Jaafar A. Aldhaibani

Development of a New Approach for High-Quality Quadrupling Frequency Optical Millimeter-Wave Signal Generation Without Optical Filter

In this paper, we propose a new approach to generate quadrupling-frequency optical millimeter-wave (mm-wave) signal with carrier suppression by using two parallel Mach-Zehnder modulators (MZMs) in Radio-over-flber (RoF) system. Among the numerous properties of this approach, the most important is that a fllterless optical mm-wave at 60GHz with an optical sideband suppression ratio (OSSR) as high as 40dB can be obtained when the extinction ratio of the MZM is 25dB. Simplicity and cost-efiectiveness have made this approach a compelling candidate for future wave-division-multiplexing RoF systems. Theoretical analysis is conducted to suppress the undesired optical sidebands for the high-quality generation of frequency quadrupling mm-wave signal. The simulation results show that a 60GHz mm-wave is generated from a 15GHz radio frequency (RF) oscillator with an OSSR as high as 40dB and an radio frequency spurious suppression ratio (RFSSR) exceeding 35dB without any optical or electrical fllter when the extinction ratio of the MZM is 25dB. Furthermore, the efiect of the non-ideal RF-driven voltage as well as the phase difierence of RF-driven signals applied to the two MZMs on OSSR and RFSSR is discussed and analyzed. Finally, we

Effect of relay location on two-way DF and AF relay for multi-user system in LTE-A cellular networks

In order to meet the increasing demand and stringent design requirements for coverage expansion, throughput and capacity enhancement relay Node (RNs) has been considered as a promising solution to LTE-A Point-to-Multi-Point (PMP) networks. In this paper two scenarios are proposed, at the first scenario this work introduced the performance analysis of two-way Multiuser system of half duplex to AF (Amplify and Forward) and DF (Decoded and Forward) Relay. At the second scenario the position of a relay problem for the maximum capacity enhancement of a two-way Relay Node (RN) to achieve an efficient and scalable Long Term Evolution-Advanced (L TE-A) wireless network design is investigated., the optimum relay location that provides the greatest achievable rate with two-way performance is derived. It has been observed from the results that the optimum location of AF relay is 0.72 of the cell coverage radius, whereas the DF relay achieved a maximum bit rate when the relay location is at 0.52 from the cell coverage radius. The proposed method will help LTE-A designer to solve relay placement problem.

Coverage Extension and Balancing the Transmitted Power of the Moving Relay Node at LTE-A Cellular Network

The poor capacity at cell boundaries is not enough to meet the growing demand and stringent design which required high capacity and throughput irrespective of users location in the cellular network. In this paper, we propose new schemes for an optimum fixed relay node (RN) placement in LTE-A cellular network to enhance throughput and coverage extension at cell edge region. The proposed approach mitigates interferences between all nodes and ensures optimum utilization with the optimization of transmitted power. Moreover, we proposed a new algorithm to balance the transmitted power of moving relay node (MR) over cell size and providing required SNR and throughput at the users inside vehicle along with reducing the transmitted power consumption by MR. The numerical analysis along with the simulation results indicates that an improvement in capacity for users is 40% increment at downlink transmission from cell capacity. Furthermore, the results revealed that there is saving nearly 75% from transmitted power in MR after using proposed balancing algorithm. ATDI simulator was used to verify the numerical results, which deals with real digital cartographic and standard formats for terrain.

Enhancing link quality in a multi-hop relay in LTE-A employing directional antenna

This paper proposes a new approach for enhancing link quality between relay node (RN) and base station (BS). Two types of antennas were proposed at the relay, the first type is the directional antenna, which is directed toward the base station to improve the relay link quality, thereby reducing outage probability by increasing relay link capacity. The second type is the omni-directional antenna, which is used for the exchange of information between the RN and attached users. An improvement of 32% in capacity and 25% in received signal strength at the relay link has been observed. An ATDI simulator, which handles the digital cartography for the first tier of interference in urban areas, verified the numerical results.

REDUCING TRANSMITTED POWER OF MOVING RELAY NODE IN LONG-TERM EVOLUTION-ADVANCED CELLULAR NETWORKS

Wireless multi-hop relay networks have become very significant technologies in mobile communications. These networks ensure data rate transfer and covera ge extension with a low cost. In this study two typ es of relay are studied; Fixed Relay Node (FRN) and Moving Relay Node (MRN). Where system analyses for uplink and downlink transmission are derived in thi s study. Moreover the optimal relay location of FRN was proposed to provide a maximum achievable rate at user in cell edge region. Finally, a new algorith m was suggested to balance and control on the transmi tted power of MRN over cell size to provide the required SNR and throughput at the users inside veh icle with reducing the consumption transmitted rela y power. Numerical results indicate an enhancement in received signal strength for users at the cell edg e from (-90 to -65) dBm and 40% increment from all cell size after de ploying FRN at proposed locations. As well as, the results revealed that there is saving nearl y 75% from transmitted power in MRN after using proposed algorithm. ATDI simulator was used to verify the nu merical results, which deals with real digital cartographic and standard formats for terrain.

Finger-shaped antenna design for ultra-wideband applications

In recent years, the UWB technology in wireless communication systems is required for many military, civilian, and medical applications, so small and economic UWB antennas need to be produced for these purposes. Since the Federal Communications Commission (FCC) reported the UWB frequency of 7.5 GHz (from 3.1 GHz to 10.6 GHz) was licensed for high data rate wireless technology and antenna plays a very role in UWB systems. The design, simulation, and fabrication of finger-shaped antenna are presented in this paper. The designed antenna has a reflection coefficient (S11) less than -10 dB and voltage standing wave ratio (VSWR) less than 2 for the frequency of 4 to 12 GHz. The far field radiation patterns are introduced with the proposed antenna dimensions and feeding by microstrip transmission line feeder. Simulation and fabrication results for S11 VSWR, radiation patterns, and gain of the proposed antenna are presented and discussed along the frequency band 4 to 12 GHz.

Low complexity burst allocation algorithm with high frame utilization for Mobile WiMAX (802.16e)

Burst allocation is one of the important parameter that affects the performance of the Mobile WiMAX systems. The burst allocation algorithm is responsible about calculating the appropriate dimensions and location of each users data to construct the bursts within the downlink subframe in term of the number of slots per user. Resource wastage in the form of unused and unallocated slots is a common problem accompanies burst allocation. In this paper, a Sequential Burst Allocation (SBA) algorithm is proposed to overcome frame wastage. The SBA algorithm is based on the sequential allocation of user slots. SBA restricts the unused slots, and eliminates unallocated slots between data bursts through burst fragmentation when necessary is forced to be used. Continuous allocation from one frame to the next has a significant impact on reducing resource wastage. It has been observed from the results that the percentage difference of the frame utilization between SBA and Standard algorithms (ST) is 32.84 %, which achieved significant reduction of resource wastage per frame, leading to more exploit of the WiMAX frame.

Analyzing mobile WiMAX base station deployment under different frequency planning strategies

The frequency spectrum is a precious resource and scarce in the communication markets. Therefore, different techniques are adopted to utilize the available spectrum in deploying WiMAX base stations (BS) in cellular networks. In this paper several types of frequency planning techniques are illustrated, and a comprehensive comparative study between conventional frequency reuse of 1 (FR of 1) and fractional frequency reuse (FFR) is presented. These techniques are widely used in network deployment, because they employ universal frequency (using all the available bandwidth) in their base station installation/configuration within network system. This paper presents a network model of 19 base stations in order to be employed in the comparison of the aforesaid frequency planning techniques. Users are randomly distributed within base stations, users’ resource mapping and their burst profile selection are based on the measured signal to interference plus-noise ratio (SINR). Simulation results reveal that the FFR has advantages over the conventional FR of 1 in various metrics. 98 % of downlink resources (slots) are exploited when FFR is applied, whilst it is 81 % at FR of 1. Data rate of FFR has been increased to 10.6 Mbps, while it is 7.98 Mbps at FR of 1. The spectral efficiency is better enhanced (1.072 bps/Hz) at FR of 1 than FFR (0.808 bps/Hz), since FR of 1 exploits all the Bandwidth. The subcarrier efficiency shows how many data bits that can be carried by subcarriers under different frequency planning techniques, the system can carry more data bits under FFR (2.40 bit/subcarrier) than FR of 1 (1.998 bit/subcarrier). This study confirms that FFR can perform better than conventional frequency planning (FR of 1) which made it a strong candidate for WiMAX BS deployment in cellular networks.The frequency spectrum is a precious resource and scarce in the communication markets. Therefore, different techniques are adopted to utilize the available spectrum in deploying WiMAX base stations (BS) in cellular networks. In this paper several types of frequency planning techniques are illustrated, and a comprehensive comparative study between conventional frequency reuse of 1 (FR of 1) and fractional frequency reuse (FFR) is presented. These techniques are widely used in network deployment, because they employ universal frequency (using all the available bandwidth) in their base station installation/configuration within network system. This paper presents a network model of 19 base stations in order to be employed in the comparison of the aforesaid frequency planning techniques. Users are randomly distributed within base stations, users’ resource mapping and their burst profile selection are based on the measured signal to interference plus-noise ratio (SINR). Simulation results reveal that the FFR ha...

Wireless rake-receiver using adaptive filter with a family of partial update algorithms in noise cancellation applications

For high data rate propagation in wireless ultra-wideband (UWB) communication systems, the inter-symbol interference (ISI), multiple-access interference (MAI), and multiple-users interference (MUI) are influencing the performance of the wireless systems. In this paper, the rake-receiver was presented with the spread signal by direct sequence spread spectrum (DS-SS) technique. The adaptive rake-receiver structure was shown with adjusting the receiver tap weights using least mean squares (LMS), normalized least mean squares (NLMS), and affine projection algorithms (APA) to support the weak signals by noise cancellation and mitigate the interferences. To minimize the data convergence speed and to reduce the computational complexity by the previous algorithms, a well-known approach of partial-updates (PU) adaptive filters were employed with algorithms, such as sequential-partial, periodic-partial, M-max-partial, and selective-partial updates (SPU) in the proposed system. The simulation results of bit error ra...

Mobile WiMAX resource allocation algorithms guidelines and performance assessment

Resource allocation management is one of the effective factors of WiMAX base station performance. Various goals could be achieved when the resource allocation scheme exploits in the right direction. However, the assessment of the resource allocation algorithms lacks to a uniform performance metrics. Where, most of the researches are trying to show authors perspectives in the finding results to show the design pros, whilst the overall performance in resource allocation perspective mostly not exist. This paper proposes a new style of primary assessment for the resource allocation algorithms to ease conducting a fair comparison between the relevant algorithms. The assessment methodology based on a set of evaluation questions. The obtained results show that the new assessment method distinguishes the overall performance to provide fair comparison.