Source-Channel Coding under Energy, Delay and Buffer Constraints

Source-channel coding for an energy limited wireless sensor node is investigated. The sensor node observes independent Gaussian source samples with variances changing over time slots and transmits to a destination over a flat fading channel. The fading is constant during each time slot. The compressed samples are stored in a finite size data buffer and need to be delivered in at most $d$ time slots. The objective is to design optimal transmission policies, namely, optimal power and distortion allocation, over the time slots such that the average distortion at destination is minimized. In particular, optimal transmission policies with various energy constraints are studied. First, a battery operated system in which sensor node has a finite amount of energy at the beginning of transmission is investigated. Then, the impact of energy harvesting, energy cost of processing and sampling are considered. For each energy constraint, a convex optimization problem is formulated, and the properties of optimal transmission policies are identified. For the strict delay case, $d=1$, $2D$ waterfilling interpretation is provided. Numerical results are presented to illustrate the structure of the optimal transmission policy, to analyze the effect of delay constraints, data buffer size, energy harvesting, processing and sampling costs.Comment: 30 pages, 15 figures. Submitted to IEEE Transactions on Wireless Communication

What does Hirsch index evolution explain us? A case study: Turkish Journal of Chemistry

The evolution of Turkish Journal of Chemistry (Turk J. Chem) Hirsch index (h-index) over the period 1995-2005 is studied and determined in the case of the self and without self-citations. It is seen that the effect of Hirsch index of Turk J. Chem has a highly positive trend during the last five years. It proves that Turk J. Chem is improving itself both in quantity and quality since h-index reflects peer review, and peer review reflects research quality of a journal.Comment: 5 pages, 3 figure

Low Power Analog-to-Digital Conversion in Millimeter Wave Systems: Impact of Resolution and Bandwidth on Performance

The wide bandwidth and large number of antennas used in millimeter wave systems put a heavy burden on the power consumption at the receiver. In this paper, using an additive quantization noise model, the effect of analog-digital conversion (ADC) resolution and bandwidth on the achievable rate is investigated for a multi-antenna system under a receiver power constraint. Two receiver architectures, analog and digital combining, are compared in terms of performance. Results demonstrate that: (i) For both analog and digital combining, there is a maximum bandwidth beyond which the achievable rate decreases; (ii) Depending on the operating regime of the system, analog combiner may have higher rate but digital combining uses less bandwidth when only ADC power consumption is considered, (iii) digital combining may have higher rate when power consumption of all the components in the receiver front-end are taken into account.Comment: 8 pages, 6 figures, in Proc. of IEEE Information Theory and Applications Workshop, Feb. 201

Energy Harvesting Broadband Communication Systems with Processing Energy Cost

Communication over a broadband fading channel powered by an energy harvesting transmitter is studied. Assuming non-causal knowledge of energy/data arrivals and channel gains, optimal transmission schemes are identified by taking into account the energy cost of the processing circuitry as well as the transmission energy. A constant processing cost for each active sub-channel is assumed. Three different system objectives are considered: i) throughput maximization, in which the total amount of transmitted data by a deadline is maximized for a backlogged transmitter with a finite capacity battery; ii) energy maximization, in which the remaining energy in an infinite capacity battery by a deadline is maximized such that all the arriving data packets are delivered; iii) transmission completion time minimization, in which the delivery time of all the arriving data packets is minimized assuming infinite size battery. For each objective, a convex optimization problem is formulated, the properties of the optimal transmission policies are identified, and an algorithm which computes an optimal transmission policy is proposed. Finally, based on the insights gained from the offline optimizations, low-complexity online algorithms performing close to the optimal dynamic programming solution for the throughput and energy maximization problems are developed under the assumption that the energy/data arrivals and channel states are known causally at the transmitter.Comment: published in IEEE Transactions on Wireless Communication

Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus

PURPOSE: To study the benefits of ultrasonography for detecting the borders of pilonidal sinus tissue. The correlation between physical and ultrasonographic examination was used for surgical planning. METHOD: Between April and December 2004, 73 patients were recruited for this study. All patients were examined, and the borders of the sinus tissue were marked on the skin according to palpation before surgery. The surgeon also made a treatment plan considering the diseased tissue and marked a possible incision line. Patients were subsequently examined with ultrasonography. According to the ultrasonographic evaluation, the margins, extensions, and openings of pilonidal sinus tissue were determined and marked on the patient in a different color by a radiologist prior to surgery. The most suitable surgical treatment was decided according to the information obtained by ultrasonography. RESULTS: The average age was 23.03 ± 3.05 (range 18-39) years. We found 81 lesions in 73 patients. Ultrasonographic borders of sinus tissue were similar to the borders marked by the surgeon in 56 patients (76.7%). In the remaining 17 patients (23.3%), ultrasonography detected branches or borders that distinctly exceeded the planned incision line. After ultrasonographic examination, the surgeon changed his incision line in 14 patients and the surgical intervention in 3 patients. CONCLUSION: Palpation and methylene blue injection do not provide appropriate information in many patients. Our study revealed that pre-operative ultrasonography can improve the identification of the sinus tract and its branches when compared to palpation and methylene blue injection

Ultrasonography Accurately Evaluates the Dimension and Shape of the Pilonidal Sinus

PURPOSE: To study the benefits of ultrasonography for detecting the borders of pilonidal sinus tissue. The correlation between physical and ultrasonographic examination was used for surgical planning. METHOD: Between April and December 2004, 73 patients were recruited for this study. All patients were examined, and the borders of the sinus tissue were marked on the skin according to palpation before surgery. The surgeon also made a treatment plan considering the diseased tissue and marked a possible incision line. Patients were subsequently examined with ultrasonography. According to the ultrasonographic evaluation, the margins, extensions, and openings of pilonidal sinus tissue were determined and marked on the patient in a different color by a radiologist prior to surgery. The most suitable surgical treatment was decided according to the information obtained by ultrasonography. RESULTS: The average age was 23.03 ± 3.05 (range 18-39) years. We found 81 lesions in 73 patients. Ultrasonographic borders of sinus tissue were similar to the borders marked by the surgeon in 56 patients (76.7%). In the remaining 17 patients (23.3%), ultrasonography detected branches or borders that distinctly exceeded the planned incision line. After ultrasonographic examination, the surgeon changed his incision line in 14 patients and the surgical intervention in 3 patients. CONCLUSION: Palpation and methylene blue injection do not provide appropriate information in many patients. Our study revealed that pre-operative ultrasonography can improve the identification of the sinus tract and its branches when compared to palpation and methylene blue injection

Integrated Access and Backhaul in Millimeter-Wave Cellular : Benefits and Challenges

The recently proposed NR-ready integrated access and backhaul (IAB) architecture promises to bring a cost-efficient deployment solution for both coverage extension and capacity boosting in the emerging 5G/5G+ systems. While its impact on the coverage extension was thoroughly addressed in the literature, the effect of advanced functionalities such as multihop, multi-connectivity, and multi-beam operations on the throughput remained unclear. We review and characterize the system-level impact of these capabilities on the performance of self-backhauled IAB systems operating in half-duplex mode and utilizing millimeter-wave (mmWave) technology across both access and backhaul. Our results indicate that the throughput gain of multihopping and multi-beaming is significant even without multi-connectivity operation. Another important lesson is that in all-mmWave systems with link blockage, multi-connectivity with link switching allows achieving self-load balancing. Finally, we outline future research directions.acceptedVersionPeer reviewe

Joint Path Selection and Resource Allocation in Multi-Hop mmWave-based IAB Systems

Recently proposed by 3GPP, Integrated Access and Backhaul (IAB) technology promises to deliver a cost-efficient and flexible solution for network densification in 5G/6G systems. Since IAB architecture is based on multi-hop topology and advanced functionalities, such as multi-connectivity transmission and multi-routing, the potential utilization of IAB systems raises an issue of efficient system design. In this paper, we develop an optimization framework capable of jointly selecting transmission paths and allocating radio resources in compliance with half-duplexing and interference constraints. The presented numerical results illustrate that directional mm Wave beams employed at the wireless backhaul are essential for capacity boosting, thus allowing to fully exploit the radio resources in self-backhauled systems. We also establish that the multi-hop IAB topology provides advantages in terms of end-to-end user throughput as compared to single-hop systems.Peer reviewe

Superficial Femoral Artery Pseudoaneurysm in a Child Which Developed After Femur Fracture

Pseudoaneurysm of the superficial femoral artery after a traumatic fracture of the femur is rarely seen. In the present study, we reported treatment with endovascular embolization and surgery in a 9-year-old male patient in whom superficial femoral artery pseudoaneurysm which developed after traumatic, comminuted femoral distal diaphyseal fracture