Sharif Digital Repository

In this paper a new iterative method is used to convert analog signals to digital (A/D) using sigma delta modulator (SDM). If intelligent reconstruction technique is used for decoding, either signals with higher bandwidth can be digitized or simpler circuitry can be utilized. An optimal family of SDM has recently been devised in order to improve performance of A/D converters. In this work, we improve performance of A/D converters even more, by combining this optimal family of SDM with iterative methods  

Abstract Reducing the NoC power is critical for scaling up the number of nodes in future many-core systems. Most NoC designs adopt packet-switching to benefit from its high throughput and excellent scalability. These benefits, however, come at the price of the power consumption and latency overheads of routers. Circuit-switching, on the other hand, enjoys a significant reduction in power and latency of communication by directing data over pre-established circuits, but the relatively large circuit setup time and low resource utilization of this switching mechanism is often prohibitive. In this paper, we address one of the major problems of circuit-switching, i.e. the circuit setup time... 

In this paper, we present a detailed analytical approach to obtain the channel capacity of optical space-division multiplexing (SDM) systems. To this aim, the nonlinearity effects of optical fiber are modeled as additive white Gaussian noise (GN) process, and accordingly a closed-form formula is derived for SDM capacity. Furthermore, we extend our result to a more generalized case, which includes different bandwidth, center frequency, and transmission powers. © 2017 IEEE  

In this paper, we study the secrecy throughput in a massive Multiple-Input-Multiple-Output (MIMO) full-duplex wireless powered communication network (WPCN). The network consists of a massive MIMO base station (BS) and two groups of single- antenna sensor nodes which harvest energy from the BS. The first group, referred to as information transmitters (ITs), use the harvested energy to transmit information back to the BS; the second group, referred to as energy receivers (ERs), use the harvested energy for non- transmission related operations. We consider a two-slot protocol. In the first time slot, all nodes harvest energy from the BS. In the second slot, ITs transmit information to the BS,... 

The transmission capacity of traditional single core fibers is reaching its upper bound. Space-division multiplexing (SDM) leveraging multi-core fibers is considered to be a promising solution for this problem. Elastic optical networks (EONs) with Multi-core fibers (MCF) are a kind of SDM-enabled EONs (SDM-EON) providing larger transmission capacity. However, the resource assignment in these networks becomes more complex due to inter-core crosstalk. Another important issue to be considered in future networks is the time domain behavior of incoming traffic which means considering Advance Reservation (AR) requests, in addition to regular Immediate Reservation (IR) requests. In this paper, the... 

In this paper, the problem of routing, modulation level, core, and spectrum assignment (RMCSA) in space-division-multiplexed elastic optical networks (SDM-EONs) is studied. We formulate this problem as a mixed-integer linear programming (MILP), in which dedicated and shared path protection schemes are supported in SDM-EONs with multi-core fibers (MCFs) and the inter-core crosstalk of MCFs is strictly modeled. Furthermore, an efficient heuristic algorithm is proposed to solve the RMCSA problem in a large scale scenario. Numerical results reveal that the formulated MILP leads to lower spectrum usage compared to the alternative methods. Moreover, the proposed heuristic algorithm performs close... 

Elastic Optical Network (EON) is a promising solution to address the high capacity, low latency, and flexibility requirements of the upcoming 5th-generation (5G) networks. Furthermore, Multi-Core Fibers (MCFs) and Space Division Multiplexing (SDM) technique can be utilized to overcome the capacity limitation of the conventional Single Mode Fibers (SMFs). On the other hand, Quantum Key Distribution (QKD) is an effective solution to address the security issues in 5G transport networks. In this paper, we investigate the performance of QKD over elastic optical networks with multi-core fibers and address the resource allocation problem for quantum and classical channels of QKD (QChs and CChs) and... 

This paper reports transistor-level design of a new continuous-time (CT), discrete-time (DT) cascaded sigma delta modulator (SDM). The combination of a CT first stage and a DT second stage was utilized to realize a high speed, high resolution analog-to-digital converter (ADC). Power consumption of CT first stage is lowered by optimizing the gain coefficients of CT integrators in a feedforward topology. Moreover double sampling (CDS) was used in second stage integrators to further reduce power consumption. Proposed new SDM is simulated in 0.18μm CMOS technology and achieves 84dB dynamic range for a 10MHz signal bandwidth. Total analog power dissipation measured was 44mW