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This paper provides insights into the impact of weight factors in multi-objective geometric programming (MOGP) optimization. Optimization of the weight factors is also considered. Generally, solving the multi-objective problem via geometric programming requires multiple objectives be combined into a scalar objective by weighing the individual objectives with arbitrary, fixed weight factors. On the...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
This paper describes a comparative analysis between two topologies of operational amplifiers to design a 40 MS/s 12-bit pipeline analog to digital converter (ADC). The analysis includes AC and transient simulation to select the proper topology. This ADC is implemented in a 0.35 mum AMS CMOS technology with 3.3 V single power supply. The capacitors and selected operational amplifiers were scaled for...
In this paper, a robust FGS video transmission scheme is proposed for streaming video over bandwidth-constrained packet loss channel, which aims to reducing both the overall distortion and quality fluctuation at the same time. We first use channel budget and packet loss property to determine the bits of enhancement layers that should be allocated per frame. Then unequal loss protection (ULP) using...
This paper concerns an approach for solving multi-objective analog circuit design problems, which is based on formulating the problem as a geometric program (GP). Multiple objectives are combined into a scalar objective thru certain convex functions and thus can be solved using GP. In contrast to single-objective optimization, simultaneous consideration of all objectives yields a compromising solution...
The distributed feedback (DFB) fiber laser strain sensor has demonstrated strain resolution comparable to that obtained from high-performance fiber-optic interferometry. This manuscript describes the characteristics and performance of this fiber laser strain sensor and discusses the technological developments necessary to obtain comparable performance from a multiplexed array of laser sensors. The...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
We designed and built a novel all-optical re-timing, re-amplifying, and re-shaping (3R) regeneration system based on terahertz optical asymmetric demultiplexers (TOADs) developed in our laboratory. The system is capable of parallel processing multiple wavelengths, a feature which will significantly improve the scalability of current wavelength division multiplexing (WDM) networks. Performance against...
In conventional optical data transmission schemes, electrical filters and/or optical filters are used to improve the quality of system performance. In this paper, improved design of dense wavelength division multiplexing (DWDM) optical systems is achieved by using a selective electrical filter assignment method. The methodology objective is to optimize system design and mitigate the effects of fiber...
The next generation of wireless networks (4G) will use OFDMA (Orthogonal Frequency Division Multiple Access) in the reverse link. In OFDMA, the reverse link resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers. Since at most one user is assigned to each of these tiles then reverse link transmissions within a sector are orthogonal. However, the...
An approach is proposed which improves the quality and speed of manual loop shaping. Loop shaping is an iterative and creative controller design procedure where the control engineer uses frequency response function (FRF) data of the plant to shape the open loop response such that it satisfies stability, performance and robustness specifications. The advantage compared to automated controller design...
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