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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28 Jan 2013
TL;DR: It is shown that topology management is able to significantly reduce energy consumption at low and medium traffic levels and energy savings increase further by an additional average of 15% at all traffic levels when combined with the proposed green channel assignment schemes.
Abstract: This paper introduces a green topology management scheme which aims to reduce energy consumption by switching off as many underutilised base stations as possible in beyond next generation mobile broadband networks. Strategies are proposed which activate or deactivate base stations according to local traffic conditions to find a trade-off between energy savings and system QoS. In addition, different green channel assignment schemes are introduced in order to further increase energy savings when used with the green topology management scheme. It is shown that topology management is able to significantly reduce energy consumption at low and medium traffic levels. These savings increase further by an additional average of 15% at all traffic levels when combined with the proposed green channel assignment schemes.
16 citations
Cites background from "LTE-advanced: next-generation wirel..."
...This shift to new data-intensive applications is a key factor behind the development of new standards for beyond next generation mobile broadband systems like Long Term EvolutionAdvanced (LTE-Advanced) [2], and beyond next generation systems [3]....
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01 Jan 2015
TL;DR: This chapter analyzes the suitability of LTE as a wireless transmission technology for future vehicular services of the categories Infotainment, Comfort, Traffic Efficiency, and Safety and shows that an accurate selection of the LTE quality of service parameters is crucial in order to meet the delay and reliability requirements of future automotive applications, especially in high-load network conditions.
Abstract: The cellular communication networks standard 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) offers low latencies and high throughputs simultaneously, thus enabling more bandwidth-demanding and real-time critical services for end-users. This is of particular interest for vehicle manufacturers who in the future intend to offer a huge variety of cooperative driver assistance services with manifold quality of service requirements. This chapter analyzes the suitability of LTE as a wireless transmission technology for future vehicular services of the categories Infotainment, Comfort, Traffic Efficiency, and Safety. The investigations are based on extensive LTE system-level simulations under different load conditions and network deployments as well as on a theoretical delay analysis. Focus is set on transmission delays and reliability aspects under various quality of service settings. The results show that an accurate selection of the LTE quality of service parameters is crucial in order to meet the delay and reliability requirements of future automotive applications, especially in high-load network conditions.
16 citations
TL;DR: It is shown that the complexity can be greatly reduced by applying the threshold in the breadth-first tree search algorithm step to eliminating paths to reduce the complexity of the proposed MIMO detection algorithm.
Abstract: In this paper, a novel efficient algorithm for MIMO detection in MIMO-OFDM systems has been proposed. This paper also shows that the complexity can be greatly reduced by applying the threshold in the breadth-first tree search algorithm step to eliminating paths. That is, this algorithm derives thresholds based on the LR-aided nonlinear algorithm and performs a simple tree search detection algorithm. This algorithm requires a lower computational complexity than the conventional QRD-M detection algorithm and achieves the same bit error performance. After the novel detection algorithm is proposed, this paper applies this algorithm to the MIMO-OFDM system for performance comparison in terms of error performance and complexity. In many cases of MIMO-OFDM receivers, the proposed method will be an excellent option for implementation.
16 citations
02 Jun 2013
TL;DR: The results show that with the flexible scheme, significant power savings can be achieved with acceptable tradeoffs in offloading, and the concept of threshold speed for inter-frequency scanning, above which mobile terminals should not search for or connect to inter- frequencies small cells, is proposed.
Abstract: Heterogeneous Network deployments are one of the key enablers in providing ubiquitous coverage and capacity enhancements for satisfying high data rate and Quality of Service requirements for LTE-Advanced networks. In this paper we propose an energy efficient small cell discovery mechanism for heterogeneous networks by means of flexible inter-frequency scanning. We also propose the concept of threshold speed for inter-frequency scanning, above which mobile terminals should not search for or connect to inter-frequency small cells. Above threshold speed, the small cell connection opportunities become so short that they offer very limited benefit. The scheme is evaluated using extensive simulations conducted on HetNet scenario specified in 3GPP LTE-A system settings. Shortcomings of the currently standardized mechanism are analyzed and advantages of the proposed scheme are presented. Numerical analysis is done based on utilization of available offloading opportunities as well as savings in terminal battery power consumption. The results show that with the flexible scheme, significant power savings can be achieved with acceptable tradeoffs in offloading.
16 citations
Cites background from "LTE-advanced: next-generation wirel..."
...LTE-Advanced systems provide the option of extending the system bandwidth up to 100 MHz using carrier aggregation of 20 MHz carriers [2]....
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TL;DR: A new technique in handover domain is designed, which consists of combining energy detection method used in cognitive radio with least mean square (LMS) process in order to prognosticate the handover impact in a realistic scenario of heterogeneous LTE network.
Abstract: Mobile communication systems present an actuality subject in academic and industrial research activities due to several phenomena such as interferences, multipath, fading and shadowing. All this lead to a severe perturbation on handover mechanism which depends on specific reports, essentially, reference signal received power (RSRP) and signal-to-interference and noise ratio (SINR). In this paper, we design a new technique in handover domain; it consists of combining energy detection method used in cognitive radio with least mean square (LMS) process in order to prognosticate the handover impact in a realistic scenario of heterogeneous LTE network. More exactly, technique sense of the word "triggering" will be changed to a probability of detection. The proposed algorithm cycle follows two main steps; Firstly, predict at what time the absence of spectrum (primary user) will occur, using a predicted sensing probability. Secondly, search others spectrums in this time by calculating the probability of detection for each sensed signal and hand-off secondary user in the best spectrum. The results achieved of the simulation are evaluating, it shows that the proposed method predict the original probability of detection correctly with minimal errors and select the best spectrum successfully contraly to standard handover process.
16 citations
Cites background from "LTE-advanced: next-generation wirel..."
...The 3GPP standardizes the multiple access technologies in downlink as orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SCFDMA) in uplink [1], [3], [4], [5]....
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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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