Project 1-3 (USRP project : 2-4 students)
802.11-like OFDM physical layer
Communication systems with multiple carrier frequencies, such as systems based on orthogonal frequency division multiplexing (OFDM), have recently become increasingly popular. Examples of the use of OFDM include both wireless LANs (802.11agn, 802.16, 802.20, HIPERLAN/2), digital audio broadcasting (DAB) as well as terrestrial digital video broadcasting (DVB), and cellular such as 3GPP-LTE.
The goal of this project is to send and receive data over a real wireless link using analog and digital hardware based on the USRP2 with xcvr2450 daugtherboards (www.ettus.com). While signals are transmitted over the air in a realistic fashion the processing will be done off-line in matlab. Thus the data sequences to be transmitted are created in matlab, downloaded to the hardware, and sent on the channel (at the actual data-rate) of the transmitting node. The signal is captured on a receiving node, and saved for post-processing.
Implement a digital OFDM communication system using the 802.11a or 802.11n specification as a basis (the number of subcarriers and/or spacing may need to be altered due to limitations in the available sample-rate). Implement algorithms for synchronization (time of arrival estimation), frequency offset estimation, channel estimation and detection. A pure simulation environment should also be created in order to compare the results obtained in reality with that of the theory. In order to do so you must be able to estimate the signal to noise ratio of the channel. The difference between measurements and simulations should be investigated. You will also need to learn how to conduct experiments.
The basic requirements should be fulfilled at the mid-term evaluation. They should be proved by a draft report and demonstration of the “prototype” (prototype here means collecting measurements and running the receiver algorithms in matlab).
Either of the following three areas should be explored further (based on the chosen project #1-#3)
- Advanced channel estimation by applying smoothing over subcarriers and sub-symbols see e.g. section 5 of .
- Channel coding using convolutional, LDPC  or turbo-codes, see e.g. .
- Inter-carrier interference suppression techniques to combat the influence of phase-noise, see e.g . This may also involve using other hardware with more phase-noise.
The performance improvement of the techniques should be carefully assessed. These advanced requirements should be demonstrated at the grand-final, and documented in a final report, poster and oral presentation.
|||"Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: High-Speed Physical Layer in the 5GHz Band"||Hitoshi Takanashi, et. al.||IEEE|
|||"Research on channel estimation for OFDM receiver based on IEEE 802.11a"||Huimei Yuan Yingzhuan Ling Hao Sun Wen Chen||6th IEEE International Conference on Industrial|
|||"Advanced Digital Communication, course reader in EE379C"||John M. Cioffi||Stanford University, 2000.|
|||"An Introduction to Orthogonal Frequency-Division Multiplexing"||Edfors et al..||Luleå University of Technology, 1996|
|||Estimation of Synchronization Parameters||Jan-Jaap van de Beek||Licentiate thesis Luleå University of Technology, 1996.|
|||Lecture notes from graduate course in OFDM||Katie Wilson||Royal Institute of Technology, 2003|
|||An ICI Reduction Sceheme for OFDM Systems with Phase Noise over Fading Channels||Florent Munier, Thomas Eriksson and Arne Svensson||IEEE Transactions on Communications, Vol 56, No 7, July 2008.|
|||Concatenated convolutional codes with interleavers||Sergio Benedetto, Guido Montosorsi and Dariush Divsalar||Communications Magazine, Aug 2003|
|||Fundamentals of Digital Communications||Upamanyu Madhow||Upamanyu Madhow, 2008|