liu.seSök publikationer i DiVA
Ändra sökning
Avgränsa sökresultatet
1 - 20 av 20
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Keong Ho, Chin
    et al.
    ASTAR, Singapore .
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Sun, Sumei
    ASTAR, Singapore .
    Optimal Energy Minimization inLoad-Coupled Wireless Networks: Computation and Properties2014Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 2.
    Keong Ho, Chin
    et al.
    ASTAR, Singapore.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Sun, Sumei
    ASTAR, Singapore.
    Power and Load Coupling in Cellular Networks for Energy Optimization2015Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 1, s. 509-519Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the problem of minimization of sum transmission energy in cellular networks where coupling occurs between cells due to mutual interference. The coupling relation is characterized by the signal-to-interference-and-noise-ratio (SINR) coupling model. Both cell load and transmission power, where cell load measures the average level of resource usage in the cell, interact via the coupling model. The coupling is implicitly characterized with load and power as the variables of interest using two equivalent equations, namely, non-linear load coupling equation (NLCE) and non-linear power coupling equation (NPCE), respectively. By analyzing the NLCE and NPCE, we prove that operating at full load is optimal in minimizing sum energy, and provide an iterative power adjustment algorithm to obtain the corresponding optimal power solution with guaranteed convergence, where in each iteration a standard bisection search is employed. To obtain the algorithmic result, we use the properties of the so-called standard interference function; the proof is nonstandard because the NPCE cannot even be expressed as a closed-form expression with power as the implicit variable of interest. We present numerical results illustrating the theoretical findings for a real-life and large-scale cellular network, showing the advantage of our solution compared to the conventional solution of deploying uniform power for base stations.

  • 3.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    From Orthogonal to Non-orthogonal Multiple Access: Energy- and Spectrum-Efficient Resource Allocation2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The rapid pace of innovations in information and communication technology (ICT) industry over the past decade has greatly improved people’s mobile communication experience. This, in turn, has escalated exponential growth in the number of connected mobile devices and data traffic volume in wireless networks. Researchers and network service providers have faced many challenges in providing seamless, ubiquitous, reliable, and high-speed data service to mobile users. Mathematical optimization, as a powerful tool, plays an important role in addressing such challenging issues.

    This dissertation addresses several radio resource allocation problems in 4G and 5G mobile communication systems, in order to improve network performance in terms of throughput, energy, or fairness. Mathematical optimization is applied as the main approach to analyze and solve the problems. Theoretical analysis and algorithmic solutions are derived. Numerical results are obtained to validate our theoretical findings and demonstrate the algorithms’ ability of attaining optimal or near-optimal solutions.

    Five research papers are included in the dissertation. In Paper I, we study a set of optimization problems of consecutive-channel allocation in single carrier-frequency division multiple access (SCFDMA) systems. We provide a unified algorithmic framework to optimize the channel allocation and improve system performance. The next three papers are devoted to studying energy-saving problems in orthogonal frequency division multiple access (OFDMA) systems. In Paper II, we investigate a problem of jointly minimizing energy consumption at both transmitter and receiver sides. An energy-efficient scheduling algorithm is developed to provide optimality bounds and near-optimal solutions. Next in Paper III, we derive fundamental properties for energy minimization in loadcoupled OFDMA networks. Our analytical results suggest that the maximal use of time-frequency resources can lead to the lowest network energy consumption. An iterative power adjustment algorithm is developed to obtain the optimal power solution with guaranteed convergence. In Paper IV, we study an energy minimization problem from the perspective of scheduling activation and deactivation of base station transmissions. We provide mathematical formulations and theoretical insights. For problem solution, a column generation approach, as well as a bounding scheme are developed. Finally, towards to 5G communication systems, joint power and channel allocation in non-orthogonal multiple access (NOMA) is investigated in Paper V in which an algorithmic solution is proposed to improve system throughput and fairness.

    Delarbeten
    1. A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
    Öppna denna publikation i ny flik eller fönster >>A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
    2013 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, nr 11, s. 5767-5779Artikel i tidskrift (Refereegranskat) 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.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2013
    Nyckelord
    Algorithm, channel allocation, optimization, single carrier frequency division multiple access
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-102855 (URN)10.1109/TWC.2013.092313.130092 (DOI)000328058400034 ()
    Anmärkning

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

    Tillgänglig från: 2014-01-07 Skapad: 2014-01-02 Senast uppdaterad: 2017-12-06
    2. Resource Scheduling to Jointly Minimize Receiving and Transmitting Energy in OFDMA Systems
    Öppna denna publikation i ny flik eller fönster >>Resource Scheduling to Jointly Minimize Receiving and Transmitting Energy in OFDMA Systems
    2014 (Engelska)Ingår i: 2014 11TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS (ISWCS), IEEE , 2014, s. 187-191Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Resource scheduling in orthogonal frequency division multiple access (OFDMA) for energy saving has attracted extensive attention. Most current research considers the reduction of energy at the transmitter or the receiver separately. In this paper, we focus on minimizing the energy consumption in both sides concurrently by formulating the problem of joint receiving and transmitting energy-efficient scheduling (RTEES) in OFDMA downlink. We show that this problem can be cast as a binary integer programme. We solve the RTEES problem by a computationally efficient algorithm. We proposed a specialized solution approach, named time-slot-oriented column generation (TSOCG) algorithm, for approaching and bounding the global optimality. Numerical studies show that the proposed algorithm solution is competitive and time-efficient to provide a close-to-optimum solution and a tight bound.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2014
    Nyckelord
    Energy saving; column generation; resource allocation; resource scheduling; OFDMA
    Nationell ämneskategori
    Samhällsbyggnadsteknik
    Identifikatorer
    urn:nbn:se:liu:diva-123094 (URN)000363906500036 ()978-1-4799-5863-4 (ISBN)
    Konferens
    11th International Symposium on Wireless Communications Systems (ISWCS)
    Tillgänglig från: 2015-12-03 Skapad: 2015-12-03 Senast uppdaterad: 2016-04-08
    3. Power and Load Coupling in Cellular Networks for Energy Optimization
    Öppna denna publikation i ny flik eller fönster >>Power and Load Coupling in Cellular Networks for Energy Optimization
    2015 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 1, s. 509-519Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We consider the problem of minimization of sum transmission energy in cellular networks where coupling occurs between cells due to mutual interference. The coupling relation is characterized by the signal-to-interference-and-noise-ratio (SINR) coupling model. Both cell load and transmission power, where cell load measures the average level of resource usage in the cell, interact via the coupling model. The coupling is implicitly characterized with load and power as the variables of interest using two equivalent equations, namely, non-linear load coupling equation (NLCE) and non-linear power coupling equation (NPCE), respectively. By analyzing the NLCE and NPCE, we prove that operating at full load is optimal in minimizing sum energy, and provide an iterative power adjustment algorithm to obtain the corresponding optimal power solution with guaranteed convergence, where in each iteration a standard bisection search is employed. To obtain the algorithmic result, we use the properties of the so-called standard interference function; the proof is nonstandard because the NPCE cannot even be expressed as a closed-form expression with power as the implicit variable of interest. We present numerical results illustrating the theoretical findings for a real-life and large-scale cellular network, showing the advantage of our solution compared to the conventional solution of deploying uniform power for base stations.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2015
    Nyckelord
    Cellular networks; energy minimization; load coupling; power coupling; power adjustment allocation; standard interference function
    Nationell ämneskategori
    Samhällsbyggnadsteknik
    Identifikatorer
    urn:nbn:se:liu:diva-115830 (URN)10.1109/TWC.2014.2353043 (DOI)000349675400041 ()
    Anmärkning

    Funding Agencies|Linkoping-Lund Excellence Center in Information Technology (ELLIIT), Sweden; Chinese Scholarship Council (CSC); Institute for Infocomm Research (I2R), A*STAR, Singapore

    Tillgänglig från: 2015-03-20 Skapad: 2015-03-20 Senast uppdaterad: 2017-12-04
    4. Optimal Cell Clustering and Activation for Energy Saving in Load-Coupled Wireless Networks
    Öppna denna publikation i ny flik eller fönster >>Optimal Cell Clustering and Activation for Energy Saving in Load-Coupled Wireless Networks
    2015 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 11, s. 6150-6163Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Optimizing activation and deactivation of base station transmissions provides an instrument for improving energy efficiency in cellular networks. In this paper, we study the problem of performing cell clustering and setting the activation time of each cluster, with the objective of minimizing the sum energy, subject to a time constraint of serving the users traffic demand. Our optimization framework accounts for inter-cell interference, and, thus, the users achievable rates depend on cluster formation. We provide mathematical formulations and analysis, and prove the problems NP hardness. For problem solution, we first apply an optimization method that successively augments the set of variables under consideration, with the capability of approaching global optimum. Then, we derive a second solution algorithm to deal with the trade-off between optimality and the combinatorial nature of cluster formation. Numerical results demonstrate that our solutions achieve more than 40% energy saving over existing schemes, and that the solutions we obtain are within a few percent of deviation from global optimum.

    Ort, förlag, år, upplaga, sidor
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2015
    Nyckelord
    Cell activation; cell clustering; energy minimization; load coupling; column generation
    Nationell ämneskategori
    Samhällsbyggnadsteknik
    Identifikatorer
    urn:nbn:se:liu:diva-123331 (URN)10.1109/TWC.2015.2449295 (DOI)000365046100020 ()
    Anmärkning

    Funding Agencies|European Union FP7 Marie Curie Project MESH-WISE [434515]; European Union FP7 Marie Curie Project WiNDOW [318992]; Chinese Scholarship Council; Institute for Infocomm Research (I2R); A*STAR, Singapore, through overseas Ph.D. research internship scheme; Swedish Research Council; European Union FP7 Marie Curie IOF [329313]

    Tillgänglig från: 2015-12-14 Skapad: 2015-12-11 Senast uppdaterad: 2017-12-01
  • 4.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Radio Resource Optimization for OFDM-based Broadband Cellular Systems2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

    Delarbeten
    1. Performance analysis of chunk-based resource allocation in wireless OFDMA systems
    Öppna denna publikation i ny flik eller fönster >>Performance analysis of chunk-based resource allocation in wireless OFDMA systems
    2012 (Engelska)Ingår i: 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, s. 90-94Konferensbidrag, Publicerat paper (Refereegranskat)
    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.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2012
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    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)
    Konferens
    17th IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), September 17-19, 2012, Barcelona, Spain
    Tillgänglig från: 2014-03-25 Skapad: 2014-03-25 Senast uppdaterad: 2014-03-25Bibliografiskt granskad
    2. Improved Resource Allocation Algorithm Based on Partial Solution Estimation for SC-FDMA Systems
    Öppna denna publikation i ny flik eller fönster >>Improved Resource Allocation Algorithm Based on Partial Solution Estimation for SC-FDMA Systems
    2013 (Engelska)Ingår i: Proceedings from the 78th IEEE Vehicular Technology Conference (VTC Fall), September 2-5, Las Vegas, USA, IEEE , 2013, s. 1-5Konferensbidrag, Publicerat paper (Refereegranskat)
    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.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2013
    Serie
    Vehicular Technology Conference, ISSN 1090-3038 ; 78
    Nyckelord
    SC-FDMA; Algorithm; Resource Allocation; Binary Integer Programming; Partial Solution; Estimation
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    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)
    Konferens
    78th IEEE Vehicular Technology Conference (VTC Fall), September 2-5, Las Vegas, USA
    Tillgänglig från: 2014-03-06 Skapad: 2014-03-06 Senast uppdaterad: 2015-03-18Bibliografiskt granskad
    3. A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
    Öppna denna publikation i ny flik eller fönster >>A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA
    2013 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, nr 11, s. 5767-5779Artikel i tidskrift (Refereegranskat) 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.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2013
    Nyckelord
    Algorithm, channel allocation, optimization, single carrier frequency division multiple access
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-102855 (URN)10.1109/TWC.2013.092313.130092 (DOI)000328058400034 ()
    Anmärkning

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

    Tillgänglig från: 2014-01-07 Skapad: 2014-01-02 Senast uppdaterad: 2017-12-06
    4. Optimal Energy Minimization inLoad-Coupled Wireless Networks: Computation and Properties
    Öppna denna publikation i ny flik eller fönster >>Optimal Energy Minimization inLoad-Coupled Wireless Networks: Computation and Properties
    2014 (Engelska)Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
    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.

    Nyckelord
    Energy minimization, load balancing, load coupling, Perron-Frobenius theorem.
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-105497 (URN)
    Konferens
    The 2014 IEEE International Conference on Communications (ICC), June 10-14, Sydney, Australia
    Tillgänglig från: 2014-03-25 Skapad: 2014-03-25 Senast uppdaterad: 2014-03-25Bibliografiskt granskad
  • 5.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Angelakis, Vangelis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Performance analysis of chunk-based resource allocation in wireless OFDMA systems2012Ingår i: 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, s. 90-94Konferensbidrag (Refereegranskat)
    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.

  • 6.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Fowler, Scott
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Improved Resource Allocation Algorithm Based on Partial Solution Estimation for SC-FDMA Systems2013Ingår i: Proceedings from the 78th IEEE Vehicular Technology Conference (VTC Fall), September 2-5, Las Vegas, USA, IEEE , 2013, s. 1-5Konferensbidrag (Refereegranskat)
    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.

  • 7.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Keong Ho, Chin
    ASTAR, Singapore .
    Sun, Sumei
    ASTAR, Singapore .
    A Unified Graph Labeling Algorithm for Consecutive-Block Channel Allocation in SC-FDMA2013Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, nr 11, s. 5767-5779Artikel i tidskrift (Refereegranskat)
    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.

  • 8.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20742 USA.
    Keong Ho, Chin
    ASTAR, Singapore.
    Sun, Sumei
    ASTAR, Singapore.
    Joint Optimization of Power and Channel Allocation with Non-orthogonal Multiple Access for 5G Cellular Systems2015Ingår i: 2015 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), is considered as a candidate multi-user access scheme for 5G cellular systems. In this paper, we provide theoretical insights and solution algorithm for optimizing multi-user power and channel allocation in NOMA systems. We mathematically formulate the NOMA resource allocation problem and prove its NP-hardness. For solving the problem, we propose an algorithm combining Lagrangian duality and dynamic programming to deliver a competitive suboptimal solution. Numerical results demonstrate that the proposed algorithmic solution can significantly improve the system performance over orthogonal frequency division multiple access (OFDMA) as well as over other existing NOMA resource allocation scheme.

  • 9.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20740 USA.
    Keong Ho, Chin
    ASTAR, Singapore.
    Sun, Sumei
    ASTAR, Singapore.
    Optimal Cell Clustering and Activation for Energy Saving in Load-Coupled Wireless Networks2015Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 11, s. 6150-6163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optimizing activation and deactivation of base station transmissions provides an instrument for improving energy efficiency in cellular networks. In this paper, we study the problem of performing cell clustering and setting the activation time of each cluster, with the objective of minimizing the sum energy, subject to a time constraint of serving the users traffic demand. Our optimization framework accounts for inter-cell interference, and, thus, the users achievable rates depend on cluster formation. We provide mathematical formulations and analysis, and prove the problems NP hardness. For problem solution, we first apply an optimization method that successively augments the set of variables under consideration, with the capability of approaching global optimum. Then, we derive a second solution algorithm to deal with the trade-off between optimality and the combinatorial nature of cluster formation. Numerical results demonstrate that our solutions achieve more than 40% energy saving over existing schemes, and that the solutions we obtain are within a few percent of deviation from global optimum.

  • 10.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Keong Ho, Chin
    Agency Science Technology and Research, Singapore.
    Sun, Sumei
    Agency Science Technology and Research, Singapore.
    Power and Channel Allocation for Non-Orthogonal Multiple Access in 5G Systems: Tractability and Computation2016Ingår i: IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, ISSN 1536-1276, Vol. 15, nr 12, s. 8580-8594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A promising multi-user access scheme, nonorthogonal multiple access (NOMA) with successive interference cancellation (SIC), is currently under consideration for 5G systems. NOMA allows more than one user to simultaneously access the same frequency-time resource and separates multi-user signals by SIC. These render resource optimization in NOMA different from orthogonal multiple access. We provide theoretical insights and algorithmic solutions to jointly optimize power and channel allocation in NOMA. We mathematically formulate NOMA resource allocation problems, and characterize and analyze the problems tractability under a range of constraints and utility functions. For tractable cases, we provide polynomial-time solutions for global optimality. For intractable cases, we prove the NP-hardness and propose an algorithmic framework combining Lagrangian duality and dynamic programming to deliver nearoptimal solutions. To gauge the performance of the solutions, we also provide optimality bounds on the global optimum. Numerical results demonstrate that the proposed algorithmic solution can significantly improve the system performance in both throughput and fairness over orthogonal multiple access as well as over a previous NOMA resource allocation scheme.

  • 11.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Keong Ho, Chin
    ASTAR, Singapore.
    Sun, Sumei
    ASTAR, Singapore.
    Resource Scheduling to Jointly Minimize Receiving and Transmitting Energy in OFDMA Systems2014Ingår i: 2014 11TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS (ISWCS), IEEE , 2014, s. 187-191Konferensbidrag (Refereegranskat)
    Abstract [en]

    Resource scheduling in orthogonal frequency division multiple access (OFDMA) for energy saving has attracted extensive attention. Most current research considers the reduction of energy at the transmitter or the receiver separately. In this paper, we focus on minimizing the energy consumption in both sides concurrently by formulating the problem of joint receiving and transmitting energy-efficient scheduling (RTEES) in OFDMA downlink. We show that this problem can be cast as a binary integer programme. We solve the RTEES problem by a computationally efficient algorithm. We proposed a specialized solution approach, named time-slot-oriented column generation (TSOCG) algorithm, for approaching and bounding the global optimality. Numerical studies show that the proposed algorithm solution is competitive and time-efficient to provide a close-to-optimum solution and a tight bound.

  • 12.
    Lei, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Värbrand, Peter
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    On Power Minimization for Non-orthogonal Multiple Access (NOMA)2016Ingår i: IEEE COMMUNICATIONS LETTERS, ISSN 1089-7798, Vol. 20, nr 12, s. 2458-2461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We formulate a power optimization problem for non-orthogonal multiple access systems mathematically, and prove its NP-hardness. For tackling the problem, we first identify a convex problem by relaxation. Based on this convexity, we then propose an efficient "relax-then-adjust" algorithm and provide results of performance evaluation.

  • 13.
    Lei, Ming
    et al.
    Xi An Jiao Tong University, Peoples R China.
    Zhang, Xingjun
    Xi An Jiao Tong University, Peoples R China.
    Zhang, Tong
    Xi An Jiao Tong University, Peoples R China.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    He, Qing
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Successive Interference Cancellation for Throughput Maximization in Wireless Powered Communication Networks2016Ingår i: 2016 IEEE 84TH VEHICULAR TECHNOLOGY CONFERENCE (VTC FALL), IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In wireless powered communication networks (WPCNs), each user node, e.g., wireless powered sensor, is capable of either harvesting energy from a power station or transmitting data to a sink node. In the previous works, time division multiple access (TDMA) is typically used for transmission scheduling in WPCNs, that is, only one node can transmit data in one time slot. The spectrum efficiency is therefore limited by this orthogonality in time-domain scheduling. In this paper, to maximize the throughput in WPCNs, we present a new scheduling approach for energy harvesting and data transmission. Unlike TDMA, we consider that multiple nodes can simultaneously transmit their data in the same time slot, and the signals are separated at the sink node by performing successive interference cancellation (SIC). We formulate the throughput maximization problem as a linear programming problem. For solving the large scale instances, we design an algorithmic framework based on column generation. Numerical results demonstrate that compared to the TDMA based scheduling approach, substantial throughput improvement is achieved by the proposed algorithm.

  • 14.
    You, Lei
    et al.
    Qingdao University, Peoples R China.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD USA.
    A Performance Study of Energy Minimization for Interleaved and Localized FDMA2014Ingår i: 2014 IEEE 19TH INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE , 2014, s. 16-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    Optimal channel allocation is a key performance engineering aspect in single-carrier frequency-division multiple access (SC-FDMA). It is of significance to consider minimum sum power (Min-Power), subject to meeting specified users demand, since mobile users typically employ battery-powered handsets. In this paper, we prove that Min-Power is polynomial-time solvable for interleaved SC-FDMA (IFDMA). Then we propose a channel allocation algorithm for IFDMA, which is guaranteed to achieve global optimum in polynomial time. We numerically compare the proposed algorithm with optimal localized SC-FDMA (LFDMA) for Min-Power. The results show that LFDMA outperforms IFDMA in the maximal supported user demand. When the user demand can be satisfied in both LFDMA and IFDMA, LFDMA performs slightly better than IFDMA. However MinPower is polynomial-time solvable for IFDMA whereas it is not for LFDMA.

  • 15.
    You, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20740 USA.
    Load Balancing via Joint Transmission in Heterogeneous LTE: Modeling and Computation2015Ingår i: 2015 IEEE 26TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE , 2015, s. 1173-1177Konferensbidrag (Refereegranskat)
    Abstract [en]

    As one of the Coordinated Multipoint (CoMP) techniques, Joint Transmission (JT) can improve the overall system performance. In this paper, from the load balancing perspective, we study how the maximum load can be reduced by optimizing JT pattern that characterizes the association between cells and User Equipments (UEs). To give a model of the interference caused by cells with different time-frequency resource usage, we extend a load coupling model, by taking into account JT. In this model, the mutual interference depends on the load of cells coupled in a non-linear system with each other. Under this model, we study a two-cell case and proved that the optimality is achieved in linear time in the number of UEs. After showing the complexity of load balancing in the general network scenario, an iterative algorithm for minimizing the maximum load, named JT-MinMax, is proposed. We evaluate JT-MinMax in a heterogeneous Network (HetNet), though it is not limited to this type of scenarios. Numerical results demonstrate the significant performance improvement of JT-MinMax on min-max cell load, compared to the conventional non-JT solution where each UE is served by the cell with best received transmit signal.

  • 16.
    You, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20740 USA.
    Optimizing Power and User Association for Energy Saving in Load-Coupled Cooperative LTE2016Ingår i: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider an energy minimization problem for cooperative LTE networks. To reduce energy consumption, we investigate how to jointly optimize the transmit power and the association between cells and user equipments (UEs), by taking into consideration joint transmission (JT), one of the coordinated multipoint (CoMP) techniques. We formulate the optimization problem mathematically. For solving the problem, a dynamic power allocation algorithm that adjusts the transmit power of all cells, and an algorithm for optimizing the cell-UE association, are proposed. The two algorithms are iteratively used in an algorithmic framework to enhance the energy performance. Numerically, the proposed algorithms can lead to lower energy consumption than the optimal energy setting in the non-JT case. In comparison to fixed power allocation in JT, the proposed dynamic power allocation algorithm is able to significantly reduce the energy consumption.

  • 17.
    Yuan, Di
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Angelakis, Vangelis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Minimum-Length Scheduling in Wireless Networks with Multi-User Detection and Interference Cancellation: Optimization and Performance Evaluation2012Ingår i: IEEE International Conference on Communication Systems (ICCS), 2012, Piscataway, NJ, USA: IEEE , 2012, s. 315-319Konferensbidrag (Refereegranskat)
    Abstract [en]

    Minimum-length scheduling has been a subject of extensive research in performance engineering of wireless ad hoc networks. We consider the problem under the unconventional setting of multi-user detection receivers that can perform decoding successively, potentially admitting interference cancellation. Thus, in contrast to classical spatial reuse, strong interference is not necessarily harmful. The paper studies fundamental aspects of assessing the achievable performance by successive decoding and interference cancellation versus that of the conventional setup. Computationally, the task is very challenging - the optimal decoding pattern is intertwined with the composition of time slots. We provide structural results of the problem, and develop integer programming formulations enabling to effectively determine the optimal schedule. Computational experiments are provided to shed light on the achievable performance gain of successive decoding with interference cancellation for minimum-length scheduling.

  • 18.
    Zhao, Hongmei
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Power efficient uplink scheduling in SC-FDMA: Bounding global optimality by column generation2013Ingår i: 2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD, IEEE , 2013, s. 119-123Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access (SC-FDMA) system with localized allocation of subcarriers, that is, the subcarriers allocated to a user equipment have to be consecutive in the frequency domain in each time slot. This problem is discrete and nonconvex, thus the use of suboptimal algorithms has been a common practice. We leverage the power of mathematical programming in order to approach global optimality or a tight bounding interval confining global optimum, to arrive at an effective scheme for gauging the performance of suboptimal algorithms. Toward this end, we first provide a straightforward integer linear programming formulation, and then an alternative and less trivial, so-called column-oriented, formulation. The latter is solved by column generation, which is a solution technique for large-scale optimization problems with certain characteristics. The computational evaluation demonstrates that the column generation method produces very highquality subcarrier allocations that either coincide with the global optimum or enable an extremely sharp bounding interval. Hence the approach serves well for the purpose of benchmarking results for large-scale instances of power efficient SC-FDMA scheduling.

  • 19.
    Zhao, Yixin
    et al.
    Nanjing Univ Sci and Technol, Peoples R China.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Correction: Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation (vol 17, pg 695, 2016)2019Ingår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 20, nr 3, s. 959-959Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    At the time of the final publication of the paper, in December 2016, Yixin Zhaos affiliation had changed.

  • 20.
    Zhao, Yixin
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation2016Ingår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 17, nr 4, s. 695-725Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access system. Due to the discrete nature of this problem and its computational difficulty, particularly in a real-time setting, the use of suboptimal algorithms is common practice. We aim at an effective way of gauging the performance of suboptimal algorithms by finding tight bounds on the global optimum. Toward this end, we first provide a basic integer linear programming formulation. Then we propose a significantly stronger column-oriented formulation and a corresponding column generation method, as well as an enhanced column generation scheme. The latter extends the first scheme through the inclusion of a stabilization technique, an approximate column generation principle, and a tailored heuristic that is embedded in the column generation scheme to find high-quality though not necessarily global optimal solutions. The computational evaluation demonstrates that compared with a poor performance by the integer linear programming formulation, the column generation method can produce near-optimal schedules that enable a sharp bounding interval. The enhanced column generation method significantly sharpens the bounding interval. Hence the column generation approach serves well for the purpose of benchmarking results for large-scale instances.

1 - 20 av 20
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf