ملخص البحث :

This paper provides the introduction of LTE and the key components of its physical layer. These descriptions are simplified version of the detailed descriptions provided by 3gpp. In LTE, the OFDMA is used as downlink and SCFDMA as uplink modulation schemes; with OFDM as the basic building block. OFDMA is used for achieving high spectral efficiency in communication system; whereas, SC-FDMA for uplink multiple access scheme in LTE system. This paper evaluates the performance of SC-FDMA and OFDMA of LTE physical layer by considering different modulation schemes (BPSK, QPSK, 16QAM and 64QAM) on the basis of PAPR, BER and error probability. From the simulated results, it is observed that for a particular value of SNR, the BER increases for high order modulation (16-QAM and 64-QAM) in both OFDMA and SC-FDMA. However, the lower order modulation schemes (BPSK and QPSK) experience less BER at receiver; thus lower order modulations improve the system performance in terms of BER and SNR. In terms of bandwidth efficiency, the higher order modulation accommodates more data within a given bandwidth and is more bandwidth efficient as compared to lower order modulation. Thus, there exists a tradeoff between BER and bandwidth efficiency among these modulation schemes used in LTE. It is also observed that the error probability increases as order of modulation scheme increases. Therefore, the selection of modulation schemes in adaptive modulation is quite crucial based on these results.

ملخص البحث :

High demands for broadband mobile wireless communications and the emergence of new wireless multimediaapplications constitute the motivation to the development of broadband wireless access technologies in recent years. The Long Term Evolution/System Architecture Evolution (LTE/SAE) system has been specified by the ThirdGeneration Partnership Project (3GPP) on the way towards fourth-generation (4G) mobile to ensure 3GPP keeping the dominance of the cellular communication technologies. Through the design and optimization of new radio access techniques and a further evolution of the LTE-A systems. Cell selection is the process of determining the cell(s) that provide service to each mobile station. In particular, we study the new possibility available in OFDMA & SC-FDMA based systems, such as IEEE 802.16m and LTE-Advanced, of satisfying the minimal demand of a mobile station simultaneously by more than one base station. We formalize the problem as an optimization problem and we presents how the mobile unit establishes this connection with the strongest cell station in vicinity. To do this, the mobile unit has to overcome the challenges of estimating the channel to communicate with the cell site and frequency synchronization. Also, multiple mobile units communicate to the same receiver and from various distances. Hence, it is up to the mobile to synchronize itself appropriately to the base stations. LTE-A uses two signals, the Primary Synchronization Signal and the Secondary Synchronization Signal sequentially to determine which of the available cell sites a mobile would lock in to. While inter-cell interference (ICI) one of problems for the downlink and uplink of multi-cell systems (in general) and OFDMA& SC-FDMA networks (in particular).

ملخص البحث :

With the high demands for broadband mobile wireless communications and the emergence of new wireless multimedia applications constitute the motivation to the development of broadband wireless access technologies in recent years. The Long Term Evolution/System Architecture Evolution (LTE/SAE) system has been specified by the Third Generation Partnership Project (3GPP) on the way towards fourth-generation (4G) mobile to ensure 3GPP keeping the dominance of the cellular communication technologies. Through the design and optimization of new radio access techniques and a further evolution of the LTE-A systems, Cell selection is the process of determining the cell(s) that provide service to each mobile station. By study the potential benefits of global cell selection versus the current local mobile SNR-based decision protocol. In particular, and present the new possibility available in OFDMA & SC-FDMA based systems, such as IEEE 802.16m and LTEAdvanced, of satisfying the minimal demand of a mobile station simultaneously by more than one base station. After formalized the problems as an optimization problem; it's present how the mobile unit establishes this connection with the strongest cell station in vicinity. To do this, the mobile unit has to overcome the challenges of estimating the channel to communicate with the cell site and frequency synchronization. Also, multiple mobile units communicate to the same receiver and from various distances. Hence, it is up to the mobile to synchronize itself appropriately to the base stations. LTE-A uses two signals, the Primary Synchronization Signal and the Secondary Synchronization Signal sequentially to determine which of the available cell sites, a mobile would lock in to it. While inter-cell interference (ICI) one of problems for the downlink and uplink of multi-cell systems (in general) and OFDMA& SC-FDMA networks (in particular)

ملخص البحث :

It is very challenging to design an efficient wireless communication system. It is because of many factors, affecting the performance of a typical wireless communication system. Single Carrier Frequency Division Multiple Access (SC-FDMA) & Orthogonal Division Multiple Access (OFDMA) are a major part of future mobile communication standards like Long Term Evolution (LTE), LTE-Advanced and Ultra Mobile Broadband (UMB). OFDMA is well utilized for achieving high spectral efficiency in communication systems. SC-FDMA was recently introduced for uplink multiple access scheme. The multiple access schemes in an advanced mobile radio system have to meet the challenging requirements, such as high throughput, good robustness, low Bit Error Rate (BER), high spectral efficiency, low delays, low computational complexity, low Peak to Average Power Ratio (PAPR) and low error probability. Therefore, this project focuses on implementing the two multiple access techniques (SC-FDMA and OFDMA) with adaptive modulation techniques BPSK, QPSK, 16-QAM and 64-QAM; in order to evaluate the performance of LTE physical layer. An introduction to LTE systems is presented in this manuscript.

ملخص البحث :

To increasing demand for higher throughput and data rates and high speed processing of data, the wireless communication systems need to operate in wider bandwidths. Long term Evolution-Advanced with carrier aggregation enables operators to maximally and optimally utilize their available spectrum resources for increased data rates and enhanced user experience. The Cell selection is the process of determining the cell(s) that provide service to each mobile station. One interesting challenge in the physical layer of LTE-A is how the mobile unit immediately after powering on, locates a radio cell and locks on to it. This paper, presents how the mobile unit establishes this connection with the strongest cell station in vicinity. To do this, the mobile unit has to overcome the challenges of estimating the channel to communicate with the cell site and frequency synchronization. Also, multiple mobile units communicate to the same receiver and from various distances. Hence, it is up to the mobile to synchronize itself appropriately to the base stations. LTE-A uses two signals, the Primary Synchronization Signal(PSS) and the Secondary Synchronization Signal (SSS), sequentially to determine which of the available cell sites a mobile would lock in. Also, its present the types of synchronization channel (SCH) like P-SCH and S-SCH