Showing papers on "LTE Advanced published in 2010"

LTE-advanced: next-generation wireless broadband technology [Invited Paper]

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.

Coordinated multipoint transmission/reception techniques for LTE-advanced [Coordinated and Distributed MIMO]

Abstract: This article presents an elaborate coordination technique among multiple cell sites called coordinated multipoint transmission and reception in the Third Generation Partnership Project for LTE-Advanced. After addressing major radio access techniques in the LTE Release 8 specifications, system requirements and applied radio access techniques that satisfy the requirements for LTE-Advanced are described including CoMP transmission and reception. Then CoMP transmission and reception schemes and the related radio interface, which were agreed upon or are currently being discussed in the 3GPP, are presented. Finally, system-level simulation evaluations show that the CoMP transmission and reception schemes have a significant effect in terms of improving the cell edge user throughput based on LTE-Advanced simulation conditions.

LTE-Advanced: Heterogeneous networks

Abstract: Long-Term Evolution (LTE) allows operators to use new and wider spectrum and complements 3G networks with higher data rates, lower latency and a flat IP-based architecture. To further improve broadband user experience in a ubiquitous and cost effective manner, 3GPP has been working on various aspects in the framework of LTE Advanced. Since radio link performance is approaching theoretical limits with 3G enhancements and LTE, the next performance leap in wireless networks will come from the network topology. LTE Advanced is about improving spectral efficiency per unit area. Using a mix of macro, pico, femto and relay base-stations, heterogeneous networks enable flexible and low-cost deployments and provide a uniform broadband experience to users anywhere in the network. This paper discusses the need for an alternative deployment model or topology using heterogeneous networks. To enhance the performance of these networks, advanced techniques are described which are needed to manage and control interference and deliver the full benefits of such networks. Range extension allows more user terminals to benefit directly from low-power base-stations such as picos, femtos, and relays. Adaptive inter-cell interference coordination provides smart resource allocation amongst interfering cells and improves inter-cell fairness in a heterogeneous network. In addition, the performance gains with heterogeneous networks using an example macro/pico network are shown.

Cell Association and Interference Coordination in Heterogeneous LTE-A Cellular Networks

Abstract: Embedding pico/femto base-stations and relay nodes in a macro-cellular network is a promising method for achieving substantial gains in coverage and capacity compared to macro-only networks. These new types of base-stations can operate on the same wireless channel as the macro-cellular network, providing higher spatial reuse via cell splitting. However, these base-stations are deployed in an unplanned manner, can have very different transmit powers, and may not have traffic aggregation among many users. This could potentially result in much higher interference magnitude and variability. Hence, such deployments require the use of innovative cell association and inter-cell interference coordination techniques in order to realize the promised capacity and coverage gains. In this paper, we describe new paradigms for design and operation of such heterogeneous cellular networks. Specifically, we focus on cell splitting, range expansion, semi-static resource negotiation on third-party backhaul connections, and fast dynamic interference management for QoS via over-the-air signaling. Notably, our methodologies and algorithms are simple, lightweight, and incur extremely low overhead. Numerical studies show that they provide large gains over currently used methods for cellular networks.

MIMO techniques in WiMAX and LTE: a feature overview

Abstract: IEEE 802.16m and 3GPP LTE-Advanced are the two evolving standards targeting 4G wireless systems. In both standards, multiple-input multiple-output antenna technologies play an essential role in meeting the 4G requirements. The application of MIMO technologies is one of the most crucial distinctions between 3G and 4G. It not only enhances the conventional point-to-point link, but also enables new types of links such as downlink multiuser MIMO. A large family of MIMO techniques has been developed for various links and with various amounts of available channel state information in both IEEE 802.16e/m and 3GPP LTE/LTE-Advanced. In this article we provide a survey of the MIMO techniques in the two standards. The MIMO features of the two are compared, and the engineering considerations are depicted.

Mode Selection for Device-To-Device Communication Underlaying an LTE-Advanced Network

Abstract: Device-to-Device communication underlaying a cellular network enables local services with limited interference to the cellular network. In this paper we study the optimal selection of possible resource sharing modes with the cellular network in a single cell. Based on the learning from the single cell studies we propose a mode selection procedure for a multi-cell environment. Our evaluation results of the proposed procedure show that it enables a much more reliable device-to-device communication with limited interference to the cellular network compared to simpler mode selection procedures. A well performing and practical mode selection is critical to enable the adoption of underlay device-to-device communication in cellular networks.

Carrier aggregation for LTE-advanced mobile communication systems

Abstract: In order to achieve up to 1 Gb/s peak data rate in future IMT-Advanced mobile systems, carrier aggregation technology is introduced by the 3GPP to support very-high-data-rate transmissions over wide frequency bandwidths (e.g., up to 100 MHz) in its new LTE-Advanced standards. This article first gives a brief review of continuous and non-continuous CA techniques, followed by two data aggregation schemes in physical and medium access control layers. Some technical challenges for implementing CA technique in LTE-Advanced systems, with the requirements of backward compatibility to LTE systems, are highlighted and discussed. Possible technical solutions for the asymmetric CA problem, control signaling design, handover control, and guard band setting are reviewed. Simulation results show Doppler frequency shift has only limited impact on data transmission performance over wide frequency bands in a high-speed mobile environment when the component carriers are time synchronized. The frequency aliasing will generate much more interference between adjacent component carriers and therefore greatly degrades the bit error rate performance of downlink data transmissions.

Carrier aggregation framework in 3GPP LTE-advanced [WiMAX/LTE Update]

Abstract: Carrier aggregation is one of the most distinct features of 4G systems including LTEAdvanced, which is being standardized in 3GPP as part of LTE Release 10. This feature allows scalable expansion of effective bandwidth delivered to a user terminal through concurrent utilization of radio resources across multiple carriers. These carriers may be of different bandwidths, and may be in the same or different bands to provide maximum flexibility in utilizing the scarce radio spectrum available to operators. Support for this feature requires enhancement to the LTE Release 8/9 PHY, MAC, and RRC layers while ensuring that LTE Release 10 maintains backward compatibility to LTE Release 8/9. This article provides an overview of carrier aggregation use cases and the framework, and their impact on LTE Release 8/9 protocol layers.

Fundamentals of LTE

Abstract: The Definitive Guide to LTE Technology Long-Term Evolution (LTE) is the next step in the GSM evolutionary path beyond 3G technology, and it is strongly positioned to be the dominant global standard for 4G cellular networks. LTE also represents the first generation of cellular networks to be based on a flat IP architecture and is designed to seamlessly support a variety of different services, such as broadband data, voice, and multicast video. Its design incorporates many of the key innovations of digital communication, such as MIMO (multiple input multiple output) and OFDMA (orthogonal frequency division multiple access), that mandate new skills to plan, build, and deploy an LTE network. In Fundamentals of LTE, four leading experts from academia and industry explain the technical foundations of LTE in a tutorial style providing a comprehensive overview of the standards. Following the same approach that made their recent Fundamentals of WiMAX successful, the authors offer a complete framework for understanding and evaluating LTE. Topics includeCellular wireless history and evolution: Technical advances, market drivers, and foundational networking and communications technologiesMulticarrier modulation theory and practice: OFDM system design, peak-to-average power ratios, and SC-FDE solutionsFrequency Domain Multiple Access: OFDMA downlinks, SC-FDMA uplinks, resource allocation, and LTE-specific implementationMultiple antenna techniques and tradeoffs: spatial diversity, interference cancellation, spatial multiplexing, and multiuser/networked MIMOLTE standard overview: air interface protocol, channel structure, and physical layersDownlink and uplink transport channel processing: channel encoding, modulation mapping, Hybrid ARQ, multi-antenna processing, and morePhysical/MAC layer procedures and scheduling: channel-aware scheduling, closed/open-loop multi-antenna processing, and morePacket flow, radio resource, and mobility management: RLC, PDCP, RRM, and LTE radio access network mobility/handoff procedures

Carrier Aggregation in LTE-Advanced

Abstract: UMTS LTE system can support flexible bandwidth configuration up to 20 MHz. Currently, system enhancements are being considered to provide substantial improvements to LTE and allow it to meet or exceed IMT-Advanced requirements. One key enhancement feature is bandwidth extension via carrier aggregation to support deployment bandwidth up to 100 MHz. This will allow peak target data rates in excess of 1 Gbps in the downlink and 500 Mbps in the uplink to be achieved. Carrier aggregation is attractive because it allows operators to deploy a system with larger bandwidth by aggregating several smaller contiguous or non-contiguous carriers while providing backward compatibility to legacy users. For instance, an 80MHz system can be constructed using contiguous or non-contiguous 4×20MHz component carriers. Legacy users can then access the system using one of the component carriers. This paper provides an overview of carrier aggregation and discusses major technical issues including aggregation structure, scenarios, implementation, control signalling design and coexistence with legacy LTE systems.

A method and apparatus for mimo repeater chains in a wireless communication network

Abstract: In one or more embodiments taught herein, a multi-band MIMO repeater is configured to translate normal wireless mobile bands into other frequency bands in the physical layer. An advantageous, multi-hop repeater chain includes two or more such repeaters, for propagating downlink signals from a base station, and for propagating uplink signals to the base station. Each such repeater may use paralleled homodyne structure transceivers for better SNR, spectrum combiners for uplink signal aggregation, spectrum separators for downlink signal de-aggregation, water mark signal inserters for optimization, and, among other things, spectrum analyzers for frequency band selection. In at least one such embodiment, a multi-hop repeater chain is configured for MIMO operation in an LTE Advanced or other MIMO network, to deliver high data rate over larger distances — e.g., further away from cell base stations.

Carrier load balancing and packet scheduling for multi-carrier systems

Abstract: -In this paper we focus on resource allocation for next generation wireless communication systems with aggregation of multiple Component Carriers (CCs), i.e., how to assign the CCs to each user, and how to multiplex multiple users in each CC. We first investigate two carrier load balancing methods for allocating the CCs to the users- Round Robin (RR) and Mobile Hashing (MH) balancing by means of a simple theoretical formulation, as well as system level simulations. At Layer-2 we propose a simple cross-CC packet scheduling algorithm that improves the coverage performance and the resource allocation fairness among users, as compared to independent scheduling per CC. The Long Term Evolution (LTE)-Advanced is selected for the case study of a multi-carrier system. In such a system, RR provides better performance than MH balancing, and the proposed simple scheduling algorithm is shown to be effective in providing up to 90% coverage gain with no loss of the overall cell throughput, as compared to independent scheduling per CC.

Signaling uplink control information in lte-a

Abstract: Methods and systems for transmitting uplink control information in an LTE Advanced system are disclosed. A user device may determine whether uplink control information and/or available channels meet certain criteria and determine whether the uplink control information should be transmitted on a physical uplink control channel, a physical uplink shared channel, or both, based on the criteria. Criteria may include the size of the uplink control information (absolute size or relative to space available on a channel or a threshold value), the type of control information bits, the number of available (i.e., active or configured) component carriers, and the amount of power that may be required to transmit the uplink control information on more than one channel.

A Novel Handover Mechanism Between Femtocell and Macrocell for LTE Based Networks

Abstract: The femtocell networks that use Home eNodeB and existing networks as backhaul connectivity can fulfill the upcoming demand of high data rate for wireless communication system as well as can extend the coverage area. It is also of interest to minimize operational effort by introducing self-optimizing mechanisms, and the optimization of the Home eNodeB involved handover is an important goal of LTE-Advanced. Since the different network architecture and functionality between Home eNodeB and LTE eNodeB, the handover procedure between the femtocell and macrocell should be modified in LTE network. In this paper, modified signaling procedure of handover is presented in the Home eNodeB gateway based femtocell network architecture. A new handover algorithm based on the UE’s speed and QoS is proposed. The comparison between the proposed algorithm and the traditional handover algorithm shows that the algorithms proposed in this paper have a better performance in the reducing of unnecessary handovers and the number of handovers.

Machine-to-Machine Communication in LTE-A

Abstract: Wireless equipped machines are increasing greatly in recent years, among which the cellular network based machine-to-machine communication (M2M) has shown the advantages of better coverage and lower network deployment cost However, the current cellular network is designed for human-to-human communication, targeting the voice/media transmission with low access delay and high throughput, so the machines in GSM and UMTS are designed like a screenless phone To extend the market to machine type communication, it is envisaged that the specific optimizations for M2M will be introduced in LTE-A, especially when M2M communication accounts for the considerable part in the total networking activities In this paper, some of the considerations of the network side improvements are presented, from the physical layer, MAC to core network

Centralized scheduling for joint transmission coordinated multi-point in LTE-Advanced

Abstract: Coordinated multi-point transmission/reception is considered for LTE-Advanced as a tool to improve the coverage of high data rates, the cell-edge throughput and/or to increase the system throughput [1]. Joint transmission schemes are mentioned in [1] as an example of coordinated transmission between cells for the downlink. Here, data are transmitted simultaneously either coherently or non-coherently from multiple cells to a single mobile station. In this paper, a centralized MAC scheduling approach for joint transmission coordinated multi-point (JT CoMP) is proposed. Since several base stations transmit jointly to a single mobile station, the base stations are grouped together in so-called clusters. Several cluster strategies are investigated as well. The focus is on schemes that add only low complexity to the existing 3GPP LTE Release 8 system. Simulation results are provided for non-coherent transmission for full buffer and bursty traffic models with various system loads for different static cell clustering approaches.

Scrambling sequence initialization for coordinated multi-point transmissions

Abstract: Methods, systems, apparatus and computer program products are provided for generating a shared initialization code for physical channel data scrambling in an LTE Advanced coordinated multipoint transmission network. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the disclosed subject matter. Therefore, it is to be understood that it should not be used to interpret or limit the scope or the meaning of the claims.

Toward LTE commercial launch and future plan for LTE enhancements (LTE-Advanced)

Abstract: As a promising radio access technology for next generation mobile communication systems, LTE (Long-Term Evolution) is being standardized by the 3rd Generation Partnership Project (3GPP) international standardization organization. LTE Release 8 has many advantages to the other systems, e.g., the peak throughput is 300Mbps in Downlink (DL) and 75Mbps in Uplink (UL), 2–3 time higher spectrum efficiency than Rel. 6 HSPA (High Speed Packet Access), very low latency around 5msec in RAN (Radio Access Network) and 100msec for connection setup time. With Release 8, the first version for LTE specification, being completed in March 2009, the LTE standard is now being developed towards commercialization in various countries in the world. This paper addresses the plan for LTE commercial launch in NTT DOCOMO and future plan for LTE Rel. 9 and LTE-Advanced (LTE Rel. 10 and beyond).

Uplink resource allocation for lte advanced

Abstract: Methods, systems, apparatus and computer program products are provided to receive downlink control information (DCI) in a downlink control channel, where the downlink control information configured to indicate an allocation of uplink resources with a clustered uplink resource allocation protocol or a contiguous uplink resource allocation protocol, to detect which of the clustered uplink resource allocation protocol and the contiguous uplink resource allocation protocol is indicated and to allocate the uplink resources based on the indicated uplink resource allocation protocol.

Long‐Term Evolution

Abstract: This chapter contains sections titled: Introduction System Architecture Transmission Techniques in the LTE System Channels in the Radio Interface of the LTE System Radio Resource Management in LTE References

LTE-advanced : next-generation wireless broadband technology [Invited Paper]

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.

On the coverage extension and capacity enhancement of inband relay deployments in LTE-advanced networks

Abstract: Decode-and-forward relaying is a promising enhancement to existing radio access networks and is currently being standardized in 3GPP to be part of the LTE-Advanced release 10. Two inband operation modes of relay nodes are to be supported, namely Type 1 and Type 1b. Relay nodes promise to offer considerable gain for system capacity or coverage depending on the deployment prioritization. However, the performance of relays, as any other radio access point, significantly depends on the propagation characteristics of the deployment environment. Hence, in this paper, we investigate the performance of Type 1 and Type 1b inband relaying within the LTE-Advanced framework in different propagation scenarios in terms of both coverage extension capabilities and capacity enhancements. A comparison between Type 1 and Type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay node deployments. System level simulations show that Type 1 and Type 1b inband relay deployments offer low to very high gains depending on the deployment environment. As well, it is shown that the effect of the relaying overhead is minimal on coverage extension whereas it is more evident on system throughput.

Cognitive Interference Management for LTE-A Femtocells with Distributed Carrier Selection

Abstract: The concept of small cells such as femtocells has been regarded as a promising solution to overcome the indoor coverage problem and deal with the growth of traffic within macrocells. However, the unpredictable deployment pattern of such cells makes centralized network planning impractical and requires more efficient interference management and distributed spectrum planning schemes to realize the benefit of femtocells. In this paper, we propose a cognitive-based interference management solution for LTE-Advanced (LTE-A) femtocells by sharing measured pathloss information among neighbors and selecting component carriers according to the estimated mutual interference. System-level simulation results demonstrate that the proposed scheme can effectively avoid spectrum collision and significantly improve overall network capacity.

A high-speed railway mobile communication system based on LTE

Abstract: Along with the developments of the high-speed railway, higher and higher technical requirements for the high-speed railway mobile communication system are raised. Since the “Global System for Mobile Communications Railways” (GSM-R) implemented today is based on GSM, the new technology in GSM evolution can be used in the highspeed railway mobile communication system to adapt to the new requirements. This paper introduces a high-speed railway mobile communication system based on “Long Term Evolution” (LTE), describes its network architecture, and especially analyzes the technical advantages and application value of the system in the high-speed railway wireless communication comparing with the existing GSM-R system. It also discusses feasibility of the GSM-R system's evolution to this high-speed railway mobile communication system and proposes the possible evolution model.

Pucch resource allocation for carrier aggregation in lte-advanced

Abstract: The invention is a method and apparatus for signaling uplink control information in a mobile communication network using carrier aggregation. The signaling mechanism allows the transmission, on a single uplink component carrier, of control information associated with a downlink transmission on multiple aggregated downlink component carriers. Semi-statically reserved resources for the transmission of control information on the uplink component carrier may be dynamically shared byuser terminals that are assigned multiple downlink component carriers for downlink transmissions. Implicit or explicit resource indication can be used in combination with dynamic resource indication.

WiMAX or LTE: Who will Lead the Broadband Mobile Internet?

Abstract: Two main technologies are competing for the International Mobile Telecommunications (IMT)-Advanced initiative: WiMAX and LTE. This comparison reviews their development and deployment and provides an outlook on their adoption as 4G technologies.

Cell-Specific Uplink Power Control for Heterogeneous Networks in LTE

Abstract: This paper provides an assessment of 3GPP standardized LTE/LTE-A uplink power control procedures in case of a co-channel operation of different types of base stations. Especially the case of femtocell deployment with an overlaying macrocell is considered. Imperfections of the currently accepted procedures in case of such networks are pointed and a modified solution is proposed. It is shown that in case of heterogeneous networks more cell-specific configuration can lead to 8% and 14% performance improvements in capacity and coverage of local cells respectively, without harm for overlying macrocells. The evaluation of the proposed scheme has been done on case of a macro and femto co-channel deployment, but should be also valid for other cell types.

Method and system for configuration of measurement reference signals in LTE-A system

Abstract: The invention discloses a method and a system for configuration of measurement reference signals in an LTE-A system, thereby leading a base station to be convenient to trigger a UE to send SRS signals at any time and measuring a channel at any time. The configuration method comprises the following steps: leading the base station to trigger one or more user equipment (UE) to send non-periodic measurement reference signals (SRS) on one or more uplink sub-frames through downlink control signaling. The adoption of the non-periodic SRS configuration method and the system can determine resources used by the non-periodic SRS, improve the UE channel measurement efficiency and better meet the requirements on the channel measurement of the LTE-A system. In addition, the impacts and the conflicts of periodic and non-periodic SRS in the LTE-A system can be effectively avoided by reserving the non-periodic SRS resources.

Performance Enhancement in LTE-Advanced Relay Networks via Relay Site Planning

Abstract: Relaying is considered a promising cost-efficient solution in 3GPP LTE-Advanced for coverage extension and throughput enhancement Due to compact physical characteristics and low power requirements of the relay nodes, the relay deployment has a high degree of freedom In this paper, the impact of site planning on the backhaul performance of relay networks within the LTE-Advanced framework is investigated The site planning strategies are formulated in terms of SNR and SINR based selection criteria 3GPP compliant simulations are performed comparing relay site planning strategies It is shown that proper site planning yields significant SINR gain on the eNB-RN link along with a clear reduction in the shadowing standard deviation compared to random deployment