From Marconi to Wireless Internet: The Wireless (R)evolution Prof. Vijay K. Bhargava Candidate for 2004 IEEE President-Elect University of Victoria Victoria, Canada Email: [email protected] Website: http://www.ece.uvic.ca/~bhargava/ieee
Jan 13, 2016
From Marconi to Wireless Internet: The Wireless (R)evolution
Prof. Vijay K. Bhargava
Candidate for 2004 IEEE President-Elect
University of Victoria
Victoria, Canada
Email: [email protected]
Website: http://www.ece.uvic.ca/~bhargava/ieee
Home
Biography
IEEE ActivitiesPosition Statement
IEEE LecturesShort CoursesPublications
Group
Awards
Lectures
Dear IEEE Member:
The Board of Directors has placed my name on the ballot for the office of IEEE President-Elect 2004. I would be pleased to serve as your president - if you honour me with your vote in September.I welcome any thoughts you may have on my position statement and issues that you feel should be addressed by the IEEE.
Kind Regards,Vijay Bhargava ([email protected])
http://www.ece.uvic.ca/~bhargava/ieee
2
Position Statement
Improve access to product and services (journals, standards, conference proceedings and continuing education courses). They account for 75% of our revenue
Manage Budget, Reduce Corporate Expenses and improve our volunteer structure
Expand membership beyond the traditional field of electrical engineers. There are tremendous opportunities in information technology and related areas
Jointly with international engineering community, make IEEE a force for promoting world peace and a better life for all.
3
ISBN: 1-4020-7251-1 © 2003
4
Presentation Outline
1. Historical Overview
2. The Three Generations
3. Beyond 3G/Wireless Internet
4. Enabling Techniques (Innovations from IT Society)
5. Malaise Afflicting the Wireless Industry
6. Possible Recovery Scenario
7. Conclusions
5
6
Maxwell
Hertz
Popov
Fessenden
7
8
9
Signal Hill, December 12, 2001
10
The Three Generations and Beyond (Overview)
First Generation : Analog Cellular
(Mainly Speech) Second Generation : Digital Cellular
(Digital Speech and messaging)
2.5G, 2.75G, … Third Generation : IMT2000
(Integrated Audio and Video)
11
Beyond 3G
The true Wireless Internet
Internet connectivity anytime anywhere
Wireless and mobile extensions to the Internet
Wireless – Wireline BB Transparency
12
Claude Elwood Shannon
Father of Information Theory
Electrical engineer, mathematician, and native son of Gaylord. His creation of information theory,
the mathematical theory of communication, in the 1940s and 1950s inspired the revolutionary
advances in digital communications and information storage that
have shaped the modern world.
This statue was donated by the Information Theory Society of the Institute of
Electrical and Electronics Engineers, whose members follow gratefully in his footsteps.
Dedicated October 6, 2000 Eugene Daub, Sculptor
13
Enabling Techniques (Innovations from IT Society)
Reed Solomon Codes
Viterbi Algorithm
Public Key Crytosystem
Compression Algorithm, Huffman, Lempel-Ziv, Algebraic Coding
Modem Design with Coded Modulation, Ungerböeck
Turbo Decoding approaches Shannon’s capacity limit by less than 0.5dB
Theory of CDMA and Multiuser Transmission
Space-Time Coding for Mobiles
14
Cryptography
Secret Key System
Public Key System15
Digital Signature
16
Source Coding for Voice and Video
Variants of Predictive Coding
For voice CELP, VCELP, RPE-LTP and other Variants
H.261 and H.263 Standards support low bit rate (30-64 kbps) Video for mobile communication
MPEG-4 (with Reed-Solomon Codes)
17
Turbo Codes
Originally Turbo code encoder was built using a parallel concatenation of two (or more) relatively simple recursive systematic convolutional (RSC) codes with large interleaving
Although the component codes are weak, the output turbo codeword is very powerful due to the “Interleaver gain” which produces a random-like codeword
dk
RSC1
RSC2
Interleaver
dk
d1,k
d2,k
Turbo Code Encoder
18
After miterations
Decoder1
Decoder2
rk
r1,k
r2,k
Turbo code Decoder
d
Turbo Codes (Iterative Decoding)
Soft Input/Soft Output MAP Decoder
Use “extrinsic information” produced from past decoder as á priori information
Gradually improvement of knowledge on transmitted information through iterations
19
Turbo Codes
Turbo codes will be used in high data rate services in the next generation CDMA systems above 32 kbps
There are already existing standards for ½ and 1/3 coding rate turbo code for 3GPP systems
The same iterative decoding principle can be applied in various different areas
Turbo equalization
Turbo multiuser detection (for coded CDMA signals)
Turbo decoding with estimation of parameters of an unknown time-varying channel
20
Multiuser Detection (MUD)
Signals from all users are considered useful instead of only interference to each other
MUD provides important performance gains over the conventional single-user receiver
Performance of single-user conventional receivers are limited in fading channel due to the near-far effect which necessitates use of strict power control
In certain cases multiuser receivers can even benefit from the diversity in powers of the received users and have better performances than in the case of equal received powers of users
21
Multiuser Detection (MUD)
•In the single user approach, each detector focuses on extracting the data of a single user•Other users are considered as interference•Simple
h(t)
1st Rake Receiver
Kth Rake Receiver
Rx MultiuserDetector
b1
bK
oscillator
• •
•In the multi-user detection approach, the common detector uses available information from all users to detect each user•Complex
oscillator
Rxh(t)
1st Rake Receiver
Kth Rake Receiver
Detector
Detector
b1
bK
22
Multiuser Detection (MUD)
Benefits of using multiuser detection
More efficient spectrum utilization (in some situations we can expect ten fold increase in spectrum efficiency)
Reduced precision requirement for power control
More efficient power utilization
Main difficulties in implementing multiuser detection
Existence of the other-cell multiple-access interference (MAI)
Difficulty in implementing multiuser detection on the downlink (cost, size, weight are of much larger concern for mobile terminals)
23
Multiuser Detection (MUD)
Some of the MUD algorithms areMaximum Likelihood (Optimal) Decoding (complexity increases exponentially with the number of users)Linear detectors (similar to the linear equalization techniques)
decor relating detectorMMSE detector
• MMSE detector can be implemented as an adaptive filter to reduce complexity
• Blind adaptive implementation of the MMSE detectorDecision Feedback Detectors where past decisions are used to improve the current ones
Conventional Decision Feedback or Successive Interference CancellationParallel Interference CancellationOptimum Decision Feedback Receiver (has the spectral efficiency equal to the optimum detector)
24
Multiuser Detection (MUD)
Implementation examples of multistage parallel interference cancellation multiuser detection:
DSP implementation [Buehrer, Woerner, 1999]VLSI implementation [Aazhang et al., 2000]
The parallel interference cancellation is prefered due to its performance complexity tradeoffHowever, MUD research is still in a phase that would not justify to make it a mandatory feature for 3G WCDMA standardsMost probably, its practical implementation and standardization is going to be defered for 4G systems
25
Space-Time Codes
Capacity of a multi-antenna systems far exceeds that of single-antenna system
Multiple transmit/receive antennas provide diversity in the space domain (space diversity)
Channel coding designed for wireless communication systems with multiple transmit/receive antennas provide both space and time diversity Space-time codes
Two categories of space-time coding
1) space-time trellis codes 2) space-time block codes
Decoding of space-time codes requires channel estimation
26
Space-Time Codes
Informationsource
Space-timeencoder
Receivers(k)
c1(k)
cN(k)
r1(k)
rN(k)s’(k)
Space-time coding system
0
1
2
3
4
5
6
7
00,01,02,03,04,05,06,07
50,51,52,53,54,55,56,57
20,21,22,23,24,25,26,27
70,71,72,73,74,75,76,77
40,41,42,43,44,45,46,47
10,11,12,13,14,15,16,17
60,61,62,63,64,65,66,67
30,31,32,33,34,35,36,37
Input: 0 1 5 7 6 4
Tx 1: 0 0 5 1 3 6
Tx 2: 0 1 5 7 6 4
0
12
3
4
56
7
Space-time trellis codes (8-PSK) with two transmit antennas
Space-time block codes with two transmit antennas (Alamouti’s scheme)
ConstellationMapper
s(k) [c1 c2]
*12
*21
cc
cc
27
Space-Time Codes
Bandwidth and power efficient – a codeword is transmitted simultaneously from different antennas with the same total transmit power
Channel information is not necessary at the transmitter
Differential scheme is available when channel information is not known at the receiver
Can be concatenated with other codes such as Reed-Solomon, TCM, turbo code
Can be applied in broadband channel – CDMA, OFDM
Adopted in standards – IS-136, W-CDMA, CDMA2000
Tested in WLAN 802.11a. Increase in link layer throughput and improving TCP performance
28
The Malaise Afflicting The Communications Industry*
A convergence of five key factors
1. Greed
2. Corporate Crime
3. Misguided Regulations
4. Too Much Debt
5. A Broken Business Model
Why did we, the engineers, allow business manipulators and bureaucrats to drive the show ?
*Peter A. Bernstein, IEEE Spectrum, January 2003
29
Possible Recovery Scenario
“Nothing lasts forever”
“This too shall pass”
“Survival of the fattest”!
Broadband: Alive and Well Mobile, and Loving it If Each is Good, Both are Better If You Build it, Killer Apps will Come
*Steven M.Cherry, IEEE Spectrum, January 2003
30
Conclusions
We have presented a historical overview of Wireless Communication
Innovations from IT Society have been discussed
Reliable high-speed mobile Internet Access will lead to innovative product and services
“It is dangerous to put limits on Wireless Communications”
31
32
WHY ARE THESE MEN SMILING ?33
34