Master thesis project Proof-of-concept demonstration of superposition by rwi74592



                 Master thesis project:
Proof-of-concept demonstration of superposition relaying
       (to be performed at Ericsson, Stockholm)
                                                        October 2009

This project involves the implementation and proof-of-concept demonstration of symmetric relaying in
a wireless communication network. The work will be performed at Ericsson Research in Stockholm, in
cooperation with LiU and KTH within the RAMCOORAN project. Salary will be paid according to a
standard remuneration policy.
The main idea of relaying in wireless communications [1] is to provide diversity/reliability for data
transmission from a source to a destination in scenarios where the destination is located far away from
the source. The classical relay channel consists of a source, destination and relay. The communication
using a conventional relay involves two phases of transmission. In first phase, source transmit its data to
both the relay and the destination. During the second phase, the relay retransmits whatever it heard from
the source during the first phase. The destination then makes optimal use of what it heard during the two
The symmetric relaying scenario involves two nodes, A and B communicating with a common destination
D. In the project, we will explore the idea of cooperation using superposition coding [2]. The key idea is
that, during a transmission slot, any node will transmits its own data packet along with the other node’s
data, for which it acts as a relay, using superposition coding. It has been shown that this strategy for
cooperation between the nodes outperforms the conventional decode-and-forward strategy by ∼ 2 dB in
signal-to-noise ratio, without increasing the system complexity.
The objective of the thesis work will be to implement symmetric relaying scenario using superposition
coding using the WARP testbed [3] and compare the results with the available theoretical results. The
WARP testbed is a full-fledged hardware platform with circuit boards comprising an FPGA/CPU for
computations, and an RF (ISM band) transmit/receive module connected to a physical antenna. Three
boards will be needed for the experiment setup described above (one for the two sources, and one for the
destination, respectively). The WARP platform can be programmed most efficiently by first constructing
a block diagram over the processing in SimuLink, which can then be automatically translated to code run
by the onboard FPGA/CPU. The entire design of the WARP and the associated software is open-source.
The candidate needs good knowledge of fundamentals of communication theory and systems, and good
programming skills. Basic understanding for hardware (FPGAs, RF) is also desirable.
Contact: To apply, write to one of the points of contacts:
LiU students: Prof. Erik G. Larsson, ISY. Phone: 073-6209426. Email:
KTH students: Prof. Mikael Skoglund, EES. Phone: 08-7908430. Email:

                                                          R EFERENCES
[1] J. N. Laneman, D. N. Tse, and G. W. Wornell, “Cooperative diversity in wireless networks: efficient protocol and outage behavior,”
    IEEE Trans. Inform. Theory, vol. 50, pp. 3062-3080, Dec 2004.
[2] E. G. Larsson and B. Vojcic, “Cooperative transmit diversity based on superposition modulation,” IEEE Communications Letters, vol.
    9, pp. 778-780, Sept. 2005.

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