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: The proposed overlay spectrum sharing scheme improves the performance of both systems as compared with the earlier proposed schemes and helps in achieving diversity gain of three and two for primary and secondary systems.
Abstract: In this study, an overlay spectrum sharing scheme has been proposed for a cognitive radio system. To achieve the desired quality of service for the licenced (i.e. primary) system and spectrum access for unlicenced (i.e. secondary) system, a three-phase cooperative decode and forward relaying is used. Furthermore, space–time block coding is used in order to cancel the interference at primary as well as secondary receiver. It has been shown that the proposed scheme helps in achieving diversity gain of three and two for primary and secondary systems, respectively. The performance of both primary and cognitive (secondary) system is appraised by deriving closed-form expression for bit error rate and outage probability. The theoretical and simulation results validate that the proposed scheme improves the performance of both systems as compared with the earlier proposed schemes.
6 citations
01 Apr 2012
TL;DR: Experimental results show excellent performance improvement in image rejection in the imbalanced modulator and a resultant very low EVM values below 0.5% across a frequency band of 90 MHz.
Abstract: Current trends in low-cost and low power consumption transmitters in state-of-the-art wireless systems is to use the direct-conversion principle. Such transmitters, however, suffer severely from the I/Q imbalance effect, which introduces mirror-frequency interference and degrades data detection. This paper proposes a novel method for frequency-dependent I/Q imbalance estimation and compensation. The I/Q imbalance is estimated jointly in the frequency domain with very low complexity and minimum error variance, by relying on a specially designed pilot and its optimization. The performance and complexity of the algorithm are evaluated through both theoretical analysis and computer simulations. The simulation results are compared with those of existing techniques and show considerable advantages of the proposed algorithm. Moreover, a new time domain I/Q imbalance compensator structure is developed which delivers ideal compensation performance as well as the low complexity benefit. Both of the proposed estimation and compensation algorithms are implemented and their respective operation is verified on a test bed utilizing a commercial wideband direct-conversion based signal generator. Experimental results show excellent performance improvement in image rejection in the imbalanced modulator and a resultant very low EVM values below 0.5% across a frequency band of 90MHz.
6 citations
28 Feb 2017
TL;DR: It is shown that for a sufficiently large number N of carriers, choosing each element of that set independently with arbitrary small probability, yields in turn a set of carriers for which the PAPR reduction problem is not solvable with certain explicitly given threshold constants with probability 1 as N goes to infinity.
Abstract: High peak values of transmission signals in wireless communication systems lead to wasteful energy consumption and degradation of several transmission performances. We continue the theoretical contributions made by B. and Farell [1, 2] towards the understanding of peak value reduction, using the strategy known as tone reservation for orthogonal transmission schemes. There it was shown that for OFDM systems, the combinatorial object called arithmetic progression plays an important role in setting limitations for the applicability of the tone reservation method. In this work, we consider ourselves with the performance of the tone reservation in the probabilistic asymptotic setting. We show in particular that for a sufficiently large number N of carriers, choosing each element of that set independently with arbitrary small probability, yields in turn a set of carriers, for which the PAPR reduction problem is not solvable with certain explicitly given threshold constants with probability 1 as N goes to infinity.
6 citations
Additional excerpts
...11 , DYB-T, LTE and LTE-advanced/4G [4], and 5G [5,6]....
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...Moreover, it has become an important part and a foundation of various current, and future standards, such as DSL, IEEE 802.11 , DYB-T, LTE and LTE-advanced/4G [4], and 5G [5,6]....
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Proceedings Article•
03 Apr 2012TL;DR: This study proposes a technique for dynamic power adjustment to enable energy-efficient data transmissions and demonstrates that the energy consumption of the proposed scheme is much better than that of the case in which all CCs are always active, when both schemes maintain the required QoS.
Abstract: Traditional resource allocation studies of wireless access networks almost all focused on the maximization of the network capacity and quality of services (QoS). As the development of the cellular technologies (such as LTE-Advanced) progress, more than one component carrier (CCs) can now be jointly utilized in a base station (BS). However, the use of some CCs may not be necessary at light traffic loads, from the point of view of green communication. In this study, we propose a technique for dynamic power adjustment to enable energy-efficient data transmissions. That is, utilize only the necessary transmission power. In our model, the activities in downlink transmissions of a BS with 2 OFDM-based CCs are considered, while simultaneously supporting both real-time and non-real-time users. We employ a computationally efficient scheme according to the fluctuating traffic load to address the problem of power minimization at the BS transceiver, subject to the constraint of minimum rates for all users. Simulation results demonstrate that the energy consumption of our proposed scheme is much better than that of the case in which all CCs are always active, when both schemes maintain the required QoS.
6 citations
Cites background from "LTE-advanced: next-generation wirel..."
...REFERENCES [1] G. Yuan, et al., “Carrier aggregation for LTE-advanced mobile communication systems,” IEEE Commun....
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...[9] Y.-L. Chung and Z. Tsai, “A quantized water-filling packet scheduling scheme for downlink transmissions in LTE-advanced systems with carrier aggregation,” in Proc....
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...Keywords— Power Saving, Green Communication, OFDM, LTEAdvanced, Radio Resource Allocation I. INTRODUCTION In order to enhance the capacity of the current cellular network to deal with the fast-growing data demand, the 4th generation (4G) system (such as LTE-advanced [1-2]) has now been developed....
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...Moreover, other main settings of the simulation parameters are referred to [1-4], as summarized in Table 1....
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...[2] A. Ghosh, et al., “LTE-advanced: next-generation wireless broadband technology,” IEEE Wireless Commun., pp. 10-22, June 2010....
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6 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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