GSM Channel Research Articles

Random sampling for effective spectrum sensing in cognitive radio time slotted environment

In the context of wireless communication, Cognitive Radio has been proposed to ensure an optimal use of the spectrum. It divides the communication transceivers into two categories. Primary User has the priority to use the spectrum band while secondary user is an opportunistic user that can transmit on that band whenever it is available. In order to determine whether a concerned band is occupied or vacant, spectrum sensing functionality is needed together with an appropriate algorithm able to analyze the produced data in order to understand whether a primary user is transmitting or not. In this paper, we contribute by investigating a narrowband spectrum sensing based on two proposed parameters obtained randomly sampling the signal and a Multilayer Perceptron neural network (MLP) classifier. We show that the use of random sampling is more effective than the use of classical uniform sampling. We analyzed the activity status in the GSM channel by using a synthetically generated signal: the signal has been sampled using both uniform and random sampling, than it has been reconstructed and finally classified with the aim of a neural network based classifier. The performances in terms of Receiver Operating Characteristic curves for different Signal to Noise Ratio are presented.

Monitoring of moving objects in the absence of a GSM signal

Many modern transport processes require constant on-line monitoring and management. However, the main difficulty lies in the lack of a stable GSM connection. One of the possible solutions to this issue is the use of MESH networks. These represent the possibility of wireless communication between multiple entities, which are nodes on a distributed network. The article presents the results of the development of original local radio modules and a base station to ensure uninterrupted transmission of digital data from the monitoring object, in conditions of insufficient GSM coverage. The complex provides the following operating modes: simple interaction via a GSM channel, data transmission via a self-organizing network, as well as sensory interaction between objects. In the absence of GSM communication, the repeater provides on-line data transmission from the monitoring object, at a distance of up to 860 m, at a distance from the base station - at least 500 m. The use of the new complex makes it possible to promptly respond to changes in operating factors and prevent emergency situations during the operation of vehicles.

Analysis of the gsm communication channel in security systems

The article outlines the basic principles initially; wireless systems were not widely used due to low reliability. But now there is a wide range of various additional devices, and new generations of wireless communication systems are actively used. The capabilities provided by mobile operators are increasingly used in security systems. The capabilities provided by mobile operators are increasingly used in security systems. To date, wireless security systems based on the base have become widespread due to their relatively low cost and ease of installation and operation. The GSM-900/1800 cellular network provides good communication quality and is already deployed in most cities.

Technological aspects of the communication channels development for data transmission in the aircraft monitoring system

The article demonstrates that the Iridium satellite constellation is of the greatest interest for the organization of data transmission in the aircraft monitoring system, since it provides a stable connection between the aircraft and the control center. In this regard, additional interfaces are also provided to facilitate user access for some data transmission services in the Iridium system. It is found that, it is necessary to use a hardware-software complex when operating Iridium satellite communications. It allows displaying information on the aircraft location on the screen, as well as information from the object’s sensors. The authors propose an automated system for monitoring mobile and stationary objects “Navigator-S” as a basic version of such a hardware-software complex. At the same time, information is transmitted over the GSM channel monitoring the location of the aircraft and the state of the contact and parametric sensors.

A systematic review of the clinical effectiveness of monitoring patients with diabetes mellitus using individual blood glucose meters with function of transmitting measurements via gsm channel or via the internet

BACKGROUND: In recent years, there has been an active introduction of telecommunication technologies in various spheres of scientific and practical knowledge, including medicine. Diabetes mellitus (DM) is one of the most common chronic non-communicable diseases requiring constant monitoring of the patients condition. For telemedicine monitoring of patients with DM, glucose self-monitoring devices with the option of transmitting patients measurements via GSM channel or via the Internet have been developed.
 AIM: To evaluate the clinical effectiveness of telemedicine observation of patients with DM using individual glucose self-monitoring devices with option of transmitting patients measurements via a GSM channel or via the Internet.
 MATERIALS AND METHODS: Publications about clinical trials were searched in PubMed. The search, selection and evaluation of the methodological quality of clinical trials were carried out by two independent researchers. Clinical trials were included in the review if the clinical efficacy of remote monitoring of patients with DM using individual glucose self-monitoring devices with the option of transmitting the results of measurements taken by the patient via a GSM channel or via the Internet was evaluated in comparison with traditional observation methods.
 RESULTS: As a result of the systematic search, 10 original randomized controlled trials (RCTs) with different methodological quality were selected. It was found that the use of remote technologies for 12 months does not affect the level of glycated hemoglobin, however, it allows to increase the frequency of achieving individual therapeutic goals in patients with type 2 DM. In addition, it was found that the use of remote technologies allows to reduce the frequency of outpatient visits of patients with type 2 DM, but does not reduce the length of hospitalization and the frequency of an emergency calls of these patients.
 CONCLUSION: Thus, evidence was obtained of the potential therapeutic benefits of remote observation of patients with diabetes based on data from foreign clinical studies. Based on the results obtained, a Russian clinical trial of this medical technology can be recommended.

Service System of Easypaisa and MobiCash: Funds Transfer System via Telecommunication Companies in Context of Service Dominant Logic

Because of emergence of new logic which is Service Dominant Logic focused on intangible resources, the co-creation of value, and relationships Service dominant logic assumed a major category of economic activity in developed countries around the world, reason is that service is an interactive process of “doing something for someone” that is valued. There is a need to understand each service sector under this logic. Many researchers are working on Service dominant logic and its impact on different aspects. And for this purpose, we have chosen Easypaisa and MobiCash to understand the fund transfer system of both service systems under this service dominant logic and studied different aspects of this service exchange to better understand how value and experience are evaluated. In this Study, the Service system of Easypaisa and the service system of MobiCash are compared under the concepts of Service system. We have conducted interview with respective person of each service system and collected information and data on each concept of service. We have used Interview Guide given by Lyons and Tracy (2013) to collect data on service system concepts. We find out that Service system of Easy paisa is covering almost all concepts of Service system but comparatively MobiCash is far behind from Easypaisa. Our analysis showed that Easypaisa is much better than MobiCash because Easypaisa rapidly built a high performing national footprint, relying exclusively on the GSM channel.

Novel Technique for Comprehensive Noise Identification and Cancellation in GSM Signal

Presence of noise significantly degrades the contents being transmitted over GSM channel. With the evolution of next generation of communication system, the challenges in noise cancellation in voice along with data transmission are not being addressed effectively by existing filters. Therefore, the proposed system offers a mechanism where emphasis is laid on identification of superior and inferior forms of GSM transient signal followed by cancellation of its noise level. Designed using analytical methodology, the proposed system harness the potential of probability theory to perform a modeling that associates allocated power of the transmitting device with the level of noise. The outcome of the study is found to offer a comprehensive identification of different forms of noise and can precisely determine the level of superior and inferior quality of signal. The outcome significantly assists in designing an accurate filter for noise cancellation in GSM signal.

English

The health of the Solar PV systems should be monitored continuously for their better performance and maintenance. For PV systems installed at rural locations, remote monitoring capabilities provide the information in advance when system performance is degraded or is likely to fail. Based on this information, preventive maintenance can be carried out to improve the performance and life of the system, thereby reducing the overall operating cost. Advantages and disadvantages of several monitoring systems for rural application is discussed and an optimum new technique is proposed as a solution to overcome the limitations of other techniques and also to reduce the cost of the system. The proposed technique uses GSM channel for the communication i.e. by sending and receiving text messages when prompted by the user and when there is any fault occurring on the system The project focuses on the development of a module that can be attached to domestic solar panel systems. These systems are located on the roof and to check them user has to move towards them multiple times a day. A simple module consisting of sensors is attached to the system that calculates the parameter of system and sends them to user via SMS.

Penyandi Persepsi Isyarat Audio Berdasar pada Model Modulasi Frekuensi (FM)

Data compression or source coding has been playing an important role in many areas in daily life. There are several audio encoders available with various methods. Each audio encoder works at a certain range bitrate depending on the signal model used and the method implemented. Based on literature reviews it is to know that there are only a view of audio encoder working at bit rate below 16 kbit/s, especially for music signals. The togetherness in having harmonically components between the audio signals and frequency modulated signals is the basic idea of proposing the perceptual encoder based on FM signal model. In estimating and extracting FM parameters, the psychoacoustic model is used to exploit the perceptual nature of humans ears. The errors of FM modeling is distributed below the masking curve of psychoacoustic model. The developed encoder allows sending music signals on the GSM channel. The developed encoder has four cascaded main processes, namely sinusoid components extraction, harmonic components separation, FM parameters estimation, and FM parameter encoding. The simulation results show the proposed method is successful to encode some audio signal types.

Calculating Limits of Base Station Emission Power in GSM

This paper compares the influence of various factors on the output power of each GSM channel and connection, and on the output power of whole base transceiver station in GSM network. The considered factors are the influence of sending signal only when speech exists (DTX), implementation of power control in signal sending, influence of users' distribution in the range of coverage of base station, the power of one intra-cell connection and the power of one half-rate connection. It is analyzed how emission power of base station can be reduced by implementing various methods in signal sending.

Influence of Users’ Density on the Mean Base Station Output Power

In this paper we developed the method for determination of output power of base station as the function of distribution of users’ density in one GSM cell. The method consists of several steps: determination of the function of density distribution (PDF) and function of distribution (CDF) of distance between user and base station, finding PDF of output power of one GSM channel. In order to prove calculated results, we developed the program for simulating seizure and release channels in one GSM cell. It is necessary that inverse function of CDF of distance between user and base station exists in order to implement this program. This simulation program can be used to estimate CDF of total emission power of base station. Calculation of CDF of total emission power is, except in simplest cases, pretty complicate. DOI: http://dx.doi.org/10.5755/j01.eee.20.9.5418

Novel Teletraffic Analysis of GSM/EDGE Orthogonal Sub Channel (OSC) and Application to Spectrum Re-farming

GSM network operators are required to free up some of the spectrum allocated for voice traffic in order to serve 3G and 4G users. Re-farming 900 MHz and 1800 MHz bands into HSPA, W-CDMA (UMTS) and LTE is a challenge faced by operators with growing GSM voice traffic as 3G systems require 5 MHz bandwidth which is 25 times more bandwidth than a typical GSM channel. 4G systems (LTE) may even use 10 MHz to show superiority over the 5 MHz 3G systems. It is required to cope with the GSM voice traffic with significantly less bandwidth in order to accommodate 3/4G users. Orthogonal Sub Channel (OSC) is a novel technique offering efficient hardware utilization that can result in doubling GSM voice capacity. This is achieved by allowing two users to share the same physical radio resources. OSC can be used in phasing-out GSM networks to release significant frequency spectrum for 3/4G users. In this work, a thorough analysis on OSC performance gain is presented. The hard capacity gain offered by OSC is calculated as a function of the OSC penetration and compared with system level simulations. It is shown that hard capacity can be maintained with less number of TRXs (transceivers), and consequently, narrower spectrum. This paves the way for re-farming the released GSM spectrum into 3/4G traffic.

A Methodology for Measuring Voice Quality Using PESQ and Interactive Voice Response in the GSM Channel Designed by OpenBTS

This article discusses a methodology for rating the quality of mobile calls. Majority telecommunications service from the perspective of the whole world is using mobile telephony networks. One of the problems affecting this service and its quality are landscape barriers, which prevent the spread signal. Price and complex construction of classic BTS does not allow their dense distribution. In such cases, one solution is to use OpenBTS technology. Design of OpenBTS is more available, so it can be applied to much more places and more complex points. Purpose of this measurement is a model for effective stations deployment, due to shape and distribution of local barriers that reduce signal power, and thus the quality of speech. GSM access point for our mobile terminals is OpenBTS USRP N210 station. The PESQ method for evaluating of speech quality is compared with the subjective evaluation, which provides Asterisk PBX with IVR call back. Measurement method was taken into account the call quality depending on terminal position. The measured results and its processing bring knowledge to use this technology for more complicated locations with degraded signal level and increases the quality of voice services in telecommunications.

Wideband SAW-Less Receiver Front-End With Harmonic Rejection Mixer in 65-nm CMOS

A wideband direct-conversion receiver front-end featuring a new harmonic rejection technique is demonstrated in 65-nm CMOS. The circuit consists of a two-stage low-noise amplifier, the first stage with capacitive feedback, a harmonic rejection mixer using 25% and 50% duty cycle local oscillator signals, and a third-order channel-select filter with configurable bandwidth. The receiver front-end is intended for surface-acoustic-wave-less cellular applications, and its performance was measured at 900- and 1800-MHz bands. The average harmonic rejection over GSM and LTE channel bandwidths is between 60 and 70 dB. Peak harmonic rejection exceeds 80 dB. The noise figures (NFs) are 3.3 and 3.9 dB for the complete receiver front-end in low band and high band, respectively, with an S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> below -15 dB from 500 MHz to 2.5 GHz. The 1-dB received signal compression points with a blocker present at 20/80 MHz offset for low/high band are 0 and +2 dBm, respectively. The NF with 0-dBm blocker is 13 dB. For low band, the in-band IIP3 and IIP2 are -14.8 and > 49 dBm, respectively, and, for high band, -18.2 and > 44 dBm. The circuit worst case consumes 80 mW of power.

A Nonuniform Sampler for Wideband Spectrally-Sparse Environments

We present a wide bandwidth, compressed sensing based nonuniform sampling (NUS) system with a custom sample-and-hold chip designed to take advantage of a low average sampling rate. By sampling signals nonuniformly, the average sample rate can be more than a magnitude lower than the Nyquist rate, provided that these signals have a relatively low information content as measured by the sparsity of their spectrum. The hardware design combines a wideband Indium-Phosphide heterojunction bipolar transistor sample-and-hold with a commercial off-the-shelf analog-to-digital converter to digitize an 800 MHz to 2 GHz band (having 100 MHz of noncontiguous spectral content) at an average sample rate of 236 Ms/s. Signal reconstruction is performed via a nonlinear compressed sensing algorithm, and the challenges of developing an efficient implementation are discussed. The NUS system is a general purpose digital receiver. As an example of its real signal capabilities, measured bit-error-rate data for a GSM channel is presented, and comparisons to a conventional wideband 4.4 Gs/s ADC are made.

Weighted Semi-Blind Channel Identification by Cross Relation Method

Problem statement: The bandwidth efficiency of many communication systems could be improved if the transmission channel was estimated blindly without resort to training sequences. GMSK was a spectrum-efficient modulation scheme and it was adopted as the modulation standard of GSM systems. Approach: However, because of its phase modulation, Gaussian filtering and partial response signalling properties, Results: The simulation results showed great potential of semi-blind identification algorithms, since we used no extra antenna or over-sampling the received signal. Conclusion: GMSK was not a linear modulation. Linear approximation of the GMSK signal made the blind equalization system model applicable for GSM. In the sequel, a linear approximation of GMSK signals was presented and a blind GSM and semi-blind channel identification algorithm based on the cross relation method was suggested.

Threats and Countermeasures in GSM Networks

Mobile networks not only provide great benefits to their users but they also introduce inherent security issues. With respect to security, the emerging risks of denial of service (DOS) attacks will evolve into a critical danger as the availability of mobile networks becomes more and more important for the modern information society. This paper outlines a critical flaw in GSM networks which opens the avenue for distributed denial of service attacks. We propose a way to mitigate the attacks by adding minimal authentication to the GSM channel assignment protocol.

Application of NB/WB AMR Speech Codecs in the 30-kHz TDMA System

A new system enhancement method is proposed for the EIA/TIA-136 system offering both channel operational range extension and improved performance within the current operational range. The existing time-division multiple-access (TDMA) (136) speech codec, the IS-641 enhanced full rate vocoder, operates at a fixed bit rate and does not allow the reallocation of bits to channel error protection as channel conditions degrade. The research presented here investigates the application of the narrow-band adaptive multirate (NB-AMR) speech codec and the wide-band AMR (WB-AMR) codec, both originally designed for the 200 kHz GSM channel, in the TDMA (TIA/EIA-136) 30-kHz system. In particular, we investigate adaptively allocating bits between NB/WB speech coding and error control coding within the limited channel bandwidth. Four modes out of 17 have been carefully chosen for the new TDMA/AMR system. Switching between codec rates as channel conditions change produces range extension below a C/I of 15 dB while also improving performance in the existing operational range above 15 dB. We keep the time slot formats unchanged so that our method is completely compatible with existing 136 systems.

Rating of Speech Quality in Mobile Phone Networks

Mobile phone users rely only on their intuition to evaluate the quality of service provided by their network operator. In this paper, we propose an output-based objective method to rate the speech quality in mobile phones. This rating, when averaged over time, will be useful in comparing between different mobile phone networks. Moreover, the rating could be incorporated into the calls tariff of mobile phones.Here, a time-delay multilayer neural network is used to rate the speech quality after a proper training stage. The training input set consists of speech features (such as linear predictive coefficients LPC and per- frame energy). The training target is a customized per-frame speech quality measure. We performed extensive simulations using the proposed method. We use speech samples from simulated channels, real GSM channel and from the more elaborate CTIMIT database. These simulations show that the proposed method can predict the speech quality within reasonable accuracy.

Softbit speech decoding: a new approach to error concealment

In digital speech communication over noisy channels there is the need for reducing the subjective effects of residual bit errors which have not been eliminated by channel decoding. This task is usually called error concealment. We describe a new and generalizing approach to error concealment as part of a modified robust speech decoder. It can be applied to any speech codec standard and preserves bit exactness in the case of an error free channel. The proposed method requires bit reliability information provided by the demodulator or by the equalizer or specifically by the channel decoder and can exploit additionally a priori knowledge about codec parameters. We apply our algorithms to PCM, ADPCM, and GSM full-rate speech coding using AWGN, fading, and GSM channel models, respectively. It turns out that the speech quality is significantly enhanced, showing the desired inherent muting mechanism or graceful degradation behavior in the case of extreme adverse transmission conditions.