<p>Genom samtal med radioamatörer visade det sig att det fanns ett intresse för att använda rumsdiversitet på deras mottagare då de upplevde fädning (vid körning med bil) som ett problem för hörbarheten. I ett system där mottagaren är stationär och sändaren mobil kommer den mottagna signalen att fäda ibland då radiovågorna tar olika vägar till mottagaren och ibland förstärker och ibland stör varandra. Tanken med detta examensarbete var att kunna ta emot två bandbegränsade audiosignaler från två mottagare med varsin antenn som tar emot samma signal (rumsdiversitet) och vikta ihop dessa med lämplig metod för att få ut en bättre signal. Om man kunde implementera ett diversitetssystem med VHDL i en FPGA så skulle man få ett system som var både billigt och flexibelt. I det här examensarbetet har jag försökt att konstruera ett sådant system.</p>

Genom samtal med radioamatörer visade det sig att det fanns ett intresse för att använda rumsdiversitet på deras mottagare då de upplevde fädning (vid körning med bil) som ett problem för hörbarheten. I ett system där mottagaren är stationär och sändaren mobil kommer den mottagna signalen att fäda ibland då radiovågorna tar olika vägar till mottagaren och ibland förstärker och ibland stör varandra. Tanken med detta examensarbete var att kunna ta emot två bandbegränsade audiosignaler från två mottagare med varsin antenn som tar emot samma signal (rumsdiversitet) och vikta ihop dessa med lämplig metod för att få ut en bättre signal. Om man kunde implementera ett diversitetssystem med VHDL i en FPGA så skulle man få ett system som var både billigt och flexibelt. I det här examensarbetet har jag försökt att konstruera ett sådant system.

<p>To be able to evaluate different radio waveforms in a laboratory environment FOI in Linköping has developed an experimental system for radio communication called Rasmus. The system consists of a transmitter, a channel emulator and a receiver. The transmitter modulates a digital signal to a desired analogue waveform. The channel emulator is used to simulate a real radio channel. The channel emulator distorts the signal by splitting it up in several propagation paths. Each path has its own statistical distribution, delay and so on. The receiver digitises the signal and saves it in a memory. Analysis of the signal is performed in non-real time. The system has some limitations concerning signal bandwidths and channel models. </p><p>This Master Thesis deals with the problem of scaling the radio channel (with respect to noise, Doppler shift and fading) in order to examine signals that have properties outside the normal operation of the Rasmus system. </p><p>The radio channel studied is a Rayleigh fading channel with two independent propagation paths. A differentially modulated QPSK signal is used as input to the channel. The signal is filtered through root-raised-cosine filter in the transmitter and receiver to reduce the effect of inter-symbol interference. </p><p>Theoretical calculations result in a method, that describe which parameters that should be scaled and how they should be scaled. Simulations are carried out in order to verify the method.</p>

To be able to evaluate different radio waveforms in a laboratory environment FOI in Linköping has developed an experimental system for radio communication called Rasmus. The system consists of a transmitter, a channel emulator and a receiver. The transmitter modulates a digital signal to a desired analogue waveform. The channel emulator is used to simulate a real radio channel. The channel emulator distorts the signal by splitting it up in several propagation paths. Each path has its own statistical distribution, delay and so on. The receiver digitises the signal and saves it in a memory. Analysis of the signal is performed in non-real time. The system has some limitations concerning signal bandwidths and channel models. This Master Thesis deals with the problem of scaling the radio channel (with respect to noise, Doppler shift and fading) in order to examine signals that have properties outside the normal operation of the Rasmus system. The radio channel studied is a Rayleigh fading channel with two independent propagation paths. A differentially modulated QPSK signal is used as input to the channel. The signal is filtered through root-raised-cosine filter in the transmitter and receiver to reduce the effect of inter-symbol interference. Theoretical calculations result in a method, that describe which parameters that should be scaled and how they should be scaled. Simulations are carried out in order to verify the method.

This thesis evaluates the possibility of using millimeter waves of frequency 28GHz for the use of wireless backhaul in small cell solutions in the coming fifth generation mobile networks. This frequency band has not been used in preceding mobile networks but is undergoing a lot of research. In this thesis simulations are performed to evaluate how the high frequency waves behave inside a three dimensional grid of buildings. The simulations use highly directive antenna arrays with antenna gains of 26dBi. A main results of the investigation was that a high bandwidth of 800MHz was not enough to provide 12Gbps in non line-of-sight propagation within the simulations. Furthermore, without interference limiting techniques, the interference is probable to dominate the noise, even though the high diffraction losses of millimeter waves propose that interference should be very limited in urban areas.