Filter Bank Based Multi-Carrier Systems for Future Broadband Wireless Communications

Lead Research Organisation: University of Surrey
Department Name: Communications Systems Res CCSR

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) technique has gained increasing popularity in both
wired and wireless communication systems, mainly due to its immunity to multipath fading, which allows for a significant
increase in the transmission rate. By inserting a cyclic prefix (CP) before each transmitted block longer than the length
of the channel, OFDM effectively transforms a frequency selective channel into a parallel of flat-fading channels. This
greatly simplifies both channel estimation and data recovery at receiver. However, these advantages come at the cost of a
loss of 10-25% spectral efficiency due to the insertion of CP, and an increased sensitivity to frequency offset and Doppler
spread as well as transmission nonlinearity accentuated by non-constant modulus of OFDM signals. Additionally, due
to the time-varying nature of wireless channels, training sequence needs to be transmitted periodically for the purpose of
channel estimation. The overhead imposed by training sequence and CP can be up to 50 percent for fast fading channels,
causing significant loss of spectral efficiency.

In this proposal we aim to tackle these problems with the filter bank based multi-carrier system employing a special
pulse shaping filter called IOTA (isotropic orthogonal transform algorithm) to yield good time and frequency localization
properties so that inter-symbol interference (ISI) and inter-carrier interference (ICI) are avoided without the use of CP.
We also investigate a linearly precoded IOTA system which facilitates blind channel estimation, resulting in a spectrally
efficient multi-carrier system without the transmission of training sequence in addition to the elimination of CP.
In order to effectively combat carrier frequency offset and high PAPR problems in the current orthogonal frequency division
multiple access (OFDMA) and single carrier frequency division multiple access (SC-FDMA) based uplink communications,
we propose a novel multiple access scheme which combines IOTA with low density signature (LDS) technique.

The focus of our work will be on the study and utilization of some special properties of IOTA which have been overlooked
by others. We aim to leverage these properties in the equalization, decoding and channel estimation design in order to
achieve optimal performance and maximum capacity with affordable computational complexity. Our goal is to provide
theoretical references and guidelines for successful implementation of IOTA systems for future wireless communications.

Planned Impact

This research will not only benefit the communications industry, enhance the UK's economic competiveness but also contribute to the country's academic standing in the areas of broadband communications and advanced signal processing which is identified in the shaping capability: EPSRC Research Portfolio 2011 an area for growth.

This research will contribute to theory, design and development of multi-carrier systems for future communications. Research outcomes from the proposed project will act as enablers of next-generation wired and wireless communication systems beyond 2020, which have adopted multi-carrier modulation as a key component to provide applications like voice/video/data communications, with higher data rates, higher mobility and higher reliability.

Publications

10 25 50
 
Description The research findings and discovers developed through the research funded on this grant have resulted in four patents.
The discoveries are summarized below.
- We developed a method for utilizing the special property of FBMC to maximize the performance gain of FBMC systems by converting the intrinsic interference into useful signal.
- We proposed a new multiple access scheme which increases the system throughput and reliability, and is a strong candidate solution for the 5G new air interface.
- We proposed a method for joint LDS and LDPC graph design to facilitate joint multiuser detection and channel decoding. With some offline processing, this method provide improved performance with reduced computational complexity.
- We developed a method to reduce the pilot overhead by one to two orders of magnitude for 5G TDD systems. It solves the 5G bottleneck problem and greatly mitigates the pilot contamination problem in massive MIMO and pilot overhead bottleneck problem in UL/DL scheduling, multi-cell joint processing/coordinated scheduling, D2D communications, all of which are important areas of 5G.
Exploitation Route Some findings will be proposed to the 5G wireless standard.
Sectors Digital/Communication/Information Technologies (including Software)

 
Description The world first FBMC prototype has been built based on the research results from this EPSRC project and demonstrated in the World Mobile Congress 2014 in Barcelona and attracted significant attention from the participants all over the world. FBMC is believed to be a strong candidate for 5G new air interface technique.
First Year Of Impact 2014
Sector Digital/Communication/Information Technologies (including Software)
Impact Types Societal,Economic

 
Description Enhanced Multi-carrier Technology for High-Mobility 5G Broadband Systems
Amount £22,900 (GBP)
Funding ID 1314-2-RECI046 
Organisation Royal Academy of Engineering 
Department The Leverhulme Trust/Royal Academy of Engineering
Sector Charity/Non Profit
Country United Kingdom
Start 06/2014 
End 10/2015
 
Description IAA - Implementation of the SCMA scheme
Amount £19,357 (GBP)
Funding ID RN0261H 
Organisation University of Surrey 
Sector Academic/University
Country United Kingdom
Start 04/2015 
End 10/2015
 
Description Impact Acceleration Account
Amount £19,357 (GBP)
Funding ID RN0221Y: Implementation of the FMBC-IOTA system 
Organisation University of Surrey 
Sector Academic/University
Country United Kingdom
Start 04/2014 
End 10/2014
 
Description Novel Multiple Access Technologies for 5G
Amount £149,500 (GBP)
Organisation ZTE Corpoation 
Sector Private
Country China
Start 01/2015 
End 01/2018
 
Description Collaboration with Aeroflex on the development of FBMC prototype 
Organisation Aeroflex Ltd
Country United States 
Sector Academic/University 
PI Contribution We provided the algorithms that have been designed and verified by software simulations during the course of this EPSRC project.
Collaborator Contribution The DSP team from Aeroflex worked with our researchers to implement the algorithms on their user-equipment emulator (TM500). Aeroflex also provided their equipment and hands-on experience in implementation.
Impact As an outcome of this collaboration, the world first full FBMC prototype was accomplished and demonstrated by us in the World Mobile Congress 2014 and attracted significant attention from the participants all over the world. Hardware implementations helped us evaluate the pros and cons of the system under the practical conditions. Novel synchronization and channel estimation schemes for FBMC were developed as by-products of this prototyping project. Moreover a collaboration framework with Aeroflex was established and can be used as a model for future implementation of 5G related novel ideas and technologies with other industrial partners.
Start Year 2013
 
Title Intrinsic interference utilization for FBMC-IOTA systems 
Description Method for utilizing the special property of FBMC-IOTA system to maximize the performance gain of FBMC system by converting the intrinsic interference into useful signal. FBMC-IOTA is a strong candidate for the 5G new air interface. 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted
Licensed No
Impact This discovery significantly improves the power efficiency of the FBMC technique which is a strong candidate for 5G air interface.
 
Title Joint sparse graph design for multiple access systems 
Description Method for joint LDS and LDPC graph design to facilitate joint multiuser detection and channel decoding. With some offline processing, this method provide improved performance with reduced computational complexity. Patent application number: GB1403382.3 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted 2014
Licensed No
Impact This discovery is very useful for the design of 5G uplink multiple access scheme which requires high spectrum efficiency and short latency.
 
Title Multi-cell Multi-user Pilot Overhead Reduction for 5G-TDD System 
Description Method to reduce the pilot overhead by one to two orders of magnitude for 5G TDD systems depending on the channel conditions. 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted
Licensed No
Impact This discovery greatly mitigates the pilot contamination problem in massive MIMO and pilot overhead bottleneck problem in UL/DL scheduling, multi-cell joint processing/coordinated scheduling, D2D communications, all of which are important areas of 5G.
 
Title Novel Multicarrier Multiple Access Scheme MIMO-LDS-IOTA 
Description This invention proposes a new multiple access scheme which increases the system throughput and reliability, and is a strong candidate solution for the 5G new air interface. 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted 2014
Licensed No
Impact This discovery leads to a new design of air interface for 5G uplink.