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: An iterative and distributed algorithm based on best-response dynamics and a practical parameter estimation are proposed to achieve the equilibrium point of contention-based synchronization in orthogonal frequency-division multiple-access communication systems.
Abstract: The purpose of this paper is to provide a novel energy-efficient perspective to the problem of contention-based synchronization in orthogonal frequency-division multiple-access communication systems. This is achieved by modeling the terminals and their corresponding receivers at the base station as economic and rational agents that engage in a noncooperative game. In the proposed game, each one trades off its available resources (transmit power and detection strategy) so as to selfishly maximize its own revenue (in terms of probability of correct detection) while saving as much energy as possible and satisfying quality-of-service requirements given in terms of probability of false alarm and timing estimation accuracy. The existence and uniqueness of the equilibrium of the game are studied. In particular, a necessary and sufficient condition on the system parameters is given for the equilibrium to exist. An iterative and distributed algorithm based on best-response dynamics (at the transmit side) and a practical parameter estimation (at the receive side) are proposed to achieve the equilibrium point. Numerical results are used to highlight the effectiveness of the proposed solution and to make comparisons with existing alternatives in terms of power consumption, synchronization time, and estimation accuracy.
32 citations
07 Apr 2013
TL;DR: An analytical model is developed to estimate power saving achieved and latency incurred by DRX operation and a tradeoff scheme is formulated to maintain a balance between these two performance parameters based on operator's preference for power saving.
Abstract: In LTE networks, mobile applications and their higher data rate requirements are the latest phenomenon causing a tremendous need in power saving for mobile devices. Discontinuous reception (DRX) is one of the key power saving mechanisms in LTE. Since DRX saves battery power of user equipment usually at the expense of potential increase in latency, an optimization is needed to find the best tradeoff between latency and power saving. In this paper, we first develop an analytical model to estimate power saving achieved and latency incurred by DRX operation. Then, a tradeoff scheme is formulated to maintain a balance between these two performance parameters based on operator's preference for power saving. We validate analytical model using system level simulation results obtained from OPNET Modeler. The results show that the proposed tradeoff scheme is highly efficient in keeping a balance between power saving and latency. We have shown that proposed scheme can achieve a significant delay improvement with a small decrease in power saving. The results also indicate that short DRX cycles are very effective in reducing latency for active traffic.
32 citations
TL;DR: In this paper, the authors proposed a new handover algorithm known as LTE Hard Handover Algorithm with Average Received Signal Reference Power (LHHAARC) in order to minimize number of handovers and the system delay as well as to maximize the system throughput.
Abstract: Hard handover mechanism is adopted to be used in 3GPP Long Term Evolution (3GPP LTE) in order to
reduce the complexity of the LTE network architecture. This mechanism comes with degradation in
system throughput as well as a higher system delay. This paper proposes a new handover algorithm
known as LTE Hard Handover Algorithm with Average Received Signal Reference Power (RSRP)
Constraint (LHHAARC) in order to minimize number of handovers and the system delay as well as
maximize the system throughput. An optimized system performance of the LHHAARC is evaluated and
compared with three well-known handover algorithms via computer simulation. The simulation results
show that the LHHAARC outperforms three well-known handover algorithms by having less number of
average handovers per UE per second, shorter total system delay whilst maintaining a higher total
system throughput.
32 citations
TL;DR: An overview of the key radio access features and functionalities of the LTE-Advanced radio access network, supported by the simulation results is presented.
Abstract: Long Term Evolution Advanced (LTE-Advanced) is the next step in LTE evolution and allows operators to improve network performance and service capabilities through smooth deployment of new techniques and technologies. LTE-Advanced uses some new features on top of the existing LTE standards to provide better user experience and higher throughputs. Some of the most significant features introduced in LTE-Advanced are carrier aggregation, enhancements in heterogeneous networks, coordinated multipoint transmission and reception, enhanced multiple input multiple output usage and deployment of relay nodes in the radio network. Mentioned features are mainly aimed to enhance the radio access part of the cellular networks. This survey article presents an overview of the key radio access features and functionalities of the LTE-Advanced radio access network, supported by the simulation results. We also provide a detailed review of the literature together with a very rich list of the references for each of the features. An LTE-Advanced roadmap and the latest updates and trends in LTE markets are also presented.
32 citations
Cites background or methods from "LTE-advanced: next-generation wirel..."
...Main features and techniques deployed in LTE-Advanced physical layer can be summarised as follows [5-13]:...
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...see [5-8]) provide such a comprehensive survey related to LTE-Advanced radio access features....
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TL;DR: A model for network coverage probability and average rate analysis in a D2D communication overlaying a two-tier downlink cellular network, where nineteen macro base stations with pico base stations placed at the end point of macro cell borders are employed according to the 3GPP specifications.
Abstract: Device-to-device (D2D) communication, which utilizes mobile devices located within close proximity for direct connection and data exchange, holds great promise for improving energy and spectrum efficiency of mobile multimedia in 5G networks. It has been observed that most available D2D-based works—considered only the single-cell scenario with a single BS. Such scenario-based schemes, although tractable and able to illustrate the relationship between D2D links and cellular links, failed to take into account the distribution of surrounding base stations and user equipments (UEs), as well as the accumulated interference from ongoing transmissions in other cells. Furthermore, the single-tier network with one BS considered in available works is far from the real 5G scenario in which multi-tier BSs are heterogeneously distributed among the whole network area. In light of such observations, we present in this article a model for network coverage probability and average rate analysis in a D2D communication overlaying a two-tier downlink cellular network, where nineteen macro base stations (MBSs) with pico base stations (PBSs) placed at the end point of macro cell (hexagons) borders are employed according to the 3GPP specifications, and mobile users are spatially distributed according to the homogeneous Poisson Point Process model. Each mobile UE is able to establish a D2D link with adjacent UEs or connect to a nearby macro or pico base station. Stochastic geometric analysis is adopted to characterize the intratier interference distribution within the MBS-tier, PBS-tier, and D2D-tier based on which network coverage probability and per-user average rate are derived with a careful consideration of important issues such as threshold value, SINR value, user density, content hit rate, spectrum allocation, and cell coverage range. Our results show that, even for the overlaying case, D2D communication can significantly improve network coverage probability and per-user average downlink rate. Another finding is that the frequency allocation for D2D communications should be carefully tuned according to network settings, which may result in totally different varying behaviors for the per-user average rate.
31 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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