電気通信システムと管理

The congestion at the lower frequency bands has forced the telecommunication system engineers to move to higher frequencies. However, microwave signal tends to undergo fading effect at frequencies above 10 GHz due to rainfall. Consequently, the 1-min rain rate data needed for the prediction of rain-induced attenuation is still very scarce in most part of the world, Nigeria inclusive. Therefore, appropriate conversion method is needed to convert the available data to the required 1-min rain rate data. In this paper, an empirical and dynamic method for conversion of long integration time to 1-min integration time has been proposed and compared with other conversion methods. In overall, conversion factor modeled with a power law (CF-PL) is found suitable to be used in this region based on an average rms error less than 2%.

The two most important algorithms used to perform traffic policing in a packet based telecommunications network were defined by Metro Ethernet Forum (MEF) and Internet Engineering Task Force (IETF) bodies. The two algorithms slightly differ both in the terms used to describe their configuration parameters and in the traffic management. Even if translating MEF set of parameters into IETF one seems trivial at a first glance, this is not the case and strongly depends upon the traffic pattern. This article, after a description of the two algorithms, tries to describe the relationship between the set of parameters.

The importance of wireless communication cannot be overlooked in this modern day of sophisticated communication world. Certainly, like any other technology, wireless communication has major challenges, most of which tremendously affect our daily conversations. This research is focused on wireless network optimization specifically on the Code Division Multiplexing Access (CDMA) technology. Emphasis will be on the importance of optimization and the various strategies adopted to optimize a wireless network. The beginning part of the research contains a comprehensive introduction of wireless optimization and specifically touched on its definition as well as the most essential aspect of its application in the wireless network. The research explicitly identified important Key performance indicators which usually monitors the performance of the wireless network. Also, in order to solve wireless network deficiencies, several approaches are used to achieve this goal. The research touched on these approaches and described how exactly they are applied to optimize a network. Wireless optimization is mainly achieved with the use of special tools such as drive test tools. As part of the research, the most important tools were identified as well as their applications. Additionally, a broad analysis was made on some common wireless issues as well as strategies adopted to resolve them. Some of the common problems identified include: handoff issues, call failure issues PN planning issues, Neighbor list planning issues as well as pilot pollution issues. Furthermore, in order to better understand the optimization in the practical sense, a case study was analyzed by comparing specific samples of results gathered before and after optimization. The results clearly demonstrated that wireless optimization improves wireless performance tremendously, which goes to attest to the fact that, the end results have a positive impact on subscribers and the composite society at large with tremendous benefits ranging from financial to great customer satisfaction.

The security and interoperability of an adopted and advanced architecture within heterogeneous components, based on the Open Geospatial Consortium (OGC) Sensor Web Enablement Architecture (SWE) and RESTful web service, requires integrity and confidentiality in the dif ferent communication protocol. RESTful services are considered a versatile lightweight solution relied upon by a number of advanced web services. At the same time, RESTful services suffer from a lack of meta-data description concerning security requirements. We introduce the REST security protocol to provide secure data transfer service, together with its quality and its performance analysis when compared to equivalen t WS-security configuration. The work in this paper aims to introduce a security protocol of communication between the sensors based on SWE services and the adopted RESTful interface. In this way, we provide a REST security protocol which will implement a secure lightweight sensor message and analyze its performance comparing to equivalent web services.

This paper examines ways in which smart phone data consumption trends influence demand for airtime data bundles. A model of subscriber response to economic and technical stimuli, conditional on cybernomic and subscriber characteristics, is developed. Three years of survey data, gathered from subscribers of data and voice bundles to evaluate the model empirically. Single SIM smartphones, subscribers are responsive to relative Data Bundle prices and Airtime volume discounts. However, different Data Bundle packages elicit different responses. In particular, some data sharing takes place primarily through subscriber-substitution and intensified smartphone use, while changes in tariff or volume discounts for subscribers having dual SIM smartphones induces frequent and spontaneous network migration. Subscriber and public power constraints bind at different points for different data bundles demand. These results suggest that because multiple data/voice bundle platform interact, subscriber smartphone response coefficient must have multiple strands in order to replace incentives to further bundle demands.

There are several technologies to transmit any signal in wireless communication. Technologies are: Integration, Differentiation, TDM (Time Division Multiplexing), FDM (Frequency Division Multiplexing), OFDM (Orthogonal Frequency Division Multiplexing). In which OFDM is superior to any other technology. It is widely used in MIMO schemes also where multiple transmission and reception process done with different types of antennas. V-BLAST is the technique where the completion of strongest signal capturing and it gives sturdiest output with the help of different receiver approximation techniques like MMSE (Minimum Mean Square Error), ZF (Zero Forcing) and ML (Maximum Likelihood). In this paper we throw some light on why choose MMSE, ZF and ML to identify overall Throughput, adjustment in pre-coding, performance of FFT (Fast Fourier Transform) and IFFT (Inverse FFT) in OFDM-VBLAST. Also examine which receiver technique is widely and very useful in practical scenario.

In today’s world as the internet users become more mobile, hence the need for location determination is a key need to provide services based on location, but many devices do not have GPS receivers or transmitters, hence the location determination of these devices is important to provide the location based services, like Advertisements, security, so forth. Location determination of mobile devices has been there for some time but most approaches are based on client intervention, so they are not suitable for integrating in security related components like intrusion detection systems or access control systems. In this paper we propose an approach based on that works on concept of trilateration to determine client location without his/her intervention.

LTE-Advanced network is commercially available at increased speed while LTE is upgrading day by day and helped to provide faster broadband services. LTE delivered all these enhancement by offering the state of the art combination of new air interface base technology (OFDMA/SC-FDMA) and greater flexibility for utilizing spectrum. As we know that LTE has flexibility of bandwidth selection and it goes up to 20 MHz bandwidth (BW). Due to this flexible nature, it can accommodate many users with permutation and combination of bandwidth allocated to operator. LTE-Advanced is required for higher data rates and full coverage in future scenario. One of the key features of LTEAdvanced is carrier aggregation. All operators are moving towards Carrier Aggregation as this feature helps to maintain the quality of network and increase the user experience in terms of data rates and peak user throughput. This paper highlights the carrier aggregation which supports the inter-band aggregation contiguous component carriers, intraband aggregation non-contiguous component carriers and inter-band aggregation. This paper also focuses on various scenario of implementation of Carrier Aggregation and there benefits in network.

Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising candidate for 4G high-data-rate broadband wireless communications. However, MIMO-OFDM inherited the problem of high Peak-to-Average Power Ratio (PAPR) from OFDM which leads to in-band distortion, undesired spectral spreading, low power efficiency and increases the cost of the RF power amplifier. Many PAPR reduction techniques were developed in last two decades to reduce the PAPR of OFDM, among them Partial Transmit Sequence (PTS) and Selected Mapping (SLM) are the important ones. This paper proposes two PAPR reduction technique; SLM and Optimum -PTS for reducing the PAPR and does performance comparison of these two techniques on the basis of reduction in PAPR level, BER and the number of redundant bits required. It shows that the use of Optimum-PTS technique with QPSK modulation comprising of 128 subcarriers provides better PAPR reduction and good BER as compared to SLM.