Research at Communication Systems

Research Projects

Current Projects

• Industrial sponsorship contract

  • Funded by: Ericsson Research (2008-2009)
  • Project leader: Prof. Prof. Erik G. Larsson
  • Project summary: The project aims at improving the performance of the forthcomming 3G LTE standard for wireless brodband access by refining the time/frequency scheduling algorithms.

• Spectrally efficient and robust future generation radio.

  • Funded by: Swedish Foundation of Strategic Research (SSF) (2008-2013)
  • Project leader: Prof. Prof. Erik G. Larsson
  • Project summary: The goal of this project is to develop new paradigms for efficient spectrum and power utilization in wireless communication networks. Two interrelated topics form the focus. Under the first, we are concerned with coordinating different multiple-antenna wireless systems (operators) that operate and compete for resources in the same unlicensed spectral band. The goals are to understand fundamental limits; to develop algorithms and protocols for resolution of spectrum conflicts; and as a bonus, to obtain a general understandi ng that can serve as input to standardization and spectrum regulation processes. The motivation for this task is the increased interest in unlicensed operation, and the coexistence problems currently faced in such spectrum bands. Our research stands out in that we focus on multiple-antenna technology, and in that our focus is on solving resource conflicts via collaborative techniques.
    
    The second direction concerns cognitive radio technology. Essentially, cognitive radio is a way of mixing licensed and unlicensed operation in the same spectral band. The proposed work consists of system and feasibility studies, and of algorithm development for spectrum sensing. An additional goal is to characterize the nature of the interference experienced in an environment where cognitive radio operation is permitted, and to develop communication receivers which are robust to this type of interference.

• Algorithms and architectures for baseband signal processing.

  • Funded by: Swedish Foundation of Strategic Research (SSF) (2008-2011)
  • Project leader: Prof. Prof. Erik G. Larsson
    Co-PIs: Profs. Håkan Johansson, Electronics Systems and Dake Liu, Computer Engineering
  • Project summary: This project brings together a consortium with long experience of both signal processing algorithm design for modern wireless standards, ASIC design, and programmable baseband processor design. The goal is to develop structures for power-efficient baseband signal processing by jointly designing algorithms that are suitable for implementation, and hardware architectures that satisfy the specific needs of these algorithms. The focus is on wireless communications and specifically on the needs of emerging wireless transmission formats and on the need for massive data processing and hardware flexibility that such systems bring. There is also a close connection to radar signal processing. Knowledge generated in the project will be strategically important for all types of performance-demanding, low-power, real-time computing.

• Sensor-network aided dynamic and cognitive radio access (SENDORA)

  • Funded by: EU FP7 (2008-2010)
    STREP project; Coordinator: Thales Communications, France
  • Project leader: Prof. Prof. Erik G. Larsson
  • Project webpage
  • Project summary: Dynamic spectrum allocation has become a key research activity in wireless communications field and in particular a key technology for "The Network of the Future" objective proposed in ICT Work Programme 2007. Following these current trends towards dynamic spectrum allocation, the SENDORA project will focus on developing innovative techniques based on sensor networks, that will support the coexistence of licensed and unlicensed wireless users in a same area. The SENDORA project ideas stem from recent fundamental works on cognitive radio technology.
     
    The capability to detect spectrum holes, without interfering with the primary network currently in use, is the actual major difficulty faced by the cognitive radio. The innovative concept proposed in SENDORA project consists in developing a "sensor network aided cognitive radio" technology which will allow to solve this issue, thanks to the introduction of sensor networks and associated networking capabilities. The sensor network aided cognitive radio proposed and studied in SENDORA project will address many different advanced techniques, but will also propose an analysis of the potential exploitation of these techniques. First, scenarios of interest will be defined and will provide the technical activities with requirements to cover. Different types of scenarios will be proposed, corresponding to real needs, mainly identified by the potential integrators of the solutions. On the technical point of view, novel spectrum sensing techniques will be first proposed to be able to identify spectrum holes. Corresponding information management and exploitation will be studied to achieve the co-existence of cognitive radios with primary licensed technology without generating harmful interferences. The design, dimensioning and networking of the wireless sensor network will be deeply addressed. Finally, a proof-of-concept demonstration will be developed to assess the theoretical research.

• Spectrum sensing techniques with cognitive radio applications

  • Funded by: CENIIT (2008-2010)
  • Project leader: Dr. Danyo Danev
  • Project summary: The goal of this project is to develop algorithms and methods that can detect the presence of very weak communications signals. The primary intended application is cognitive radio. Cognitive radio is an emerging technique with which licensed spectrum can be locally reused by unlicensed users. One of the fundamental problems in cognitive radio is to be able to detect the presence of weak signals from a primary (licensed) system, and this is the problem that we address. The work is closely connected to the FP7 sponsored project ``Sensor network for dynamic and cognitive radio access'' (SENDORA).
  • Detailed project description

• Multiple-model framework for detection in communications.

  • Funded by: Swedish Research Council (VR) (2005-2008)
  • Project leader: Prof. Prof. Erik G. Larsson
  • Project summary: This project will explore a novel concept for optimal detection and demodulation in communications for the case that the underlying structure of the transmission model is only partially known. The key idea of our approach is to use multiple, parallel detectors, where each detector makes different assumptions on the transmission model, and then optimally combine the results. This concept stands in contrast to conventional detection (where only a single detector is used, that assumes that the transmission model is fully known), and to previously proposed solutions that employ multiple detectors and adaptively switch between them.
    
    The problem we study is a very fundamental one, but it is relevant to several practical applications. One important application example is multiuser detection and interference suppression. When performing demodulation in the presence of interference, one may not fully know the structure of the interference signals. Our proposed framework will be able to adaptively and optimally combine decisions that result from different assumptions on the interference structure. Practical applications include antijamming for GPS and communications, and CDMA multiuser detection. In this context, the most exciting possibility with our approach is to create a detector that adaptively and autonomously trades off between joint multiuser detection and ``noise-whitening'' interference suppression.

• Open problems in communication theory.

  • Funded by: Swedish Royal Academy of Sciences (KVA) (2007-2012)
  • Project leader: Prof. Prof. Erik G. Larsson
  • Project summary: This project addresses a number of interrelated, open problems in the area of communication theory for multiuser systems. Specifically:
    
    Coding and resource allocation for relay channels. The relay channel is a building block in many current and proposed real systems. At the same time, coding for the relay channel is a classic information theoretic problem. Under this topic we study a number of intertwined, fundamental issues related to relaying.
     
    Transmitter interference cancellation: This is basic, important problem rooted in information theory, and solutions to it---even good approximate such, are building blocks in many applications. In particular this is important for wireless multiuser systems where the transmitters and the receivers use antenna arrays.

• Modulation and coding techniques, spectrum and propagation.

  • Funded by: VINNOVA - Swedish Governmental Agency for Innovation Systems (2008-2011)
  • Project leader: Dr. Jonas Eriksson
  • Project summary: The objective of this Sino-Swedish collaboration project is to identify and find solutions for the challenges of ´Beyond-IMT-Advanced´ mobile telephony systems. An important aspect of this project is its contribution to the strengthening of the cooperative spirit between the involved research groups in China and Sweden. The project has three partners on the Swedish side, namely Lund university, Linköping university and KTH. Lund university is acting as overall project leader.
    At the core of the project is the organization of collaborative workshops on the subject of ´Beyond-IMT-Advanced´ mobile telephony systems. Through cooperative research, the project will cultivate Ph.D. and master degree students with an international view. This will be beneficial for establishing bases of researchers that will contribute to the continuance of cooperative research on the new generation of mobile communications.

• Practical Algorithms for Highly Efficient Cooperative Transmission in Wireless Networks

  • Funded by: VINNOVA - Swedish Governmental Agency for Innovation Systems (2008-2011)
  • Project leader: Prof. Prof. Erik G. Larsson
    Co-PI: Dr. Oscar Gustafsson, ISY/Electronic Systems
  • Project summary: The project aims at evaluating methods for cooperative transmission in wireless networks. Algorithms that perform theoretically well have recently been proposed by many groups. In this work the focus is on implementation aspects and eventually power consumption. Many different aspects must be taken into account and one should find a balance between power consumption and quality of transmission. This project is a collaboration between LiU/ISY and BIT and BUPT, China, under the IMT-Advanced Sino-Swedish cooperation framework.

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Previous Projects

• Modulation and decoding in digital transmission systems.

  • Funded by: CENIIT (2005-2007)
  • Project leader: Dr. Danyo Danev
  • Detailed project description