In today’s modern era of technology mobile communication is evolving with a higher pace than ever before. New features and applications are added in the existing networks each day. The faster development pace requires a faster way to prototype and test the mobile communication standards/ applications to offer faster delivery to the end user. In traditional practices hardware updates and new features growth take long time to market implementations. Technology tends to be obsolete by the time it is to be launched to the market. The reason being long time required for hardware production. However, in the recent days the trend is changing with the emergence of open source cellular stacks to be used with affordable software defined radio (SDR) hardware platforms. Long term evolution (LTE) open source cellular stacks along with the SDR technology are widely used in research these days. However, the performance and limitations of these SDR based open source cellular stacks needs to be explored. In this project a thorough study is performed to access the performance of an open source SDR based LTE user equipment (UE) software stack. A prototype of Category 4 LTE modem is implemented using the srsLTE application suite. Performance analysis is done by looking into the datarate, SNR and radio frequency (RF) characteristics of the implemented solution for multiple system bandwidth settings. A performance comparison is presented between the high performance SDR platform Universal Software Radio Peripheral x310 and the LimeSDR. The results show that the SDR technology is capable of handling wideband signals like LTE. The choice of SDR hardware platform and open source cellular stack depends on the application. The chosen solution for this project i.e. srsLTE performed well for LTE bandwidths 10 MHz and above in terms of downlink data rate. However, the radio frequency characteristics of selected SDR platforms do not comply fully with the 3GPP standard requirements. / I dagens moderna era av teknik utvecklas mobilkommunikation med en högre takt än någonsin tidigare. Nya funktioner och applikationer läggs till i befintliga nätverk varje dag. Den snabbare utvecklingstakten kräver ett snabbare sätt att prototypa och testa mobil kommunikationsstandarder / applikationer för att erbjuda snabbare leverans till slutanvändaren. I traditionell praxis tar hårdvaruuppdateringar och nya funktioner tillväxt lång tid att implementera marknaden. Teknik tenderar att vara föråldrad när den ska lanseras på marknaden. Anledningen är att det krävs lång tid för hårdvaruproduktion. De senaste dagarna förändras emellertid trenden med uppkomsten av cellulära stackar med öppen källkod som ska användas med programvarudefinierad radio (SDR) till överkomliga programvara. par Långtidsutveckling (LTE) med öppna källor, cellulära staplar tillsammans med SDR-tekniken används i stor utsträckning i forskning idag. Prestandan och begränsningarna för dessa SDR-baserade öppna källkodsstapelar måste dock utforskas. I detta projekt utförs en grundlig studie för att fååtkomst till prestanda för en open source SDR-baserad LTE-användarutrustning (UE) -programvarubunke. En prototyp av kategori 4 LTEmodem implementeras med srsLTE-applikationssviten. Prestandeanalys görs genom att undersöka egenskaperna för datarate, SNR och radiofrekvens (RF) för den implementerade lösningen för flera systembandbreddinställningar. En prestandajämförelse presenteras mellan den högpresterande SDR-plattformen Universal Software Radio Peripheral x310 och LimeSDR. Resultaten visar att SDR-tekniken kan hantera bredbandssignaler som LTE. Valet av SDR-hårdvaruplattform och öppen källkods cellstapel beror påapplikationen. Den valda lösningen för detta projekt, dvs srsLTE, fungerade bra för LTE-bandbredd 10 MHz och högre i termer av nedlänks datahastighet. Radiofrekvensegenskaperna för utvalda SDR-plattformar uppfyller dock inte helt 3GPP-standardkraven.

The work deals with the use of software-defined radio as a probe for monitoring the operation of wireless communication according to the IEEE 802.11a/g standard. In the theoretical introduction, the concept of software-defined radio as a hardware device with software programmable circuits enabling the transmission or reception of signals in theoretically any frequency band is introduced. The introduction also contains adescription of selected devices and the IEEE 802.11 protocol with its most used additionsand modulations. In the first part of the practical part of the work, wireless communication is capturedusing a wireless network card in monitoring mode. The intercepted communication was decrypted and this decrypted traffic was compared with the data captured by the probe within the network. These results then served as acomparative basis for software-defined radio capturing. The focus of this work is to verify the capabilities of software-defined radio and its use for sniffing wireless communicationin the frequency band 2.4 GHz and 5 GHz. The attempt to use a software-defined radio here results from the scalability and adaptability that a wireless card cannot offer due to fixed hardware parameters. LimeSDR mini, LimeSDR and bladeRF 2.0 devices were used for capture. First, the configuration of the operating system, the installation of drivers and programs for control and work with selected devices are described. After verifying the functionality of the software-defined radio, a model of a signal decoder with the parameters of the IEEE 802.11g standard captured from the radio spectrum was put into operation. Finally, the data streams captured by the software-defined radio and the wireless network card were compared side by side. The results showed that the software-defined radio in the used configuration captures only a part of the total volume of transmitted frames.

Drone-mounted ground penetrating radar (GPR) has the capability to investigate terrain that is inaccessible or hazardous to humans. A linear frequency-modulated (LFM) radar with the potential for GPR applications is described based on the LimeSDR Mini software defined radio (SDR). Challenges of the LimeSDR Mini radar include the SDR's lack of support for transmitter-receiver synchronization and high bleedthrough leakage. These issues are overcome through corrective software processing techniques including deconvolution of the SDR's system impulse response and digital feed-through nulling. Feed-through nulling is effective at reducing bleedthrough leakage, achieving a 26 dB reduction in power. Although high noise can confound the identification of targets with small radar cross sections in dynamic environments, the LimeSDR Mini radar is demonstrated to display a moving target across multiple ranges. This research demonstrates the increasing accessibility of SDR radar for drone applications, as the LimeSDR Mini is lightweight and low-cost compared to high-end SDRs typically used in SDR radar.

Massive deployment of diverse ultra-low power wireless devices necessitates the rapid development of communication protocols. Software Defined Radio (SDR) provides a flexible platform for deploying and evaluating real-world performance of these protocols. But SDR platform based communication systems suffer from high and unpredictable delays. There is a lack of comprehensive understanding of the characteristics of the delays experienced by these systems for new SDR platforms like LimeSDR. This knowledge gap needs to be filled in order to reduce these delays and better design protocols which can take advantage of these platforms. We design a GNU Radio based IEEE 802.15.4 experimental setup, where the data path is time-stamped at various points of interest to get a comprehensive understanding of the characteristics of the delays. Our analysis shows GNU Radio processing and LimeSDR buffering delay are the major delays in these data paths. We try to decrease the LimeSDR buffering delay by decreasing the USB transfer size but it comes at the cost of increased processing overhead. The USB transfer packet size is modified to investigate which USB transfer size provides the best balance between buffering delay and the processing overhead across two different host computers. Our experiments show that for the best-measured configuration the mean and jitter of latency decreases by 37% and 40% respectively for the host computer with higher processing resources. We also show that the throughput is not affected by these modifications. Higher processing resources help in handling higher processing overhead and can better reduce the buffering delay. / Stora installationer av heterogena extremt energisnåla trådlösa enheter ställer krav på snabb utveckling av kommunikationsprotokoll. Mjukvarubaserad radio (Software Defined Radio, SDR) tillhandahåller en flexibel plattform för att installera och utvärdera faktisk prestanda för dessa protokoll. Men SDR-baserade system har problem med stora och oförutsägbara fördröjningar. Verklig förståelse av hur dessa fördröjningar beter sig i nya plattform som LimeSDR saknas. Dessa kunskapsbrister behöver överbryggas för att kunna minska fördröjningarna och för att mer framgångsrikt kunna designa protokoll som drar nytta av de nya plattformarna. Vi skapar en försöksuppställning för IEEE 802.15.4 baserad på GNU Radio. Data som passerar systemet tidsstämplas för att ge underlag till att förstå fördröjningarnas egenskaper. Vår analys visar att fördröjningarna främst kommer från processande i GNU-radion och buffertider för LimeSDR. Vi försöker minska buffertiderna för LimeSDR genom att minska paketstorleken för USB-överföring, men det kommer till priset av ökade bearbetningskostnader. Paketstorleken för USB-överföring modifieras för att på två olika testdatorer undersöka den bästa balansen mellan buffertider och bearbetningskostnader. Våra experiment visar att för att den mest noggrant undersökta försöksuppställningen så minskar medelvärdet och jittret för fördröjningarna med 37% och 40% för testdatorn med mest beräkningskraft. Vi visar också att genomströmningen inte påverkas av dessa ändringar. Med mer beräkningskraft kan de ökade bearbetningskostnader hanteras, och buffertiderna kan förkortas mer effektivt.

High cost is a current problem with modern radar systems. Software-defined radios (SDRs) offer a possible solution for low-cost customizable radar systems. An SDR is a radio communi- cation system where, instead of the traditional radio components implemented in hardware, many of the components are implemented in software on a computer or embedded system. Although SDRs were originally designed for wireless communication systems, the firmware of an SDR can be configured into a radar system. With new companies entering the market, various types of low- cost SDRs have emerged. This thesis explores the use of a LimeSDR-Mini in a short-range radar through open software tools and custom code. The LimeSDR-Mini is successfully shown to detect targets at a short range. However, due to the instability of the LimeSDR-Mini, the consistent detection of a target is not possible. This thesis shows how the LimeSDR is characterized and how timing synchronization and instability issues are mitigated. The LimeSDR-Mini falls short of operating reliable in a radar system and other SDR boards need to be explored as viable options. Test setups using coaxial cables and test setups using antennas in an outdoor environment show the instability of the LimeSDR-Mini. The transmitter and the receiver are asynchronous. The timing difference varies slightly from run to run, which results in issues that are exacerbated in a short-range radar. The bleed-through signal is the signal leakage from the transmitter to the receiver. The bleed-through signal prevents the detection of targets at a short-range. Feed-through nulling is a signal processing technique used to eliminate the bleed-through signal so that short- range targets can be detected. The instability of the LimeSDR-Mini reduces the effectiveness of feed-through nulling techniques.