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 outage behavior and power allocation problem in a two-user network-coded cooperative cognitive radio network over Rayleigh fading channels is investigated and the benefits of network coding cooperation are substantial for both power allocation schemes.
Abstract: This paper investigates the outage behavior and power allocation problem in a two-user network-coded cooperative cognitive radio network over Rayleigh fading channels. First, we derive an exact expression for the outage probability of the secondary transmissions, and then we propose an approximate expression whose validity limits are later evaluated. To improve the power efficiency of the secondary network, two power allocation schemes are proposed. In the first scheme, the transmit power is adjusted as a function of the average channel gains and the power control is formulated as a convex optimization problem where the objective is to minimize the total transmit power subject to outage probability constraints. In the second scheme, the transmit power is adjusted as a function of the instantaneous channel gains to guarantee a target signal-to-interference-plus-noise ratio at the receiver. We evaluate the performance of both schemes under cooperative and non-cooperative scenarios considering different network geometries. Our results indicate that the benefits of network coding cooperation are substantial for both power allocation schemes.
31 citations
04 Dec 2014
TL;DR: A new AMC scheme is designed that exploits a reinforcement learning algorithm to adjust at run-time the MCS selection rules based on the knowledge of the effect of previous AMC decisions and the salient features of the proposed solution are the low-dimensional space that the learner has to explore and the use of direct link throughput measurements to guide the decision process.
Abstract: Adaptive Modulation and Coding (AMC) in LTE networks is commonly employed to improve system throughput by ensuring more reliable transmissions. Most of existing AMC methods select the modulation and coding scheme (MCS) using pre-computed mappings between MCS indexes and channel quality indicator (CQI) feedbacks that are periodically sent by the receivers. However, the effectiveness of this approach heavily depends on the assumed channel model. In addition CQI feedback delays may cause throughput losses. In this paper we design a new AMC scheme that exploits a reinforcement learning algorithm to adjust at run-time the MCS selection rules based on the knowledge of the effect of previous AMC decisions. The salient features of our proposed solution are: i) the lowdimensional space that the learner has to explore, and ii) the use of direct link throughput measurements to guide the decision process. Simulation results obtained using ns3 demonstrate the robustness of our AMC scheme that is capable of discovering the best MCS even if the CQI feedback provides a poor prediction of the channel performance.
29 citations
Cites methods from "LTE-advanced: next-generation wirel..."
...nologies, such as OFDMA and multi-antenna techniques, and it supports new Radio Resource Management (RRM) functions for link adaptation [1]....
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10 Jun 2012
TL;DR: It is concluded how the spatial UE distribution, the used propagation models, and pico eNB transmit power settings influence the performance and the optimal eICIC parameter choice.
Abstract: Heterogeneous Networks (HetNet) have been recognized as a key enabler for providing high data rates. However, co-channel deployed HetNet will experience inter-layer interference, and hence calls for use of enhanced Inter-Cell Interference Coordination (eICIC) to solve such interference problems. In order to achieve the full performance benefits of eICIC, its corresponding configuration parameters shall be carefully adjusted. In this paper we study how sensitive the HetNet performance is for different eICIC parameters in different HetNet scenarios, and provide guidelines on how to set them. Among others, it is concluded how the spatial UE distribution, the used propagation models, and pico eNB transmit power settings influence the performance and the optimal eICIC parameter choice.
28 citations
Cites background from "LTE-advanced: next-generation wirel..."
...It offers wide area coverage and also allows for high data rate transmissions in traffic hotspot areas [1][2]....
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TL;DR: A novel hierarchical game theoretic framework to jointly optimize the transmit powers and subband allocations of the UUs and the pricing strategies of the MCO and its uniqueness and optimality are proved.
Abstract: This paper studies the resource-allocation problem for a heterogeneous network (HetNet) in which the spectrum owned by a macrocell operator (MCO) can be shared by both unlicensed users (UUs) and licensed users (LUs). We formulate a novel hierarchical game theoretic framework to jointly optimize the transmit powers and subband allocations of the UUs and the pricing strategies of the MCO. In our framework, an overlapping coalition formation (OCF) game has been introduced to model the cooperative behaviors of the UUs. We then integrate this OCF game into a Stackelberg game-based hierarchical framework. We prove that the core of our proposed OCF game is nonempty and introduce an optimal subband-allocation scheme for UUs. A simple distributed algorithm is proposed for UUs to autonomously form an optimal coalition formation (CF) structure. The Stackelberg equilibrium (SE) of the proposed hierarchical game is derived, and its uniqueness and optimality are proved. A distributed joint optimization algorithm is also proposed to approach the SE of the game with limited information exchanges between the MCO and the UUs.
28 citations
09 Jun 2013
TL;DR: An analytical model is developed to estimate power saving achieved and latency incurred by DRX operation and the results show that proposed scheme efficiently optimizes the DRX configuration for the battery power saving and latency requirements of various diverse data applications based on the preferences determined by operator.
Abstract: Discontinuous reception (DRX) can be configured as a power saving mechanism for user equipment (UE) in connected mode in the long term evolution advanced (LTE-A) network. Since DRX saves UE's battery power usually at the cost of increased latency, a tradeoff between these two conflicting performance metrics are inevitable. DRX parameters can be optimized for either maximizing power saving or minimizing latency based on the applications running at the UE. In this paper, we first develop an analytical model to estimate power saving achieved and latency incurred by DRX operation. We then propose a scheme to tune DRX parameters in order to keep a balance between these conflicting performance metrics by formulating a multi-objective optimization problem. The tradeoff between power saving and latency is achieved based on the operator's relative preferences for these metrics. We also validate our analytical model by system level simulation results from OPNET Modeler. OPNET simulation results are well aligned with the MATLAB results based on analytical model and the results show that proposed scheme efficiently optimizes the DRX configuration for the battery power saving and latency requirements of various diverse data applications based on the preferences determined by operator.
28 citations
Cites methods from "LTE-advanced: next-generation wirel..."
...The increased data rate is achieved by adopting higher transmission bandwidth, higher order modulation, advanced coding techniques and multiple advanced antenna schemes [1][2][3]....
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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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