Main goal of this dissertation is read over principal and properties of the OFDM modulation. Onward we become acquainted with basic methods for PAPR dynamics reduction in OFDM such as Clipping or Interleaving. Simulation of reduction methods will be realized in Scilab environment, in which are made basic functions for OFDM modulator and demodulator. Furthermore there are created functions for PAPR reduction methods. All established functions are implemented in the GUI.

Forensic analysis on a media with fragmented and deleted files is a difficult task. There is a lack of tools and techniques that can accurately and quickly detect fragmented suspect files. Fragmented file data that resides in slack space is often overlooked by digital forensic tools. This thesis proposes to use a prefix signature of 4, 8, 16, or 32 bytes instead of either a complete sector comparison or a hash of the complete sector. The experiments show that the 32 byte has as much discrimination as an MD5 or SHA hash in uniquely identifying a sector. It is shown that the false positive rate does not exceed 10% for prefix signature sizes of 32, 16, and 8 bytes. Also the difference in false positive rates for the 32 and 16 byte prefixes does not exceed 25% as compared to MD5 and SHA hashes.

Border Gateway Protocol (BGP) prefix hijacking is a serious problem in the Internet today. Although there are several services being offered to detect a prefix hijack, there has been little work done to prevent a hijack or to continue providing network service during a prefix hijack attack. This thesis proposes a novel framework to provide defense against prefix hijacking which can be offered as a service by Content Distribution Networks and large Internet Service Providers. Our experiments revealed that the hijack success rate reduced from 90.36% to 30.53% at Tier 2, 84.65% to 10.98% at Tier 3 and 82.45% to 8.39% at Tier 4 using Autonomous Systems (ASs) of Akamai as Hijack Prevention Service Provider. We also observed that 70% of the data captured by Hijack Prevention Service Provider (HPSP) can be routed back to Victim. However if we use tunneling, i.e. trying to route data to neighbors of Victims which in turn sends the traffic to Victims, we observed that data can be routed to Victim 98.09% of the time. Also, the cost of such redirection is minimal, since the average increase in path length was observed to be 2.07 AS hops.

Parallel prefix sums algorithms are one of the simplest and most useful building blocks for constructing parallel algorithms. A generic implementation is valuable because of the wide range of applications for this method. This thesis presents a generic C++ implementation of parallel prefix sums. The implementation applies two separate parallel prefix sums algorithms: a recursive doubling (RD) algorithm and a binary-tree based (BT) algorithm. This implementation shows how common communication patterns can be separated from the concrete parallel prefix sums algorithms and thus simplify the work of parallel programming. For each algorithm, the implementation uses two different synchronization options: barrier synchronization and point-to-point synchronization. These synchronization options lead to different communication patterns in the algorithms, which are represented by dependency graphs between tasks. The performance results show that point-to-point synchronization performs better than barrier synchronization as the number of processors increases. As part of the applications for parallel prefix sums, parallel radix sort and four parallel tree applications are built on top of the implementation. These applications are also fundamental parallel algorithms and they represent typical usage of parallel prefix sums in numeric computation and graph applications. The building of such applications become straighforward given this generic implementation of parallel prefix sums.

Border Gateway Protocol (BGP) prefix hijacking is a serious problem in the Internet today. Although there are several services being offered to detect a prefix hijack, there has been little work done to prevent a hijack or to continue providing network service during a prefix hijack attack. This thesis proposes a novel framework to provide defense against prefix hijacking which can be offered as a service by Content Distribution Networks and large Internet Service Providers. Our experiments revealed that the hijack success rate reduced from 90.36% to 30.53% at Tier 2, 84.65% to 10.98% at Tier 3 and 82.45% to 8.39% at Tier 4 using Autonomous Systems (ASs) of Akamai as Hijack Prevention Service Provider. We also observed that 70% of the data captured by Hijack Prevention Service Provider (HPSP) can be routed back to Victim. However if we use tunneling, i.e. trying to route data to neighbors of Victims which in turn sends the traffic to Victims, we observed that data can be routed to Victim 98.09% of the time. Also, the cost of such redirection is minimal, since the average increase in path length was observed to be 2.07 AS hops.

Submitted to the Faculty of Arts in fulfilment of the requirements for Master of Arts in the Department of African Languages at the University of Zululand, 1996. / In this work an attempt is made to discuss a noun prefix in general. Particular attention is given to moving away from the thought that the noun prefix is only the part of the noun that is agreement giving. It also incorporates elements that are non agreement giving. The simple noun prefix is differentiated from the composite noun prefix. Criteria of discerning the simple noun prefix are given, viz. phonological, syntactic, morphological and intergrated criteria. Once identification of the simple noun prefix is properly handled, it is only then that one is able to identify the composite noun prefix. The composite noun prefix has more than one morphological entry. Compound noun prefixes have series of simple prefixes while complex noun prefixes have an additional element bearing some semantic content. The noun ubuntombi and isangoma have composite noun prefixes. The noun ubuntombi has a series of simple prefixes therefore compound, in ubu- (cl. 14) followed by -in-(cl.9) forming a compound ubu-fOn. On the other hand the noun isangoma. over and above the series of simple prefixes isi; (cl.7) and -in- (cl.9), has an additional element ^a-, hence the complex prefix isi-a-in- . The identification of composite noun prefix contributes to a proper identification of the noun stem. From nouns ubuntombi and isangoma the noun stems are -thomb(a)-i (become of age) and -goma (heal), rather than *-ntombi and *-angoma respectively. The identification of composite prefixes is lexicographically friendly, wherein a dictionary the entry would be -goma (heal) rather than -angoma fNkabinde. A.C. (1982:1) Doke CM., Malcolm D.M. & Sikakana. J.M. (1958:4) and Doke, CM. & Vilakazi, B.W. (1990:11)). Of interest, to confirm the importance of composite prefix identification, is a related word to isangoma. viz. ubungoma. At present the entry for ubungoma is -ngoma (Doke,C.M. Vilakazi B.W. (1990:557)) whereas that of -isangoma is -angoma. Infact both nouns ubungoma and isangoma must have the same entry as -soma. The noun ubungoma has a compound prefix ubu- (el. 14) and in^ (cL9), as ubu-in-; whereas isangoma has a complex noun prefix isi-a-in. The dynamics of the (simple) noun prefix is vested on what is termed evolution of the noun prefix in this work. The noun prefix undergoees changes. The changes within the noun prefix is at present literature mixed with morphological constraints brought about by the phonological shape of the noun stem. The noun prefix with [+High] vowels is susceptible to change. The noun umufana has the noun prefix umu- but it changes to urn- as in umfana without being constrained by a vowel initiated stem. This is evolution experienced by a noun prefix. Some changes become permanent and others remain temporary. Permanent changes necessitate sub-classes. The noun ugogo has the noun prefix that evolved from umu- The fact that the changes from umu- to um- to t£ have ultimately caued u- to be a permanent evolutionary form then it sub-classes to umu- Scholars in Zulu have noted the sub-classes but without showing how they came into being. The noun prefix is generally known to play arole of giving agreerfient to other word forms with which it co-occurs. The role of the noun prefix goes beyond agreement giving. This work reveals other roles significant to the noun prefix, viz. deictic, emotive and meaning-structure significances. A fully fledged simple noun prefix signals to a 3rd person, pointing to non-proximate object. Spatially, it points yonder. If a speaker does use a fully fledged noun prefix he (generally) has a reference to the hearer (nearer to him), or even himself. The following utterances will indicate the positions: Umuntu uhambile. (A person has gone.) The reference 'umuntu' is not somewhere near the speaker, because of umu- fully fledged noun prefix. But, if the noun prefix is used without the initial prefix, we have: Sukuma mfana (Stand up boy!) Sengjshiio mina mthakathi wezindaba. (I have said it I of the daring one.) The reference is near the speaker. The reason being that the noun prefix has not been used in its rully fledged form. Non-emotive nouns become emotive if the noun prefix is used without the initial vowel in nouns that pertain to body and belongings. Hamba lapha sidwaba senja. (Away from here you the skirt made of dog's skin.) Woza lapha mhlathi wakho. (Come here you jaws of yours!) The nouns sidwaba and mhlathi are now emotive as against normal nouns isidwaba and umhlathi. The meaning contained within the noun prefixes makes the noun stem to be selective as to which noun prefix to append/affix to give to a particular meaning to the noun. The range of meaning within nouns is falling within the broad spectum of [+ Human] to [-Concrete] vested on the noun prefix. Hendrikse, A.P. and Paulos, G. (1992:195-209) refer to this spectrum as a continuum interpretation of the Bantu noun class system. They visualise the continuum interpretation as ranging from [+ Concrete] to [- Concrete] (abstract). In this work [+ Human] feature is cosidered to be the one that plays an important role as this feature may be found from class I umu- as in umukhwe (father-in-law) to class 11 as in u(lu)hlanva (madman). In Hendrikse and Paulos (1992:203) class II is interpreted as attributive class. In this work [+Human] feature has been used as a diagnostic measure, hence [+Human] and [-Concrete] dichotomy. Also of importance in meaning-structure significance is the interaction of meaning within the composite prefix. This work looks closely how 'noun prefix' within the composite prefix inteact in terms of meaning to effect their composite structure. In the nooun ubunja (dog-like behaviour), we have composite noun prefix ubu-in-. The noun ubunja is derived from the noun inja with only simple prefix JHK The in^ prefix is [-Human, + Concrete], and the ubu- prefix is [-Human,-Concrete]. After preposing ubu- to inja deriving ubunja. the composite nun prefix ubu - in' becomes [-Human - Concrete]. The interaction is that the ubu- features dominates over the in- features. The aspect of'dominance' goes hand in hand with percolation' of Leber (1981), Selkirk (1982), Mbadi (1988). They advocate that the derived word adopts all the feature values of its outermost morpheme.' (Mbadi, L.M. (1988:124) in Nkabinde, A.C. {1988)). The outermost morpheme, inhis case, the pre-posed noun prefix interact with the rest of the noun prefixes' by dominating over them. This work maintains that the last morpheme to be introduced, whether preposed, (post-posed) or imposed dominated over the others. The word abelungu (whites) we have the outermost noun prefix aba- which is [-(-Human]. We have *aba-lungu. as in aba-ntu etc. After the imposing of additional morpheme -e- with its semantic content [+Race] we have now the composite noun prefix ' ab(a)-e- which is {+Human, + Race) as in: which is {+Human, + Race} as in : ab(a) - e - Suthu (Sotho people) ab(a) - e - Nguni (Nguni people) etc.

This thesis focuses on algorithms for longest prefix match (LPM), which is the key operation in packet classification and routing in TCP/IP networks. A space for analysis of commonly used algorithms with emphasis on their speed and memory efficiency is dedicated along with necessary theory. Focus is then oriented on IPv6 networks, their typical prefix sets and comparison of suitable algorithms. Afterwards, the optimization for selected algorithm is suggested and implemented in programming language Python.

Digital wireless communications have considerably changed not only the way people communicate, but also the way research is conducted in the field of telecommunications. In fact, the nature of the wireless medium has created a number of new challenging and fascinating research topics. In particular, a prerequisite for achieving higher and higher transmission rates in wireless systems is to develop strategies for efficiently dealing with the frequency selectivity of the wireless channel. A good candidate is the so-called cyclic prefixed block transmission, and in particular its two most popular variants which are the cyclic prefixed single-carrier (CPSC) and orthogonal frequency division multiplexing (OFDM) modulations. In this context, this thesis aims at analyzing and optimizing the use of cyclic prefixed block transmission for wireless communications. Firstly, this thesis contributes to the current state-of-the-art on the performance comparison between CPSC and OFDM, focusing on the derivation of analytical results when possible. If the channel state information is not available at the transmitter side, CPSC with minimum mean square error linear receiver is shown to achieve the best trade-off between performance and complexity, as it exploits the multipath diversity under some realistic hypotheses. Secondly, this thesis aims at using a system-based or cross-layer criterion, called goodput, for allocating resource in a coded OFDM system. Interestingly, the well-known waterfilling solution, when adequately parametrized, is proved to be near-optimal from a goodput point of view. Finally, this thesis discusses the possibility of improving the performance of a CPSC system by exploiting the cyclic prefix for equalization purposes.

In the Internet today, learnt prefixes are forwarded within autonomous systems (ASs) over internal Border Gateway Protocol (iBGP) sessions. Existing schemes for iBGP routing include the full-mesh (FM) solution, route reflection (RR) solution and confederation. Optimal prefix routing and route diversity are the main strength of the FM solution. However, it is rarely employed in a large networks due to its deficiency in aspects including scalability and large Routing Information Base (RIB) size requirement of routers. This is due to the fact that routers in this topology are required to peer with every other router within the AS. To combat these challenges, the RR scheme provides solution for scalability by decreasing the iBGP sessions requirement. Notwithstanding, the RR solution has its own challenges which includes reduced route diversity, introduction of divergence and forwarding anomalies. Also, the FM optimality may be lost since the Route Reflectors are responsible for reflecting the learnt prefixes to their corresponding clients based on its partial view of the network. The concept of Software Defined Networking (SDN) entails decoupling of the control plane from the forwarding plane such that the control plane is logically centralized benefiting from an overall knowledge of the network for decision making. In this work, we propose a solution based on multicasting which employs relay nodes in the iBGP message dissemination. Our solution brings session management scalability and minimization of duplicate prefix announcement through elimination of peer sessions deemed unnecessary. SDN controller is employed to configure and coordinate the multicast tree.

Syftet med mitt examensarbete var att ta reda på hur läromedel i matematik för år 4-6 tar upp kunskapen om prefixen kring vikt, längd och volym och vilka kunskaper elever i år 6 har i ämnet. Jag har analyserat fem olika läromedel och gjort en enkätundersökning i fem klasser. Genom min undersökning har jag kommit fram till att läromedlen ger eleverna för få tillfällen att praktiskt erfara kunskaper om de olika enheterna. De flesta informerar om vad prefixen betyder men det förekommer inga arbetsuppgifter där eleverna får lära och förstå sammanhanget och nyttan med att kunna dem. Resultatet av min enkätundersökning visade att många elever vet vad enheterna för längd, vikt och volym heter, men har dåliga kunskaper i vad prefixen betyder och svårigheter med att omvandla enheterna. I slutet av mitt examensarbete ger jag några förslag på hur undervisningen kan läggas upp för att ge eleverna större möjlighet att förstå prefixens betydelse och nyttan med kunskapen.