Vi fick kontakt med ett företag i Halmstad som tidigare haft examensarbeten isammarbete med maskiningenjörsporgrammet på Högskolan i Halmstad. Vidförfrågan om tillgänglighet till ett examensarbete så fick vi ett förslag om attvidareutveckla ett tidigare examensarbete som företaget haft hos sig. Vi närmareundersökningar av examensarbetet så beslutades det om att en hel trailer skullekonstrueras. Vår rapport innefattar våra steg för att ta fram ett koncept till entrailer. Alla de väsentliga stegen vi har tagit beskrivs i rapporten, från idéstadie tillatt man har möjlighet att ta fram en prototyp. Vi har utgått från de regelverk ochstandarder som finns inom ämnet, dessa finns närmare omnämnda i rapporten.Resultatet av examensarbetet är en konceptdesign till en trailer, där vi anser att detfinns möjlighet till vidareutveckling framförallt genom att ta fram en prototyp. / We got in touch with a company in Halmstad with a history of having theises inconnection with the mechanical engineering programs at Halmstad University. Asa response to the availability to a thesis we got a proposal to develop an earlierthesis that the company has had with them. Upon further investigation of thethesis, we decided with the company that a full trailer would be constructed. Ourreport includes our steps to develop a concept design of a trailer. All the essentialsteps we have taken are described in the report, from the conceptual stage to thepoint where you’re able to produce a prototype. We started with the regulationsand standards that exist in the subject, these are closer mentioned in the report.The result of the thesis is a concept design for a trailer, we do believe there isopportunity for further growth, especially through the development of a prototype

In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is seriously distorted by the multiple propagation paths. The available bandwidth is divided into a lot of small parts in Multi-carrier-CDMA system. Selecting the number of subcarriers according to the environment of channel will make the bandwidth of spread spectrum signals smaller than the coherence bandwidth of channel. And then the system can overcome the question of multiple propagation paths. The performance of Multi-carrier CDMA system is sensitive to frequency offset. Frequency offset results from Doppler shift due to mobile movement, as well as from a mismatch between the carrier frequency of local oscillators at the transmitter and receiver. Consequently, the subcarriers¡¦ orthogonality are lost, causing Inter-carrier Interference (ICI). The interference of other subcarriers will make the error of estimated channel coefficients. Effect of frequency offset will lower the performance of the combing detector that needing channel estimated. In this thesis, we propose a method to correct the frequency offset. Using the relation of two continuous received signals to estimate the frequency and compensate it. We will analysis and compare this method in different condition. Simulation results will demonstrate the performance of this proposed method.

There has been a growing demand for wireless communication services in the past few years. Recent reports reveal that the demand will not only increase in the number of subscribers but also in more diverse applications such as Machine-to-Machine (M2M) communications and the Internet of Things. With such demand for capacity increase, there is a necessity to shift from today’s Static Frequency Allocation (SFA) to Dynamic Spectrum Access (DSA). The change will make efficient use of spectrum by utilizing the unused parts in different times, frequencies and spaces. With this regard, cognitive radio (CR) is a powerful potential candidate for the spectrum scarcity problem. This work addresses the two main current discussions in Cognitive Radio Networks (CRN), spectral efficiency and interference mitigation problem. There are two main spectrum sharing techniques in CRN, overlay and underlay, which have been thoroughly investigated in the literature. Unlike the relative works which separate the use of overlay and underlay, this works considers the joint overlay and underlay as a hybrid system to enhance the spectral efficiency and Bit Error Rate (BER) performance in CRNs. MC-CDMA is proposed for underlay transmission for two main advantages. Firstly, for low power spectral density due to spreading. Secondly, for its capability to mitigate high interference. Two hybrid MC-CDMA schemes are proposed in this work. The first scheme spreads the underlay signal through the whole bandwidth to mitigate PU interference and benefit from the frequency diversity. To maximize data rate, overlay utilizes the available bands while keeping orthogonality with underlay using Orthogonal Variable Spreading Factor (OVSF) codes. To further increase capacity, an overload MC-CDMA system is proposed. In this scheme, overlay utilizes the full signal dimension, while underlay overloads the system. Two layered spreading is applied to differentiate overlay and underlay users. In order to detect the underlay signal, the overlay signal is detected first and is cancelled from the received signal. The underlay data is then detected from this modified signal. The framework is then extended to a multi-user underlay scenario. A code allocation algorithm is proposed in order to achieve low cross-correlation between the overlay and underlay users. The results show that the proposed overload system maintains good performance even in high PU interference level. Furthermore, the proposed hybrid capacities are optimized and compared with the two available hybrid systems in the literature. The proposed overload system showed to increase capacity significantly, both in AWGN and fading environment, in compared with the existing methods.

Wireless mobile ad-hoc networks consist of a collection of peer mobile nodes that form a network and are capable of communicating with each other without help from stationary infrastructure such as access points. The availability of low-cost, com-modity network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC protocol for wireless mobile ad-hoc net-works, even though it is not optimal. The IEEE 802.11 MAC protocol is designed to have stations share a single channel in a given network. However, many of the IEEE 802.11 physical (PHY) layer specifications define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, multiple communications can occur at the same time, offering the opportunity to increase the effective network capacity. We present an innovative routing protocol that utilizes multiple channels to im-prove the performance of wireless ad-hoc networks. The basic idea of the protocol is to use multiple channels so that multiple useful transmissions can occur simultane-ously, thus increasing network capacity. The proposed scheme requires minor changes to existing proactive ad-hoc routing protocols and no modifications to the current IEEE 802.11 MAC protocol. To reduce inefficiencies due to periodic updates in the proactive routing protocols, the proposed scheme divides the network layer into control and data planes. Nodes send routing updates using the control channel and user packets using the data channel. To demonstrate the multi-channel routing scheme, we extend the Destination-Sequenced Distance-Vector (DSDV), Open Shortest Path First-Minimal Connected Dominating Set (OSPF-MCDS), and Optimized Link State Routing (OLSR) protocol to multiple channel (MC) versions, denoted as DSDV-MC, OSPF-MCDS-MC, and OLSR-MC, respectively. Simulation results for DSDV-MC, OSPF-MCDS-MC, and OLSR-MC are presented and experimental results for OLSR-MC are presented. Simulation results indicate that DSDV-MC and OSPF-MCDS-MC effectively exploit multiple channels to improve network capacity. Goodput, the throughput consider-ing only useful error-free packets, increases with an increased number of available channels as the number of nodes and network load increase in both single-hop and multiple-hop networks. Experimental results with OLSR-MC also support that the proposed scheme increases network capacity without modification to the MAC proto-col in a real implementation. Although simulation and experimental results show that proposed scheme im-proves network capacity by exploiting multiple channels, problems exist with channel distribution. We introduce a new metric, the Channel Distribution Index (CDI) to in-vestigate these issues. The CDI indicates the fairness of the channel distribution. We identify the channel convergence problem, where a particular channel is over-utilized, and propose a channel reallocation scheme to mitigate the impact of the channel convergence problem using the CDI. / Ph. D.

Abstract Development of the Fourth Generation of mobile communication systems, or 4G, has already begun in various organizations and research institutions worldwide. There is currently no single conclusive definition for 4G systems, and the process of 4G standardization will only begin after the World Radiocommunication Conference in 2007. The purpose of this report is to provide an objective definition of 4G systems based on user requirements, and to use this definition to determine an appropriate 4G access network architecture. By examining the current trends in user requirements, and the methodologies proposed by different researchers, an objective definition of 4G systems was developed. The definition states that the purpose of 4G systems is to provide users with the capacity to access any service at any time at a reasonable cost and at the required levels of quality. There are two developmental methodologies which are currently being considered to achieve this objective: first the evolution and convergence of existing systems, including cellular, IT and broadcasting communication systems, and second, the development of a new 4G access network capable of providing users with access to advanced services. The primary specification for this new access network is that it must provide a throughput of 1 Mbps for mobile users and 1 Gbps for users that are stationary. Other requirements include high spectral efficiency and high capacity and coverage. The primary focus of this report is the examination of the second of the above methodologies by evaluating the performance of candidate 4G air-interface architectures so that a recommendation could be made as to which of the architectures is the preferred choice as the core component in a new 4G access network. Orthogonal Frequency Division Multiplexing (OFDM) modulation is a high performance modulation technique capable of achieving high levels of spectral efficiency and is widely accepted as the technique most capable of meeting 4G access network requirements. There are two primary access network architectures that make use of OFDM modulation and could form the core components of a 4G air-interface, the physical component of a 4G access network. To determine which architecture is the appropriate choice for 4G systems, a series of simulations were run using realistic models of a wireless environment. The results of those simulations were analyzed, and it was determined that, due to the absence of multiple access interference found in MC-CDMA, OFDMA systems better met the defined requirements for a 4G air-interface. The use of additional techniques such as radio resource management, multi-antennae technologies and software defined radios are cited as potential methods for improving both OFDMA and MC-CDMA performance.

<p>Den snabba tillväxten av organiserad brottslighet under de senaste tio åren ger en bra möjlighet att undersöka dess inverkan på brottsförekomst – ett relativt outforskat område i Sverige. Denna studie syftar till att undersöka hur kommuners brottsfrekvens påverkas av förekomsten av kriminella MC-gäng. En panel med kommundata för åren 1996–2003 ligger till grund för den modell, med kommun- och tidsspecifika effekter, som används för att undersöka effekterna av kriminella MC-gäng på ett antal brottskategorier. De brottskategorier som undersöks är: tillgrepp av fordon, stöld ur och från fordon och inbrottsstöld samt misshandel mot män utomhus, och därtill även total brottslighet, total tillgreppsbrottslighet, total våldsbrottslighet och total hotbrottslighet. För flera brottskategorier visar resultatet tecken på att antalet anmälda brott minskar då kriminella MC-gäng finns etablerade i kommunen, vilket kan vara följden av en avskräckande effekt som framkallas på grund av gängens närvaro, och/eller genom hot och andra metoder. En avskräckande effekt kan medföra att anmälningsbenägenheten sjunker vilket följaktligen skulle betyda att antalet anmälda brott minskar.</p>

Den snabba tillväxten av organiserad brottslighet under de senaste tio åren ger en bra möjlighet att undersöka dess inverkan på brottsförekomst – ett relativt outforskat område i Sverige. Denna studie syftar till att undersöka hur kommuners brottsfrekvens påverkas av förekomsten av kriminella MC-gäng. En panel med kommundata för åren 1996–2003 ligger till grund för den modell, med kommun- och tidsspecifika effekter, som används för att undersöka effekterna av kriminella MC-gäng på ett antal brottskategorier. De brottskategorier som undersöks är: tillgrepp av fordon, stöld ur och från fordon och inbrottsstöld samt misshandel mot män utomhus, och därtill även total brottslighet, total tillgreppsbrottslighet, total våldsbrottslighet och total hotbrottslighet. För flera brottskategorier visar resultatet tecken på att antalet anmälda brott minskar då kriminella MC-gäng finns etablerade i kommunen, vilket kan vara följden av en avskräckande effekt som framkallas på grund av gängens närvaro, och/eller genom hot och andra metoder. En avskräckande effekt kan medföra att anmälningsbenägenheten sjunker vilket följaktligen skulle betyda att antalet anmälda brott minskar.

In this thesis, the feasibility of complete complementary code based OFDM CDMA system is studied. The complete complementary code is composed of several sets of auto-complementary codes, any two of which are cross-complementary codes. The perfect correlation between code sets is the distinguishing feature of complete complementary code. In this thesis, we designed a new OFDM CDMA system architecture according the property of complete complementary code. The most obvious characteristic is that the bit stream in the new system is no longer aligned one bit after another in time. Instead, a new bit will start only after one chip delay relative to the previous bit, which is spread by an element code of complete complementary code. The proposed new CDMA architecture can offer an MAI-free operation in both down-link (synchronous channel) and up-link (asynchronous channel) transmission under the AWGN channel, because of the use of the CC-codes. However, due to the special spreading modulator-offset stacking modulator (OSM), we¡¦ll encounter a ¡§ multi-level ¡¨ problem . If we can¡¦t solve this problem , the linear power amplifier will not be able to support the whole system . Hence , we try to clip the multilevel into a smaller magnitude . And also , we try some other mapping methods to solve the multilevel problem .

In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is transmitted in the frequency-selective channel, and the signal is severely distorted by the multiple propagation paths. Each bandwidth of the signals for Multi-Carrier CDMA system is smaller. If the bandwidth is smaller than the coherence bandwidth of the channel, the channel is said to be frequency-nonselective. Besides, the data rate of Multi-carrier-CDMA is higher than the data rate of CDMA. If the traditional combing detector is used for Multi-Carrier CDMA system, the channel coefficients have to be estimated first. The error of the estimated channel coefficients will result in the performance of detector degrade. The blind adaptive algorithm doesn

Zugl.: Ulm, Univ., Diss.