Utility Maximization in LTE-Advanced Systems with Carrier Aggregation

doi:10.1109/VETECS.2011.5956494

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Utility Maximization in LTE-Advanced Systems with Carrier Aggregation

Proceedings Article•DOI•

Utility Maximization in LTE-Advanced Systems with Carrier Aggregation

Yuanye Wang¹, Klaus I. Pedersen², Troels B. Sorensen¹, Preben Mogensen¹•Institutions (2)

Aalborg University¹, Nokia Networks²

15 May 2011-pp 1-5

TL;DR: A mathematical model of the log-measure utility in an LTE-Advanced system is provided, and proof that the previously developed cross-CC Proportional Fair (PF) packet scheduler maximizes this utility is given.

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Abstract: Long Term Evolution (LTE)-Advanced is expected to aggregate multiple Component Carrier (CC)s to fulfil the high data rate requirement. It may serve users with different capabilities in accessing these CCs, e.g., some can access all CCs, whereas some may operate on only one CC. This gives challenges to the packet scheduler to maximize the system performance over all CCs. In this paper we provide a mathematical model of the log-measure utility in an LTE-Advanced system, and give proof that our previously developed cross-CC Proportional Fair (PF) packet scheduler maximizes this utility. System level simulations are performed, which confirm that cross-CC PF scheduling offers much higher utility than independent PF and channel blind schedulers. This scheduler is then generalized to adjust the resource sharing among users. It can trade off between average cell throughput and cell edge user throughput. However, any adjustment in the resource sharing leads to a loss in utility.

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Journal Article•DOI•

A Survey of Radio Resource Management for Spectrum Aggregation in LTE-Advanced

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Haeyoung Lee¹, Seiamak Vahid¹, Klaus Moessner¹•Institutions (1)

University of Surrey¹

22 Jan 2014-IEEE Communications Surveys and Tutorials

TL;DR: On-going research on the different RRM aspects and algorithms to support CA in LTE-Advanced are surveyed, followed by requirements on radio resource management (RRM) functionality in support of CA.

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Abstract: In order to satisfy the requirements of future IMT-Advanced mobile systems, the concept of spectrum aggregation is introduced by 3GPP in its new LTE-Advanced (LTE Rel. 10) standards. While spectrum aggregation allows aggregation of carrier components (CCs) dispersed within and across different bands (intra/inter-band) as well as combination of CCs having different bandwidths, spectrum aggregation is expected to provide a powerful boost to the user throughput in LTE-Advanced (LTE-A). However, introduction of spectrum aggregation or carrier aggregation (CA) as referred to in LTE Rel. 10, has required some changes from the baseline LTE Rel. 8 although each CC in LTE-A remains backward compatible with LTE Rel. 8. This article provides a review of spectrum aggregation techniques, followed by requirements on radio resource management (RRM) functionality in support of CA. On-going research on the different RRM aspects and algorithms to support CA in LTE-Advanced are surveyed. Technical challenges for future research on aggregation in LTE-Advanced systems are also outlined.

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170 citations

Cites background or methods from "Utility Maximization in LTE-Advance..."

...As pointed out earlier, a challenge for UG-PF scheme is how to obtain a good trade-off between throughput and fairness....
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...Basic Round Robin (RR) [40], [43], [44], [45] - is used as the reference scheme - simple But with no consideration of different channel characteristics and CA capability Proportional Fair (PF) [4], [27], [36] - is utilized as the basic scheme to be extended in the literature - supports tradeoff between the system throughput and fairness - But has no consideration of different CA capability of terminals and does not exhibit good delay performance To improve fairness between UEs of different channel conditions User grouping PF (UG-PF) [52] - allows for user grouping based on the number of CCs which the users can be scheduled on from their locations - introduces a weighting factor so that the user group in cell-edge can have the advantage to access RBs in the CCs of lower frequencies - How to attain a good trade-off between fairness and throughput remains a challenge To improve fairness between UEs of different CA capability Cross-CC PF [27], [36] - by taking the past user throughput information over all aggregated CCs, makes the scheduling metric of CA-capable UEs smaller - achieves better fairness and coverage performance with no degradation in average cell throughput - results in optimal CC assignment once the CC assignment is determined - But the need for exchange of the user past throughput over each CC, remains an issue To improve fairness between UEs of different channels & CA capability Cross-CC Generalized PF (G-PF) [42] - introduces two tunable parameters into Cross-CC PF scheme - α: to adjust the fairness between UEs with different CA capability - β: to adjust the fairness among users with different average throughput - How to set two parameters adaptively remains a challenge To reduce delay M-LWDF [5] - introduces factors associated with packet loss ratio and delay, into PF scheme To improve delay fairness Packet Fragmentation approach [29] - achieves delay fairness among user groups of UG-PF scheme - supports buffering of the arriving packets into the queues of the group and then partitions the packets over several fragments and distributes on multiple CCs - shows better performances in terms of the delay in each group...
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...CC selection followed by RB assignment on each CC [22], [32], [36], [42]....
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...It is proven [42] that Cross-CC PF is the optimal scheduling scheme for a given CC selection scheme....
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...The UG-PF scheduling can be described in Eq....
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Journal Article•DOI•

An Efficient Downlink Radio Resource Allocation with Carrier Aggregation in LTE-Advanced Networks

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Hong-Sheng Liao¹, Po-Yu Chen², Wen-Tsuen Chen²•Institutions (2)

Chunghwa Telecom¹, Academia Sinica²

06 Jan 2014-IEEE Transactions on Mobile Computing

TL;DR: A novel greedy-based scheme is proposed to maximize the system throughput while maintaining proportional fairness of radio resource allocation among all UEs and shows that this scheme can guarantee at least half of the performance of the optimal solution.

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Abstract: In long term evolution-advanced (LTE-A) networks, the carrier aggregation technique is incorporated for user equipments (UEs) to simultaneously aggregate multiple component carriers (CCs) for achieving higher transmission rate. Many research works for LTE-A systems with carrier aggregation configuration have concentrated on the radio resource management problem for downlink transmission, including mainly CC assignment and packet scheduling. Most previous studies have not considered that the assigned CCs in each UE can be changed. Furthermore, they also have not considered the modulation and coding scheme constraint, as specified in LTE-A standards. Therefore, their proposed schemes may limit the radio resource usage and are not compatible with LTE-A systems. In this paper, we assume that the scheduler can reassign CCs to each UE at each transmission time interval and formulate the downlink radio resource scheduling problem under the modulation and coding scheme constraint, which is proved to be NP-hard. Then, a novel greedy-based scheme is proposed to maximize the system throughput while maintaining proportional fairness of radio resource allocation among all UEs. We show that this scheme can guarantee at least half of the performance of the optimal solution. Simulation results show that our proposed scheme outperforms the schemes in previous studies.

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86 citations

Cites background from "Utility Maximization in LTE-Advance..."

...To achieve the peak data rate required by IMT-Advanced, Long Term Evolution-Advanced (LTE-A) under the 3rd Generation Partnership Project (3GPP) specifies that user equipments (UEs) support bandwidth up to 100 MHz....
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...IN recent years, the number of users using intelligenthand-held equipments increases significantly due to rapid development of information and communication technologies and novel applications....
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Journal Article•DOI•

Dual connectivity for LTE-advanced heterogeneous networks

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Hua Wang¹, Claudio Rosa², Klaus I. Pedersen¹•Institutions (2)

Aalborg University¹, Nokia Networks²

01 May 2016-Wireless Networks

TL;DR: Simulation results show that the performance of DC over traditional backhaul connections is close to that achievable with inter-site carrier aggregation (CA) and virtually zero-latency fronthaul connections, and in any case it is significantly higher compared to the case without DC.

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Abstract: Dual connectivity (DC) allows user equipments (UEs) to receive data simultaneously from different eNodeBs (eNBs) in order to boost the performance in a heterogeneous network with dedicated carrier deployment. Yet, how to efficiently operate with DC opens a number of research questions. In this paper we focus on the case where a macro and a small cell eNBs are inter-connected with traditional backhaul links characterized by certain latency, assuming independent radio resource management (RRM) functionalities residing in each eNB. In order to fully harvest the gain provided by DC, an efficient flow control of data between the involved macro and small cell eNBs is proposed. Moreover, guidelines for the main performance determining RRM algorithms such as UE cell association and packet scheduling are also presented. It is demonstrated how proper configuration of the proposed flow control algorithm offers efficient trade-offs between reducing the probability that one of the eNBs involved in the DC runs out of data and limiting the buffering time. Simulation results show that the performance of DC over traditional backhaul connections is close to that achievable with inter-site carrier aggregation (CA) and virtually zero-latency fronthaul connections, and in any case it is significantly higher compared to the case without DC.

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64 citations

Cites methods from "Utility Maximization in LTE-Advance..."

...As studied in [27, 28], the solution to this imbalance is to use a modified form of PF when calculating the scheduling metric....
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...By applying this modification, it was shown in [27, 28] that the underlying utility function P i log (Ri) is maximized also for the cases where some users are served only by one cell, while other users are served by multiple cells using CA functionality, resulting in more fair resource sharing among the users....
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Dissertation•

Resource Allocation for Smart Phones in 4G LTE-Advanced Carrier Aggregation

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Rebecca Lynne Kurrle

10 Dec 2012

33 citations

Cites background or methods from "Utility Maximization in LTE-Advance..."

...The assumption is also made that the utility is defined as a function of time [27]....
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...The assumption is made that the utility of a user can be defined as a function of throughput and that throughput is defined by information capacity of a given user [27]....
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...10) represents the scheduling condition [27], where r(k, n,m, t) is the expected throughput for a user k on the n component carrier, the m PRB, at time t, and R(k, t) is the average throughput for user k at time t....
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...8) [27], where U(t) is the total network utility as a function of time, t....
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...In this method, maximizing the utility is approximated to maximizing the increase in utility based on user resource allocation [27]....
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Proceedings Article•DOI•

A Carrier Aggregation Based Resource Allocation Scheme for Pervasive Wireless Networks

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Fan Wu, Yuming Mao, Supeng Leng, Xiaoyan Huang

12 Dec 2011

TL;DR: Numerical results indicate that MSUL is able to improve the system performance in terms of network utility, average throughput and fairness compared with the algorithms optimizing CCs and RBs allocation separately.

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Abstract: The mixture of users with different bandwidth capability presents new challenges to optimize the transmission performance of the next generation wireless networks. This paper focuses on resource allocation for pervasive wireless networks with component carrier (CC) aggregation. Distinguished from many existing methods that decompose the resource optimization problem into two sequence steps, i.e., CC scheduling and resource block (RB) assignment on each carrier, we develop a novel joint CC and RB allocation algorithm to maximize network utility, namely Minimizing System Utility Loss (MSUL) algorithm. Numerical results indicate that MSUL is able to improve the system performance in terms of network utility, average throughput and fairness compared with the algorithms optimizing CCs and RBs allocation separately.

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32 citations

Cites background from "Utility Maximization in LTE-Advance..."

...It becomes the key issue for the resource management in a muti-CC system that how to assign the CCs to each user according to its carrier capability, as well as how to multiplex multiple users in each CC. Recently, there have been a few studies on resource allocation with CA [4][5][6][7][8]....
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References

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Open Access

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Journal Article•DOI•

Charging and rate control for elastic traffic

[...]

Frank Kelly¹•Institutions (1)

University of Cambridge¹

01 Jan 1997

TL;DR: This paper addresses the issues of charging, rate control and routing for a communication network carrying elastic traffic, such as an ATM network offering an available bit rate service, from which max-min fairness of rates emerges as a limiting special case.

...read moreread less

Abstract: This paper addresses the issues of charging, rate control and routing for a communication network carrying elastic traffic, such as an ATM network offering an available bit rate service. A model is described from which max-min fairness of rates emerges as a limiting special case; more generally, the charges users are prepared to pay influence their allocated rates. In the preferred version of the model, a user chooses the charge per unit time that the user will pay; thereafter the user's rate is determined by the network according to a proportional fairness criterion applied to the rate per unit charge. A system optimum is achieved when users' choices of charges and the network's choice of allocated rates are in equilibrium.

...read moreread less

3,067 citations

Proceedings Article•DOI•

Data throughput of CDMA-HDR a high efficiency-high data rate personal communication wireless system

[...]

A. Jalali¹, R. Padovani¹, Rajesh K. Pankaj¹•Institutions (1)

Qualcomm¹

15 May 2000

TL;DR: Forward link data throughput performance of a high data rate wireless access system is presented and the throughput of the forward link of the embedded sector is simulated for stationary terminals.

...read moreread less

Abstract: Forward link data throughput performance of a high data rate wireless access system is presented. On the forward link of the proposed system data is transmitted to different access terminals (AT) in a TDM fashion. The rate transmitted to each AT is variable and depends on each AT's measured SINR. ATs send to the access points (AP) the index of the highest data rate which can be received reliably. A scheduler at the AP determines the next terminal to be served based on the reported data rate requests from the terminals and the amount of data that has already been transmitted to each terminal. A cell layout of 19 3-sector and 6-sector hexagonal cells is considered. The throughput of the forward link of the embedded sector is simulated for stationary terminals.

...read moreread less

1,589 citations

"Utility Maximization in LTE-Advance..." refers background or methods in this paper

...1) Independent PF Scheduling: With the independent PF scheduler the resource is assigned to the user that maximizes the following scheduling metric [9]:...
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...On the n CC at time t + 1, R(k, n, t) is updated according to the following equation [9]:...
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...100 slots in [12], 1000 slots in [9])....
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Journal Article•DOI•

Convergence of proportional-fair sharing algorithms under general conditions

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Harold J. Kushner¹, Philip Whiting²•Institutions (2)

Brown University¹, Alcatel-Lucent²

01 Jul 2004-IEEE Transactions on Wireless Communications

TL;DR: It is shown that the ordinary differential equation (ODE) has a unique equilibrium and that it is characterized as optimizing a concave utility function, which shows that PFS is not ad-hoc, but actually corresponds to a reasonable maximization problem.

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Abstract: We are concerned with the allocation of the base station transmitter time in time-varying mobile communications with many users who are transmitting data. Time is divided into small scheduling intervals, and the channel rates for the various users are available at the start of the intervals. Since the rates vary randomly, in selecting the current user there is a conflict between full use (by selecting the user with the highest current rate) and fairness (which entails consideration for users with poor throughput to date). The proportional fair scheduler of the Qualcomm High Data Rate system and related algorithms are designed to deal with such conflicts. The aim here is to put such algorithms on a sure mathematical footing and analyze their behavior. The available analysis, while obtaining interesting information, does not address the actual convergence for arbitrarily many users under general conditions. Such algorithms are of the stochastic approximation type and results of stochastic approximation are used to analyze the long-term properties. It is shown that the limiting behavior of the sample paths of the throughputs converges to the solution of an intuitively reasonable ordinary differential equation, which is akin to a mean flow. We show that the ordinary differential equation (ODE) has a unique equilibrium and that it is characterized as optimizing a concave utility function, which shows that PFS is not ad-hoc, but actually corresponds to a reasonable maximization problem. These results may be used to analyze the performance of PFS. The results depend on the fact that the mean ODE has a special form that arises in problems with certain types of competitive behavior. There is a large set of such algorithms, each one corresponding to a concave utility function. This set allows a choice of tradeoffs between the current rate and throughout. Extensions to multiple antenna and frequency systems are given. Finally, the infinite backlog assumption is dropped and the data is allowed to arrive at random. This complicates the analysis, but the same results hold.

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481 citations

"Utility Maximization in LTE-Advance..." refers background in this paper

...According to [10], [13], the problem of maxi-...
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...It is shown in [10] that with sufficient large value of t, R(k, n, t) weakly converges to a constant value for a certain user k....
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...The value of T should be chosen to offer a good estimation of the average throughput, with the ability to track changes in the channel characteristics [10] (e....
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Journal Article•DOI•

Carrier aggregation for LTE-advanced mobile communication systems

[...]

Guangxiang Yuan¹, Xiang Zhang¹, Wenbo Wang¹, Yang Yang²•Institutions (2)

Beijing University of Posts and Telecommunications¹, Chinese Academy of Sciences²

01 Feb 2010-IEEE Communications Magazine

TL;DR: In this paper, a brief review of continuous and non-continuous CA techniques is given, followed by two data aggregation schemes in physical and medium access control layers, and possible technical solutions for the asymmetric CA problem, control signaling design, handover control and guard band setting are reviewed.

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Abstract: In order to achieve up to 1 Gb/s peak data rate in future IMT-Advanced mobile systems, carrier aggregation technology is introduced by the 3GPP to support very-high-data-rate transmissions over wide frequency bandwidths (e.g., up to 100 MHz) in its new LTE-Advanced standards. This article first gives a brief review of continuous and non-continuous CA techniques, followed by two data aggregation schemes in physical and medium access control layers. Some technical challenges for implementing CA technique in LTE-Advanced systems, with the requirements of backward compatibility to LTE systems, are highlighted and discussed. Possible technical solutions for the asymmetric CA problem, control signaling design, handover control, and guard band setting are reviewed. Simulation results show Doppler frequency shift has only limited impact on data transmission performance over wide frequency bands in a high-speed mobile environment when the component carriers are time synchronized. The frequency aliasing will generate much more interference between adjacent component carriers and therefore greatly degrades the bit error rate performance of downlink data transmissions.

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446 citations

"Utility Maximization in LTE-Advance..." refers background in this paper

...Therefore, several Component Carrier (CC)s need to be aggregated, leading to carrier aggregation [3]....
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Proceedings Article•DOI•

LTE-Advanced - Evolving LTE towards IMT-Advanced

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Stefan Parkvall¹, Erik Dahlman¹, Anders Furuskär¹, Ylva Jading¹, Magnus Olsson¹, Stefan Wänstedt¹, K.C. Zangi¹ - Show less +3 more•Institutions (1)

Ericsson¹

24 Oct 2008

TL;DR: High-level overview of some technology components currently considered for the evolution of LTE including complete fulfillment of the IMT-advanced requirements, including extended spectrum flexibility, multi-antenna solutions, coordinated multipoint transmission/reception, and the use of advanced repeaters/relaying are provided.

...read moreread less

Abstract: This paper provides a high-level overview of some technology components currently considered for the evolution of LTE including complete fulfillment of the IMT-advanced requirements. These technology components include extended spectrum flexibility, multi-antenna solutions, coordinated multipoint transmission/reception, and the use of advanced repeaters/relaying. A simple performance assessment is also included, indicating potential for significantly increased performance.

...read moreread less

398 citations

"Utility Maximization in LTE-Advance..." refers background in this paper

...Apart from using several techniques to improve the spectral efficiency, e.g., Multiple Input Multiple Output (MIMO) transmission, LTE-Advanced requires a much wider bandwidth than current Third Generation systems, up to 100 MHz [2]....
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..., Multiple Input Multiple Output (MIMO) transmission, LTE-Advanced requires a much wider bandwidth than current Third Generation systems, up to 100 MHz [2]....
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