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Long Term Evolution (LTE) mobile networks, time-frequency radio resources are allotted with respect to Quality of Service (QoS) requirements using scheduling algorithms. Buffer Occupancy (BO), Average Cellular Throughput (ACT), Average User Throughput (AUT), Blocking Probability (BP) and Fairness Index (FI) are the parameters to be considered when designing a scheduler. A new scheduling policy is proposed in this paper, called “Channel Aware Optimized Proportional Fair (CAOPF)” to optimize the channel behavior based on Channel Quality Indicator (CQI). The performance of the introduced scheduler is investigated and compared with the other schedulers such as Round Robin (RR) and Proportional Fair (PF). Simulation results indicate that the new scheduler gives the best level of QoS performance in terms of the above said parameters when compared with the other schedulers taken into account. It provides no pending data of users in good channel condition, higher ACT, higher improvement in user throughput in good and average channel conditions. In addition, very low blocking of user data in good channel condition and optimized FI and resource block (RB) allocated to the users in all channel conditions are seen.

The OFDM system is the mainly proficient in addition to well-known variety of modulation for transporting the message with higher speed. The OFDM is essentially the effective method to overcome multiple path fading, resist delay spread, SNR (signal to noise ratio) increments among negligible Inter symbol in addition to Inter carrier Interference. The main problem in the system is offset in carrier signal, that reduces the orthogonality between the signal and reduces amplitude of needed signal. In sequence to overcome this carrier offsets various methods of evaluation with better way suggested.

A carrier frequency offset (CFO) is addressed as a main type of wireless communication system imperfections in this paper. Carrier frequency offset (CFO) severely deteriorates the performance of OFDM receiver. Here an effective time domain CFO estimation and compensation method using symmetric subcarrier allocation (SCA) for multiband orthogonal frequency division multiplexing (MBOFDM) based ultra-wideband system is proposed. A data supported CFO estimation technique, which is robust to a larger offset, is presented as a novel method in compensation of CFO. An effective separation matrix scheme of OFDM signal with CFO is obtained. Subsequently, independent component analysis (ICA) based CFO estimation is stated. On fully exploiting the ECMA-368 preamble symbols, the proposed technique is capable for carrier frequency offset of 100 ppm, and the result is confirmed through simulations.

A novel compact Coplanar Wave Guide (CPW)-fed metamaterial (MTM)-inspired multiband antenna is designed for Wireless Local Area Network (WLAN), C-Band, Universal Mobile Telecommunication System (UMTS) and Worldwide Interoperability for Microwave Access (WiMAX) applications. The new multiband antenna with the dimensions of 40 × 40 × 0.8 mm3 is fabricated on FR4 substrate. It consists of circular shaped Split Ring Resonator (SRR) with five rings and resonates at 2.10 GHz (UMTS), 2.9 GHz (WLAN), 3.5 GHz (WiMAX), 4.5 GHz (C-band), 5.7 GHz (WLAN) and 6.5 GHz (WLAN-IEEE 802.11ax). Parametric studies are performed on a number of metallic rings, height of the CPW-fed ground plane and different substrate materials for the proposed penta-ring SRR. A prototype antenna is fabricated and the results are measured to examine the simulated results. The measurement of the radiation pattern shows an omnidirectional pattern in H-plane and a dipole like pattern in E-plane.

The complexity of the exhaustive search decoding technique such as Maximum Likelihood Block Detection (MLBD) grows exponentially with the size of transmitted data. In this paper, a Lattice Sphere Decoding (LSD) technique is proposed for detection in block data transmission systems (BDTS). Simulation results at 10dB channel SNR of BDTS with LSD using block size of 20 performs are near Hybrid Micro Genetic Algorithm (HMGA) and slightly inferior than the exhaustive search technique using the channels with spectral nulls. In term of complexity, the proposed LSD technique requires only 460 and 126 objective functions evaluation using radius selection based on Babai Estimation (BE) and off-line observation respectively, while the HMGA and exhaustive search requires 3750 and 220 objective functions evaluation respectively.

A low-complexity detection scheme, which consists of a Hybrid Micro Genetic Algorithm (Hybrid- µGA), is proposed for Orthogonal Frequency Division Multiplexing (OFDM) systems. In the absence of orthogonality, intercarrier-interference (ICI) occurs because a signal from one subcarrier causes interference to others. In several environment, the OFDM signal reflections from a far obstacle generate inter-block-interference (IBI) due to long time delays. To avoid these unpleasant effects of IBI and ICI in OFDM system, a Hybrid-µGA detection algorithm is proposed. The proposed detector combines the conventional one-Tap equalizer and the Micro Genetic Algorithm (µGA) search engine. The output of one-Tap equalizer is considered as the input to µGA search engine. Therefore, the µGA starts with some knowledge rather than blindly to speed up the search. Theoretical analysis and simulation results show that the proposed detection Hybrid- µGA scheme substantially improves the performance of OFDM systems. Moreover, its complexity is 10 times lower than the conventional GA.

Block Data Transmission Systems (BDTS) are used in high-speed wireless communication systems with time dispersive channel characteristics. In such systems, blocks of data are separated by zeros to mitigate the effect of Inter-Symbol-Interference (ISI) between the blocks. An optimal detection process employs the Maximum Likelihood Block Detection (MLBD) technique on each block individually in the presence of ISI and Gaussian noise based on the Euclidean distance as an objective function. The detection process is computationally expensive therefore Genetic Algorithms have been used to reduce the overall design complexity. In this work, three types of Genetic Algorithms have been incorporated in the detection process i.e. the conventional GA, Micro GA(µGA), and Hybrid µGA to reduce computational load. In particular, a novel training method for Hybrid µGA has been proposed. Simulation results at 10dB channel SNR for the BDTS with Hybrid µGA executes as low as 3,750 number of objective functions evaluation for a block size of 20. The Bit Error Rate (BER) performance of this system is relatively good i.e. around 1dB inferior to the BDTS using the Exhaustive Search method that requires as many as 220 number of objective functions evaluation.

Objective: Designing energy efficient mobile communication system is the main challenge for the LTE researchers due to increasing of users and their demands in accessing broadband services on mobile phones. High data rate, reduced Bit Error Rate (BER) and low Peak to Average Power Ratio (PAPR) are the requirement of the current telecommunication technology in both uplink and downlink. In this paper, various modulations techniques (QPSK, BPSK and QAM) and pre-coding schemes (DPC, THP, and RS) are proposed to analyze the uplink characteristics. Methods/Analysis: This paper investigates Single Carrier Frequency Division Multiple Access (SC-FDMA) and performs its link level models with Tomlinson-Harashima Precoder (THP) and Reed Solomon coding (RS) in separate and integrative manner which is proposed. Findings: In order to prove the hypothetical results, various simulations performed for BER of SC-FDMA system. Results proved that the integration of THP and RS coder in the SC-FDMA transmission, improves the system performance in case of BER. The proposed techniques can be implemented in GPRS, UMTS, GSM, EDGE, HSPA and LTE.

The recent wireless communication networks rely on the new technology named Long Term Evolution (LTE) to offer high data rate real-time (RT) traffic with better Quality of Service (QoS) for the increasing demand of customer requirement. LTE provide low latency for real-time services with high throughput, with the help of two-level packet retransmission. Hybrid Automatic Repeat Request (HARQ) retransmission at the Medium Access Control (MAC) layer of LTE networks achieves error-free data transmission. The performance of the LTE networks mainly depends on how effectively this HARQ adopted in the latest communication standard, Universal Mobile Telecommunication System (UMTS). The major challenge in LTE is to balance QoS and fairness among the users. Hence, it is very essential to design a down link scheduling scheme to get the expected service quality to the customers and to utilize the system resources efficiently. This paper provides a comprehensive literature review of LTE MAC layer and six types of QoS/Channel-aware downlink scheduling algorithms designed for this purpose. The contributions of this paper are to identify the gap of knowledge in the downlink scheduling procedure and to point out the future research direction. Based on the comparative study of algorithms taken for the review, this paper is concluded that the EXP Rule scheduler is most suited for LTE networks due to its characteristics of less Packet Loss Ratio (PLR), less Packet Delay (PD), high throughput, fairness and spectral efficiency.

Block transmission systems are used in inter symbol interference (ISI) channels for high data rate communication. In this system, messages are sent as blocks separated by known symbols. Detectors employing block-by-block detection basis is the optimum system and it can be implemented with global search techniques. The performance of such system is found better than block linear equalizers, block decision feedback equalizer. This paper presents the practical difficulty of such system and proposes usage of micro genetic algorithms as an alternative. The performance in terms of bit error rate is evaluated for channels with spectral nulls and hardware complexity is compared with present systems.

In this work, the current-voltage property at a high electric field region (1000V/cm, 1000A/cm/sup 2/) is described. From the relationship among average power dissipation (P), upturn nonlinear coefficient (/spl alpha//sub up/) and ZnO grain resistivity (/spl rho//sub gr/, a new current-voltage equation is derived (upturn equation) and four constants are found. A generic form of this equation is /spl alpha/ = SR/sub up/+ c/sub i/ where S is the upturn power constant, R/sub up/ is the upturn resistance at 1000A/cm/sub 2/ and c/sub i/ is the ideal constant. In this high-field region, also known as upturn region, the current-voltage characteristic is almost ohmic whereby the /spl alpha//sub up/ values are less than 5. Due to the diminished Schottky barrier in the upturn region, ZnO grains play the key role in determining the I-V characteristics. SEM micrograph photos of the starting ZnO powder show presence of intrinsic defects (ID) in the form of irregularly-shaped microclusters of nanocrystallites 40nm-300nm in size. A new model is introduced to describe the impact of these ID on the power dissipation in the I-V upturn region. It is believed that charge carriers are trapped in the potential wells created by ID, and when they are annihilated by opposite charges, thermal energy is dissipated. The fabricated ZnO varistors, categorised as low-voltage models (/spl les/17V/sub rms/), can be used as external surge protection devices (SPDs) for microprocessor-controlled equipment.