B. Siddik Yarman

Immitance data modelling via linear interpolation techniques: A classical circuit theory approach

With the advancement of the manufacturing technologies to produce new generation analog/digital communication systems, immitance data modelling has gained renewed importance in the literature. Specifically, models are utilized for behaviour characterization, simulation of physical devices or to design sub-systems with active and passive solid-state devices. Therefore, in this paper, new computer aided tools are presented to model one port immitance data by means of linear interpolation techniques. The basic philosophy of the new modelling tools is based on the numerical decomposition of the immitance data into its minimum and Foster parts. Computer algorithms are presented to model the minimum and the Foster parts of the given immitance data. Implementations of these algorithms are exhibited by means of examples. Depending on the application, modelling tools based on linear interpolation techniques may present ‘computational and practical’ advantages over the existing interpolation techniques, non-linear curve fittings or regression methods. It is expected that the new modelling tools will be utilized to provide initial circuit topologies to the commercially available analysis/simulation and design packages. Copyright

A novel method to represent the speech signals by using language and speaker independent predefined functions sets

In this paper, a new modeling method of speech signals is introduced. The proposed method is based on the generation of the so-called predefined signature S = {s/sub R/(t)} and envelope function E = {e/sub K/ (t)} sets (PSEFS). The function sets are independent of any speaker and any language. Once the speech signals are divided into frames with selected lengths, then each frame signal piece X/sub i/(t) is synthesized by means of the mathematical form of x/sub i/(t) = C/sub i/e/sub K/(t)s/sub R/(t). In this representation, C/sub i/ is called the frame coefficient, s/sub R/(t) and e/sub K/(t) are properly assigned from PSEFS respectively. It is shown that the proposed method provides fast reconstruction and substantial compression with acceptable hearing quality.

A new speech modeling method: SYMPES

In this paper, the method of speech modeling which is called SYMPES is introduced and it is compared with the commercially available methods. It is shown that for the same compression ratio or better, SYMPES yields considerably better hearing quality over the coders such as G.726 at 16 Kbps and voice excited LPC-10E of 2.4Kbps

Impact of channel estimation error on physical layer security in dual-hop half/full-duplex two-way wireless relaying networks

This paper investigates the impact of the imperfect channel state information that is caused by the channel estimation errors on physical layer security. The investigation considers a dual-hop single amplify-and-forward (AF) based untrustworthy half/full-duplex bi-directional relay with a finite number of friendly jammers in the system model. According to Monte-Carlo simulation results, the channel estimation error causes system coding gain losses at low signal-to-noise ratio (SNR) regimes both for half and full-duplex cases. Results also show that the CEE effects turn out to be at negligible levels in high SNR regimes. Results also show that friendly jammer, besides improving the secrecy performance of the system model, also degrades the curves and causes system coding gain losses at high SNR regimes. Results also show that better secrecy performance can be achieved when the relay terminal operates in full-duplex mode.

Sum-rate based opportunistic relay selection method for a dual-hop multiple half/full-duplex bi-directional wireless relaying networks

This paper investigates the opportunistic relay selection method for bi-directional wireless relaying networks. The investigation considers a dual-hop network with a multiple half/full-duplex two-way relay terminal in the system model. The sum-rate based opportunistic relay selection (SR-ORS) strategy selects the best relay terminal based on maximum sum-rate of user-pair and related relay terminal. According to analytical, asymptotic and Monte-Carlo simulation results, the SR-ORS strategy provides better performance results when the relay terminal operates in full-duplex mode.

A Novel Fast Algorithm for Speech and Audio Coding

In this work, a new mathematical modeling approach is proposed for the representation of the speech and audio signals. This approach is based on the generation of the so called predefined signature sequence (PSS) and predefined envelope sequence (PES) sets. After the generation process of the PSS and PES sets, they are clustered by effective k-means clustering algorithm and the PSS and PES are redefined by using these centroids. By using this approach, the drawbacks by means of the size of the sets, speed of the reconstruction process (computational complexity) which arise in the proposed methods previously are highly eliminated. In spite of these improvements, the initial results proved that, the quality of the reconstructed signals remains within the limitations of the acceptable hearing quality.

Gain-Bandwidth Limitations of 0.18μm Si-CMOS RF technology

In this paper, gain bandwidth limitations of a regularly processed 0.18 mum Si CMOS FET is investigated over the frequency band of 450 MHz-10 GHz. It is exhibited that 0.18 mum Si CMOS processing technology can safely be utilized to manufacture ultra wideband RF-amplifiers for commercial wireless communication systems placed silicon chips up to X-Band.

Sum-rate based opportunistic relay selection with channel estimation error for a dual-hop multiple half/full-duplex bi-directional wireless relaying networks

This paper investigates the channel estimation error effects on the opportunistic relay selection strategy. The opportunistic relay selection strategy is based on selecting the maximum sum-rate of half/full-duplex relay terminal among N. The investigation considers a dual-hop multiple half/full-duplex bi-directional wireless relaying networks in the system model. According to Monte-Carlo simulation results, sum-rate based relay selection strategy achieves cooperative diversity in high signal-to-noise regimes both for half/full-duplex cases. However, for the full-duplex based case, if the loop interference variances are relatively high, the achievable cooperative diversity turns out to be 0 from N while also causes system coding gain losses. The CEE causes system coding gain losses in low signal-to-noise ratio regimes. However, in high signal-to-noise ratio regimes, the CEE effects turn out to be at negligible levels.

Sum-rate based relay selection with feedback delay for a multiple half/full-duplex two-way relaying

This paper investigates the feedback delay effects on opportunistic relay selection strategy. The investigation considers a dual-hop multiple half/full-duplex two-way wireless relaying network in the system model. The selection strategy is based on the sum-rate of user-pair and related relay terminal. According to Monte-Carlo simulation results, sum-rate based relay selection strategy achieves cooperative diversity order in high signal-to-noise regimes for half-duplex and full-duplex cases. If the loop-interference variances are chosen relatively low, sum-rate based full-duplex relay selection strategy outperforms the sum-rate based half-duplex relay selection strategy. Feedback delay does not have any effects on the system performance in low signal-to-noise regimes but it does affect the performance curves and degrades the achievable diversity order from M to 0 and causes system coding gain losses in high signal-to-noise regimes.

Zero-if second harmonic SiGe mixer with DC offset cancellation

In this work, a new SiGe mixer circuit topology operating with the second harmonically pumped mixing technique is proposed. The proposed circuit is developed for to be used in IC receivers which use Zero-IF mixers at their front ends. The Analysis of the circuit is performed and the appropriate operation conditions for second harmonically pumped mixing are investigated. The topology is quite suitable for the wide band applications and has a unique mechanism to prevent the LO to RF leakage which results in DC offset at the output. Simulations are performed and according to the simulation results, 21dB of conversion voltage gain is obtained within 2-12 GHz RF range while the DC voltage component at the output stays more than 80dB below the IF component.