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.
Citations
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TL;DR: Ethics-Aware Object-Oriented Smart City Architecture (EOSCA), an object oriented layered architecture where an object represents an abstraction of a real world thing along with requisite security and ethics parameters, is proposed to integrate socio-cultural and ethical aspects within the smart city architecture by dedicating a separate ethics layer.
Abstract: A novel initiative in providing advanced civic amenities is the idea of smart city driven by the Internet of Things. Owing to a lack of consensus regarding what constitutes a smart city, diverse smart city architectures have been proposed. However, it is observed that adequate consideration is not given to the most important element of a smart city i.e. its people. In our opinion, energy efficient technologically driven city does not necessarily lead to a smart city. Ethics, tradition and law form essential ingredients of complex social palette that cannot be ignored. In this work we propose Ethics-Aware Object-Oriented Smart City Architecture (EOSCA) that has two distinguishing features. Firstly, we propose an object oriented layered architecture where an object represents an abstraction of a real world thing along with requisite security and ethics parameters. Secondly, we propose to integrate socio-cultural and ethical aspects within the smart city architecture by dedicating a separate ethics layer. Such enhancement not only addresses the challenge of privacy and security of a smart city, but also makes it people friendly by incorporating ethics. Such measures would facilitate social acceptance of smart city paradigm and augment its economic value.
21 citations
01 Sep 2014
TL;DR: This work investigates, by means of simulation, the performance ofDRoF in several contexts: single channel and in coexistence scenario, and shows that the DRoF system is compatible with a NG-PON2 with respect to the wavelength plan and bandwidth requirements.
Abstract: The current trends on traffic and mobile users' growth is pushing the capacity of the current networks to the limit, which has led telecommunication operators to expand their investment in infrastructure. In this context, centralized RAN (C- RAN) comes with an innovative solution for the changes that will occur in the network. C-RAN shifts all the complex functionalities from the base stations (BS) to the central office (CO). A new segment called fronthaul connects the base band unit (BBU) with the remote antenna over a digital radio over fiber (DRoF) transmission based on the common public radio interface (CPRI). In this work we investigate, by means of simulation, the performance of DRoF in several contexts: single channel and in coexistence scenario. To meet this goal, we first investigate the key aspects of DRoF in an isolated transmission and next we proceed with a coexistence scenario based on the ITU-T G.989 standard (NG-PON2). The results show that the DRoF system is compatible with a NG-PON2 with respect to the wavelength plan and bandwidth requirements.
21 citations
01 Sep 2017
TL;DR: This paper investigates the so-called discrete Fourier transform- mutually unbiased bases (DFT-MUB) aided codebook design conceived for limited-feedback mmWave systems, where the MUB aided code book is applied in the baseband, while the DFT codebook is invoked for RF analog phase shifters.
Abstract: The millimeter wave (mmWave) frequency band offers substantial hitherto unused spectral resources for future wireless communication systems in order to meet the increasing capacity demand. However, mmWave frequencies suffer from high propagation losses, which may be mitigated by directional beamforming in addition to baseband precoding. This is usually referred to as hybrid beamforming. In this paper, we investigate the so-called discrete Fourier transform- mutually unbiased bases (DFT-MUB) aided codebook design conceived for limited-feedback mmWave systems, where the MUB aided codebook is applied in the baseband, while the DFT codebook is invoked for RF analog phase shifters. We demonstrate that our DFT- MUB codebook design performs similarly to the optimal digital precoding matrix, where the precoder is selected as the right singular matrix of the channel. However, our solution significantly reduces the search complexity in the baseband, while performing within 2.5 dB from the optimal digital precoder.
21 citations
Cites background from "LTE-advanced: next-generation wirel..."
...Recent studies show a dearth of spectral resources to meet the increasing data rate demands of mobile users in the microwave band [1]....
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TL;DR: The achievable rate and power allocation to improve the uplink (UL) spectrum efficiency in a Long-Term Evolution Advanced (LTE-A) cooperative cellular network with the deployment of Type-II in-band decode-and-forward (DF) relay stations (RSs) are studied.
Abstract: This paper studies the achievable rate and power allocation to improve the uplink (UL) spectrum efficiency in a Long-Term Evolution Advanced (LTE-A) cooperative cellular network with the deployment of Type-II in-band decode-and-forward (DF) relay stations (RSs). The physical-layer UL transmission technology is based on single-carrier frequency-division multiple access (SC-FDMA) with frequency-domain equalization (FDE). Different from the downlink (DL) orthogonal FDMA system, signals on all subcarriers in the SC-FDMA system are transmitted sequentially rather than in parallel; thus, the user's achievable rate is not simply the summation of the rates on all allocated subcarriers. Moreover, each user equipment (UE) device has its own transmission power constraint instead of a total power constraint at the base station in the DL case. Therefore, the UL resource allocation problem in the LTE-A system is more challenging. To this end, we first derive the achievable rates of the SC-FDMA system with two commonly used FDE techniques, namely, zero-forcing (ZF) equalization and minimum-mean-square-error (MMSE) equalization, based on the joint superposition coding for cooperative relaying. We then propose optimal power allocation schemes among subcarriers at both the UE and RS to maximize the overall throughput of the system. Both theoretical analysis and numerical results demonstrate that our proposed power allocation schemes can drastically improve system throughput.
20 citations
Cites background from "LTE-advanced: next-generation wirel..."
...Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org....
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...In addition to the advanced physical-layer transmission technologies, LTE-Advanced networks further incorporate several enhancements, e.g., carrier aggregation and heterogeneous network topologies to improve capacity and coverage and to ensure user fairness [1]....
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Posted Content•
TL;DR: In this article, an improved soft-input soft-output M-algorithm (ISS-MA) was proposed for tree detection in high-dimensional multi-antenna wireless communication systems.
Abstract: Tree detection techniques are often used to reduce the complexity of a posteriori probability (APP) detection in high dimensional multi-antenna wireless communication systems. In this paper, we introduce an efficient soft-input soft-output tree detection algorithm that employs a new type of look-ahead path metric in the computation of its branch pruning (or sorting). While conventional path metrics depend only on symbols on a visited path, the new path metric accounts for unvisited parts of the tree in advance through an unconstrained linear estimator and adds a bias term that reflects the contribution of as-yet undecided symbols. By applying the linear estimate-based look-ahead path metric to an M-algorithm that selects the best M paths for each level of the tree we develop a new soft-input soft-output tree detector, called an improved soft-input soft-output M-algorithm (ISS-MA). Based on an analysis of the probability of correct path loss, we show that the improved path metric offers substantial performance gain over the conventional path metric. We also demonstrate through simulations that the ISS-MA provides a better performance-complexity trade-off than existing soft-input soft-output detection algorithms.
20 citations
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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