Browsing by Subject "Global system for mobile communications"

Now showing 1 - 6 of 6

Open Access
ALACA: a platform for dynamic alarm collection and alert notification in network management systems
(John Wiley and Sons Ltd., 2017) Solmaz, S. E.; Gedik, B.; Ferhatosmanoğlu, H.; Sözüer, S.; Zeydan, E.; Etemoğlu, Ç. Ö.
Mobile network operators run Operations Support Systems that produce vast amounts of alarm events. These events can have different significance levels and domains and also can trigger other ones. Network operators face the challenge to identify the significance and root causes of these system problems in real time and to keep the number of remedial actions at an optimal level, so that customer satisfaction rates can be guaranteed at a reasonable cost. In this paper, we propose a scalable streaming alarm management system, referred to as Alarm Collector and Analyzer, that includes complex event processing and root cause analysis. We describe a rule mining and root cause analysis solution for alarm event correlation and analyses. The solution includes a dynamic index for matching active alarms, an algorithm for generating candidate alarm rules, a sliding window–based approach to save system resources, and a graph-based solution to identify root causes. Alarm Collector and Analyzer is used in the network operation center of a major mobile telecom provider. It helps operators to enhance the design of their alarm management systems by allowing continuous analysis of data and event streams and predict network behavior with respect to potential failures by using the results of root cause analysis. We present experimental results that provide insights on performance of real-time alarm data analytics systems. Copyright © 2017 John Wiley & Sons, Ltd.
Open Access
Dikgen frekans bölmeli çoklu erişim sistemlerinde telsiz erişim terminallerinin işbirliği
(IEEE, 2009-04) Tokel, Turgut Barış; Aktaş, Defne
Gelecek nesil kablosuz iletişim sistemlerinde öngörülen veri hızlarına ulaşabilmek için bu sistemlerde frekans yeniden kullanım oranının 1 olmasına ihtiyaç¸ vardır, bu ise özellikle hücre sınırlarındaki kullanıcıların önemli ölçüde hücreler arası girişime maruz kalmalarına neden olur. Telsiz erişim terminalleri arasında işbirliği hücreler arası girişimin azaltılmasında önemli bir rol oynamaktadır. Bu bildiride çok hücreli, çok girdili çok çıktılı, dikgen frekans bölmeli çoklu erişim sistemlerinde telsiz erişim terminallerinden kullanıcılara işbirlikli veri iletimi problemini ele alıyoruz. Telsiz erişim terminallerinin aralarında kısıtlı ileti paylaşımı ile çizelgeleme ve veri iletimi yaptıkları etkin bir işbirlikli algoritma öneriyoruz.
Open Access
An FPGA implementation architecture for decoding of polar codes
(IEEE, 2011) Pamuk, Alptekin
Polar codes are a class of codes versatile enough to achieve the Shannon bound in a large array of source and channel coding problems. For that reason it is important to have efficient implementation architectures for polar codes in hardware. Motivated by this fact we propose a belief propagation (BP) decoder architecture for an increasingly popular hardware platform; Field Programmable Gate Array (FPGA). The proposed architecture supports any code rate and is quite flexible in terms of hardware complexity and throughput. The architecture can also be extended to support multiple block lengths without increasing the hardware complexity a lot. Moreover various schedulers can be adapted into the proposed architecture so that list decoding techniques can be used with a single block. Finally the proposed architecture is compared with a convolutional turbo code (CTC) decoder for WiMAX taken from a Xilinx Product Specification and seen that polar codes are superior to CTC codes both in hardware complexity and throughput. © 2011 IEEE.
Open Access
Novel predistortion algorithm for OFDMA
(IEEE, 2009) Ali, S.; Markarian, G.; Arıkan, Erdal
The RF amplifier in a wireless communication system is usually non-linear in nature. If such an amplifier is used in OFDMA based systems, it will cause serious degradation. This degradation will be both in terms of the reduction in BER and the generation of out of band noise. In this paper we have worked on the linearization method of the amplifier. This work is on a hybrid methodology, in which estimation of the model is performed in frequency domain and compensation is performed in time domain. The downlink preamble of the IEEE802.16e system is used here for the estimation purpose. The results for the suppression of spectra are shown at the end.
Open Access
An optimal network dimensioning and initial energy assignment minimizing the monetary cost of a heterogeneous WSN
(IEEE, 2009) Sevgi, Cüneyt; Kocyigit, A.
In this paper, a novel method is proposed to dimension a randomly deployed heterogeneous Wireless Sensor Network (WSN) of minimum monetary cost satisfying minimum coverage and minimum lifetime requirements. We consider WSNs consisting of two different types of nodes clusterheads and ordinary sensor nodes, randomly deployed over a sensing field. All devices are assumed to be stationary and have identical sensing capabilities. However, the clusterheads are more energetic and powerful in terms of processing and communication capabilities compared to sensor nodes. For such a network, finding minimum cost WSN problem is not a trivial one, since the distribution of the mixture of two different types of devices and the batteries with different initial energies in each type of device primarily determine the monetary cost of a WSN. Therefore, we formulated an optimization problem to minimize the monetary cost of a WSN for given coverage and lifetime requirements. The proposed optimization problem is solved for a certain scenario and the solution is validated by computer simulations. © 2009 IEEE.
Open Access
A strong user authentication protocol for GSM
(IEEE, 2005-06) Aydemir, Özer; Selçuk, Ali Aydın
Traditionally, the authentication protocols for cellular phone networks have been designed for device authentication rather than user authentication, which brings certain limitations and restrictions on the functionality of the system. In this paper we propose a user authentication protocol for the Global Standards for Mobile (GSM) which permits the use of weak secrets (e.g. passwords or PINs) for authentication, providing new flexibilities for the GSM users. © 2005 IEEE.