Monday, 30 April 2007


Global Megatrends
1. Internationalization
2. Information networking
3. Distance of science and technology

The greatest engineering achievements of the 20th century
1. electrification
2. automobile
3. airplane
4. purification
5. electronics-Transistor
6. Radio and TV
7. agriculture
8. computer

First monolithic IC by R.N.Noyce
First enhancement MOSFET

Evolution of FinFET

Moore’s law (

First microprocessor
Itanium microprocessor

Top 30 world markets in year 2030
1. portable data communications
2. PC
3. Mobile phone service
4. CPU
5. Digital contents products
6. Magnetic memory
7. Electronic commerce

Monday, 16 April 2007

Canada's closely-watched tech giant

CBC News

Nortel Networks, the Canadian telecommunications equipment giant, began its corporate life in 1895 making equipment for traditional phone companies in Canada, a few years after Alexander Graham Bell invented the telephone. Originally, part of Bell Telephone, it morphed into Northern Telecom, and finally Nortel. The company remade itself as an Internet company in the 1990s and was often called the poster boy for companies making the transition into the new economy.

But when the Internet bubble burst in 2000, Nortel went from poster boy to whipping boy.
Major changes began at Nortel when John Roth took office in 1997 as the company's president and chief executive officer. He saw that the marketplace of communications was shifting from telephone technology to the Internet. The trick was figuring out how to speed up the process of getting new products and services into the market so Nortel could keep ahead of the fast-paced Web world. In the past, it often took as long as five years to complete a research and development project.

Under Roth's leadership, Nortel was dramatically restructured. Forums were created where nominated employess from every level gathered to help make the company more in tune with the wireless and optical marketplace. Nortel moved to outsourcing much of its production, resulting in the closure of 18 of the company's 24 plants.
The changes helped put Nortel at the top of its league. By some estimates, Nortel equipment was carrying 75 per cent of the Internet traffic in North America as the 1990s came to a close.
Nortel's growth was in part based on acquisitions. It went on frequent buying sprees, often using its own stock to make acquisitions. In 2000 alone, it bought 11 companies for a total of $19.7 billion US.

And then the bubble burst.
Nortel's best customers – telephone and data carriers – began warning that they would be drastically cutting back on their purchases of specialized Nortel equipment. Nortel's sales plunged by 50 per cent. The value of the companies Nortel had bought collapsed too. In less than a year, firms that Nortel had paid billions for were worth just hundreds of millions.
Following the dramatic downward revision in the company's outlook for 2001, some industry watchers (who used to be cheerleaders for Nortel) began questioning Roth's leadership and credibility, especially since the company earlier promised three times that it would meet its 2001 financial targets. Irate investors filed numerous lawsuits against the firm.

Roth – named Canada's "Business leader of the year" in 2000 – stepped down as president and CEO in early October 2001, replaced by Frank Dunn. The company announced another 10,000 job cuts and a third-quarter loss of $3.47 billion later that month.

The jobs cuts continued as Nortel struggled to deal with the unprecedented downturn in its business. By the end of 2001, Nortel had just 45,000 employees – half the workforce it had begun the year with.

The bottom line for 2001 was brutal – a loss of $27.3 billion US.
And 2002 brought more misery, and mere glimmers of hope. In February 2002, the company's chief financial officer, Terry Hungle, resigned following allegations that he broke the company's trading rules in some of his personal stock transactions.
In subsequent months, Nortel warned that business was still not picking up; its long-term debt was downgraded to "junk" status by both Moody's Investors Services and Standard & Poor's; and by October, its shares had plunged to just 69 cents – more than 99 per cent lower than where it had been barely two years earlier.
More job cuts brought the company's work force to 35,000 by the end of 2002, about one-third of the work force Nortel had at the start of 2001.
Then, two years of savage job-cutting started to pay off. In January 2003, Nortel reported better-than-expected results that led some analysts to raise their outlooks.
Nortel said it was on track to report a profit by the middle of the year.
As it turned out, the company managed a $54-million US profit in the first quarter – its first quarterly profit in three years.
Its stock price began to rally, topping $6 by September as it signed billions of dollars in new deals with Verizon Wireless in the U.S. and Orange in France.
Technology companies were again spending – not like they were in 1999 – but at least they were spending.
Nortel announced new deals with mobile phone companies Verizon and Orange. In October 2003, the company posted another quarterly profit, and in January 2004 it announced its first annual profit since 1997.
But in March 2004, Nortel warned that it would delay filing its audited financial statements for 2003 and would likely make more financial restatements, sending the stock plunging. The company then put its chief financial officer and controller on paid leave. The stock sank again.
Both the U.S. Securities and Exchange Commission and the Ontario Securities Commission began investigations in April 2004 of Nortel's earnings restatements.
Then on April 28, 2004, Nortel fired its top executive, Frank Dunn, and the two executives who had been on paid leave, and put four more on paid leave. It said a preliminary review suggests its calculated profit for 2003 will have to be reduced by 50 per cent.
In May 2004, the U.S. Attorney's Office in Dallas launched a criminal probe into Nortel, requesting documents going back to Jan. 1, 2000. The Ontario Public Service Employees Union Pension Trust filed a class-action lawsuit against Nortel a few days later.
Nortel's problems continued when it said on June 2, 2004, that its updated financial results for 2003 and the first quarter of 2004 still weren't ready. It subsequently missed three self-imposed reporting deadlines as it struggled to unravel the accounting mess left by the previous management.
Another criminal investigation into Nortel's accounting practices, this time by the RCMP, began in August 2004. Days later, Nortel cut 3,500 jobs, about 10 per cent of its workforce, and fired seven more people from its finance department over accounting problems. Nortel later announced the job cuts would total 3,250, with 950 of those jobs coming from Canada.
When Nortel finally filed its 2003 financials in January 2005, the revisions lowered the company's initially-stated profit of $732 million US to $434 million US. Its 2004 financials, reported in May 2005, showed that the company actually lost money that year – $51 million US. Revenues fell 3.6 per cent from 2003. CEO Bill Owens said he wasn't happy with the results, but said that Nortel, at last, was "now stable."
Just a month later, the company's president and chief operating officer, Gary Daichendt, and its chief technology officer, Gary Kunis, resigned. Both had been with the company less than three months.
In October 2005, Nortel picked former Motorola executive Mike Zafirovski to succeed Bill Owens as CEO. Several months later, Nortel announced it had put aside $2.5 billion US to settle some class-action lawsuits stemming from the company's 2004 accounting scandal.
In March 2006, Nortel once again announces its financial filings will be delayed and it will restate financial results for 2003, 2004 and the first nine months of 2005. It also announces a $2.2-billion US loss for the last quarter of 2005, due mainly to the cost of litigation to settle lawsuits from its shareholders.
In May 2006, Nortel Networks warned investors that its first quarter revenues would be flat or down slightly, and that it would post a slightly higher loss than in the first quarter of 2005. In a conference call with analysts, CEO Zafirovski pledged to "recreate" the "great company" that Nortel once was.
Just weeks later, CEO Zafirovski announced a further restructuring. The changes include the elimination of another 1,100 jobs, the creation of two new "centres of excellence," the conversion of the company's pension plan to one that doesn't guarantee a specific pension benefit, and a trimming of other retirement benefits. The company hopes to save $175 million US a year by 2008.
On Dec. 1, 2006, the company went ahead with a 1-for-10 stock consolidation. Its shares jumped 10-fold in price to over $24, but the number of shares plunged from 4.33 billion to 433 million.
But Nortel's restructuring efforts were not over yet. Despite shedding more than 60,000 jobs in six years, the company announced another 2,900 job cuts in February 2007 — a move that would bring the payroll down to 31,000. Another 1,000 jobs would switch to lower-cost countries like China, India and Mexico.
Even after all those cuts, Nortel is still North America's largest maker of telephone equipment.
But it was still making news for the wrong reasons. In March 2007, the U.S. Securities and Exchange Commission and the Ontario Securities Commission announced legal proceedings against former CEO Frank Dunn and three other former senior executives. The SEC accused the four of civil fraud relating to Nortel's accounting and its restatements. The OSC alleged that Dunn and two others broke securities laws by making "material misstatements" in Nortel’s financial filings that they knew or should have known were "materially misleading."

Audio Watermarking Algorithm for Copyright Protection

(Photo quoted from NeAsia)

Digital watermark technology is now drawing attention as a new method of protecting digital content from unauthorized one.

Critical band
It can be shown that the sensitivity of the ear to every frequency is not quite the same.

Masking effect
Frequency domain masking also called simultaneous masking. If two signals have close frequency, the louder one will make the weaker one inaudible. For example, conversation at a bus stop can be completely impossible if a loud bus is driving past. The masking phenomenon occurs because any loud sound will distort the Absolute Threshold of Hearing, making quieter, otherwise perceptible sounds inaudible.

(Wikipedia)In telecommunications, direct-sequence spread spectrum (DSSS) is a modulation technique. As with other spread-spectrum technologies, the transmitted signal takes up more bandwidth than the information signal that is being modulated. The name 'spread spectrum' comes from the fact that the carrier signals occur over the full bandwidth (spectrum) of a device's transmitting frequency.
Math formula Tb = NTc, where N is the length of PN sequence

Watermark embedding
(Quoted from MusicTrace) With the aid of the software products of the ContentMark product family, it is possible to embed additional information into audio signals. This additional information is transmitted to the final user hidden in the music in a form that is imperceptible to human hearing. A further characteristic is the fact that embedding of a watermark does not change the format. The final user does not have to purchase special player devices, instead he can still play these titles using conventional equipment.
The additional data are robustly embedded in the audio signal; this means that they cannot be removed by simple means. The objective of developing the audio watermark technique was to ensure that the watermark does not become unusable until intentional or inadvertent disturbances have degraded the audio quality to such an extent that the recorded title no longer has any economic value.
The information to be embedded is transferred in so-called data containers. Several data containers have already been developed, they differ in the volume of data that is to be transferred, the data rate and the robustness of the watermark. The two most commonly used data containers transfer 48 bits in 5 or 2.7 seconds. Other data containers can be generated as agreed with the customer.

Watermark extraction
(quoted from Watermark Extraction project (WatEx) was established in October 2004 as a Ph.D. research study, the aim of this project is to automatically retrieve and store paper watermarks in a digital representation in order to preserve its historical value, and to provide better access and distribution with the current Information and Computing Technology (ICT). The focus will be on the digital acquisition, and automatic processing and analysis of the visible paper-based watermark, probing beyond the paper surface data to extract the watermark design and to create a digital representation for long term preservation.

GPS receiver

(Photo quated from
Galileo system
1. Europe’s own global navigation satellite system
2. It ascertains one’s precise position in space
3. European Union support
(Wikipedia)Galileo is tasked with multiple objectives including the following: to provide a higher precision to all users than is currently available through GPS or GLONASS, to improve availability of positioning services at higher latitudes, and to provide an independent positioning system upon which European nations can rely even in times of war or political disagreement. The current project plan has the system as operational by 2011–12, three or four years later than originally anticipated.

GPS/Galileo Signal and Channel
GPS Galileo
Pilot channel none yes
BOC modulation none yes
Satellite code length 1ms 4ms

GPS signal
The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. It uses spread spectrum communication.

Design of complex filter
1.Complex filter is a bandpass filter with an asymmetric amplitude response
2.Use the transconductor and capacitor to replace resistor and inductor

Tuesday, 10 April 2007

GPRS Overview

GPRS functional overview

The General Packet Radio Service (GPRS) is a wireless packet data service that is
an extension to the GSM network. It provides an efficient method
to transfer data by optimizing the use of network resources. The GPRS radio
resources allocator allows to provide multiple radio channels to only one user in
order to reach high data user rate. Furthermore, one radio channel can be shared by
multiple users in order to optimize the radio resources. Then, the GPRS enables a
high spectrum efficiency by sharing time slots between different users, supporting
data rates up to 170 kbit/s and providing very low call set-up time.
Additionally, GPRS offers direct Internet Protocol (IP) connectivity in a
point-to-point or a point-to-multipoint mode and provides packet radio access to
external packet data networks (PDN).

GPRS introduces a minimum impact on the BSS infrastructure and no new physical
radio interface. The Nortel Networks GPRS network architecture is implemented
on the existing wireless infrastructure with the inclusion of the following network

BSS side:

-Packet Control Unit Support Node (PCUSN)
Core Network side:

-Serving GPRS Support Node (SGSN)
-Gateway GPRS Support Node (GGSN)
-SS7/IP Gateway (SIG)
Nortel Networks

Sunday, 8 April 2007

long-hop transimission in sensor networks

(photo quoted from
Application of Sensor Networks
1.In military
Intelligence, surveillance and reconnaissance.
2.In health
Monitor patients and assist disabled patients.
3.Other Commercial applications
Managing inventory, monitoring product quality and monitoring disaster areas.

Sensor network: small size, low cost, low-power
In some situations, log-hop transmission is better than short-hop transmission.

(Wikipedia)A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations. The development of wireless sensor networks was originally motivated by military applications such as battlefield surveillance. However, wireless sensor networks are now used in many civilian application areas, including environment and habitat monitoring, healthcare applications, home automation, and traffic control.
In addition to one or more sensors, each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontroller, and an energy source, usually a battery. The size of a single sensor node can vary from shoebox-sized nodes down to devices the size of grain of dust. The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few cents, depending on the size of the sensor network and the complexity required of individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth.
In computer science, wireless sensor networks are an active research area with numerous workshops and conferences arranged each year.

Tuesday, 3 April 2007

Optical Transmission

Optical Fiber
(photo quoted from European Space Agency)
Why? Because it is immune to electrical interferences, it does not radiate signals, it uses less duct space than cooper or coax, goes longer distances and has now very low cost and huge information capacity.

An optical fiber consists of a very thin core (where light travels) and a large cladding which keeps the light in the core. A coating on the outside protects the fiber. The core not being perfectly circular create the optical pulse to get distorted (giving optical non linear effects).

Optical transmission

A laser generates optical pulses (pulses of light) controlled by the incoming electrical signal ‘1’ and ‘0’. A light sensitive component (photo diode) detects these pulses of light and reconstitutes the original electrical signal ‘1’ and ‘0’. Usually optical transmission is on a fiber pair – one for transmit and one for receive however transmit and receive can also travel on the same fiber. Optical transmission circuit characteristics (such as in a synchronous network): fixed size; pipe exists whether data flows or not; no concept of congestion in a transmission network as the total size of the pipes coming in, adds up exactly to the total size of the pipes going out.

Key differences between Metro and Long Haul networks
Metro Networks have a large range of services for 1.5M to 10G (DS1, DS3, Optical Ethernet, ESCON, FibreChannel, etc).

They are rapidly changing networks as new nodes are added for new customers, have short distances between nodes and lots of Network Elements hence need to keep NE cost to a minimum. Long Haul networks provide big transport pipes (moving to Terabits per fiber pair); a more stable network topology than Metro networks, less services than in the Metro (34M/45M, 2.5G, 10G, 40G future, GbE, 10GbE future) and greater distances between nodes (100’s of km). Long haul networks can be classified as backbone (many points, average circuit length less than 600km) and express (circuit length greater than 1000km).

Transmission requirements:
Optics performance adapted to the distance (cheap optics for the metro and optics to go thousands of km in the Long Haul); Flexibility (for instance in terms of traffic add/drop at a node or size of junction) and best use of fiber (which means 100’s of wavelengths in the Long Haul and 10’s in the Metro).


How to get the maximum capacity on a link: have the max number of bits per second for a signal (TDM) and have the max number of optical signals sharing a fiber (WDM).
Multiplexing: way to allow signals to share the same medium with each signal having the illusion to have their own line.

TDM gives a time slot to each signal. This means that the position in time determines which signal it is.

Multiplexing examples: 24 phones calls are multiplexed into a T1 in North America. 30 phones calls are multiplexed into an E1 outside North America.
WDM allows different optical signals (different bit rate and protocol) to share the same fiber by giving each signal a different frequency or color.

Types of circuit:

Fixed point to point: no bandwidth management/signal allocation flexibility – all signals are multiplexed at one end and demultiplexed at the other end. In synchronous networks (TDM) the mux is called Terminal mux or Line System. In optical networks it is an Optical Mux/Demux which multiplexes different optical signals.

Flexible networks can be a mesh of cross connect or switches or/and rings of ADM (Add Drop Muxes). A Cross connect is a piece of equipment with lots of ports: semi permanent connections between ports are under the control of the cross connect management system (not the end user of the network). Crossconnect with high capacity optical interfaces are called switches. They can be electrical inside (opaque switch) or purely optical (photonic switch).

An ADM allows traffic to get in and out of the main traffic flow.

Architecture for resilience:
A ring provides 2 ways to connect 2 points hence provides a fast protection mechanism; a Mesh provides various levels of protection (versus just protected or not) but this is more complex than a ring; Point to point system can be protected by sending the signal simultaneously on 2 transmitters and the receiver at the other end selects the signal.

Optical transmission:
Parameters affecting light transmission: attenuation causes the light pulse to loose intensity (the light pulse gets smaller); chromatic dispersion causes the light pulse to broaden.
Attenuation: Regenerators and amplifiers control attenuation. A regenerator terminates the optical signal, meaning that it converts the signal back to the original ‘1’ and ‘0’ and from that generates a brand new optical signal again. An amplifier gives energy to the optical signal and allows it to go further (a single amplifier amplifies an optical signal made of several wavelengths).

Amplifiers replace a regenerator ‘mountains’ since regenerator acts on a single channel and at a regenerator site, the signal has to be optically demultiplexed for each signal to be regenerated. Amplifier can be cascaded up to a certain number then regenerators need to be used.
Dispersion: Fiber types, Dispersion Compensation Module (DCM) and types of transmitter can be used to control dispersion;
Laying new fiber is expensive and some networks have already existing standard fiber;
DCM (length of special fiber) can be inserted in the network to compensate for dispersion;
Laser modulation in the transmitter controls dispersion too. Directly modulated transmitters are cheap however the laser going on and off creates heavy dispersion hence these transmitters are suitable only for short distances.

Externally modulated lasers (laser stays on and an external circuit masks the light to create the pulses) provide better pulse for long distances.

Nortel Networks

Monday, 2 April 2007

RF Transceiver Design

(photo quoted from European Space Agency)
1. Search RF spec.’s from communication standards
Take IEEE 802.11a/b/g as an example: You can read standards from IEEE802.11a Sub clause 17.3
-Operation frequency band and channel number
-TX and RX in-Band and out-of-band spurious emissions: Conform to national regulations. For Europe, ETS range is 300-328
-Operating temperature: 00C to 400C for office environment
-Transmitted power: IEEE802.11b 1000mW
-Transmitted spectrum mask
-Transmitted center frequency tolerance
-Allowed relative constellation error versus data rate.
-Transmit modulation accuracy.
-Power-on ramp and power-down ramp
-Receiver minimum input level sensitivity
-Adjacent channel rejection: Interfering signal power at adjacent channel, referenced to the desired signal level set at 3dB above th3 sensitivity, for packet error rate <10%>
-Receiver maximum input level: -30dBm measured at that the antenna connector for a minimum error rate.
2. RF Transceiver Architecture and link budget
-Dual-band transceiver architecture: Heterodyne or homodyne, Switched or concurrent dual-based
-Receiver power and gain budget: IEEE 802.11a max power (-30dBm) to sensitivity (-82dBm)
-Transmitter power and gain budget
3. RF Circuit Design
-Dual-band switch
-Dual-band VCO and frequency synthesizer
4. RF Transceiver Integration and Measurement
5. Conclusion(Five steps toward accomplishment)
-Search RF spec. from studying communication standard
-Determine RF transceiver architecture
-Calculate and simulate transceiver link to determine RF sub-circuit spec.
-Design RF sub-circuits with proper technologies such as CMOS/HBT/pHEMT MMIC, HMIC
-RF transceiver integration and measurement

Sunday, 1 April 2007

Spontaneous Speech

(photo quoted from Nippon Telegraph and Telephone Corporation )
Spontaneous speech requires no special training, efficient, minimal cognitive load and wealth of information at multiple levels. There are some features such as variable speaking rate, greater use of short words and function words, and a tendency towards more coarticulation and generally less precise coarticulation.

1. Recovering hidden punctuation
Punctuation is everything in written language other than the actual letters, including punctuation marks and inter-word spaces.
2. Coping with disfluences
Disfluency: Lack of skilfulness in speaking or writing, such as filled pauses, repetitions, repairs, false starts
3. Allowing for realistic turn-taking
Listeners project the end of a current speaker’s turn using syntax, semantics, pragmatics, and prosody.
4. Hearing more than words
Distinguish emotion and do user state detection. Especially, it’s important for certain dialog system application