost-efficient and revenue generating M2M solutions. This would mean new relationships in the value network, which is no longer, same as visible in the mainstream mobile market.
• Major operators can gain greater control of the value network due to their financial power. However, smaller operators can also play a major role as service operators. There are numerous forecasts predicting an enormous increase in the number of M2M-enabled devices and an increase in the M2M-related revenue generation.

Monday, June 18, 2012

Wireless Communication Technologies: that connect the entire world without limit.

Md. Bahadur Ali
GM (Finance & Accounts)

Network technology plays a significant role in the science and business area. Scientists innovate and develop some new technologies to fit businesses’ needs and to satisfy people’s demands. The first generation, 1G wireless mobile communication systems, was introduced in the early 1980s and completed in the early 1990s. 1G wireless was analog and supported the first generation of analog cell phones with the speeds up to 2.4kbps. The second generation, 2G system, fielded in the late 1980s and finished in the late 1990s, was planned mainly for voice transmission with digital signal and the speeds up to 64kbps. The third generation, 3G wireless system, was developed in the late 1990s and might be well-done in the late 2000s. 3G is not only provided the transmission speeds from 125kbps to 2Mbps, but also included many services, such as global roaming, superior voice quality and data always add-on. The fourth generation (4G) is a conceptual framework and a discussion point to address future needs of a high seed wireless network that can transmit multimedia and data to and interface with wire-line backbone network perfectly just raised in 2002. The speeds of 4G can theoretically be promised up to 1Gbps. The beyond will be 5G with incredible transmission speed with no limitation for access and zone size.

The main distinguishing factors between 3G and 4G will be data rates, services, transmission ways, access technology to the internet, the compatibility to interface with wire-line backbone network, quality of service and security. 4G should support at least 100 Mbps peak rates in full-mobility wide area coverage and 1Gbps in low-mobility local area coverage. The speeds of 3G can be up to 2Mbps, which is much slower than the speeds of 4G. For the service, 3G marketing is difficult to roam globally and interoperate across networks, yet 4G will be a global standard that provides global mobility and service portability so that service provider will not longer be limited by single-system. In order words, 4G should be able to provided very smooth global roaming ubiquitously with lower cost. Furthermore, 3G is based on a wide-area concept applying circuit and packet switching for transmission with limited access technology, such as WCDMA, CDMA and TD-SDMA. However, the 4G standard will base on broadband IP-based packet switching method of transmission with seamlessly access convergence. It means that 4G integrated all access technologies, services and applications can unlimitedly be run through wireless backbone over wire-line backbone using IP address. In the other words, 4G will bring us almost perfect real world wireless or called “wwww: World Wide Wireless Web.
Comparison among technologies (Generations)
Time period
14.4Kbps (peak)
During 1G Wireless phones are used for voice only
Digital Narrow band circuit data
9.6/14.4 Kbps
2G capabilities are achieved by allowing multiple users on a single channel via multiplexing. During 2G Cellular phones are used for data also along with voice.
Packet Data
171.2 Kbps (peak) 20-40 Kbps
In 2.5G the internet becomes popular and data becomes more relevant. 2.5G multimedia services and streaming starts to show growth.
Digital Broadband Packet Data
3.1 Mbps (peak) 500-700 Kbps
3G has Multimedia services support along with streaming are more popular. In 3G, Universal access and portability across different device types are made possible. (Telephones, PDA,s, etc.
Packet Data
14.4 Mbps (peak) 1-3 Mbps
3.5G supports higher throughput and speeds to support higher data needs of the consumers.
Digital Broadband Packet All IP Very high throughput
100-300 Mbps (peak) 3-5 Mbps 100 Mbps (Wi-Fi)
Now (Read more on Transitioning to 4G)
Speeds for 4G are further increased to keep up with data access demand used by various services. High definition streaming is now supported in 4G.
Not Yet
Probably gigabits
Not Yet
Soon (probably 2020)
Currently there is no 5G technology deployed. When this becomes available it will provide very high speeds to the consumers.

How 4G works:
In the 4G wireless networks, each node will be assigned a 4G-IP address (based on IPv6), which will be formed by a permanent “home IP address and a dynamic” care-of address that represents its actual location. When a device (computer) in the Internet wants to communicate with another device (cell phone) in the wireless network, the computer will send a packet to the 4G-IP address of the cell phone targeting on its home address. Then a directory server on the cell phone’s home network will forward this packet to the cell phone’s care-of address through a tunnel, mobile IP; moreover, the directory server will also inform the computer that the cell phone’s care-of address (real location), so next packets can be sent to the cell phone directly. The idea is that the 4G-IP address (IPv6) can carry more information than the IP address (IPv4) that we use right now. IPv6 means Internet Protocol Version 6 including 128 bits, which is 4 times more than 32bits IP address in IPv4. 32 bits IP address looks like this or 11011000.00100101.10000001.00001001 (32bits). However, the IP address in IPv6 version will be 4 times of IPv4; it looks like,,, It includes 4 sets of IPv4 address defined in different functions and usages. In previous example for the case, the first set of the IP address ( cab be defined to be the “home address purpose. It just likes the normal IP address that we use for addressing in the Internet and network. The second set of the IP address ( can be declared as the “care-of address. It is the address set up for the communication from cell phones to computers. After these addresses from cell and PC established a link, care-of address will instead of home address; it means that communication channel will switch from the first set to the set to the second set of the IPv6 address. The third set of the IP address ( can be signed as a tunnel (mobile IP address). It is the communication channel to wire-line network and wireless network. An agent, a directory server, between the cell phones and PC will use this mobile IP address to establish a channel to cell phones. Then, the last set of IP address ( can be local network address for virtual private network (VPN) sharing purpose. In this rich data IP address, software can use them to distinguish different services and to communicate and combine with other network areas, such as computer (PC) and cell phones network in the case of the example. In addition, the table bellow is a basic comparison of IPv6 and IPv4 showing that how IPv6 richer than IPv4 in data containing capacity. Moreover, in 4G wireless network, not only has it IPv6 transmission protocol, but also be supported by OFDM, MC-CDMA, LAS-CDMA, UWB and Network-LMDS.

OFDM stands for Orthogonal Frequency Division Multiplexing, transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. In the other words, OFDM is a digital modulation technology in which in one time symbol waveform, more than thousands of orthogonal waves are multiplexed for increasing signal strength. This is good for high bandwidth digital data transition. In OFDM, two wireless devices will establish a connection tunnel before they start their communication. Therefore, after making a connection between a certain target, the radio signal will split into many smaller sub-signals with accurate direction to the target.

MS-CDMA stands for Multi-Carrier Code Division Multiple Access, which is actually OFDM with a CDMA overlay. The users are multiplexed with orthogonal codes to distinguish users in MS-CDMA and single-carrier CDMA systems. It allows flexible system design between cellular system and signal cell system. However, in MC-CDMA, each user can be allocated several codes, where the data is spread in time or frequency.

LAS-CDMA, Large Area Synchronized Code Division Multiple Access, is developed by LinkAir Communication, a patented 4G wireless technology. “Las-CDMA enables high-speed data and increases voice capacity and the latest innovative solution, Code-Division Duplex (CDD), merges the highly spectral efficient LAS-CDMA technology with the superior data transmission characteristics of Time-Division Duplex (TDD) This resulting combination makes CDD to be the most spectrally efficient, high-capacity duplex system available today. In the 4G area, LAS-CDMA is played as a global transmission protocol (“World Cell) as showing in the following picture, Zone size. It means that if the distance is too for to two wireless devices, they have to use this protocol with IPv6 to establish their connection.

In 4G technologies, UWB radio can help solve the multi-path fading issues by using very short electrical pulses to across all frequencies at once. However, UWB can only be used indoor or underground because of its low-power requirement. Thus, UWB has to be used with OFDM, which can transmit large among of digital data with multi-path algorithm; OFDM running outdoor, UWB running indoor to ensure signal strength purpose. In the 4G wireless technology, UWB will be played as “Pico Cell of very limited distance in the buildings.”

The Network-LMDS, Local Multipoint distribution system, is the broadband wireless technology used to carry voice, data Internet and video services in 25GHz and higher spectrum. Its broadcast method consisted simultaneous voice, data, Internet, and video traffic can be the solution of signal fading issue in local area. Therefore, Network-LMDS can be played as Micro Cell and Micro Cell in the 4G technology to be the main transmission protocol for the wireless devices, showing as the picture below.

The idea of the complementation of IPv6, OFDM, MC-CDMA, LAS-CDMA, UWB and Network-LMDS can be arranged in different zone size. IPv6 can be designed for running in the all area because it is basic protocol for address issue LAS-CDMA can be designed for the global area as zone 1, world cell. OFDM and MC-CDMA can be designed for running in the wide area (zone 3), called Macro cell. Network-LMDS in Zone 2, Micro cell and UWB is in Zone 1, Pico cell. Based on above transmission protocol, we knew that each of them has its drawback(s) in somewhere; although the complementation with all of them, it is not perfect yet go implement 4G’s great idea. Academic research and experiments are still required for further developing of 4G in the following few to 10 years.

Nowadays, wireless technology is getting popular and important in the network and the Internet field. In this paper, I briefly introduced the history background of 1G to 5G, compared the differences of 3G and 4G, and illustrated how 4G may work for more convenient and powerful in the future. 4G just right started from 2002 and there are many standards and technologies, which are still in developing process. Therefore, no one can really sure what the future 4G will look like and what services it will offer to people. However, we can get the general idea about 4G from academic research; 4G is the evolution based on 3G’s limitation and it will fulfill the idea of wwww. World Wide Wireless Web, offering more services and smooth global roaming with inexpensive cost.

-           Internet
-           Mr. Mirza Ahmed Hussain,  Ex Dir. BTTB.

Saturday, June 9, 2012

Dense Wavelength Division Multiplexing (100 G Solution) adopted in SMW-5 Submarine Cable System - What is in the Laboratory for Higher Bandwidth Solution?

Md. Monwar Hossain *
Parvez M. Ashraf **


Ever since the internet from the research lab of the scientists and engineers came into the people’s world during the 1990’s, there had been exponential growth of demand for bandwidth. The society and the economy started to be shaped by the wide spread use of internet. Today internet has put its spell on people with numerous features such as browsing, emailing, blogging, twitting, facebooking, online gaming, conferencing, audio/video streaming, internet TV, etc. Having access to high speed (or, in other term, high capacity) triple play (voice, data and video) communication for various business and non-business oriented activities has become the norm of today’s students, educators, researchers, professionals and other people.
So meeting the rapidly increasing demand for capacity in the global and national information superhighways is a great challenge as ever, making the telecommunication technology today to go through major innovations and developments to meet up the capacity requirements in the core communication systems and networks. As we have indicated in a Teletech article last year, the exponential growth of Bandwidth demand has made the 10 and 40 G technology of optical networking insufficient to meet future needs.
The SMW-4 Consortium’s Submarine Cable system was originally built with 10 G systems but it is now being upgraded with 40 G and 100 G technologies. BSCCL has been a member of the SMW-4 and also became a party of the newly formed SMW-5 Submarine cable consortium with a bid to join Bangladesh to a second submarine cable. SMW-5 cable has been planned based on the 100 G technology, which is now more matured and has become the standard since more than a couple of years. We hope that by the year 2014 Bangladesh will be able to take advantage of a technologically advanced system made althrough by using the 100 G technology.

2. Status of 100 G Technology

Fig. 1: A comparison between the Constellation points at different modulation schemes at bit rate 46 Gbps (aprrox. 40 Gbps)

The optical line terminal equipments of the present and near future need to be able to handle very high speed traffic transported to a long distance. Because of the notable technical

Fig. 2: A depiction of BER vs OSNR at different modulation schemes at bit rate 46 Gbps (aprrox. 40 Gbps)

developments on the DWDM components, it can be said that DWDM approaches have surpassed the time division multiplexing (TDM) for the high speed transmission over long distance which can be even on a single fiber instead of a pair of fibers for transmission and reception with a specific terminal. The economic and technical challenges associated with achieving a 100G transmission solution has been overcome within the last 4 years. 100Gbps error free transmission has been demonstrated in 2008 by companies such as the Nortel (now, Ciena), at the Optical Fiber Conference/National Fiber Optical Engineer Conference. The key breakthrough factor of the solution has been the coherent receiver. For the past three decades or so, optical system receivers have been working by detection of the transmitted signal’s intensity with on-off keying.
A coherent receiver operates by mixing a local oscillator and the incoming signal to be received. If the local oscillator is tuned into the frequency of the incoming signal, then only the information from the incoming signal is extracted, and neighboring channel information is ignored, thus unwanted signal elimination became much better. Most vendors basically applied this method towards solving optical transmission challenges at higher line rates.
The bit-rate of a channel can be described as the simple product of the baud rate or symbol-rate, bits per symbol and the number of carriers used. Recent commercial coherent systems at 40 Gbps and 100 Gbps have exploited all of these dimensions. The technology that made this

Fig. 3: Coherent 100 G System

100 G transmission possible is Dual Polarization QPSK modulation (DP-QPSK) with a coherent receiver. Modulation is required to ensure propagation, to perform multiple accesses and to enhance the SNR, as well as to achieve bandwidth compression. DP-QPSK modulation technique would decrease the baud or symbol rate of the system, using four bits per symbol, keeping the optical spectrum four times narrower than the unreduced baud rate. Because of the capability to pass through multiple Optical Add-Drop Multiplexers (OADMs) and its practical PMD (Polarization Mode Dispersion) tolerance, DP-QPSK is recognized as a viable format for deployment within 50GHz-spaced systems.

3. SEA-ME-WE-5

Fig. 4: Proposed Route Diagram of SMW-5 (Bangladesh will join through a branch cable with the main cable)

Existing SMW-4 cable is the only submarine cable that has kept Bangladesh connected with the international information superhighway. Due to any calamity or other reasons, if this cable get into any kind of physical damage or disruption, country’s international long distance telecommunication would suffer badly. That’s why Bangladesh has been working for long to acquire a second submarine cable so that the international links can be maintained without outage. In this sequence of efforts, Bangladesh established contact with a new consortium,
SEA-ME-WE-5, and already signed a MoU (Memorandum of Understanding) with the Consortium. Initially, there will be 16 parties in the Consortium. The submarine cable this time will extend from Japan up to London for a total of 25000 Km. The estimated cost for joining this project is 48 million USD for Bangladesh. However, the cost will be reduced to 38 million USD if Myanmar joins and shares the branch cable with Bangladesh. Bangladesh might get 17 lambda of 100 Gbps capacity for each altogether coming to 1700 Gbps. Upto now, the Landing Station of the second submarine cable has been planned to be in Mongla of Bagerhat district. The physical infrastructure of the Landing Station is expected to be built by 2012-2013. It is expected that by the end of 2014, the process of joining of Bangladesh with a second submarine cable will be completed.

Fig. 5: System Configuration Diagram (proposed) of SMW-5

4. Beyond 100 G Technology: Coherent Systems, Super channels or Optical OFDM might be the solutions
In the recent years, due to the new developments in polarization multiplexed phase modulated DWDM transmission over long distance, optical coherent detection, sophisticated DSP (Digital Signal Processing) and high performance ICs (application specific integrated circuits or ASICs), the transceiver equipment for optical transmission is emerging with high
level of capacity & sophistication. Specially, coherent detection has made possible to choose among wide range of modulation formats, such as the use of dual polarization or multiple sub-carriers. Also, use of digital signal processing techniques for leveling out various linear and nonlinear impairments has become viable with coherent detection. It has been practically found that the coherent systems can provide robust tolerance against unwanted transient signals. Therefore, the future high speed and high performance transmission systems are expected to be based on coherent systems. Optical coherent systems are likely to bring future optical transmission systems at 200 G, 400 G, and later 1 (one) Terra or 1000 G systems.
DWDM is considered as an important technique enabling multiple optical carriers to travel in coexistence in parallel through a fiber that facilitates more efficient use of the expensive fibers over thousands of Kilometers. The present “state of the art” for DWDM in 2012 or 2013 may be still 100 Gbps. However, the growth in the internet has created requirement for new scale for bandwidth and that is preferably without adding any more complexity to the operations. It is clear that for a high capacity network beyond the 100G, in addition to a move toward larger, more powerful transport switches, the mechanisms of DWDM optical transmission may have to change.

Fig. 6: Bandwidth Virtualization with Super-channels

A new approach to DWDM capacity, the super-channel could be an effective solution to the challenges posed by today’s internet growth. In simple terms, the super-channel is an evolution in DWDM in which several optical carriers are combined to create a composite line side signal of the desired capacity, and which is provisioned in one operational cycle. It could be more practical to combine multiple carriers into a super-channel to move beyond 100 Gbps than it is to simply increase the data rate of an individual carrier. However super-channels are indistinguishable from a single carrier channel of the same data rate as long as normal end
users are concerned. Similar to CPU multi core processing the concept of super channels resemble to Bandwidth virtualization through multi-carrier techniques. DWDM super channels have the potential to offer an ideal solution to the problems of increasing optical transport capacity beyond 100 Gbps, up to 1 (one) Terra bps. This will also provide reduction in complexity with electronic circuitry by using large scale PICs (Photonic Integrated Circuit).