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You searched for subject:(rate adaption). Showing records 1 – 3 of 3 total matches.

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Texas A&M University

1. Su, Hang. Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks.

Degree: PhD, Computer Engineering, 2012, Texas A&M University

As more and more wireless applications/services emerge in the market, the already heavily crowded radio spectrum becomes much scarcer. Meanwhile, however,as it is reported in the recent literature, there is a large amount of radio spectrum that is under-utilized. This motivates the concept of cognitive radio wireless networks that allow the unlicensed secondary-users (SUs) to dynamically use the vacant radio spectrum which is not being used by the licensed primary-users (PUs). In this dissertation, we investigate protocol design for both the synchronous and asynchronous cognitive radio networks with emphasis on the medium access control (MAC) layer. We propose various spectrum sharing schemes, opportunistic packet scheduling schemes, and spectrum sensing schemes in the MAC and physical (PHY) layers for different types of cognitive radio networks, allowing the SUs to opportunistically utilize the licensed spectrum while confining the level of interference to the range the PUs can tolerate. First, we propose the cross-layer based multi-channel MAC protocol, which integrates the cooperative spectrum sensing at PHY layer and the interweave-based spectrum access at MAC layer, for the synchronous cognitive radio networks. Second, we propose the channel-hopping based single-transceiver MAC protocol for the hardware-constrained synchronous cognitive radio networks, under which the SUs can identify and exploit the vacant channels by dynamically switching across the licensed channels with their distinct channel-hopping sequences. Third, we propose the opportunistic multi-channel MAC protocol with the two-threshold sequential spectrum sensing algorithm for asynchronous cognitive radio networks. Fourth, by combining the interweave and underlay spectrum sharing modes, we propose the adaptive spectrum sharing scheme for code division multiple access (CDMA) based cognitive MAC in the uplink communications over the asynchronous cognitive radio networks, where the PUs may have different types of channel usage patterns. Finally, we develop a packet scheduling scheme for the PU MAC protocol in the context of time division multiple access (TDMA)-based cognitive radio wireless networks, which is designed to operate friendly towards the SUs in terms of the vacant-channel probability. We also develop various analytical models, including the Markov chain models, M=GY =1 queuing models, cross-layer optimization models, etc., to rigorously analyze the performance of our proposed MAC protocols in terms of aggregate throughput, access delay, and packet drop rate for both the saturation network case and non-saturation network case. In addition, we conducted extensive simulations to validate our analytical models and evaluate our proposed MAC protocols/schemes. Both the numerical and simulation results show that our proposed MAC protocols/schemes can significantly improve the spectrum utilization efficiency of wireless networks. Advisors/Committee Members: Zhang, Xi (advisor), Reddy, AL Narasimha (committee member), Welch, Jennifer L. (committee member), Loguinov, Dmitri (committee member).

Subjects/Keywords: Cognitive radio; multi-channel MAC; dynamic spectrum access; cross-layer design; M/G^Y/1 queuing theory; QoS provisionings; cooperative spectrum sensing; channel hopping; decision process; rate adaption; opportunistic scheduling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Su, H. (2012). Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8943

Chicago Manual of Style (16th Edition):

Su, Hang. “Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks.” 2012. Doctoral Dissertation, Texas A&M University. Accessed January 22, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8943.

MLA Handbook (7th Edition):

Su, Hang. “Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks.” 2012. Web. 22 Jan 2021.

Vancouver:

Su H. Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Jan 22]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8943.

Council of Science Editors:

Su H. Design and Analysis of Opportunistic MAC Protocols for Cognitive Radio Wireless Networks. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8943


KTH

2. Eklöf, William. Adaptive Video Streaming : Adapting video quality to radio links with different characteristics.

Degree: CoS, 2008, KTH

During the last decade, the data rates provided by mobile networks have improved to the point that it is now feasible to provide richer services, such as streaming multimedia, to mobile users. However, due to factors such as radio interference and cell load, the throughput available to a client varies over time. If the throughput available to a client decreases below the media’s bit rate, the client’s buffer will eventually become empty. This causes the client to enter a period of rebuffering, which degrades user experience. In order to avoid this, a streaming server may provide the media at different bit rates, thereby allowing the media’s bit rate (and quality) to be modified to fit the client’s bandwidth. This is referred to as adaptive streaming. The aim of this thesis is to devise an algorithm to find the media quality most suitable for a specific client, focusing on how to detect that the user is able to receive content at a higher rate. The goal for such an algorithm is to avoid depleting the client buffer, while utilizing as much of the bandwidth available as possible without overflowing the buffers in the network. In particular, this thesis looks into the difficult problem of how to do adaptation for live content and how to switch to a content version with higher bitrate and quality in an optimal way. This thesis examines if existing adaptation mechanisms can be improved by considering the characteristics of different mobile networks. In order to achieve this, a study of mobile networks currently in use has been conducted, as well as experiments with streaming over live networks. The experiments and study indicate that the increased available throughput can not be detected by passive monitoring of client feedback. Furthermore, a higher data rate carrier will not be allocated to a client in 3G networks, unless the client is sufficiently utilizing the current carrier. This means that a streaming server must modify its sending rate in order to find its maximum throughput and to force allocation of a higher data rate carrier. Different methods for achieving this are examined and discussed and an algorithm based upon these ideas was implemented and evaluated. It is shown that increasing the transmission rate by introducing stuffed packets in the media stream allows the server to find the optimal bit rate for live video streams without switching up to a bit rate which the network can not support. This thesis was carried out during the summer and autumn of 2008 at Ericsson Research, Multimedia Technologies in Kista, Sweden.

Under det senaste decenniet har överföringshastigheterna i mobilnätet ökat så pass mycket att detnu är möjligt att erbjuda användarna mer avancerade tjänster, som till exempel strömmandemultimedia. I mobilnäten varierar dock klientens bandbredd med avseende på tiden på grund avfaktorer som störningar på radiolänken och lasten i cellen. Om en klients överföringshastighetsjunker till mindre än mediets bithastighet, kommer…

Subjects/Keywords: Streaming; Bit rate adaption; Video Quality; RTP; RTCP; GPRS; EDGE; UMTS; TECHNOLOGY; TEKNIKVETENSKAP

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Eklöf, W. (2008). Adaptive Video Streaming : Adapting video quality to radio links with different characteristics. (Thesis). KTH. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91662

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Eklöf, William. “Adaptive Video Streaming : Adapting video quality to radio links with different characteristics.” 2008. Thesis, KTH. Accessed January 22, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91662.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Eklöf, William. “Adaptive Video Streaming : Adapting video quality to radio links with different characteristics.” 2008. Web. 22 Jan 2021.

Vancouver:

Eklöf W. Adaptive Video Streaming : Adapting video quality to radio links with different characteristics. [Internet] [Thesis]. KTH; 2008. [cited 2021 Jan 22]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91662.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Eklöf W. Adaptive Video Streaming : Adapting video quality to radio links with different characteristics. [Thesis]. KTH; 2008. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91662

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Cincinnati

3. GODBOLE, AMIT ARUN. ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE.

Degree: MS, Engineering : Aerospace Engineering, 2003, University of Cincinnati

One key element in improving air traffic capacity and efficiency is the ability of the air traffic management system to predict accurately the future position of a vehicle along a standard route. Perhaps the most challenging problem in the current practice is to predict accurately the altitude profile of an aircraft during the ascent phase of flight. During the ascent, the vehicle performance is extremely sensitive to uncertainties in the vehicle weight, thrust and piloting procedures, none of which are currently known to air traffic controller whose job is to merge this departure aircraft into an en route stream of traffic. This thesis work investigates the use of adaptive control techniques to improve climb performance prediction. The aim is to accurately predict time to ‘top of climb’ in the ascending phase of aircraft trajectory. The study is conducted in support of the CTAS air traffic control software, which is in development at NASA Ames Research Center in California. This investigation consists of a comparison between actual departure trajectories for MD80 type of aircraft and the results of MATLAB-based numerical simulation attempting to duplicate the measured energy rate and hence the trajectory during the climb phase. The technical approach taken in this thesis is to start with initial a priori models of aerodynamics and engine thrust. The thrust dependency is adapted based on the observed and calculated energy rates of the vehicle. The results indicate that this adaptive model can greatly improve climb performance prediction. Advisors/Committee Members: Slater, Dr. Gary (Advisor).

Subjects/Keywords: Engineering, Aerospace; air traffic management; trajectory prediction; adaptive control; thrust adaption; rate of climb

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

GODBOLE, A. A. (2003). ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE. (Masters Thesis). University of Cincinnati. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061303791

Chicago Manual of Style (16th Edition):

GODBOLE, AMIT ARUN. “ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE.” 2003. Masters Thesis, University of Cincinnati. Accessed January 22, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061303791.

MLA Handbook (7th Edition):

GODBOLE, AMIT ARUN. “ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE.” 2003. Web. 22 Jan 2021.

Vancouver:

GODBOLE AA. ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE. [Internet] [Masters thesis]. University of Cincinnati; 2003. [cited 2021 Jan 22]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061303791.

Council of Science Editors:

GODBOLE AA. ADAPTIVE IMPROVEMENT OF CLIMB PERFORMANCE. [Masters Thesis]. University of Cincinnati; 2003. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061303791

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