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 proposes a hybrid approach to reduce the PAPR of OFDM signals using an iterative clipping and filtering technique and an enhanced nonlinear companding scheme, and shows that the proposed method achieves better performance on BER.
Abstract: Orthogonal frequency division multiplexing (OFDM) is an important technology that has been widely used in broadband wireless communications. However OFDM has some drawbacks, one of which is the high peak-to-average power ratio (PAPR) problem. Many techniques for reducing PAPR thus have been proposed in the literatures, where clipping and companding are effective techniques and have gained a lot of research interest. Based on the study of clipping and companding, this paper proposes a hybrid approach to reduce the PAPR of OFDM signals. An iterative clipping and filtering (ICF) technique and an enhanced nonlinear companding (ENC) scheme are used as the typical clipping and companding techniques in this paper. The results of the analysis show that the computational complexity of the proposed method is slightly higher than that of ENC, but much lower than that of ICF. And the simulation results show that the proposed method has better performance on PAPR reduction and bit error rate (BER) in contrast to ICF. On the other hand, compared to ENC with equal PAPR reduction, the proposed method still achieves better performance on BER.
17 citations
Additional excerpts
...INTRODUCTION Orthogonal frequency division multiplexing (OFDM) is one of the most popular technologies for broadband wireless communication and has been used in several widely used standards, such as Digital Video Broadcasting (DVB), Wireless Local AreaNetwork (WLAN) and 4G-LTE [1]–[4]....
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TL;DR: A unified analytical framework for robust channel- and queue-aware QoS-guaranteed cross-layer SRA algorithms for the downlink of MIMO-OFDMA networks with imperfect CSIT is introduced.
Abstract: Multiple-input—multiple-output (MIMO) orthogonal frequency-division multiple access (OFDMA) has been selected as the core physical-layer access scheme for the downlink of state-of-the-art and next-generation wireless communications standards. In these systems, scheduling and resource allocation (SRA) algorithms, jointly assigning transmission data rates, bandwidth, and power, become crucial in optimizing resource utilization while providing support to multimedia applications with heterogeneous quality-of-service (QoS) requirements. To this end, the transmitter is assumed to have channel state information at the transmitter (CSIT) that will typically be imperfect. This paper introduces a unified analytical framework for robust channel- and queue-aware QoS-guaranteed cross-layer SRA algorithms for the downlink of MIMO-OFDMA networks with imperfect CSIT. The framework is based on the statistical characterization of the signal-to-noise ratio (SNR) under imperfect CSIT and is general enough to encompass spatial correlation effects in the Tx and Rx antenna arrays, different types of traffic, uniform and continuous power allocation, discrete and continuous rate allocation, and protocols with different amounts of channel and queue awareness. Simulation results using parameters drawn from the Third-Generation Partnership Project Long-Term Evolution (3GPP-LTE) standard demonstrate the validity and advantages of the proposed robust cross-layer unified approach.
17 citations
Cites methods from "LTE-advanced: next-generation wirel..."
...For instance, Turbo codes showing these characteristics have been standardized by 3GPP for use in the evolved-UTRAN (E-UTRAN) radio access of Long Term Evolution (LTE) and LTE-Advanced (LTE-A) systems [21], [22]....
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...I. INTRODUCTION Orthogonal frequency division multiple access (OFDMA), combined with multiple-input multiple- output (MIMO) strategies, has been chosen as the core physical layer access scheme for state-ofthe-art and next-generation wireless communications standards such as IEEE 802.16e/m-based WiMAX systems [1] and the Third Generation Partnership Project (3GPP) networks based on the Long-Term Evolution (LTE) and LTE-Advanced (LTE-A) [2]....
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...16e/m-based WiMAX systems [1] and the ThirdGeneration Partnership Project (3GPP) networks based on Long-Term Evolution (LTE) and LTE-Advanced (LTE-A) [2]....
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TL;DR: In this article, the authors address ongoing research efforts in Europe, United States and East Asia, and beyond that, propose an overall 5G architecture and set of system requirements, and then provide the bridge towards the possible set of scientific and technology solutions that will be elaborated in subsequent chapters, each one considered timely and a piece of the 5G jigsaw.
Abstract: The first wave of 4th Generation systems is finally being deployed over Europe, providing a vehicle for broadband mobile services at any time and anywhere. However, mobile traffic is still growing and the need for more sophisticated broadband services will further push the limit on current standards to provide an even tighter integration between wireless technologies and higher speeds, requiring a new generation of mobile communications: the so‐called 5G. The evolution towards 5G is considered to be the convergence of Internet services with legacy mobile networking standards, leading to what is commonly referred to as the ‘mobile Internet’ over Heterogeneous Networks (HetNets), with very high connectivity speeds. In addition, green communications seem to play a pivotal role in this evolutionary path with key mobile stakeholders driving momentum towards a greener society through cost‐effective design approaches. In fact, it is becoming increasingly clear from new emerging services and technological trends that energy and cost‐per‐bit reduction, service ubiquity, and high‐speed connectivity are becoming desirable traits for next‐generation networks. In this chapter, we address ongoing research efforts in Europe, the United States and East Asia, and beyond that, propose an overall 5G architecture and set of system requirements. The architecture will then provide the bridge towards the possible set of scientific and technology solutions that will be elaborated in subsequent chapters, each one considered timely and a piece of the 5G jigsaw.
16 citations
TL;DR: There are still a lot of problems that need to be addressed in every linearization technique in order to achieve 5G specifications, and a systematic view on PA linearization problems should be useful to researchers of this field.
Abstract: Development of 5G networks requires a substantial increase to both spectral and power efficiency of transmitters. It is known that these two parameters are subjected to a mutual trade-off. To increase the linearity without losing power efficiency, linearization techniques are applied to power amplifiers. This paper aims to compare most popular linearization techniques to date and evaluate their applicability to upcoming 5G networks. The history of each respective linearization technique is followed by the main principle of operation, revealing advantages and disadvantages supported by concluding the latest research results. Three main groups of linearization methods currently known are feedforward, feedback, and predistortion, each with its own tradeoffs. Although digital predistortion seems to be the go-to method currently, other techniques with less research attention are still non-obsolete. A generalized discussion and a direct comparison of techniques analyzed are presented at the end of this paper. The article offers a systematic view on PA linearization problems which should be useful to researchers of this field. It is concluded that there are still a lot of problems that need to be addressed in every linearization technique in order to achieve 5G specifications.
16 citations
Cites background from "LTE-advanced: next-generation wirel..."
...In the case of a 100 MHz LTE-A signal [72], the signal spectrum expands up to 500 MHz–700 MHz and requires converters with speeds from 1 GS/s to 1....
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06 May 2012
TL;DR: In this paper, the analysis of channel capacity and bit error probability simulation based on the measured MU-MIMO-OFDM channels obtained during the demonstration, and their comparison with the results based on channels simulated by a novel geometric optics based channel model suitable for MU MIMO OFDM in rural areas.
Abstract: Commonwealth Scientific and Industrial Research Organisation (CSIRO) has recently conducted a technology demonstration of a novel fixed wireless broadband access system in rural Australia. The system is based on multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM). It demonstrated an uplink of six simultaneous users with distances ranging from 10~m to 8.5 km from a central tower, achieving 20 bits/s/Hz spectrum efficiency. This paper reports on the analysis of channel capacity and bit error probability simulation based on the measured MU-MIMO-OFDM channels obtained during the demonstration, and their comparison with the results based on channels simulated by a novel geometric optics based channel model suitable for MU-MIMO-OFDM in rural areas. Despite its simplicity, the model was found to predict channel capacity and bit error rate probability accurately for a typical MU-MIMO- OFDM deployment scenario.
16 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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