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Radio Resource Optimization for OFDM-based Broadband Cellular Systems
Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The rapid growth of users’ traffic demand in broadband wireless communication systems requires high-speed data transmission and intelligent resource allocation approaches. The Third Generation Partnership Project-Long Term Evolution (3GPPLTE) has standardized multiple access (MA) schemes for 4G cellular networks. Two advanced schemes, orthogonal frequency division multiple access (OFDMA) and single carrier frequency division multiple access (SC-FDMA), have been adopted for downlink and uplink, respectively.

Optimization-based approaches play a crucial role in network operation and resource management. The optimization problems considered in this thesis are addressed in four research papers. For the single cell scenario, the optimization problems of joint power and channel allocation in OFDMA and consecutive-channel assignment in SCFDMA are investigated in Papers I, II, and III. For the OFDM-based multi-cell scenario, an energy minimization problem is addressed in Paper IV.

In the thesis, theoretical analysis, algorithm development, and numerical studies are carried out. Mathematical optimization is applied as the main approach to facilitate the problem solving. In Paper I, we evaluate the performance gain and loss for various  allocation policies in the OFDMA system. In Papers II and III, resource allocation algorithms are proposed to obtain competitive and high-quality solutions for consecutive-channel allocation problems in the SC-FDMA system. The theoretical analysis and the proposed algorithm in Paper IV provide optimal solution for energy minimization.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. , 20 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1649
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-105500ISBN: 978-91-7519-374-8 (print)OAI: oai:DiVA.org:liu-105500DiVA: diva2:707733
Presentation
2014-04-10, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2014-03-25 Created: 2014-03-25 Last updated: 2014-03-25Bibliographically approved
List of papers
1. Performance analysis of chunk-based resource allocation in wireless OFDMA systems
Open this publication in new window or tab >>Performance analysis of chunk-based resource allocation in wireless OFDMA systems
2012 (English)In: Proceedings from the 17th IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), September 17-19, 2012, Barcelona, Spain, IEEE , 2012, 90-94 p.Conference paper, Published paper (Refereed)
Abstract [en]

In typical resource allocation for Orthogonal Frequency Division Multiple Access (OFDMA), assigning subcarriers to the more favorable users provides beneficial diversity and increased system performance. It is however relevant to consider OFDMA resource allocation with a subcarrier adjacency restriction, grouping a number of adjacent subcarriers into a chunk, both for physical design simplicity and for complexity mitigation. In this paper, we classify different resource allocation policies for chunk-based allocation. We investigate how to optimally allocate resources by using discrete rates and discrete power levels. This is enabled by developing binary integer optimization models to obtain the optimal solution for this comparative study. We present numerical results to evaluate the performance of different resource allocation policies under different parameters and scenarios.

Place, publisher, year, edition, pages
IEEE, 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105496 (URN)10.1109/CAMAD.2012.6335386 (DOI)978-1-4673-3123-4 (ISBN)978-1-4673-3124-1 (ISBN)
Conference
17th IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), September 17-19, 2012, Barcelona, Spain
Available from: 2014-03-25 Created: 2014-03-25 Last updated: 2014-03-25Bibliographically approved
2. Improved Resource Allocation Algorithm Based on Partial Solution Estimation for SC-FDMA Systems
Open this publication in new window or tab >>Improved Resource Allocation Algorithm Based on Partial Solution Estimation for SC-FDMA Systems
2013 (English)In: Proceedings from the 78th IEEE Vehicular Technology Conference (VTC Fall), September 2-5, Las Vegas, USA, IEEE , 2013, 1-5 p.Conference paper, Published paper (Refereed)
Abstract [en]

Single carrier frequency division multiple access (SC-FDMA) has been adopted as the standard multiple access scheme for 3GPP LTE uplink. In comparison to orthogonal frequency division multiple access (OFDMA), the subcarriers assigned to each user are required to be consecutive in SC-FDMA localized scheme, which imposes more difficulties on resource allocation problem. Subject to this constraint, various optimization objectives, such as utility maximization and power minimization, have been studied for SC-FDMA resource allocation. In this paper, we focus on developing a general algorithm framework with near-optimal performance and polynomial-time complexity to maximize the total utility for SC-FDMA systems. The proposed algorithm is based on low-complexity estimation for the partial solution space. Compared with existing algorithms, simulation results show that our algorithm improves the system utility significantly and has less deviation to global optimum. In addition, the proposed algorithm framework allows a flexible trade-off between computational effort and solution performance by varying the complexity of estimation approaches.

Place, publisher, year, edition, pages
IEEE, 2013
Series
Vehicular Technology Conference, ISSN 1090-3038 ; 78
Keyword
SC-FDMA; Algorithm; Resource Allocation; Binary Integer Programming; Partial Solution; Estimation
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105049 (URN)10.1109/VTCFall.2013.6692229 (DOI)000330585400207 ()978-1-4673-6187-3 (Article) (ISBN)978-1-4673-6185-9 (ISBN)
Conference
78th IEEE Vehicular Technology Conference (VTC Fall), September 2-5, Las Vegas, USA
Available from: 2014-03-06 Created: 2014-03-06 Last updated: 2015-03-18Bibliographically approved
3. A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
Open this publication in new window or tab >>A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
2013 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, no 11, 5767-5779 p.Article in journal (Refereed) Published
Abstract [en]

Optimal channel allocation is a key performance engineering aspect in single-carrier frequency-division multiple access (SC-FDMA). In SC-FDMA with localized channel assignment, the channels of each user must form a consecutive block. Subject to this constraint, various performance objectives, such as maximum utility, minimum power, and minimum number of channels, have been studied. We present a unified graph labeling algorithm for these problems, based on the structural insight that SC-FDMA channel allocation can be modeled as finding an optimal path in an acyclic graph. By this insight, our algorithm applies the concept of labeling and label domination that represent non-trivial extensions of finding a shortest or longest path. The key parameter in trading performance versus computation is the number of labels kept per node. Increasing the number ultimately enables global optimality. The algorithms approach is further justified by its global optimality guarantee with strong polynomial-time complexity for two specific scenarios, where the input is user-invariant and channel-invariant, respectively. For the general case, we provide numerical results demonstrating the algorithms ability of attaining near-optimal solutions.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2013
Keyword
Algorithm, channel allocation, optimization, single carrier frequency division multiple access
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-102855 (URN)10.1109/TWC.2013.092313.130092 (DOI)000328058400034 ()
Note

R)||A*STAR, Singapore||Linkoping-Lund Excellence Center in Information Technology (ELLIIT), Sweden||

Available from: 2014-01-07 Created: 2014-01-02 Last updated: 2017-12-06
4. Optimal Energy Minimization inLoad-Coupled Wireless Networks: Computation and Properties
Open this publication in new window or tab >>Optimal Energy Minimization inLoad-Coupled Wireless Networks: Computation and Properties
2014 (English)Conference paper, Published paper (Other academic)
Abstract [en]

We consider the problem of sum transmission energy minimization in a cellular network where base stations interfere with one another. Each base station has to serve a target amount of data to its set of users, by varying its power and load, where the latter refers to the average level of channel resource usage in the cell. We employ the signal-tointerference-and-noise-ratio (SINR) load-coupled model that takes into account the load of each cell. We show analytically that operating at full load is optimal to minimize sum energy. Moreover, we provide an iterative power adjustment algorithm for all base stations to achieve full load. Numerical results are obtained that corroborate the analysis and illustrate the advantage of our solution compared to the conventional solution where uniform power is used for all base stations.

Keyword
Energy minimization, load balancing, load coupling, Perron-Frobenius theorem.
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105497 (URN)
Conference
The 2014 IEEE International Conference on Communications (ICC), June 10-14, Sydney, Australia
Available from: 2014-03-25 Created: 2014-03-25 Last updated: 2014-03-25Bibliographically approved

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