Performance Analysis of OFDM Systems with Adaptive Sub Carrier Bandwidth

Das, Suvra Sekhar; Carvalho, Elisabeth de; Prasad, Ramjee

doi:10.1109/twc.2008.060761

Cited by 55 publications

(36 citation statements)

References 9 publications

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“…Accordingly, system performance can be enhanced by adjusting transmission parameters such as subcarrier bandwidth based on these changing environmental phenomena. Significant performance improvements can be made by using adaptive channel width [6], [8] and adaptive subcarrier bandwidth (ASB) [11], [37] techniques. Based on our findings and analysis in this paper, we can argue that an underground communication system using adaptive subcarrier bandwidth (ASB) approach is expected to enhance capacity of underground channel.…”

Section: Discussionmentioning

confidence: 99%

“…The subcarrier bandwidth depends on the delay spread of the underground channel and needs to be in proportion to the delay spread of the channel in order to solve the issues caused by the delay spread impairments. However, an underground multicarrier communication system designed on a fixed sub-carrier bandwidth may experience inter carrier interference (ICI) [11]. ICI is caused by time-varying coherence bandwidth channel statistics due to soil moisture variations.…”

Section: Introductionmentioning

confidence: 99%

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Impacts of Soil Type and Moisture on the Capacity of Multi-Carrier Modulation in Internet of Underground Things

Salam

Vuran

2016

2016 25th International Conference on Computer Communication and Networks (ICCCN)

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Abstract-Unique interactions between soil and communication components in wireless underground communications necessitate revisiting fundamental communication concepts from a different perspective. In this paper, capacity profile of wireless underground (UG) channel for multi-carrier transmission techniques is analyzed based on empirical antenna return loss and channel frequency response models in different soil types and moisture values. It is shown that data rates in excess of 124 Mbps are possible for distances up to 12 m. For shorter distances and lower soil moisture conditions, data rates of 362 Mbps can be achieved. It is also shown that due to soil moisture variations, UG channel experiences significant variations in antenna bandwidth and coherence bandwidth, which demands dynamic subcarrier operation. Theoretical analysis based on this empirical data show that by adaption to soil moisture variations, 180% improvement in channel capacity is possible when soil moisture decreases. It is shown that compared to a fixed bandwidth system; soilbased, system and sub-carrier bandwidth adaptation leads to capacity gains of 56%-136%. The analysis is based on indoor and outdoor experiments with more than 1, 500 measurements taken over a period of 10 months. These semi-empirical capacity results provide further evidence on the potential of underground channel as a viable media for high data rate communication and highlight potential improvements in this area.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impacts of Soil Type and Moisture on the Capacity of Multi-Carrier Modulation in Internet of Underground Things

Salam

Vuran

2016

2016 25th International Conference on Computer Communication and Networks (ICCCN)

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“…Furthermore, the heuristic based on the proposed Lagrange relaxation partly improves the achieved rate-region compared to that based on the previously proposed heuristics (IWF and discrete bit-allocation). 4 Comparing this previously proposed heuristic to the previously proposed upper bound (neglecting ICI) under sum-rate maximization, its resulting upper bound on the suboptimality is between 6.7 % and 7.5 % in the three network scenarios. However, comparing the heuristic and upper bound based on the proposed Lagrange relaxation to each other, we obtain a resulting upper bound on the sum-rate suboptimality of only between 3.0 % and 4.1 %.…”

Section: Simulationsmentioning

confidence: 90%

Multiuser Spectrum Balancing under Inter-Carrier Interference

2012

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Abstract-Inter-carrier interference (ICI) in multicarrier systems results in a coupling among all subcarriers. This greatly complicates the problem of multiuser bit and power allocation, also referred to as spectrum balancing. We propose a Lagrange relaxation of the ICI coupling terms, and an optimal algorithm for solving the resulting relaxed spectrum balancing problem. While this gives us a rate-performance upper bound, based on it we also propose a novel heuristic for computing a lower bound. The relaxation is exemplarily applied to digital subscriber lines (DSL) with asynchronous far-end crosstalk in near-far scenarios. The results confirm the existence of scenarios where the performance upper and lower bounds obtained by the relaxation are significantly tighter than those previously proposed.

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“…The bandwidth is chosen large enough to tolerate a certain amount of Doppler spread. In [15][16][17] the impact of varying the subcarrier bandwidth on the system performance in time-and frequencyselective channels was studied, and an approach for adaptive bandwidth for subcarriers for single-user OFDM was proposed [18,19]. This analysis was extended to a multiuser scenario in [20].…”

Section: Introductionmentioning

confidence: 99%

An OFDM throughput analysis for cognitive radio application in contiguous or noncontiguous TV white spaces

Çiflikli¹,

Tuncer²,

Öztürk³

2015

Turk J Elec Eng & Comp Sci

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Abstract:Radio frequency spectrum is a finite and scarce resource. Efficient use of the radio frequency spectrum is a fundamental research issue. Since a large portion of the assigned radio frequency spectrum is used only sporadically, the bands currently allocated to TV services can be opportunistically reassigned to support broadband networking services while continuing to provide broadcast TV. The fragmented and unused TV channels named white spaces have a considerable amount of bandwidth potential and long transmission ranges. Bandwidth scalability can be supported by bonding multiple contiguous or noncontiguous consecutive channels using orthogonal frequency division multiplexing (OFDM)-based cognitive radio.In this paper, an in-depth throughput analysis of OFDM fixed carrier spacing and fixed carrier number approaches has been done for various modulation schemes in TV white spaces. Signal propagation delay is studied under various channel conditions. An analytical model-based estimation of the throughput by taking into account channel bonding is presented.

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Performance Analysis of OFDM Systems with Adaptive Sub Carrier Bandwidth

Cited by 55 publications

References 9 publications

Impacts of Soil Type and Moisture on the Capacity of Multi-Carrier Modulation in Internet of Underground Things

Impacts of Soil Type and Moisture on the Capacity of Multi-Carrier Modulation in Internet of Underground Things

Multiuser Spectrum Balancing under Inter-Carrier Interference

An OFDM throughput analysis for cognitive radio application in contiguous or noncontiguous TV white spaces

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