LTE-advanced: next-generation wireless broadband technology [Invited Paper]
TL;DR: An overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed, which includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, and heterogeneous networks with emphasis on Type 1 and Type 2 relays.
Abstract: LTE Release 8 is one of the primary broadband technologies based on OFDM, which is currently being commercialized. LTE Release 8, which is mainly deployed in a macro/microcell layout, provides improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operation and seamless integration with existing systems. LTE-Advanced (also known as LTE Release 10) significantly enhances the existing LTE Release 8 and supports much higher peak rates, higher throughput and coverage, and lower latencies, resulting in a better user experience. Additionally, LTE Release 10 will support heterogeneous deployments where low-power nodes comprising picocells, femtocells, relays, remote radio heads, and so on are placed in a macrocell layout. The LTE-Advanced features enable one to meet or exceed IMT-Advanced requirements. It may also be noted that LTE Release 9 provides some minor enhancement to LTE Release 8 with respect to the air interface, and includes features like dual-layer beamforming and time-difference- of-arrival-based location techniques. In this article an overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed. This includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, uplink spatial multiplexing including extension to four-layer MIMO, and heterogeneous networks with emphasis on Type 1 and Type 2 relays. Finally, the performance of LTEAdvanced using IMT-A scenarios is presented and compared against IMT-A targets for full buffer and bursty traffic model.
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Dissertation•
16 Dec 2015
TL;DR: Cette these propose des nouvelles strategies de l’allocation des blocs de ressources (RB) dans les systemes LTE sur le lien descendant, ganant la formation des faisceaux, la capacite des RB varie mais l'ordonnanceur conserve the meme allocation.
Abstract: La recherche effectuee dans cette these a pour cadre les reseaux radio prives dedies aux forces de securite civile. En effet, dote actuellement d’un service bande etroite, ils doivent evoluer pour faire face a de nouveaux besoins comme la video ou le multimedia. L’objectif est donc d’adapter la technologie LTE aux contraintes et proprietes de ces reseaux particulier. Ainsi, le nombre d’utilisateurs est limite mais le service doit toujours etre disponible et des priorites peuvent etre mises en œuvre.Dans ce contexte, l’allocation des ressources de communication est un probleme important avec des prerequis differents des reseaux d’operateurs. Notre conception d’algorithmes d’allocation a donc ete menee avec deux objectifs principaux : maximiser l'efficacite du spectre et servir equitablement les utilisateurs au lieu de maximiser le debit global du reseau.Cette these propose des nouvelles strategies de l’allocation des blocs de ressources (RB) dans les systemes LTE sur le lien descendant. Au contraire des algorithmes classiques d'allocation des ressources qui se basent sur la capacite de RB deja estimee, nos strategies d’allocation des RB cherchent a ameliorer le debit utilisateur, en utilisant la cooperation a base de Beamforming et les modeles de la theorie des jeux.1. L’interference inter-cellulaire est le principal probleme des systemes OFDMA. Grâce aux antennes MIMO (Multiple-Input-Multiple-Output), la technique de Beamforming ameliore le signal recu afin d'augmenter le SINR (Signal-to-Interference-plus-Noise-Ratio), mais le signal ameliore peut egalement influencer l’interference inter-cellulaire dans les cellules voisines. Dans les methodes traditionnelles, le controleur alloue les RBs aux UEs (User Equipement) en fonction de la capacite des RB et d'autres parametres, le systeme applique alors la technique de Beamforming aux equipements utilisateurs choisis. Apres la formation des faisceaux, la capacite des RB varie mais l'ordonnanceur conserve la meme allocation. Au contraire, notre systeme alloue les RBs et choisit les vecteurs de Beamforming conjointement pour ameliorer les performances de la technique de Beamforming. Il accroit le debit moyen en augmentant la capacite moyenne du RB. Comme plusieurs parametres sont pris en compte, la complexite augmente exponentiellement aussi. Dans cette these, nous avons developpe une methode iterative pour reduire la complexite. Notamment, elle ameliore de plus de 10% le debit des utilisateurs en bord de la cellule.2. Contrairement aux performances des algorithmes qui maximisent le debit global du reseau, les approches d’allocation de ressources a base de theorie des jeux maximisent la fonction d'utilite des UE du point de vue economique. Si le modele a une solution NBS (Nash Bargaining Solution) il offre une solution optimale de Pareto de la fonction d'utilite. L’allocation traditionnelle est d'optimiser l'allocation de sous-porteuses a chaque intervalle de temps, mais dans le systeme OFDMA, les sous-porteuses sont formees de RBs dans le temps. Nous proposons une approche RB NBS, qui est plus efficace que les schemas existants. Nous analysons les canaux de fast-fading et les comparons sans l'influence de l’attenuation. En raison de la grande attenuation de signal en bordure de la cellule, l’utilisateur a toujours des RB de plus faible capacite que celui au centre de la cellule. Notre idee est d'ajouter un facteur de compensation pour combattre l'influence de la perte de propagation. Les facteurs de compensation sont soigneusement choisis afin de maximiser la fonction NBS. Cependant, le calcul de ces facteurs a une grande complexite et nous developpons quatre solutions approchees qui donnent les memes performances avec une bonne precision. L'evaluation des performances de notre approche confirme que notre methode et ses solutions approchees sont capables de partager equitablement les ressources sur toute la cellule.
2 citations
TL;DR: An improved error correction code using Iterative decoding involves the substitution of extrinsic probabilities among the main decoders and observed that Reciprocal data Max-log-map (RD-MLMAP) is ideal for performance over existing MLMAP methods.
Abstract: An improved error correction code using Iterative decoding involves the substitution of extrinsic probabilities among the main decoders. The output of two-component decoders had the properties of the Reciprocal data and perceived with external Logarithmic likelihood Ratio (LLR) based turbo codes. The improved of interactive data analysis and probable performances among the Reciprocal data between each external decoders. The residual information of the transmission channel decoder estimation is provided with precise evaluation. As an application, the Reciprocal information between extrinsic is used for arranging and progressing capable correction segment approach and error data directed to the decoder side. The specific performance of the proposed code significantly depends on the extended, enlarged interpreting data at the receiver under various environmental situations. Then the separate decoder includes a redundant data between consequent decoders and unpredictability of the decoding process. Then estimated independent mean and change are used to tune the LLR correction segments in the turbo decoder. From the Bit Error Rate, it was observed that Reciprocal data Max-log-map (RD-MLMAP) is ideal for performance over existing MLMAP methods.
2 citations
01 Jan 2021
TL;DR: In this article, the authors proposed to use the sector analysis method for optimizing the load distribution between base stations when predicting the coverage areas of base stations, in addition to using the frequency-spatial planning method, when forecasting service areas of BSs.
Abstract: Cellular network generates a lot of signaling data. A large part of signaling data is generated to handle the mobility of subscribers and contains location information that can be used to fundamentally change our understanding of mobility principle. However, location data available from standard interfaces in cellular networks is very an important research question is how this data can be processed in order to efficiently use it for traffic state estimation and traffic planning. The design of the mobile operator’s network is carried out by the method of frequency spatial planning. It is believed that the solution to this problem provides the required indicators of electromagnetic compatibility of network elements, and as a result, performance of the network. Ideally, these findings should be replicated in a study where uniformity of traffic over network elements is relegated to the background. Results provide a basis for affects both throughput and quality of service. In this paper, it is proposed to use the sector analysis method for optimizing the load distribution between base stations when predicting the coverage areas of base stations, in addition to using the frequency-spatial planning method, when forecasting service areas of base stations. The technology of cellular systems is changing at such a speed that 4G networks have not yet had time to fully deploy, as 5G is already being introduced. The fourth generation is characterized by LTE-advanced technology, which implies an intelligent network with self-training and partial adjustment of its parameters. The distribution functions of the radio resource of the cellular communication network of this standard lie at the base stations. However, clear control algorithms for such networks have not yet been developed. As part of situationally adaptive planning of radio resources in radio communication systems, a method is proposed for determining the optimal coverage areas of base stations depending on the distribution of subscribers according to billing data. To this end, in addition to the statistics for base stations for servicing the load, enrich it with billing system data.
2 citations
29 Oct 2014
TL;DR: Analytical results show that the proposed improved Call Admission Control (CAC) mechanism with prioritized handoff queuing scheme prioritizes the handoff calls effectively and reduces dropping probability of the system by 78.57% for real-time traffic without degrading the number of failed new call attempts.
Abstract: Nowadays, due to increased demand for using the Broadband Wireless Access (BWA) networks in a satisfactory manner a promised Quality of Service (QoS) is required to manage the seamless transmission of the heterogeneous handoff calls. To this end, this paper proposes an improved Call Admission Control (CAC) mechanism with prioritized handoff queuing scheme that aims to reduce dropping probability of handoff calls. Handoff calls are queued when no bandwidth is available even after the allowable bandwidth degradation of the ongoing calls and get admitted into the network when an ongoing call is terminated with a higher priority than the newly originated call. An analytical Markov model for the proposed CAC mechanism is developed to analyze various performance parameters. Analytical results show that our proposed CAC with handoff queuing scheme prioritizes the handoff calls effectively and reduces dropping probability of the system by 78.57% for real-time traffic without degrading the number of failed new call attempts. This results in the increased bandwidth utilization of the network.
2 citations
Book•
01 Jan 2016
TL;DR: This thesis proposes a novel conditional l1 regularized minimum mean square error channel estimation and chained turbo estimation algorithms to solve the inter-block-interference (IBI) problem incurred as the result of pursuing spectral efficiency.
Abstract: Future broadband wireless communication systems are expected to increase both their transmission (TX) rate and their spectrum efficiency under the constraints of low TX power and a low computational complexity. In general, a data sequence is transmitted together with overheads such as training sequence (TS) required to perform energyand computationally-efficient reception techniques. We hence have a trade-off between the spectral efficiency and the receiver performance. The objective of this thesis is to enhance robustness of the receiving algorithms with reasonable complexity, aiming to improve the trade-off. For this purpose, l1 regularized channel estimation techniques are studied under an assumption that broadband wireless channels observed at a receiver does not fully exhibit dense nature in a low to moderate signal-to-noise ratio (SNR) regime. This thesis proposes a novel conditional l1 regularized minimum mean square error (MMSE) channel estimation and chained turbo estimation (CHATES) algorithms to solve the inter-block-interference (IBI) problem incurred as the result of pursuing spectral efficiency. A new l1 least squares (LS) and l2 MMSE-based hybrid channel estimation algorithm is also proposed to solve the tracking error problem often observed with intermittent transmission. Moreover, performance analysis shows that an l1 regularized MMSE channel estimation algorithm can achieve the Cramér-Rao bound (CRB) asymptotically even when random TSs are used. This thesis further studies frequency domain turbo equalization techniques without cyclic prefix (CP) transmission to improve the spectral efficiency. The previously-proposed chained turbo equalization, referred to as CHATUE1, allows us to use a lower rate code. However, it can suffer from the noise enhancement problem at the equalizer output. As a solution to the problem, this thesis proposes a new algorithm, CHATUE2. The theoretical analysis supported with simulation results shows that the proposed CHATUE2 can solve the problem after performing enough turbo iterations by utilizing a new composite replica constructed with the conventional soft replica and received signals.
2 citations
Cites background or methods from "LTE-advanced: next-generation wirel..."
...The mean μq[2] and the variance σ(2) q[2] of the equalizer output with CHATUE2, respectively, converge into: μq[2] → Nd Nd + (Nd + (1− β)L)σ2 z , (3....
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...Broadband wireless communication systems are expected to increase both their transmission (TX) rate and their spectral efficiency [1, 2] under the constraints of low TX power and a low computational complexity....
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...Thereby, CHATUE2 improves the signal to noise power ratio SNRq[2] at the final equalizer output and it approaches that with TEQ-CP when β → 1, as...
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...σ(2) q[2] → Nd(Nd + (1− β)L)σ(2) z {Nd + (Nd + (1− β)L)σ2 z}(2) , (3....
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References
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01 Sep 2006
TL;DR: A preliminary look at the air interface for Evolved UTRA (E-UTRA) and associated key technologies required to reach its design objectives are provided.
Abstract: With the emergence of packet-based wireless broadband systems such as 802.16e, it is evident that a comprehensive evolution of the universal mobile telecommunications system specifications is required to remain competitive. As a result, work has begun on long term evolution (LTE) of the UMTS terrestrial radio access and radio access network aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration with existing systems. To reach these goals, a new design for the air interface is envisioned. This paper provides a preliminary look at the air interface for Evolved UTRA (E-UTRA) and associated key technologies required to reach its design objectives. Initial E-UTRA system performance results show a 2 to 3x improvement over a reference Rel-6 UMTS system configuration [1, 2] for both uplink and downlink.
30 citations
24 Oct 2008
TL;DR: The proposed channel estimation technique is shown to have significant gains in performance compared to other well known channel estimation techniques such as the maximum-likelihood (ML) and the inverse fast Fourier transform (IFFT) channel estimation methods.
Abstract: The performance of the uplink physical channel of the 3GPP LTE system is considered in this paper. Assuming a single user spatial division multiple access transmission scheme, where users' signals are transmitted over different subcarriers, a low complexity channel estimation technique is proposed for the physical uplink shared channel (PUSCH). The proposed channel estimation technique is shown to have significant gains in performance compared to other well known channel estimation techniques such as the maximum-likelihood (ML) and the inverse fast Fourier transform (IFFT) channel estimation methods [5]. Simulation results for different channel models and modulation and coding schemes (MCS) using incremental redundancy (IR) based hybrid automatic repeat request (HARQ) operation are also shown. Finally, a robust detection scheme is proposed for the physical uplink control channel (PUCCH) and simulation results are summarized.
10 citations
"LTE-advanced: next-generation wirel..." refers methods in this paper
...The DFT precoding operation is performed to reduce the cubic metric (CM) of the signal, leading to higher maximum transmit power [2]....
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