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.
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Dissertation•
10 Jul 2012
TL;DR: In this article, a first-order two-dimensional Markov model of the PHY layer is developed, which takes into account the wireless channel characteristics and rate-adaptive modulation and coding (AMC) scheme, resulting in its adoption in most state-of-theart wireless communications standards.
Abstract: [eng] In the last years, the explosive development of wireless services and applications has produced an unprecedented revolution in wireless communications systems. The impact of wireless fading channels on the quality of service (QoS) provisioning for such heterogeneous mobile users is one of the most challenging issues for nextgeneration wireless networks. In order to support the diverse QoS requirements of wireless applications, innovative techniques have been proposed at the physical (PHY) layer. Among them, the rate-adaptive modulation and coding (AMC) scheme has received significant research attention, resulting in its adoption in most state-of-the-art wireless communications standards. With the aim of enhancing the link reliability to guarantee the QoS constraints of new applications, most modern communication systems use error control strategies at the data link control (DLC) layer. Among them, we can distinguish two basic approaches: the forward error correction (FEC) scheme, in which an errorcorrection code is used, and the automatic repeat request (ARQ) scheme, in which a code with good error-detection capability is used. In the latter case, when a received codeword is detected in error, the packet is retransmitted until it is correctly received (infinitely persistent ARQ) or until a preset number of retransmissions have taken place (truncated ARQ). In order to achieve the advantages of both strategies, most state-of-the-art wireless communications standards use combinations of ARQ and FEC. Moreover, recent proposals make use of one or multiple intermediate relay stations to forward data from a source node to the corresponding destination node. As a result, a performance improvement is obtained due to spatial diversity, which is generated by transmitting signals from different locations (source and relay(s)), thus providing independently faded versions of the signal at the receiver. Cross-layer design in wireless networks, where one allows the stack protocol layers to interact and share information, has become increasingly popular over the past few years. In particular, many recent cross-layer proposals coincide in combining AMC at the PHY layer with an ARQ protocol at the DLC layer. These cross-layer designs improve the spectral efficiency by jointly exploiting the adaptability of AMC to the wireless channel conditions and the error-correcting capability of ARQ-based error control strategies. The main goal of this dissertation is to provide a unified view of the crosslayer design, analysis and optimization of AMC/ARQ-based wireless systems to allow the joint optimization of both the PHY and the DLC layers. The adopted approach for tackling this problem will rely on the use of discrete time Markov i chains (DTMCs) to jointly consider the packet arrival, the queueing process and the PHY layer. To that end, a novel first-order two-dimensional Markov model of the PHY layer is developed, which takes into account the wireless channel characteristics and de AMC scheme. The availability of accurate models for the PHY layer characterization is one of the key motivations of this work in order to guarantee a correct analysis of the QoS metrics at the DLC layer. Using this model, the interactions between the PHY and DLC layers are analyzed either when infinitely persistent or truncated ARQ-based error control protocols are implemented. Additionally, a cooperative scheme is also proposed, in which the relay node is in charge of retransmitting the erroneously received packets at the destination. This DTMC-based model allows the analytic derivation of various system performance metrics, namely, throughput, average packet delay and packet loss rate (both due to buffer overflow and due to exceeding the maximum number of allowed retransmissions). For the sake of comparison with non Markov-based analytical tools, the infinitely persistent ARQ protocol is also analyzed through the effective bandwidth/capacity theory. Both analytical frameworks are compared, showing the superiority of the Markov-based approach, which more faithfully reproduces the real system behaviour at the cost of higher complexity in the analysis. The proposed analytical framework allows the formulation of cross-layer multidimensional design strategies, aiming at the maximization of the average throughput of the system while satisfying prescribed QoS requirements in the form of average packet loss rate and average delay. Finally, an explicit analysis of the impact on the system performance of the delay in the channel state information (CSI) feedback is also presented
1 citations
30 Aug 2019
1 citations
IMEC1
TL;DR: In this article, the authors demonstrate the high energy efficiency of the proposed Domain Specific Instruction set Processor (DSIP) architecture template with a case study on a challenging Multiple Input Multiple Output (MIMO) detector design.
Abstract: In this chapter we demonstrate the high energy efficiency of the proposed Domain Specific Instruction set Processor (DSIP) architecture template with a case study on a challenging Multiple Input Multiple Output (MIMO) detector design. Section 4.1 motivates this case study and summarizes related work on MIMO detector implementations. MIMO detection and the flexibility requirements of this functional block are explained in Sect. 4.2. The previously applied algorithm optimizations and the characteristics of the considered algorithm are reviewed in Sect. 4.3. In Sect. 4.4, the DSIP architecture instance for MIMO detection is proposed. Software mapping and hardware implementation results are given in Sect. 4.5. Section 4.6 compares the results to Application Specific Integrated Circuit (ASIC) references and to other programmable implementations. Finally, Sect. 4.7 concludes this chapter.
1 citations
TL;DR: The results show that AF relaying incurs higher capacity loss due to HPA nonlinearity than the DF relaying, and that high-order MIMO systems suffer more capacity loss than low-orders MIMo systems, and more capacity losses are experienced in multihop relaying over nonlinear channels as more relay hops are involved.
Abstract: This paper derives the ergodic capacity of nonlinear MIMO---OFDM relaying communication channels. We consider MIMO---OFDM relaying system where the transmitter, relays, and the receiver are all equipped with $$N_t$$Nt transmitting and $$N_r$$Nr receiving antennas, and the high-power amplifiers (HPAs) at the transmitter and relays exhibit general nonlinear behaviors. We derive closed-form expressions for the ergodic capacity of the system for both the amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols. Our results show that AF relaying incurs higher capacity loss due to HPA nonlinearity than the DF relaying. The results also indicate that high-order MIMO systems suffer more capacity loss due to HPA nonlinearity than low-order MIMO systems, and that more capacity loss are experienced in multihop relaying over nonlinear channels as more relay hops are involved. This analysis complements existing works in the literature, where the effects of HPA on the error rate performance of MIMO systems have been documented. It also helps to stress the need for highly linearized HPA when relaying methods of wireless transmissions are desired.
1 citations
Cites background from "LTE-advanced: next-generation wirel..."
...Recently, the two prominent 4G cellular systems, WiMAX and LTE-advanced, have defined relaying as an integral part of the network design to enhance the quality of service (QoS) performance and extend the coverage of communication systems [9,10]....
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18 Jul 2012
TL;DR: The progressive block matching algorithm (PBMA) is proposed, which utilizes the Euclidean distance to consider the affection of corrupted-residual in block matching principle and outperforms sophisticated EC algorithms by 0.13dB at least on average PSNR, as indicated from experiment result.
Abstract: The robustness of video transmission over wireless channel becomes more and more important especially for 4G mobile communication era. The video error concealment (EC) can recover the visual quality while the transmission error occurs. In this paper, the progressive block matching algorithm (PBMA) is proposed. The PBMA utilizes the Euclidean distance (ED) to consider the affection of corrupted-residual in block matching principle. The PBMA successively recovers the corrupted MB with minimizing the impact of corrupted-residual by ED information. At packet error rate of 20%, this work outperforms sophisticated EC algorithms by 0.13dB at least on average PSNR, as indicated from experiment result.
1 citations
Cites background from "LTE-advanced: next-generation wirel..."
...This trend could be standardized into one of following two technologies: Worldwide Interoperability for Microwave Access (WiMAX) [1] and Third Generation Partnership Project (3GPP) technologies on Long-Term Evolution (LTE) [2]....
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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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