Carrier load balancing and packet scheduling for multi-carrier systems
TL;DR: A simple cross-CC packet scheduling algorithm is proposed that improves the coverage performance and the resource allocation fairness among users, as compared to independent scheduling per CC.
Abstract: -In this paper we focus on resource allocation for next generation wireless communication systems with aggregation of multiple Component Carriers (CCs), i.e., how to assign the CCs to each user, and how to multiplex multiple users in each CC. We first investigate two carrier load balancing methods for allocating the CCs to the users- Round Robin (RR) and Mobile Hashing (MH) balancing by means of a simple theoretical formulation, as well as system level simulations. At Layer-2 we propose a simple cross-CC packet scheduling algorithm that improves the coverage performance and the resource allocation fairness among users, as compared to independent scheduling per CC. The Long Term Evolution (LTE)-Advanced is selected for the case study of a multi-carrier system. In such a system, RR provides better performance than MH balancing, and the proposed simple scheduling algorithm is shown to be effective in providing up to 90% coverage gain with no loss of the overall cell throughput, as compared to independent scheduling per CC.
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TL;DR: This article presents a summary of the supported CA scenarios as well as an overview of the CA functionality for LTE-Advanced with special emphasis on the basic concept, control mechanisms, and performance aspects and demonstrates how CA can be used as an enabler for simple yet effective frequency domain interference management schemes.
Abstract: Carrier aggregation is one of the key features for LTE-Advanced. By means of CA, users gain access to a total bandwidth of up to 100 MHz in order to meet the IMT-Advanced requirements. The system bandwidth may be contiguous, or composed of several non-contiguous bandwidth chunks that are aggregated. This article presents a summary of the supported CA scenarios as well as an overview of the CA functionality for LTE-Advanced with special emphasis on the basic concept, control mechanisms, and performance aspects. The discussion includes definitions of the new terms primary cell (PCell) and secondary cell (SCell), mechanisms for activation and deactivation of CCs, and the new cross-CC scheduling functionality for improved control channel optimizations. We also demonstrate how CA can be used as an enabler for simple yet effective frequency domain interference management schemes. In particular, interference management is anticipated to provide significant gains in heterogeneous networks, envisioning intrinsically uncoordinated deployments of home base stations.
263 citations
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.
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.
170 citations
Cites background or methods from "Carrier load balancing and packet s..."
...In [27], with the scenario of co-existing LTE-Advanced and LTE UEs, LL provides a higher throughput for the LTE UEs, but lower throughput for the LTE-Advanced UEs, as compared with RS....
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...By better balancing the load [32], [44], this scheme leads to better user fairness [36]....
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...Mobile Hashing (MH), which relies on the output from UE’s hashing algorithm, can be utilized to choose CCs randomly [27], [33], [36]....
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...However, the average throughput of LTE-Advanced UEs decreases with the increase of back-off power setting....
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...Since the LTE-Advanced UEs will be scheduled on more CCs than the LTE users, the LTE UEs achieve much lower throughput than the LTE-Advanced UEs [36]....
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TL;DR: A new dynamic carrier aggregation (DCA) scheduling scheme to improve the energy efficiency of uplink communications and build an ideally balanced system (IBS) to investigate the performance upper bound of the DCA scheme, and derive closed-form expressions.
Abstract: Energy efficiency is of vital importance for telecommunications equipment in future networks, especially battery-constrained mobile devices. In the long term evolution-Advanced (LTE-Advanced) network, the carrier aggregation (CA) technique is employed to allow user equipment (UE) to use multiple carriers for high data rate communications. However, multi-carrier transmission entails increased power consumption at user devices in uplink networks. In this paper, we propose a new dynamic carrier aggregation (DCA) scheduling scheme to improve the energy efficiency of uplink communications. Two scheduling methods, i.e., serving the longest queue (SLQ) and round-robin with priority (RRP), are designed to reduce transmit power while maximizing the utilization of wireless resources. The proposed scheme is analyzed in terms of both the data rate and energy conservation. We build an ideally balanced system (IBS) to investigate the performance upper bound of the DCA scheme, and derive closed-form expressions. Simulation results demonstrate that the proposed scheme can not only enhance the energy efficiency but also perform closely to the optimal IBS.
121 citations
TL;DR: This article recommends the use of enhanced interference coordination, or eICIC, to mitigate cross-tier interference and ensure sufficient offload of users from macro to small cells in LTE-Advanced heterogeneous network scenarios with macro and small cells.
Abstract: In this article we present two promising practical use cases for simple multicell cooperation for LTE-Advanced heterogeneous network scenarios with macro and small cells. For co-channel deployment cases, we recommend the use of enhanced interference coordination, or eICIC, to mitigate cross-tier interference and ensure sufficient offload of users from macro to small cells. It is shown how the eICIC benefit is maximized by using a distributed inter-base station control framework for dynamic adjustment of essential parameters. Second, for scenarios where macro and small cells are deployed at different carriers an efficient use of the fragmented spectrum can be achieved by using collaborative inter-site carrier aggregation. In addition to distributed coordination/collaboration between base station nodes, the importance of explicit terminal assistance is highlighted. Comprehensive system-level simulation results illustrate the performance benefits of the presented techniques.
113 citations
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.
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.
86 citations
Cites background from "Carrier load balancing and packet s..."
...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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References
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01 Jan 2001
TL;DR: Here the authors haven’t even started the project yet, and already they’re forced to answer many questions: what will this thing be named, what directory will it be in, what type of module is it, how should it be compiled, and so on.
Abstract: Writers face the blank page, painters face the empty canvas, and programmers face the empty editor buffer. Perhaps it’s not literally empty—an IDE may want us to specify a few things first. Here we haven’t even started the project yet, and already we’re forced to answer many questions: what will this thing be named, what directory will it be in, what type of module is it, how should it be compiled, and so on.
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02 Jan 1975
TL;DR: The purpose of this document is to summarize the main points of the book written by Leonard Kleinrock, titled, ‘Queueing Systems’, which is about queueing systems.
Abstract: The purpose of this document is to summarize the main points of the book written by Leonard Kleinrock, titled, ‘Queueing Systems”.
2,885 citations
"Carrier load balancing and packet s..." refers background in this paper
...The ’birth’ is the transition towards increasing the active number of users by 1, and a ’death’ is the transition towards decreasing the number of active users by 1 [21]....
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TL;DR: A traffic model and analysis for cellular mobile radio telephone systems with handoff, which shows, for example, blocking probability, forced termination probability, and fraction of new calls not completed, as functions of pertinent system parameters.
Abstract: A traffic model and analysis for cellular mobile radio telephone systems with handoff are described. Three schemes for call traffic handling are considered. One is nonprioritized and two are priority oriented. Fixed channel assignment is considered. In the nonprioritized scheme the base stations make no distinction between new call attempts and handoff attempts. Attempts which find all channels occupied are cleared. In the first priority scheme considered, a fixed number of channels in each cell are reserved exclusively for handoff calls. The second priority scheme employs a similar channel assignment strategy, but, additionally, the queueing of handoff attempts is allowed. Appropriate analytical models and criteria are developed and used to derive performance characteristics. These show, for example, blocking probability, forced termination probability, and fraction of new calls not completed, as functions of pertinent system parameters. General formulas are given and specific numerical results for nominal system parameters are presented.
1,654 citations
"Carrier load balancing and packet s..." refers background in this paper
...Although the negative exponential distribution of service time is usually assumed for voice calls [ 23 ], it can also roughly represent the time for users to download a finite buffer due to channel quality variations, when assuming PF alike scheduling....
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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.
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.
1,589 citations
"Carrier load balancing and packet s..." refers methods in this paper
...With the PF scheduler, the resource is assigned to the user that maximizes the following scheduling metric on each CC [18]:...
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...The scheduling metric is calculated by dividing the instantaneous throughput by the average throughput [18]:...
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