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: This paper considers the analysis and optimization of random caching in multi-antenna small-cell networks with limited backhaul, and obtains a local optimal solution with low complexity in the high user density region.
Abstract: Caching at base station is a promising technology to reduce the backhaul loads in future wireless networks. To exploit the content diversity gain and multiple antenna transmission, in this paper, we consider the analysis and optimization of random caching in multi-antenna small-cell networks with limited backhaul. We analyze the performance of the success probability, which is defined as the probability that the requested file is not only obtained from the cache or the backhaul at the small base station (SBS), but also successfully delivered via the wireless link from the SBS to the user. Using tools from stochastic geometry, we first derive an exact expression and an upper bound of the success probability. Based on the analytical results, we then consider network throughput maximization by optimizing the design parameters in the cache-enabled multi-antenna small-cell networks. The optimization problem is a complicated mixed-integer optimization problem. After analyzing the optimal properties, we obtain a local optimal solution with low complexity. To further simplify the optimization, we solve an asymptotic optimization problem in the high user density region, using the upper bound as the objective function. Numerical simulations show that our proposed scheme improves the performance by up to $14\%$ when the Zipf parameter is 0.4 and the antenna number is 8.
3 citations
Cites background from "LTE-advanced: next-generation wirel..."
...However, as pointed in [22], [23], in Long-Term Evolution (LTE) or 5G networks, multi-antenna techniques are widely used to enhance the performance....
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25 Jun 2014
TL;DR: A system model of frequency domain load balancing-based inter-cell interference coordination (ICIC) is investigated to minimize the total interference, while satisfying the required quality of service constraints, and a heuristic solution by joint spectrum and antenna allocation is proposed.
Abstract: In this paper, a novel multi-carrier and multi-antenna for a multi-tier cellular network is presented for Long-Term Evolution Advanced (LTE-A) heterogeneous networks (Het-Nets) with carrier aggregation enhancement. First, we investigate a system model of frequency domain load balancing-based inter-cell interference coordination (ICIC) to minimize the total interference, while satisfying the required quality of service constraints. To achieve the desired system performance, a heuristic solution by joint spectrum and antenna allocation is then proposed, which operates at the base station side to enable efficient interference management. The optimal deployment for component carriers and antennas at the serving base station is updated for specific time periods while passively receiving the system information transmitted from neighboring base stations. Furthermore, system level simulations are carried out to demonstrate how the throughput can be greatly improved by our solution, as compared to conventional methods such as the randomized and static ICIC approaches.
3 citations
Cites background from "LTE-advanced: next-generation wirel..."
...First of all, to balance the loading of CCs, each serving UE’s azimuth angle parameter with respect to BS is collected statistically via techniques such as location services with angle of arrival (AOA) or coordinated multipoint transmission and reception (CoMP) in LTE-A....
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...The first approach consists of macro-cell networks and small-cell networks that are expected to be identified by both 3GPP Long-Term Evolution Advanced (LTE-A) [3] and WiMAX (IEEE 802.16m) [4] as key features of nextgeneration cellular systems....
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...In this paper, a combination of promising features, including the HetNet, carrier aggregation, and multiple antennas coordination is presented for 3GPP LTE-A....
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...The first approach consists of macro-cell networks and small-cell networks that are expected to be identified by both 3GPP Long-Term Evolution Advanced (LTE-A) [3] and WiMAX (IEEE 802....
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...With reference to the simulator study [6] and LTE-A specification [7], further details about the adopted downlink system level simulation parameters are outlined....
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TL;DR: This paper aims to demonstrate the efforts towards in-situ applicability of EMMARM, as to provide real-time information about the electrical properties of the E-modulus of the response of the human eye.
Abstract: 1Department of Electrical Engineering, National Cheng Kung University, Tainan 600, Taiwan 2Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan 3Department of Information and Communication Engineering, Inha University, Inncheon, Republic of Korea 4 School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 5Department of Electrical & Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA
3 citations
30 Sep 2015
TL;DR: In this article, the performance of a low-cost digital radio over fiber (DRoF) system in a single channel and in coexistence scenario is investigated by means of simulation, and the results show 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 user's  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 propose and investigate, by means of simulation, the performance of the low cost DRoF system 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.
3 citations
01 Jan 2014
TL;DR: In this paper, non-coherent orthogonal frequency division multiplexing (OFDM) is proposed to mitigate inter-symbol interference caused by channel frequency selectivity and achieve high spectral efficiency.
Abstract: Future indoor wireless networks will need alternative RF spectral resources to support the multi-gigabit per second (Gb/s) data speeds demanded by next generation multimedia applications. Although RF spectra in millimeter-wave, terahertz and optical bands are relatively uncongested, the communication systems operating in these frequency bands are difficult to implement, since they often suffer from stability problems due to the very high carrier frequencies. Hence, new physical layer technologies that can offer stable and low-complexity transceivers need to be developed.
In this research work, non-coherent orthogonal frequency division multiplexing (OFDM) is studied to meet this demand. Non-coherent OFDMs can mitigate inter-symbol interference caused by channel frequency selectivity and achieve high spectral efficiency. Moreover, compared to conventional OFDMs, non-coherent OFDM uses simple passive direct detection without the need of complex RF frontend components such as mixers and oscillators. In this study, various non-coherent OFDM schemes with new detection enhancements are proposed to improve the performance of millimeter-wave, terahertz, optical, and optical wireless communication systems. It is shown analytically and by simulation that the proposed non-coherent OFDMs offer better bit error rate performance with much lower complexity, when compared to conventional OFDMs. In addition, a simple non-linear pre-distortion technique is explored to further improve the spectral efficiency of non-coherent OFDMs. Finally, space-time block coded (STBC) multiple-input multiple-output (MIMO) transmission
schemes are incorporated with the proposed non-coherent OFDMs to offer improved system performance.
3 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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