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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01 Jan 2011
TL;DR: The 3GPP (3rd Generation Partnership Project) as mentioned in this paper ) is a project that aims to develop a 3G network for long-term evolution (LTE) technologies.
Abstract: 近年，スマートフォンのような高機能端末が一般層へ普及してきたことを起爆剤として，動画配信等のブロードバンドサービスを中心に無線ネットワークにおけるデータトラヒックが爆発的に増大している．本稿では，そのような背景の下，10年後の未来に向けて飛躍的な無線ネットワークの大容量化を実現する次世代の無線アクセス (将来無線アクセス) の要求条件を示すとともに，それを達成するための技術課題について，3GPP (3rd Generation Partnership Project) で標準化が行われているLTE (Long Term Evolution) 及びLTE-Advancedの技術動向を考慮しつつ考察する．
1 citations
TL;DR: The novel active bias circuit indeed improves the linearity performance of the LNA MMIC without degradation and the OIP3 is improved about 2–3 dBm.
Abstract: In this work, we demonstrated a low noise and high linearity low noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) with novel active bias circuit for LTE applications. The device technology used in this work relies on a process involving a 0.25-μm GaAs pseudomorphic high electron mobility transistor (PHEMT). The LNA MMIC with a novel active bias circuit has a small signal gain of 19.7±1.5 dB and output third order intercept point (OIP3) of 38–39 dBm in the frequency range 1.75–2.65 GHz. The noise figure (NF) is less than 0.58 dB over the full bandwidth. Compared with the characteristics of the LNA MMIC without using the novel active bias circuit, the OIP3 is improved about 2–3 dBm. The small signal gain and NF showed no significant change after using the active bias circuit. The novel active bias circuit indeed improves the linearity performance of the LNA MMIC without degradation.
1 citations
Dissertation•
01 Jun 2016
TL;DR: A Multi-Start Particle Swarm Optimization Algorithm (MSPSOA) is included in this thesis and used to present an eficient beamformer that achieves equivalent backhaul reduction and high spectral eficiency.
Abstract: Next-generation cellular networks and beyond are expected to adopt a frequency reuse factor of one to support high spectral eficiency. Consequently, Inter-Cell Interference (ICI) represents a serious issue among neighboring cells, especially for cell-edge users. In addressing this, Joint Transmission (JT) represents one of the most sophisticated techniques for mitigating ICI stemming from implementing a frequency reuse factor of one. Moreover, JT also converts the interfering signals into useful signals to improve the spectral eficiency of the system. However, JT produces enormous overhead on both the feedback and backhaul interfaces; thus, partial JT was proposed as a trade of between signaling demand and increased spectral eficiency. Maintaining an equivalent Beamforming (BF) matrix based on a sparse aggregated channel matrix is a challenging issue with regard to linear BF schemes such as Zero-Forcing (ZF). This is mainly because ZF can only invert a well-conditioned matrix. Therefore, a Multi-Start Particle Swarm Optimization Algorithm (MSPSOA) is included in this thesis and used to present an eficient beamformer that achieves equivalent backhaul reduction and high spectral eficiency. Moreover, addressing the lack-of-diversity issue in Basic Particle Swarm Optimization Algorithm (BPSOA) is a primary concern of this work. As a contribution of this thesis, diversity loss can be solved by replacing the inactive particles adaptively based on the difference between local best and global best optimization criterion. In this study, the performance of ZF, BPSOA and the proposed MSPSOA BF are evaluated by using different metrics like acquired sum rate, level of actual interference and transmitting power along with total utility of three different internet applications. The beamformer obtained with the objective function of sum rate maximization achieves a spectral eficiency of 15.3% compared to BPSO BF in some of the conducted scenarios.
1 citations
TL;DR: System throughput of combined direct/cooperative communication is evaluated by exploiting the proposed analytical model based on the IEEE 802.11 MAC protocol and it is observed that the proposed BCC scheme can outperform both the FCC protocol and conventional direct transmission with enhanced system throughput.
Abstract: In recent years, cooperative communication has been developed as a new communication strategy that incorporates a relay node to assist direct point-to-point transmission. By exploiting cooperative diversity, different types of techniques have been proposed to improve transmission reliability from the physical layer perspective. However, owing to the longer transmission time resulting from the cooperative schemes, there is no guarantee to enhance network throughput in view of the medium access control (MAC) performance. In this paper, system throughput of combined direct/cooperative communication is evaluated by exploiting the proposed analytical model based on the IEEE 802.11 MAC protocol. The feasibility of adopting either cooperative or direct communication is also studied in the analytical model. In terms of network throughput, whether to adopt cooperative schemes depends on the tradeoff between cooperative transmission delay and channel quality of direct communication. Moreover, two cooperative MAC protocols are proposed to determine the circumstances to activate cooperative communication according to the channel quality. The full-channel quality indicator based cooperative (FCC) MAC protocol is introduced to choose both the transmission scheme and the relay node according to the full channel quality information. However, the overhead caused by the FCC scheme can degrade the throughput performance as the number of available relays is significantly increased. Therefore, the bitwise competition based cooperative (BCC) MAC protocol is utilized to efficiently determine a feasible relay node for data transmission. Simulations are performed to validate the effectiveness of proposed analytical models and cooperative MAC protocols. It is observed that the proposed BCC scheme can outperform both the FCC protocol and conventional direct transmission with enhanced system throughput.
1 citations
Dissertation•
01 Aug 2014
TL;DR: The pairing optimization is formulated as an axial 3-D assignment problem which is NP-hard, and an iterative optimization method to solve it with complexity O(N) is proposed, based on SNR over each subchannel.
Abstract: We consider two-way amplify-and-forward relaying in a mult ichannel system with two end nodes and a single relay, using a two-slot multi-access b roadcast (MABC) as well as time-division broadcast (TDBC) relaying strategies. We in vestigate the problem of joint subchannel pairing and power allocation to maximize the ach ievable sum-rate in the network, under an individual power budget at each node. To solve this challenging joint optimization problem, an iterative approach is proposed to deco mpose the problem into pairing optimization and joint power allocation optimization, and solve them iteratively. For given power allocation, we first consider the problem of s ubchannel pairing at the relay to maximize the achievable sum rate in TDBC-based netw ork. Unlike in the one-way relaying case, our result shows that there exists no explici t SNR-based subchannel pairing strategy that is optimal for sum-rate maximization for twoay relaying. Nonetheless, for TDBC-based two way relaying, we formulate the pairing optimization as an axial 3-D assignment problem which is NP-hard, and prop ose an iterative optimization method to solve it with complexity O(N). Based on SNR over each subchannel, we also propose sorting-based algorithms for scenarios with a nd without direct link, with a low complexity ofO(N logN). For the joint power allocation at the relay and the two end nod es, we propose another iterative optimization procedure to optimize the power at t he two end nodes and at the relay iteratively. By using different forms of optimization para meters, the sum-rate maximization problem turns out to be convex and the optimal solutions can be obtained for each subproblem. The simulation first demonstrates the proposed sorting-bas ed pairing algorithm offers the performance very close to the iterative optimization me thod. Then, shows the gain of joint optimization approach over other pairing-only or pow er-allocation-only optimization
1 citations
Cites background from "LTE-advanced: next-generation wirel..."
...It has been the underlying system for the current 4G and future wireless system such as L TE [14] and LTE-advanced [15]....
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...It has been the underlying system for the current 4G and future wireless system such as LTE [14] and LTE-advanced [15]....
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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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