Enhanced direct sequence spread spectrum (eDSSS) Method to Mitigate SINR mismatch in LTE-Wi-Fi integrated networks

Demand of data usage and increase of subscribers in Long Term Evolution (LTE) has urged Third Group Partnership Project (3GPP) to find a solution of traffic data growth. In Release 12, the 3GPP introduced Wi-Fi as an alternative to ease the heavy traffic at the LTE base station in dense areas. In contrary with the traffic offloading, Wi-Fi users suffer the worst network degradation because of co-channel interference at frequency 2.4GHz due to collided with LTE band 40. Interference management in LTE-Wi-Fi integrated network is crucial as it affect user’s experiences and services. In this paper, we enhanced a method which is Direct Sequence Spread Spectrum (DSSS) to improve user’s performance in LTE-Wi-Fi network. The DSSS has advantages such as more robust and ability to expand to higher data rates. We introduce a new coefficient called as chip rate coefficient (α) to investigate Signal-to-Interference-Noise Ratio (SINR) expression for User Equipments (UEs) in LTE-Wi-Fi networks. The simulation results discovered that proposed α with value of 0.2 gave the optimum improvement of SINR for LTE and Wi-Fi users. By modifying the SINR expression of the standard DSSS, SINR values at MUE and WUE show better improvement with 4.69% and 17.94%, respectively

MECC scheduling algorithm in vehicular environment for uplink transmission in LTE networks

Single Carrier Frequency Division Multiple Access (SC-FDMA) is chosen because of the lower peak-to-average power ratio (PAPR) value in uplink transmission. However, the contiguity constraint is one of the major constraint presents in uplink packet scheduling, where all RBs allocated to a single UE must be contiguous in the frequency-domain within each time slot to maintain its single carrier. This paper proposed an uplink-scheduling algorithm namely the Maximum Expansion with Contiguity Constraints (MECC) algorithm, which supports both the RT and NRT services. The MECC algorithm is deployed in two stages. In the first stage, the RBs are allocated fairly among the UEs. The second stage allocates the RBs with the highest metric value and expands the allocation on both sides of the matrix, M with respect to the contiguity constraint. The performance of the MECC algorithm was observed in terms of throughput, fairness, delay, and Packet Loss Ratio (PLR) for VoIP, video and best effort flows. The MECC scheduling algorithm is compared to other algorithms namely the Round Robin (RR), Channel-Dependent First Maximum Expansion (CD-FME), and Proportional Fairness First Maximum Expansion (PF-FME). From here, it can be concluded that the MECC algorithm shows the best results among other algorithms by delivering the highest throughput which is up to 81.29% and 90.04% than CD-FME and RR scheduler for RT and NRT traffic respectively, having low PLR and delay which is up to 93.92% and 56.22% of improvement than CD-FME for the RT traffic flow. The MECC also has a satisfactory level of fairness for the cell-edge users in a vehicular environment of LTE network

Performance Analysis of Propagation in VHF Military Tactical Communication System

يتمثل التحدي الرئيسي لأنظمة الاتصالات التكتيكية العسكرية في إمكانية الوصول إلى المعلومات ذات الصلة حول بيئة التشغيل الخاصة المطلوبة لتحديد الاستخدام المثالي لشكل الموجة. يركز نموذج الانتشار الحالي بشكل أساسي على البث والاتصالات اللاسلكية التجارية باستخدام هوائي جهاز إرسال واستقبال عالي الارتفاع غير مناسب للعديد من أنظمة الاتصالات التكتيكية العسكرية. تقدم هذه الورقة دراسة لنموذج خسارة المسير المتعلق بمظهر الانتشار الراديوي داخل الضواحي في كوالالمبور. تم جمع نمذجة خسارة المسير التجريبية لانتشار الموجات المترية (VHF) من إعدادات الضواحي المختلفة لمدى التردد 30-88 MHz. تأثرت هذه التجربة بشدة بالعوامل البيئية وتأثيرات انتشار الموجات الحالية مثل الانعكاس والحيود والتشتت وتأثير دوبلر. يتم تقييم أداء الانتشار الراديوي من خلال جمع القدرة المستلمة في المحطة الفرعية المخصصة ومقارنتها مع نماذج الانتشار الحالية. كما سيتم ضبط نموذج الانتشار الحالي بالقرب من قيمة القياس عن طريق تحديد الأس الأفضل لخسارة المسير لتنفيذ نموذج مناسب لمنطقة الضواحي. تُظهر التقييمات والتحليلات النظرية لمرحلة القياس الأولية للانتشار الراديوي المساهمة الواسعة للمجال الراديوي من العوائق المحتملة عند ترددات VHF المنخفضة لكل من النطاقات القصيرة والمتوسطة هناك. يشير التفسير إلى نماذج التنبؤ بالانتشار الراديوي القياسية المعقولة عمومًا لمنطقة الضواحي. من تحليل الخطأ العام ، يتضح أن أداء LDPL مع تعديل أس خسارة المسار هو النموذج المناسب لأنه يحتوي على أقل قيمة لمقاييس الخطأ.The main challenge of military tactical communication systems is the accessibility of relevant information on the particular operating environment required for the determination of the waveform's ideal use. The existing propagation model focuses mainly on broadcasting and commercial wireless communication with a highs transceiver antenna that is not suitable for numerous military tactical communication systems. This paper presents a study of the path loss model related to radio propagation profile within the suburban in Kuala Lumpur. The experimental path loss modeling for VHF propagation was collected from various suburban settings for the 30-88 MHz frequency range. This experiment was highly affected by ecological factors and existing wave propagation effects such as reflection, diffraction, scattering, and Doppler effect. Radio propagation performance is evaluated by collecting received power at the allocated substation and comparing it against existing propagation models. The existing propagation model also will be tuned close to the measurement value by identifying the best path loss exponent to perform a suitable model for a suburban area. Theoretical assessments and analysis of the initial measurement stage for radio propagation show the extensive contribution of radio field from potential obstacles at lower VHF frequencies for both short and medium ranges around there. The explanation indicates the standard radio propagation prediction models that are generally reasonable for the suburban area. From the general error analysis, it is seen that, the performance of the LDPL with adjusting path loss exponent is the suitable model since it has least value of error metrics

Quality of service adaptive modulation and coding scheme for IEEE 802.11ac

Nowadays, the rising demand for digital communication technologies has contributed to the increase in the volume of traffic. This continuous trend of internet traffic has led to the deterioration of the quality of service (QoS) with reduced throughput and increased latency. This also is due to the proliferation of new broadband applications which require low latency and high throughput such as virtual reality and real-time gaming. Therefore, considering the aforementioned challenge in QoS of wireless networks, a link adaptation method is suggested in this study, in order to enhance the performance of the QoS in IEEE 802.11ac amendment wireless local-area network (WLAN). The proposed technique adaptively changes the transmission data rate by increasing or decreasing the modulation and coding scheme (MCS) level according to the traffic conditions. With the use of an OMNeT++ computer-aided design (CAD)-based simulation model, the effectiveness of the suggested approach is examined. Simulated findings were compared with the link adaptation approach of the default condition. The results of the simulation demonstrate that the proposed technique significantly increases throughput (36.48%) and decreases latency in comparison to the default situation. These findings demonstrate the technique's potential to improve WLAN QoS efficiency, notably in regard to throughput and latency

Mobile Relay Handover Procedure in Train for 4G LTE-Advanced Network

High speed train has been the most prominent transportation that been used by the public to save the travel time due to the road congestion especially during the peak hour. In parallel with the development of high speed trains nowadays as the trains’ speed can reach up to 350km/h, there have been extensive researches to improve the data rates for mobile wireless communication. Higher data rate and reliable mobile communication are desirable when moving in high speed train. These are a challenge when moving in high speed mobile environment. The major concern is the handover process when travelling from one cell to the other is unable to complete successfully. This is due to the time delay allocates for the handover process to take place is lesser than the time taken for the train to travel across a cell area. Therefore, a solution is solution is required to maintain continuity of services for the passengers on board in order to avoid simultaneous call drop. LTE-Advanced technology seems to be a convincing platform to overcome the problem by proposing better handover signaling procedure when adapting mobile relay on top of the train. A mathematical equation has been derived in order to compare the differences of signaling cost of 3G and 4G networks. The proposed signaling solution is then used in simulation to analyze the number of handover calls between conventional and proposed scheme. The simulation results show that the proposed scheme has better performance in number of handover calls. Thus by adapting relay node in LTE-Advanced network, the problem of drop call can be reduced

Interferences and Solutions in Long Term Evolution (LTE) Network: A Review

LTE is an enhanced of Universal Mobile Telecommunications Systems (UMTS) network, enriched with new and outstanding features geared towards its network and mobile users. Hence, it can improve poor network coverage and quality of service (QoS). Improper network designed by network operators and random deployments of femtocell behaviour will attract interferences and severely degraded the LTE network. This paper reviewed several interference management techniques to improve LTE network performances based on Third Generation Partnership Project (3GPP) in Rel-8 until Rel-12 from recent studies. This paper covers several interferences i.e. co-channel interference (CCI), cross-tier interference and inter-cell interference (ICI). The techniques reviewed focus on victim users e.g. at cell-edge and indoor areas in heterogeneous networks (HetNets). All techniques were explained and the variables used were reviewed

HANDOVER TRIGGER SCHEME FOR MOBILE COMMUNICATION IN HIGH SPEED MOBILE ENVIRONMENT

ABSTRACT High speed rail has been developed rapidly in recent years. The passengers travelled by trains demand for higher data rate and service continuity in order for them to access the Internet. The realization to provide reliable communication for the users in high speed mobility is challenging due to the frequent request for handover since the trains moving in high speed which resulting heavy overhead implementation. Since the User Equipment (UE) in trains communicates directly to the outside of the Base Station (BS), it reduced handover successful rate and hence, degraded the service quality. This research identified the system parameters to improve handover performance in high speed railway network. Moreover, mathematical equation has been derived by integrating the information of train speed and time travelled across the cell. This research has improved handover performances by reducing the probability of drop call rate and increasing the number of handover successful rate. Keywords: receive signal strength (RSS), base station (BS), orthogonal frequency division multiplexing (OFDM), long term evolution (LTE), time to trigger (TTT), quality of service (QOS). INTRODUCTION LTE is a wireless broadband technology designed to support roaming on cell phones and handheld devices. LTE offers significant improvements over previous cellular communication standards. OFDM used in LTE systems make it possible to supply high-speed data service on railway The authors in The

SINR Performance of Macro and Femto LTE-A Network by Fractional Frequency Reuse Jointly Dynamic Power Control Method

This paper studies a two-tier macrocell/ femtocell covered heterogeneous network based on Orthogonal Frequency Division Multiple Access (OFDMA) technology. In order to survive the surge in demand for stable and high data rates among mobile users, femtocell has been developed to increase indoor capacity and coverage. However, arrangement of femtocells has a challenge which is interference between femtocells itself as well to the present macrocells due to the femtocells sharing the similar frequency band assigning as macrocells. This will deteriorate the SINR user’s performance. Therefore, the Fractional Frequency Reuse (FFR) of six jointly a Dynamic Power Control (DPC) is proposed for mitigating the interference experienced between macro and femto users. This paper studied the effect of path loss compensation factor, α on the value of Signal to Interference Noise ratio (SINR) and proposed the best value of α. The simulation results indicate the proposed method is advantageous and can control the transmit power of the UE in femtocell along with the SINR (Signal to Interference plus Noise Ratio)