Integration with Existing/Future Mobile Station,Systems and ...Presentation Transcript
The Future of Mobile Communications Professor Rolando Carrasco BSc(Hons), PhD, CEng, FIEE [email_address] 1 School of Electrical, Electronic and Computing Engineering
Research Project 1
The Capacity and Throughput Improvement of Fixed Broadband Wireless Access Systems
Dr. Pei Xiao, Research Fellow (three years)
Mr. M. K. Khan BEng, MSc, Research Student (2 1/2 years)
EPSRC Grant in collaboration with Dr. I. Wassell, Cambridge University and Cambridge Broadband Ltd
Network Interface Subscriber Unit Standard 4 Sector Base Station AP AP AP AP 90 ° x 8 ° antenna 23 ° x 23 ° antenna 3 options for user interfaces 100 BaseT 100 BaseT & E1 100 BaseT & 2x POTS VectaStar System Configuration Copyright Cambridge University 3 AP AP AP AP 256 x CPE 256 x CPE 256 x CPE 256 x CPE SDH / ATM Network
Research Project 2
Space-Time Diversity Coding Combined with Equalisation for MIMO Wireless Channels.
Mr. Cameron B Shaw BEng(Hons), MEng (PhD Student), 15 months remaining
EPSRC grant in collaboration with Lancaster University (Professor Honary) and MOD (Ministry Of Defence)
The world of mobile communications 5
Have you ever heard the phrase “the future is here today”? Well, in the case of mobile communication technologies, this phrase is true.
However, it is not yet fully realized.
Challenges in the Migration to Future Mobile Systems
2G, 3G and 4G wireless systems
Mobile Stations, Systems, Services
2G Mobile Systems
GSM, IS-95 and CDMA one carry speech and low bit rate data
3G Mobile Systems
Higher data rate
WLAN and HiperLAN
Developing new standards and hardware
4G Mobile Systems (2006)
Resource coordination to add new users
Support for multicasting and Quality of Service
Wireless security and authentication
Network failure and backup
Pricing and billing
The world of mobile communications 9
Out of a world population of 6.32 billion people, approximately 1.12 billion, or 1 in 6, have a mobile phone and 71.6% are GSM customers
Total Operator revenues for 2006 have been estimated to be over $100 billion for Western Europe
China Mobile with over 100 million customers are connecting 2 million new customers each month
About 2 billion people in the world have yet to make a phone call and it is likely that when it happens it will be on a mobile phone rather than a fixed line
What is Wireless Data?
Vehicle tracking and dispatch
Subscriber information services
Wireless remote access to host
File transfer to/from laptop,J2ME
Wireless Internet access and Video Teleconferencing
Browsing on Laptops, PDAs ,Phones
Mobile Computing Systems
Future Mobile Systems
Personalised Services providing stable system performance and Quality of Service (QoS)
Service and standards
Mobile VCE (www.mobilevce.com), MIRAI and DocoMo
VCE = Virtual Centre of Excellence in Mobile and Personal Communication 11
Mobile Computing Systems
Some key features of Future Mobile Systems
Anytime, anywhere and with any technology (all-IP based heterogeneous networks)
Support for Multi-media Services at low transmission cost
Personalisation(having human characteristics)
Everything is IP 13
Multimode user terminals(multi-functional,software upgrades)
Wireless system discovery(searching for wireless system)
Wireless system selection(suitable technology)
Terminal Mobility(to locate and update the locations)
Network infrastructure and QoS support
Security, performance and complexity
Fault tolerance and Survivability
Multi-operators and billing system
Mobile Stations An ideal software radio system
New coding/interleaving/diversity/equalisation/SISO channel/MIMO channels
Multicarrier, spread spectrum and antenna solutions
Adaptive coding modulation, detection, synchronisation and automatic repeat request
Multimedia protocols, new access,timing control and QoS
A software radio approach can be used so that the user terminal adapts itself to the wireless
15 Multimode user Terminals: To design a single user terminal that can operate in different wireless networks
Scarce Radio Spectrum
Radio Channel Characteristics
- Limits on Signal Coverage
- Limits on Data Rates
Efficient Network Architectures and Protocols
Authentication and Security
Infrared Versus Radio
Link Performance Measures Efficiency
- a measure of the data rate per unit bandwidth for a given bit error probability and transmitted power
- a measure of the required received power to achieve a given data rate for a given error probability and bandwidth
HOW DO WE OVERCOME THE LIMITATIONS IMPOSED BY THE RADIO CHANNEL?
Flat Fading Counter measures
- Fade Margin
- Coding and Interleaving
- Adaptive Techniques
Delay Spread Counter measures
- Spread Spectrum
- Antenna Solutions
EQUALIZER TYPES AND STRUCTURES 20
Convolutional ‘outer’ code I ISI Channel I I -1 SISO Equaliser SISO ‘outer’ decoder data Estimated data Turbo Equaliser AWGN Turbo Equalisation 21
MIMO Turbo Equalisation Data Model: 2-User, 2-Path, 2-Antenna ( Example) h 11 (1) h 11 (0) h 12 (1) h 12 (0) h 21 (0) h 21 (1) h 22 (0) h 22 (1) User 1 User 2 b 1 ( n ) b 2 ( n ) r 1 ( n ) r 2 ( n ) Space Domain Sampling 22
Algebraic geometry is a powerful tool for constructing codes with good parameters e.g. Hamming distance, code rate and large code length.
Very long codes can be constructed by choosing curves containing many points. Reed Solomon codes are constructed from a line, which has less points, and hence they are much shorter than AG codes
There is almost no limit to the number of AG codes that can be constructed from a variety of different classes of curve. There are not many Reed Solomon codes.
AG codes perform better than Reed Solomon codes for high code rates over smaller finite fields and are suitable for application in mobile communications and storage devices
Further investigation is needed into constructing new codes from different classes of curves and the development of low complexity decoding algorithms for future hardware implementation.
Hermitian curves can be used to construct very long codes:
Example: C ( x,y ) = x 5 + y 4 + y , defined over GF(16) gives codes 64 symbols long. A Reed Solomon code over GF(16) is only 15 symbols long
Construction of LDPC codes for Application with Broadband Communication Systems 25
LPDC codes are a class of Block codes that perform very close to Shannon limit.
Uses efficient encoding and iterative decoding schemes to achieve low latency .
Highly parallel nature and low complexity of decoding algorithm results in fast iterative decoding and less complex Hardware architecture.
Better performance using equalisation techniques in dispersive MIMO/SISO ISI fading channels.
Performance is drastically improved by concatenating with Space time Codes
Suitable for high data rate applications.
SUI-3 LDPC-QPSK With SRK Equalisation 26
Broadband Fixed Wireless Access (BFWA) systems
Aim of BFWA is to deliver broadband data services to homes and businesses in a flexible and efficient manner.
Main driver is to provide Internet access for applications such as E-mail, web-browsing, file downloading and transfer, audio and video services over Internet.
In BFWA systems, radio signal travels via multipath from transmitter to receiver antennas. Multipath propagation causes intersymbol interference and degrade the system performance.
Turbo equalization is a powerful technique to remove the effect of intersymbol interference.
Comparison of different equalisation schemes in BFWA systems 28
MIMO Channels for BFWA Systems
Use MIMO space-time coding to increase the capacity of BFWA system.
Signals from different antennas can be separated through orthogonal design, such as Alamouti algorithm.
When used over frequency selective channels, a channel equalizer has to be used at the receiver along with the space-time decoder.
STBC can be applied in conjunction with OFDM which converts the frequency selective channel into a set of independent parallel frequency-flat subchannels. The Alamouti scheme is then applied to each subcarrier.
Space-Time Ring Trellis Coded Modulation
The uncorrelated fading channels are used to provide diversity
Very good results can be obtained with just 2 tx & 2 rx antennas.
Higher coding gains achieved and error floors removed by using higher state codes.
Higher coding gains are achieved and error floors removed by using higher state codes.
Cannot fully recover vehicular channel data. Equalisation is needed.
30 Tx1 Tx2 r 1 (x) r 2 (x) g 11 (x) g 22 (x) g 12 (x) g 21 (x) ST-Ring TCM Decoder
Maximum a-posteriori Turbo Equalisation
Realistic channel models are created to properly test the mobile communication systems.
Indoor, pedestrian and vehicular scenarios are simulated based on actual measured results from urban mobile radio channels.
Over realistic channels (such as the urban mobile channel) the intersymbol interference produced needs mitigation to improve performance.
The goal of equalisation is the cancellation of the Inter-Symbol Interference (ISI), or equivalently the flattening of the radio channel’s frequency response
Turbo equalisation combines decoding and equalisation by converting the channel into a type of ‘code’ which can then be iteratively decoded with a symbol-by-symbol decoder.
Mobile Station Via PC server Via smart card OTA Scanning… Available Systems Way to download Software Wireless system discovery 32 Via PDA
To discover available wireless systems by processing the signals sent from different wireless
systems (different access protocols)
Via Memory card WLAN UMTS CDMA GPRS GSM
Wireless System Selection: Selection of the most suitable technology for a particular service
We can choose any available wireless device for each particular
communication session (fit to user QoS requirements)
Right network selection can ensure the QoS required by each Session Initiation
Protocol (SIP) messages.
Adequate knowledge of each network is required before a selection is made
Location information of the source mobile nodes, available networks of both
mobile nodes and user preference are all taken into account in the selection
when a mobile node makes a call to another mobile node
System Terminal Mobility Location Management The system tracks and locates a mobile terminal for possible connection
To locate and update the locations of the terminals in various
Location Management: Information about the roaming terminals
such as original and current located cells, authentication
information and QoS
Service Mobility: Keep same service while mobile
34 Terminal moves between subnets
Enhanced Mobile IPv6 Schemes
Figure shows an example of horizontal and vertical handoff UMTS coverage GSM coverage WLAN coverage Vertical handoff Horizontal handoff 35
Main problems: - handover performance
- handover failure due to lack of resources
- authentication of redirection
Real-Time Multimedia Services that are highly time-sensitive
It is unacceptable if the MIPv6 handoff process significantly
degrades system performance.
New handoff decision policies and new handoff algorithms.
The terminal moves from one cell to another (two different
wireless systems e.g. WLAN and GSM).
To integrate the existing non-IP-based and IP-based systems
Non-IP-based systems (voice delivery) e.g. GSM, CDMA2000
IP-based systems (data services) e.g. 802.11 WLAN and
Problems : Integration, QoS guarantee for end-to-end
Network Infrastructure and QoS Support 37
The heterogeneity of wireless networks complicates the security
2G/3G have been widely studied
The key concern in security designs for 4G networks is flexibility.
The key sizes and encryption and decryption algorithms of
existing schemes are also fixed.
Reconfigurable security mechanisms are needed (Tiny SESAME)
Modifications in existing security schemes may be applicable to
Mobile Station – GSM Functional Architecture Interface to other networks Transition to ISDN, PDN, PSTN Radio Interface MS MS MS BTS-BSC Interface Base Station Subsystem (BSS) Network and Switching Subsystem (NSS) Operation Subsystem (OSS) Points of reference Radio Subsystem 39 BTS BTS BTS BSC BSC HLR VLR AuC OMC MSC EIR
Reliability, availability and survivability of the network
A cellular wireless access network is typically designed as a tree-like topology
that has several levels (device, cell, switch and network levels)
Problems: Any level fails (hardware/software), all levels below will be affected
Consideration, power consumption, user mobility, QoS management, security,
system capacity and link error rates of many different wireless networks.
The first is to use hierarchical cellular network systems
The second is to use collocated or overlapping heterogeneous wireless network
Fault Tolerance and Survivability: To minimise the failures and Their potential impacts in any level of tree-like topology 40
Multiple Operators and Billing System
More comprehensive billing and accounting systems are needed (different types of
Multiple service providers
Operators need to design new business architecture, accounting processes and
accounting data maintenance.
Future Wireless Networks support multimedia communications, which consists of
different media components with possibly different charging units
This adds difficulty to the task of designing a good charging scheme for all customers
Scalability, flexibility, stability, accuracy and usability
The movement of users instead of users’ terminals and involves the provision of
personal communication and personalised operating environments
Personal Mobility: different terminals, same address 42
Mobile-agent based infrastructure is one widely studied
(Agent Support for Personal Mobility)
Agents act as intermediaries between the user and the
Personal Mobility 43
Mobile computing in a Fieldwork Environment Ecologists, archaeologists, computer scientists and engineers
Communication and Ad Hoc Networking in the field, prevent disaster, reduce crime and terrorism
Health and Education
E-Commerce, E-Business, E-Government
Entertainment, games, smart home
Improving the way we work 45
The way and means that people use to communicate is changing
People need the ability to work anywhere, anytime, anyplace
Best Value, being effective and efficient
Work is an activity not a building or place
In this presentation research challenges in the emigration to future networks are studied and described
The challenges are grouped into three aspects: Mobile Station, System and Service
Wireless technologies used to decrease crime and prevent emergency disasters and terrorism
The challenges were identified, such as multicarrier user terminals, wireless system discovery, terminal mobility, QoS support and business opportunities
Mobile communication impact in urban/rural areas
Project of Innovation for job creation using wireless technologies