Abstract Complex software systems need a precise specification of their intended behaviour. While graph theory plays an important role in several aspects of building such software systems, formal methods provide a rigorous mathematical framework within which a system can be described. In this paper, an algorithm for decomposing a graph into disjoint paths is presented. Such decompositions are useful, particularly in... Complex software systems need a precise specification of their intended behaviour. While graph theory plays an important role in several aspects of building such software systems, formal methods provide a rigorous mathematical framework within which a system can be described. In this paper, an algorithm for decomposing a graph into disjoint paths is presented. Such decompositions are useful, particularly in implementing software testing. VDM representation of the proposed algorithm facilitates automation of testing process without any ambiguity. Read More Read Less

Abstract This paper proposes an implementation of the inverse function of the Advanced Encryption Standard using the field of prime numbers instead of the Galois Field originally proposed by Rijndael. The paper will show that the former approach is simpler and requires less execution time and implementation circuitry compared to the latter. The authors analyzed several implementations of the inverse function... This paper proposes an implementation of the inverse function of the Advanced Encryption Standard using the field of prime numbers instead of the Galois Field originally proposed by Rijndael. The paper will show that the former approach is simpler and requires less execution time and implementation circuitry compared to the latter. The authors analyzed several implementations of the inverse function for the S-Box using various approaches in search for an optimal one. In particular, simulation was used to analyze performances of algorithms for computing the inverse function based on: the arithmetic modulo a power-of-two; arithmetic modulo a power-of-two plus one; and arithmetic modulo a prime number. The simulation revealed that the modulo a prime number approach has the best performance. Furthermore, the analysis revealed that using this approach may enhance security relative to the original approach. The proposed implementation will provide a better alternative that can be embedded in many systems. Read More Read Less

Abstract This paper proposes a simple and efficient method for layered MIMO-OFDM system with channel equalization. Temporal variations in the channel are due to Doppler spread, a sign of relative motion between transmitter and receiver. Results are simulated in both Rayleigh channel and additive white Gaussian noise (AWGN) channel. Decision feedback equalizer (DFE) with recursive least square (RLS) algorithm is used... This paper proposes a simple and efficient method for layered MIMO-OFDM system with channel equalization. Temporal variations in the channel are due to Doppler spread, a sign of relative motion between transmitter and receiver. Results are simulated in both Rayleigh channel and additive white Gaussian noise (AWGN) channel. Decision feedback equalizer (DFE) with recursive least square (RLS) algorithm is used for channel equalization. Different type of Layered structure is applied to MIMO-OFDM system and their performance is evaluated. Different modulations schemes are used with same number of transmit and receive antennas. Simulation results are shown for both vertical and horizontal coded layered structure MIMO-OFDM systems with different modulation schemes and different number of transmit antennas. Read More Read Less

Abstract In this paper, the system throughput of an OFDM system is enhanced by adding turbo coding and adaptive modulation (AD). Simulation is done over a time varying Raleigh fading channel. Each OFDM block is individually modulated according to channel state information acquired during the previous burst. The system automatically switches from higher to lower order modulation in order to maintain... In this paper, the system throughput of an OFDM system is enhanced by adding turbo coding and adaptive modulation (AD). Simulation is done over a time varying Raleigh fading channel. Each OFDM block is individually modulated according to channel state information acquired during the previous burst. The system automatically switches from higher to lower order modulation in order to maintain a constant bit error rate. Turbo codes are added for forward error correction, in addition to adaptive modulation. The end goal is to increase the system throughput while maintaining a bit error rate (BER) of 10-2. Read More Read Less

Abstract In this paper, the author presents a method to synthesize the Algorithm State Machines (ASM) for synchronous digital systems using Combined Addressing. In This proposed method, the microinstructions are divided into subsets, and thus the Numbers of microinstructions are apparently minimized and the throughput time of the automation is reduced.... In this paper, the author presents a method to synthesize the Algorithm State Machines (ASM) for synchronous digital systems using Combined Addressing. In This proposed method, the microinstructions are divided into subsets, and thus the Numbers of microinstructions are apparently minimized and the throughput time of the automation is reduced. Read More Read Less

Abstract Computer networks can be built using either wired or wireless technology. Although wired network has been the traditional choice, wireless technologies are becoming more popular. One of the most challenges is to have an existing wired network to which a wireless network extension could be added. Specifically the challenge is to connect a group of wireless networks through a wired... Computer networks can be built using either wired or wireless technology. Although wired network has been the traditional choice, wireless technologies are becoming more popular. One of the most challenges is to have an existing wired network to which a wireless network extension could be added. Specifically the challenge is to connect a group of wireless networks through a wired backbone. The primary purpose of this study is to develop an integrated mathematical model by integrating Packet Reservation Multiple Access (PRMA) one of the most wireless LAN protocols and Token Ring wired network protocol. Performance parameters of an integrated PRMA-Token Ring model such as delay and throughput have be analyzed. The numerical analysis presented in this paper may help in studying the affect of some parameters on the system performance and stability. Read More Read Less

Abstract In order to improve the performance of current embedded systems, Network -on-Chip (NoC) offers many advantages, especially in terms of flexibility and low cost. Applications require more and more intensive computations, especially multimedia applications such as video encoding. Developing product and application using such an architecture offers many challenges and opportunities. Many tools will be required to develop a NoC... In order to improve the performance of current embedded systems, Network -on-Chip (NoC) offers many advantages, especially in terms of flexibility and low cost. Applications require more and more intensive computations, especially multimedia applications such as video encoding. Developing product and application using such an architecture offers many challenges and opportunities. Many tools will be required to develop a NoC architecture for a specific application. A tool which can map and schedule an application or a set of applications to a given NoC architecture will be essential and must be able to satisfy many relative trade-offs (real-time, performance, low power consumption, time to market, re-usability, cost, area, etc). In this paper, we survey most approaches used to solve this problem with different goals. We then describe our approach based on a genetic algorithm and its implementation and its design objective. Read More Read Less