LONG TERM EVOLUTION INVOLVES CHANGES TO BOTH RADIO INTERFACE AND NETWORK ARCHITECTURE IN ORDER TO KEEP 3RD GENERATION PARTNERSHIP PROJECT TECHNOLOGY COMPETITIVE. OFDMA WAS CHOSEN AS THE DOWNLINK AIR INTERFACE DUE TO ITS ADVANTAGES SUCH AS HIGH SPECTRAL EFFICIENCY AND ROBUSTNESS. THE PAPER DESCRIBES THE CELL SEARCH PROCEDURE AND POTENTIAL DESIGNS FOR THE PRIMARY AND SECONDARY SYNCHRONIZATION CHANNELS TO FACILITATE TIMING AND FREQUENCY SYNCHRONIZATION WITH LOW COMPLEXITY. SEVERAL
This document provides formulas and proposed targets for key performance indicators (KPIs) related to LTE network monitoring. It includes KPIs for LTE OSS statistics measured at the network level and LTE drive test KPIs measured through field testing. For each KPI, it provides the detailed formula, measurement methodology, and a brief description. The goal is to establish a framework for initial discussion on monitoring LTE network performance.
The document discusses LTE network architecture including nodes like the eNodeB, MME, SGW and PGW, and their functions. It also outlines the basic LTE call flows for initial call setup, detach procedures, idle-to-active transitions, and handovers. Key call flow steps include attach request, authentication, context setup, and establishment of bearers between the UE and PDN gateway.
TTI bundling is a technique used in LTE to improve uplink coverage for voice calls by transmitting the same transport block containing voice data over multiple consecutive subframes without waiting for HARQ feedback. This provides a coding gain of up to 4dB compared to single subframe transmission, allowing power-limited UEs at the cell edge to be received with sufficient quality. TTI bundling can be implemented in both FDD and TDD LTE networks but with some differences due to limitations on consecutive uplink subframes in TDD configurations. It provides lower latency voice transmission compared to alternatives like RLC segmentation while reducing overhead.
3GPP SON Series: Mobility Load Balancing (MLB)3G4G
This SON tutorial is part of the 3GPP Self-Organizing Networks series (#3GPPSONSeries). In this part we discuss the load balancing feature that was introduced as part of 3GPP Release-8 LTE. We also look at the enhancements in Release-9 and then the extension of this procedure to GSM (2G) and UMTS (3G) as part of Release-10.
All our #3G4G5G slides and videos are available at:
Videos: https://www.youtube.com/3G4G5G
Slides: https://www.slideshare.net/3G4GLtd
5G Page: https://www.3g4g.co.uk/5G/
Free Training Videos: https://www.3g4g.co.uk/Training/
SON Page: https://www.3g4g.co.uk/SON/
The document discusses key performance indicators (KPIs) for the E-UTRAN and EPC components of an LTE network, including accessibility, retainability, integrity, availability, and mobility metrics for E-UTRAN and accessibility, mobility, and utilization KPIs for EPC. It provides definitions and formulas for calculating various KPIs related to EPS attach success rate, dedicated bearer creation success rate, handover success rates, and other measures of network and service performance.
This document discusses LTE network coverage optimization. It identifies six main causes of coverage problems: incorrect network planning, deviations from planned site positions, differences between actual and planned parameters, changes to the wireless environment, new coverage requirements, and increased network load. The document notes that coverage optimization aims to eliminate downlink coverage issues like holes, weakness, overshooting, and lack of a dominant cell, as well as optimize uplink coverage, balance uplink/downlink coverage, reduce interference, and improve handovers. Common optimization methods include antenna, feeder and parameter adjustments.
1) The mobile device searches for synchronization signals to detect available LTE cells and identifies key parameters like PCI from the PSS and SSS.
2) It then receives the MIB and SIBs containing configuration details to access the network from the selected cell.
3) The attach procedure is started, establishing an RRC connection and authenticating the user to activate a default bearer for IP data transmission.
This document provides formulas and proposed targets for key performance indicators (KPIs) related to LTE network monitoring. It includes KPIs for LTE OSS statistics measured at the network level and LTE drive test KPIs measured through field testing. For each KPI, it provides the detailed formula, measurement methodology, and a brief description. The goal is to establish a framework for initial discussion on monitoring LTE network performance.
The document discusses LTE network architecture including nodes like the eNodeB, MME, SGW and PGW, and their functions. It also outlines the basic LTE call flows for initial call setup, detach procedures, idle-to-active transitions, and handovers. Key call flow steps include attach request, authentication, context setup, and establishment of bearers between the UE and PDN gateway.
TTI bundling is a technique used in LTE to improve uplink coverage for voice calls by transmitting the same transport block containing voice data over multiple consecutive subframes without waiting for HARQ feedback. This provides a coding gain of up to 4dB compared to single subframe transmission, allowing power-limited UEs at the cell edge to be received with sufficient quality. TTI bundling can be implemented in both FDD and TDD LTE networks but with some differences due to limitations on consecutive uplink subframes in TDD configurations. It provides lower latency voice transmission compared to alternatives like RLC segmentation while reducing overhead.
3GPP SON Series: Mobility Load Balancing (MLB)3G4G
This SON tutorial is part of the 3GPP Self-Organizing Networks series (#3GPPSONSeries). In this part we discuss the load balancing feature that was introduced as part of 3GPP Release-8 LTE. We also look at the enhancements in Release-9 and then the extension of this procedure to GSM (2G) and UMTS (3G) as part of Release-10.
All our #3G4G5G slides and videos are available at:
Videos: https://www.youtube.com/3G4G5G
Slides: https://www.slideshare.net/3G4GLtd
5G Page: https://www.3g4g.co.uk/5G/
Free Training Videos: https://www.3g4g.co.uk/Training/
SON Page: https://www.3g4g.co.uk/SON/
The document discusses key performance indicators (KPIs) for the E-UTRAN and EPC components of an LTE network, including accessibility, retainability, integrity, availability, and mobility metrics for E-UTRAN and accessibility, mobility, and utilization KPIs for EPC. It provides definitions and formulas for calculating various KPIs related to EPS attach success rate, dedicated bearer creation success rate, handover success rates, and other measures of network and service performance.
This document discusses LTE network coverage optimization. It identifies six main causes of coverage problems: incorrect network planning, deviations from planned site positions, differences between actual and planned parameters, changes to the wireless environment, new coverage requirements, and increased network load. The document notes that coverage optimization aims to eliminate downlink coverage issues like holes, weakness, overshooting, and lack of a dominant cell, as well as optimize uplink coverage, balance uplink/downlink coverage, reduce interference, and improve handovers. Common optimization methods include antenna, feeder and parameter adjustments.
1) The mobile device searches for synchronization signals to detect available LTE cells and identifies key parameters like PCI from the PSS and SSS.
2) It then receives the MIB and SIBs containing configuration details to access the network from the selected cell.
3) The attach procedure is started, establishing an RRC connection and authenticating the user to activate a default bearer for IP data transmission.
The document describes parameter handling for Nokia's BSC/TCSM base station controller. It contains over 20 commands for modifying parameters related to general BSC configuration, radio network supervision, quality of service, GPRS, and background data activation. The commands allow operators to control functions like priority levels, dynamic frequency allocation, network monitoring thresholds, and more. Release notes describe changes between documentation issues, such as new parameters and updated output formats.
1. The document discusses NSA mobility management for Huawei's 5G network, including procedures for adding, changing, and releasing the secondary node (SgNB).
2. Key procedures covered include SgNB addition triggered by the MeNB, intra-SgNB and inter-SgNB PSCell changes, and intra-MeNB and inter-MeNB handovers.
3. NSA mobility is anchored to the LTE network, with the eNodeB delivering NR measurement configurations and processing measurement reports.
The document describes network identities and procedures used in LTE attach flows. It discusses identifiers like GUTI, RNTI, and bearers. The attach flow involves the UE sending an attach request to the eNB which triggers authentication and establishment of default bearer towards the PGW, after which the UE receives an attach accept. Timers are involved at different nodes during this process.
The document describes call flows for circuit switched fallback (CSFB) in an EPS network. It discusses the network architecture involving an MME, MSC Server and SGs interface. It then provides details on attach procedures, SMS over SGs, and mobile originating and terminating call flows. The flows illustrate how a device registered in both the MME and MSC can initiate and receive CS services like calls and SMS when camped on an LTE network via CSFB.
The document discusses LTE system signaling procedures. It begins with objectives of understanding LTE architecture, elementary procedures of interfaces like S1, X2 and Uu, and procedures for service setup, release and handover. It then covers topics like system architecture, bearer service architecture, elementary procedures on Uu including connection establishment and release, and procedures on S1 and X2 interfaces. The document aims to help readers understand LTE signaling flows and procedures.
The document describes the 5G registration process between a UE and AMF. It involves the following key steps:
1. The UE sends a registration request to the AMF via the (R)AN.
2. The AMF authenticates the UE and retrieves subscription data. If a new AMF is selected, it retrieves the UE context from the old AMF.
3. If registration is successful, the AMF sends a registration accept message to the UE to complete the process. It also notifies other network functions like SMFs and PCF.
This document provides an overview of LTE functionalities and features. It begins with background on LTE development and standardization. It then describes the LTE network elements and interfaces, including the radio interface between UE and eNB. The document reviews the RRM framework and lists key RRM features, providing status updates on which features are ready in the current release or planned for future releases. It also includes roadmaps showing the planned features and timeline for LTE releases. The document appears to be an internal presentation on LTE technologies and the Nokia Siemens Networks product roadmap.
This document discusses LTE CS Fallback features which allow LTE networks to reuse CS infrastructure to provide voice and other circuit switched services. CS Fallback enables LTE terminals to redirect to 2G/3G networks when initiating CS services like voice calls. The key aspects covered include the CS Fallback network architecture using the SGs interface, the combined attach procedure used for location updates, advantages/disadvantages of different CS Fallback mechanisms, and signaling flows for CS Fallback and paging.
Beginners: 5G Terminology (Updated - Feb 2019)3G4G
This document discusses 5G terminology and deployment options. It provides an overview of the evolution of mobile technology standards over time. It explains the differences between 4G LTE and 5G NR networks, as well as various options for non-standalone and standalone 5G network deployment and the migration strategies between these options. Key 5G concepts like gNBs, NG-RAN architecture and the 5G system architecture are also summarized.
This document provides instructions for logging into an LMT base station, configuring the FTP server and Java settings, and downloading and uploading the data configuration file (XML) to and from the base station. It lists the default IP address and login credentials for accessing the base station interface, provides guidance on changing the FTP password, downloading the FTP server software, and configuring the allowed Java sites. It also outlines the steps to select the server IP, folder location, username, and FTP password when downloading or uploading the XML file between the laptop and base station.
The document provides an overview of LTE and its evolution from previous cellular standards. It discusses the targets of LTE including high data rates up to 100 Mbps, low latency, high spectral efficiency, and flexibility in spectrum and bandwidth. It also describes the EPS architecture with E-UTRAN, EPC, and the air interface structure of LTE including OFDMA in the downlink and SC-FDMA in the uplink. Key layers like the PHY, MAC, and RLC layers are also summarized.
We are going to cover complete list of VoLTE IMS KPI and performance Indicators . This includes :-
VoLTE IMS Control Plane KPI
- RSR : Registration Success Ratio (%)
- CSSR : Call Setup Success Rate (%)
- CST : Call Setup Time (s)
- MHT/ACD : Average Call duration (s)
VoLTE IMS User Plane KPI
- Mute Rate (%)
- MOS Score (1-5)
- RTP Packet Loss (%)
- One Way Calls (%)
Packet Core 4G Network LTE KPI
- Volte Attach Success Rate (%)
- VoLTE QCI=5 Paging Success Rate (%)
- Dedicated Bearer Activation Success Rate (%)
- IMS IP POOL Utilization (%)
- Create Bearer Success Rate (%)
Radio VoLTE KPI
- Call Drop rate (%)
- SRVCC Success Rate (%)
- Handover SR (%)
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
- To support CS services like voice in LTE networks, different phases of evolution have been proposed including CSFB and VoLTE.
- CSFB allows CS services to work by falling back to legacy 2G/3G networks, while VoLTE supports native voice over IP capabilities in LTE.
- SRVCC allows seamless handover of VoLTE calls between LTE and legacy networks by transferring sessions between the core networks.
This document is a thesis submitted by Abdul Basit in partial fulfillment of the requirements for a Masters of Science degree. The thesis focuses on dimensioning of LTE networks, including describing models and tools for coverage and capacity estimation of the 3GPP Long Term Evolution radio interface. The thesis developed methods and models for coverage and capacity planning in LTE network dimensioning. It also created an easy-to-use Excel-based tool to calculate the number of cells needed to cover a given area based on user-provided dimensioning parameters. The tool is designed to cover the basic aspects of dimensioning LTE access networks in a clear and user-friendly manner.
The document provides an overview of cellular communications signaling for LTE, LTE-A, and 4G technologies. It describes the LTE architecture including functions of the evolved node B, mobility management entity, serving gateway, home subscriber server, and PDN gateway. It also provides details on the LTE physical layer including OFDMA modulation, reference signal measurements for handover, and an example handover procedure using the X2 interface. In conclusion, it discusses key criteria for designing handovers and aspects for further research.
This document summarizes the key procedures and signal flows in setting up an LTE session for a UE:
1) The UE establishes an RRC connection with the eNodeB through random access and preamble signaling.
2) The UE then attaches to the core network through the MME, and authentication procedures are performed.
3) Finally, the default bearer for user data is established through signaling between the UE, eNodeB, MME, SGW and PGW. Once complete, user data sessions can be exchanged.
This document discusses key aspects of providing Quality of Service (QoS) and priority access for public safety in LTE networks. It covers:
1. Controlling access to the air interface through mechanisms like access class barring which allow reserving access for priority users.
2. Controlling the use of network resources by mapping applications to EPS bearers that have QoS Class Identifiers and Allocation Retention Priority levels assigned.
3. Ensuring roaming and handover do not impact the QoS and priority access provided to public safety users.
Self-Configuration and Self-Optimization NetworkPraveen Kumar
The document discusses self-configuration and self-optimization capabilities in cellular networks. It describes functions like dynamic configuration of interfaces between network elements, automatic neighbor relation functions to detect neighboring cells, and framework for physical channel identification selection. It also covers self-optimization aspects like energy saving, interference reduction, mobility robustness optimization, load balancing optimization, and interference coordination.
The document describes parameter handling for Nokia's BSC/TCSM base station controller. It contains over 20 commands for modifying parameters related to general BSC configuration, radio network supervision, quality of service, GPRS, and background data activation. The commands allow operators to control functions like priority levels, dynamic frequency allocation, network monitoring thresholds, and more. Release notes describe changes between documentation issues, such as new parameters and updated output formats.
1. The document discusses NSA mobility management for Huawei's 5G network, including procedures for adding, changing, and releasing the secondary node (SgNB).
2. Key procedures covered include SgNB addition triggered by the MeNB, intra-SgNB and inter-SgNB PSCell changes, and intra-MeNB and inter-MeNB handovers.
3. NSA mobility is anchored to the LTE network, with the eNodeB delivering NR measurement configurations and processing measurement reports.
The document describes network identities and procedures used in LTE attach flows. It discusses identifiers like GUTI, RNTI, and bearers. The attach flow involves the UE sending an attach request to the eNB which triggers authentication and establishment of default bearer towards the PGW, after which the UE receives an attach accept. Timers are involved at different nodes during this process.
The document describes call flows for circuit switched fallback (CSFB) in an EPS network. It discusses the network architecture involving an MME, MSC Server and SGs interface. It then provides details on attach procedures, SMS over SGs, and mobile originating and terminating call flows. The flows illustrate how a device registered in both the MME and MSC can initiate and receive CS services like calls and SMS when camped on an LTE network via CSFB.
The document discusses LTE system signaling procedures. It begins with objectives of understanding LTE architecture, elementary procedures of interfaces like S1, X2 and Uu, and procedures for service setup, release and handover. It then covers topics like system architecture, bearer service architecture, elementary procedures on Uu including connection establishment and release, and procedures on S1 and X2 interfaces. The document aims to help readers understand LTE signaling flows and procedures.
The document describes the 5G registration process between a UE and AMF. It involves the following key steps:
1. The UE sends a registration request to the AMF via the (R)AN.
2. The AMF authenticates the UE and retrieves subscription data. If a new AMF is selected, it retrieves the UE context from the old AMF.
3. If registration is successful, the AMF sends a registration accept message to the UE to complete the process. It also notifies other network functions like SMFs and PCF.
This document provides an overview of LTE functionalities and features. It begins with background on LTE development and standardization. It then describes the LTE network elements and interfaces, including the radio interface between UE and eNB. The document reviews the RRM framework and lists key RRM features, providing status updates on which features are ready in the current release or planned for future releases. It also includes roadmaps showing the planned features and timeline for LTE releases. The document appears to be an internal presentation on LTE technologies and the Nokia Siemens Networks product roadmap.
This document discusses LTE CS Fallback features which allow LTE networks to reuse CS infrastructure to provide voice and other circuit switched services. CS Fallback enables LTE terminals to redirect to 2G/3G networks when initiating CS services like voice calls. The key aspects covered include the CS Fallback network architecture using the SGs interface, the combined attach procedure used for location updates, advantages/disadvantages of different CS Fallback mechanisms, and signaling flows for CS Fallback and paging.
Beginners: 5G Terminology (Updated - Feb 2019)3G4G
This document discusses 5G terminology and deployment options. It provides an overview of the evolution of mobile technology standards over time. It explains the differences between 4G LTE and 5G NR networks, as well as various options for non-standalone and standalone 5G network deployment and the migration strategies between these options. Key 5G concepts like gNBs, NG-RAN architecture and the 5G system architecture are also summarized.
This document provides instructions for logging into an LMT base station, configuring the FTP server and Java settings, and downloading and uploading the data configuration file (XML) to and from the base station. It lists the default IP address and login credentials for accessing the base station interface, provides guidance on changing the FTP password, downloading the FTP server software, and configuring the allowed Java sites. It also outlines the steps to select the server IP, folder location, username, and FTP password when downloading or uploading the XML file between the laptop and base station.
The document provides an overview of LTE and its evolution from previous cellular standards. It discusses the targets of LTE including high data rates up to 100 Mbps, low latency, high spectral efficiency, and flexibility in spectrum and bandwidth. It also describes the EPS architecture with E-UTRAN, EPC, and the air interface structure of LTE including OFDMA in the downlink and SC-FDMA in the uplink. Key layers like the PHY, MAC, and RLC layers are also summarized.
We are going to cover complete list of VoLTE IMS KPI and performance Indicators . This includes :-
VoLTE IMS Control Plane KPI
- RSR : Registration Success Ratio (%)
- CSSR : Call Setup Success Rate (%)
- CST : Call Setup Time (s)
- MHT/ACD : Average Call duration (s)
VoLTE IMS User Plane KPI
- Mute Rate (%)
- MOS Score (1-5)
- RTP Packet Loss (%)
- One Way Calls (%)
Packet Core 4G Network LTE KPI
- Volte Attach Success Rate (%)
- VoLTE QCI=5 Paging Success Rate (%)
- Dedicated Bearer Activation Success Rate (%)
- IMS IP POOL Utilization (%)
- Create Bearer Success Rate (%)
Radio VoLTE KPI
- Call Drop rate (%)
- SRVCC Success Rate (%)
- Handover SR (%)
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
- To support CS services like voice in LTE networks, different phases of evolution have been proposed including CSFB and VoLTE.
- CSFB allows CS services to work by falling back to legacy 2G/3G networks, while VoLTE supports native voice over IP capabilities in LTE.
- SRVCC allows seamless handover of VoLTE calls between LTE and legacy networks by transferring sessions between the core networks.
This document is a thesis submitted by Abdul Basit in partial fulfillment of the requirements for a Masters of Science degree. The thesis focuses on dimensioning of LTE networks, including describing models and tools for coverage and capacity estimation of the 3GPP Long Term Evolution radio interface. The thesis developed methods and models for coverage and capacity planning in LTE network dimensioning. It also created an easy-to-use Excel-based tool to calculate the number of cells needed to cover a given area based on user-provided dimensioning parameters. The tool is designed to cover the basic aspects of dimensioning LTE access networks in a clear and user-friendly manner.
The document provides an overview of cellular communications signaling for LTE, LTE-A, and 4G technologies. It describes the LTE architecture including functions of the evolved node B, mobility management entity, serving gateway, home subscriber server, and PDN gateway. It also provides details on the LTE physical layer including OFDMA modulation, reference signal measurements for handover, and an example handover procedure using the X2 interface. In conclusion, it discusses key criteria for designing handovers and aspects for further research.
This document summarizes the key procedures and signal flows in setting up an LTE session for a UE:
1) The UE establishes an RRC connection with the eNodeB through random access and preamble signaling.
2) The UE then attaches to the core network through the MME, and authentication procedures are performed.
3) Finally, the default bearer for user data is established through signaling between the UE, eNodeB, MME, SGW and PGW. Once complete, user data sessions can be exchanged.
This document discusses key aspects of providing Quality of Service (QoS) and priority access for public safety in LTE networks. It covers:
1. Controlling access to the air interface through mechanisms like access class barring which allow reserving access for priority users.
2. Controlling the use of network resources by mapping applications to EPS bearers that have QoS Class Identifiers and Allocation Retention Priority levels assigned.
3. Ensuring roaming and handover do not impact the QoS and priority access provided to public safety users.
Self-Configuration and Self-Optimization NetworkPraveen Kumar
The document discusses self-configuration and self-optimization capabilities in cellular networks. It describes functions like dynamic configuration of interfaces between network elements, automatic neighbor relation functions to detect neighboring cells, and framework for physical channel identification selection. It also covers self-optimization aspects like energy saving, interference reduction, mobility robustness optimization, load balancing optimization, and interference coordination.
Determine the required delivery characteristics of a packet stream and how a Traffic Management (TM) module can offload compute-intensive tasks. Hear more about the latest innovations in both DPI & TM solutions.
Lte default and dedicated bearer / VoLTEmanish_sapra
LTE uses EPS bearers to carry user data traffic. There are two types of EPS bearers - default bearers and dedicated bearers. Default bearers are created for each PDN connection and provide basic "best effort" internet access. Dedicated bearers provide additional tunnels for specific traffic like VoLTE and can have guaranteed bitrates. Dedicated bearers are linked to a default bearer and inherit properties like the PDN address from the default bearer. GTP is the protocol used to encapsulate and carry bearer traffic through the LTE core network.
Understanding Telecom SIM and USIM/ISIM for LTEntel
SIM cards have been witnessing increasing adoption with the growing use of smartphones and other devices requiring always-on connectivity. SIM cards represent a key platform for value added services and applications, and are a core element in providing interoperability among the telecom industry players while ensuring security and safe authentication.
Key Features:
Form factors: mini-SIM (2FF), micro-SIM (3FF) and nano-SIM (4FF)
Memory size: from 32k up to 256k
High security standards and strong authentication algorithms
Over-The-Air (OTA) content management
Wide range of Value Added Services applications
The document discusses various LTE measurement parameters and procedures including:
1. The eNB reports a list of detected PRACH preambles and measures timing advance, average RSSI, average SINR, UL CSI, and transport BLER for RRM purposes.
2. UE measurements include CQI, RSRP, and RSRQ while eNB measurements include timing advance, RSSI, SINR, UL CSI, detected preambles, and transport BLER. Inter-RAT measurements are also discussed.
3. Examples of RSRP, RSRQ, and timing advance procedures are provided along with CQI measurement details. PLMN selection, cell selection,
Long Term Evolution (LTE) is the next generation of mobile broadband technology that provides higher data rates and network throughput compared to 3G. LTE networks use OFDM and SC-FDMA for downlink and uplink, respectively, along with MIMO and an all-IP architecture to improve performance. The network elements include eNBs, SGWs, PDN GWs and MMEs. For operators, LTE provides an opportunity to increase ARPU through new applications and services while decreasing CCPU through an all-IP infrastructure. Mass deployment of LTE is expected to begin around 2012, with LTE Advanced enabling data rates up to 1 Gbps.
This document discusses implementing security and steganography in 802.11n networks. It proposes hiding information in the cyclic prefix of OFDM symbols. Modifying the cyclic prefix does not require additional bandwidth and increases the potential hidden transmission capacity depending on the modulation scheme. Simulation results show the steganographic system does not increase costs for ordinary users and security is improved by using private keys to randomly select modified symbols.
HYBRID LS-LMMSE CHANNEL ESTIMATION Technique for LTE Downlink Systemsijngnjournal
- The document proposes a hybrid LS-LMMSE channel estimation technique for LTE downlink systems that is robust to the effect of channel length.
- The technique chooses between LS and LMMSE estimation depending on whether the cyclic prefix is longer than or shorter than the channel length, and on the SNR value.
- When the cyclic prefix is longer than the channel length, LMMSE is used directly. When it is shorter, LMMSE is used for low SNR and LS is used for high SNR.
- Simulation results show the hybrid technique performs better than LMMSE alone, especially at high SNR values when the cyclic prefix is shorter than the channel length.
This document presents an implementation of an ant colony optimization adaptive network-on-chip routing framework using a network information region. The proposed method combines backward ant mechanism with a network information region framework to improve network performance, area efficiency, and reduce congestion. Simulation results show that updating routing tables is faster with the proposed method, leading to improved network performance and area efficiency while reducing congestion compared to other approaches.
PERFORMANCE ANALYSIS OF RESOURCE SCHEDULING IN LTE FEMTOCELLS NETWORKScscpconf
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and time dimension. So several scheduling algorithms need to be analyzed for femtocells networks. In this paper we introduce a performance analysis of three distinct scheduling algorithms of mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in terms of throughput, packet loss ratio, fairness index and spectral efficiency.
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize
the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and
time dimension. So several scheduling algorithms need to be analyzed for femtocells networks.
In this paper we introduce a performance analysis of three distinct scheduling algorithms of
mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in
terms of throughput, packet loss ratio, fairness index and spectral efficiency.
This document reviews the OFDM-IDMA technique and its implementations. It begins with introductions to OFDM and OFDM-IDMA. OFDM-IDMA uses interleaving instead of spreading sequences to distinguish users, avoiding bandwidth expansion without coding gain. The document then summarizes various implementations of OFDM-IDMA using discrete wavelet transform, MIMO systems, and implementations on FPGA. It also discusses implementations using finite Radon transform and discrete wavelet transform. Finally, it proposes future work on implementing OFDM-IDMA using Radon transform and performing comparative analysis of wavelet, FFT, and Radon-based OFDM-IDMA systems over AWGN and Rayleigh fading channels.
An adaptive channel estimation scheme based on redundancy minimization for fi...TELKOMNIKA JOURNAL
Filtered orthogonal frequency division multiplexing (F-OFDM), a technology which is being considered as a promising platform for beyond 4G era is expected to help deliver the new features at millimeter wave in the new 5th generation of cellular communication. Some of its key features notably better spectral utilization, enhanced throughput and immunity to interference can be enabling for the new cellular standards. These features of filtered OFDM comes with strict requirements of filter design, guard tone managements, and efficient channel state information harness. This paper is intended to propose an intuitive channel estimation scheme which will allow efficient acquisition of channel state information (CSI) through exploiting the redundant steps of the conventional pilot training-based algorithms and by also using an adaptive weight to expedite the minimization of the error between the estimated values and the actual values. Various simulations will follow to demonstrate the superiority of the scheme over traditional pilot-based algorithms and thus prove its utility in the current 5G cellular era.
Macro with pico cells (hetnets) system behaviour using well known scheduling ...ijwmn
This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.. A simulation platform called LTE-Sim has been used to collect the data and produce the paper’s outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
Long-Term Evolution (LTE), an emerging and promising fourth generation mobile technology, is expected
to offer ubiquitous broadband access to the mobile subscribers. In this paper, the performance of Frame
Level Scheduler (FLS), Exponential (EXP) rule, Logarithmic (LOG) rule and Maximum-Largest Weighted
Delay First (M-LWDF) packet scheduling algorithms has been studied in the downlink 3GPP LTE cellular
network. To this aim, a single cell with interference scenario has been considered. The performance
evaluation is made by varying the number of UEs ranging from 10 to 50 (Case 1) and user speed in the
range of [3, 120] km/h (Case 2). Results show that while the number of UEs and user speed increases, the
performance of the considered scheduling schemes degrades and in both case FLS outperforms other three
schemes in terms of several performance indexes such as average throughput, packet loss ratio (PLR),
packet delay and fairness index.
This document provides an overview of the LTE uplink transmission scheme, specifically the use of Single-Carrier Frequency Division Multiple Access (SC-FDMA). SC-FDMA is used instead of OFDMA in the uplink to reduce the high Peak-to-Average Power Ratio (PAPR) of OFDMA. The document describes the SC-FDMA transmission process, including discrete Fourier transforms, subcarrier mapping, and frame structure. It also discusses localized and distributed subcarrier mapping schemes and presents results from a PAPR analysis comparing the schemes. Finally, an adaptive hybrid mapping scheme is proposed to achieve good transmission performance with low PAPR.
This document summarizes the physical layer frame structure used in 4G LTE and LTE-Advanced downlink transmissions. It describes how the LTE system toolbox in MATLAB can be used to generate physical signals and channels, and map them to resource elements in the time-frequency grid. Key aspects covered include the use of OFDM, resource block structure, and how synchronization signals, broadcast channels, control channels, and shared data channels are allocated in the frame. The document provides technical details on frame configurations and illustrates example resource grids for a subframe and radio frame.
ESTIMATION OF SYMBOL TIMING AND CARRIER FREQUENCY OFFSET USING SYNCHRONIZATI...Michael George
OFDM/OQAM is preferred as multicarrier system which operates over a multipath channel. By using the multipath channel the signal-to-noise ratio. In earlier, sub carriers are used to transmit the signals. Nowadays, FFT and DFT are used for transmitting the signals based upon the bit values. AWGN is a channel used to identify the noise produced at the output by adding the noise in the blind signal. By reducing subcarriers the noise and timing are reduced. FFT bit value was increased which provides better performance. In the multicarrier system, the error and noise was reduced by increasing the bit value.
The document discusses the evolution of 3GPP's Long Term Evolution (LTE) radio technology and System Architecture Evolution (SAE). It describes the initial feasibility study in 2004 to develop a high-data-rate, low-latency packet-optimized radio access technology. Key requirements were identified for peak data rates, latency, capacity, throughput, spectrum efficiency, mobility, and more. Radio interface options were evaluated, leading to the selection of OFDM for the downlink and SC-FDMA for the uplink. The evolved UTRAN architecture was defined consisting of eNBs interconnected by the X2 interface.
Filters are required in wireless communication systems for multiple reasons:
1) At the transmitting end, filters are needed to limit the bandwidth of the transmitted signal and prevent interference with other frequency bands. Without filters, a wide range of frequencies would be transmitted.
2) At the receiving end, filters are required to select the desired incoming signal and reject signals from other transmitters using nearby frequencies. Without filters, the receiver would not be able to distinguish different signals.
3) If no filters are used at all, the system would be unable to isolate different frequency bands and signals would interfere with each other, degrading performance and preventing reliable communication from taking place. Filters are necessary to allow multiple access techniques like FDMA
This document summarizes a research paper that implemented SC-FDMA and OFDMA in MATLAB to evaluate the performance of the LTE physical layer. It provided background on LTE standards and an overview of the key aspects of LTE systems, including frame structure, bandwidth allocation, modulation schemes, and multiple access techniques. The document also reviewed literature on the LTE physical layer design and described how time and frequency resources are divided in LTE.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document summarizes the LTE access procedure, with a focus on the cell search process.
The cell search process involves two main steps:
1. Primary synchronization signal (PSS) detection, which allows the UE to detect the base station sector and obtain timing/frequency synchronization. The PSS uses Zadoff-Chu sequences for good detection properties.
2. Secondary synchronization signal (SSS) detection, which provides the UE with the physical cell ID, frame timing properties, and cyclic prefix length. The SSS uses maximum length sequences.
After synchronization, the UE proceeds to obtain system information, perform random access, and connect to the network. The document then discusses existing cell search algorithms
This document summarizes the LTE access procedure, with a focus on the cell search process.
The cell search process involves two main steps:
1. Primary synchronization signal (PSS) detection, which allows the UE to detect the base station sector and obtain timing/frequency synchronization. The PSS uses Zadoff-Chu sequences for good detection properties.
2. Secondary synchronization signal (SSS) detection, which provides the UE with the physical cell ID, frame timing properties, and cyclic prefix length. The SSS uses maximum length sequences.
After synchronization, the UE proceeds to obtain system information, perform random access, and connect to the network. The document then discusses existing cell search algorithms
The document provides an overview of 3GPP LTE (Long Term Evolution) technology. Key points include:
- LTE is designed to provide high-speed data and media transport with high-capacity voice support through the next decade.
- It enables high-performance mobile broadband services using high bitrates and system throughput in both uplink and downlink with low latency.
- The LTE infrastructure is designed to be simple to deploy and operate across flexible frequency bands from less than 5MHz to 20MHz.
- The LTE-SAE architecture reduces network nodes and supports flexible configurations for high service availability across multiple standards.
Lte training an introduction-to-lte-basicsSaurabh Verma
The document provides an overview of LTE (Long Term Evolution) technology. It discusses that LTE was standardized by 3GPP in 2008 to improve the performance and efficiency of wireless networks. Key aspects of LTE include the use of OFDMA for downlink and SC-FDMA for uplink, support for flexible bandwidths, and an evolved packet core network architecture. LTE aims to provide higher speeds, lower latency, and more efficient use of spectrum compared to previous 3G technologies.
The document discusses Beam Division Multiple Access (BDMA) as a new multiple access technique for 5G networks to increase system capacity. BDMA divides antenna beams according to mobile station locations, allocating orthogonal beams to allow multiple access. This significantly increases capacity compared to existing techniques like FDMA, TDMA, CDMA, and OFDMA. The base station transmits directional beams to mobile stations based on their positions and speeds. Mobile stations sharing beams divide frequency/time resources. BDMA maximizes spatial reuse of resources and solves inter-cell interference and control channel problems. It is proposed as a radio interface for 5G cellular systems.
The document discusses power management and mobility management in LTE. It describes two activity states for user equipment (UE) - connected mode and idle mode. In connected mode, the UE's radio is on and it is constantly communicating with the network. In idle mode, the UE turns off its transmitter and only listens periodically to conserve power. The document outlines the processes involved in transitioning between these states, including mobility management procedures for UE movement within the network.
This document discusses NTT DOCOMO's views on 5G mobile network requirements, concepts, and technologies. It outlines the need for 5G networks to support 1000x higher capacity, 100x more connected devices, and 1ms latency to enable new services like remote monitoring, augmented reality, and high resolution video. DOCOMO proposes a dual-layer 5G network using both existing lower bands for coverage and new higher bands for capacity. Key 5G technologies include exploiting massive MIMO, new waveforms, and non-orthogonal multiple access to achieve these goals and integrate lower and higher frequency bands.
This document discusses the three phases of LTE network deployment:
Phase 1 focuses on LTE for data only services using USB modems. Phase 2 introduces LTE handsets but relies on circuit switched fallback for voice. Phase 3 transitions to a full IP LTE/IMS environment for integrated voice, messaging, and data services. However, replacing existing circuit switched infrastructure with IMS will be a long-term goal due to significant costs and time required for such a transition. Operators will take an incremental approach, initially focusing on policy and charging platforms that can work with both legacy and new systems.
The document discusses VoLTE (Voice over LTE) using the IMS (IP Multimedia Subsystem) platform standardized by 3GPP to maximize international interoperability. It describes the GSMA VoLTE profile, which specifies the minimum functions for the interface between terminals and core networks to implement VoLTE using IMS. Key aspects covered include IMS registration procedures, voice call origination processes, voice codecs, emergency calling capabilities, and quality of service controls in the LTE/EPC network.
The document describes 4 scenarios for IMS/MMD call flows involving session establishment. Scenario 1 involves the originating UE having resources ready before sending the INVITE message, and the terminating UE having resources ready before sending the first provisional response. The call flow shows the SIP signaling messages exchanged between the UEs and IMS network entities, including an INVITE with an SDP offer from UE-1, and a 180 Ringing response from UE-2 with an SDP answer.
This document discusses considerations for introducing LTE technology into existing GSM-UMTS networks. It will take several years for LTE deployments to reach the scale of existing 2G and 3G networks, so operators need solutions to provide seamless service and mobility between network technologies during the transition. The document outlines various strategies for LTE deployment, including options for data-only, voice and data services. It also examines expectations around subscriber and operator experience, and analyzes potential solutions for interworking LTE with 2G-3G networks to support seamless service continuity.
The document provides an overview of UMTS (Universal Mobile Telecommunication System) or 3G technology. It discusses how UMTS represents an evolution from 2G systems like GSM and 2.5G systems like GPRS, with expectations of faster communication and the ability to combine voice and data. The document also describes some of the key technical challenges in building UMTS infrastructure and the complexity and costs involved for vendors and mobile operators.
The document summarizes an interoperability event in 2012 that tested standards compliance for Rich Communication Suite (RCS) and Voice over LTE (VoLTE) network scenarios. The event validated key GSMA technical recommendations and was conducted across two test labs connected via IPX network. A total of 210 test cases were run across scenarios for RCS/VoLTE in a single network and for roaming and interconnect. The results demonstrated interoperability of the GSMA specifications based on 3GPP standards.
This technical bulletin discusses dual transfer mode (DTM) capabilities that allow a mobile station to operate in dedicated mode on the circuit switched domain while having an active packet data protocol context in the packet switched domain. Key points include:
- DTM overcomes restrictions of separate circuit switched and packet switched domains by sending packet data on timeslots contiguous with those used for circuit switched connections.
- The core network is modified to coordinate paging across both domains when no Gs interface is present.
- Mobility management follows that of class A mobiles, with routing area updates signaled on a dedicated channel.
- Handover coordination uses additional signaling over the A interface to indicate DTM capability.
The document summarizes three main options for supporting voice and SMS in LTE networks:
1) Circuit switched fallback (CSFB) allows subscribers to use voice services on legacy networks like GSM when in LTE coverage areas.
2) SMS over SGs allows network operators to support SMS as a circuit switched service within LTE via the SGs interface to legacy networks.
3) Voice over LTE (VoLTE) supports voice and SMS natively over the IMS framework in the long run, but requires additional network elements and was slower to be commercially deployed than initially expected.
This document provides an overview of RRC procedures in LTE, including:
1. Key differences from 3G include simplified RRC states (connected/idle instead of multiple states), single shared MAC entity, and elimination of common/dedicated channels.
2. RRC functions like system information broadcasting, connection control, configuration of signaling radio bearers, and measurement reporting.
3. Core RRC procedures like paging, connection establishment, reconfiguration, and handover are described at a high-level. Paging is simplified compared to 3G which had multiple paging types.
This document discusses opportunities for network sharing in LTE mobile networks. It describes how network sharing can help mobile service providers address challenges of rapidly increasing data usage while generating limited additional revenue. The document outlines how LTE network standards support infrastructure sharing and analyzes different sharing models used by customers, including a wholesale LTE network and a joint venture sharing multiple radio access networks. Key challenges of quality, regulation, commercial agreements, and cost sharing are also reviewed.
This document defines a minimum mandatory set of features for wireless devices and networks to implement to guarantee an interoperable, high quality IMS-based telephony service over LTE radio access. It covers IMS capabilities and supplementary services for voice calls, real-time media aspects like codecs and transport, required LTE radio and packet core functions, and common functionalities across subsystems. The profile aims to identify a baseline for interoperability between IMS networks and devices for voice and SMS services.
This document is a technical specification from the European Telecommunications Standards Institute (ETSI) that defines the General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access, also known as LTE. It covers the general aspects of architecture and functions for packet data networks and connected devices. The specification addresses topics like network access control, packet routing and transfer, security, mobility management, radio resource management, selection functions, and the network elements involved like E-UTRAN, MME, gateways, and PCRF.
This document defines numbering, addressing and identification for telecommunications networks and subscriptions. It specifies:
- The structure and allocation principles of identifiers such as IMSI, TMSI, P-TMSI and GUTI.
- Numbering plans for mobile stations and network elements.
- Identification schemes for location areas, base stations, MSCs, GSNs and HLRs.
- Numbering and addressing for IP multimedia networks, WLAN interworking, MBMS and the GAA subsystem.
This document is a technical specification from ETSI that defines protocols for digital cellular telecommunications and Universal Mobile Telecommunications Systems (UMTS). It focuses on the core network protocols in the mobile radio interface and covers topics such as mobility management, call control, and session management. The document is over 100 pages and provides in-depth information on protocols and procedures for cellular networks.
This document is a technical specification from the European Telecommunications Standards Institute (ETSI) that defines the Non-Access Stratum (NAS) protocol for the Evolved Packet System (EPS). The NAS protocol handles mobility management, session management, and other common functions for both UMTS and LTE systems. The document specifies procedures, message formats, and states for the EPS mobility management entity. It is a 3GPP technical specification from ETSI for LTE and UMTS networks.
2. search procedures are described, and several timing and
LONG TERM EVOLUTION INVOLVES CHANGES frequency offset detection methods are presented. Perfor-
TO BOTH RADIO INTERFACE AND NETWORK mance results of different primary synchronization chan-
ARCHITECTURE IN ORDER TO KEEP 3RD nel design solutions are simulated and compared.
GENERATION PARTNERSHIP PROJECT
TECHNOLOGY COMPETITIVE.
System Description and Design Considerations
The diagram of the downlink OFDMA air interface is
shown in Figure 1. In the OFDMA system, modulated bits
multiple access (OFDMA) provides several advantages, are converted from serial to parallel first, and then
such as high spectral efficiency, simple receiver resign, mapped to different subcarriers. After IFFT, the output
and robustness in a multi-path environment. Due to signals are converted back to serial signals called an
these advantages, OFDMA was chosen as the downlink OFDM symbol. Cyclic prefix (CP) is attached to the begin-
air interface of 3GPP LTE systems [1]. ning of the OFDM symbol before transmission. Subcarrier
When a terminal powers on in a cellular system, it spacing of 15 kHz is used in the 3GPP LTE system.
needs to perform cell search to acquire its frequency ref- As in UMTS systems, the cell search in 3GPP LTE sys-
erence, frame timing, and the fast Fourier transform (FFT) tems will enable the terminal to obtain frame and symbol
symbol timing with the (best) cell, and also to identify the timing, frequency offset and the cell ID. However, cell
cell ID. In order to obtain good cell search performance, search in 3GPP LTE systems has to consider multiple
an appropriate synchronization channel structure needs transmission bandwidths (UMTS has a fixed bandwidth of
to be designed. 5MHz, while 3GPP LTE systems support 1.25, 2.5, 5, 10, 15
We start in this article by briefly describing the and 20 MHz bandwidths). Moreover, cell search proce-
OFDMA air interface. The design considerations of the dure in 3GPP LTE systems should be completed with low
synchronization channel are then discussed, and several processing complexity at the terminal and within a much
potential synchronization channel design solutions (syn- shorter time than that in UMTS systems. All of these
chronization symbol structures and corresponding requirements are expected to be fulfilled with system
sequences) for 3GPP LTE system are presented. Cell overhead on par with UMTS systems.
It is desirable to define a synchronization chan-
nel that is common to all cells in the system irre-
spective of the bandwidth being used in the cell,
since this will yield faster cell search and lower com-
plexity. Therefore, it is agreed that the synchroniza-
tion channel should be transmitted using the central
1.25 MHz bandwidth regardless of the entire band-
width of the system [1]. In this way, the same syn-
chronization channel is mapped to the central part
of transmission bandwidth for all system band-
widths. The central 1.25 MHz corresponds to 76 sub-
FIGURE 1 OFDMA air interface in 3GPP LTE systems. carriers with subcarrier spacing of 15 kHz.
The downlink frame structure of the 3GPP LTE
system is shown in Figure 2. Each radio frame (10
ms) is divided into 10 sub-frame of 1 ms. Each sub-
frame consists of 2 slots. There are 7 OFDM symbol
per slot. There are two kinds of synchronization
channels (SCH): primary SCH (P-SCH) and sec-
ondary SCH (S-SCH). P-SCH and S-SCH symbols are
time division multiplexed. Each radio frame con-
tains two equal-spaced pairs of P-SCH and S-SCH
symbols. For coherent detection of S-SCH symbols,
P-SCH and S-SCH symbols are placed adjacent to
each other in the last two OFDM symbols of the
first slot within a sub-frame.
Cell search in the WCDMA based UMTS system
relies mainly on time domain processing to achieve
low receiver complexity and efficient hardware
FIGURE 2 Downlink frame structure of 3GPP LTE systems. implementation. In order to provide good timing
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3. detection performance, the synchronization sequence in
UMTS systems should have very good auto-correlation. OFDMA PROVIDES SEVERAL ADVANTAGES,
Due to this property, the Golay sequence was chosen as SUCH AS HIGH SPECTRAL EFFICIENCY, SIMPLE
the synchronization sequence for UMTS systems. For RECEIVER RESIGN, AND ROBUSTNESS IN A
3GPP LTE systems, the synchronization sequence is MULTI-PATH ENVIRONMENT, AND SO WAS
mapped to the central band of entire bandwidth due to
CHOSEN AS THE DOWNLINK AIR INTERFACE OF
the OFDMA based downlink air interface. However, the
3GPP LTE SYSTEMS.
terminal does not know the downlink timing of the sys-
tem at the beginning of the cell search; hence, frequency
domain processing (e.g., DFT) based timing detection at non-repetitive pattern can be generated using consecu-
each sample will make the cell search processing com- tive subcarriers in the frequency domain.
plexity too high for the terminal. In order to obtain good There are two methods to generate the time domain
timing detection performance with low complexity, the repetitive and symmetrical-and-periodic P-SCH symbols:
synchronization symbol structure should therefore be frequency domain and time domain. In the former, a fre-
designed to allow the robust detection of the symbol quency domain synchronization sequence is mapped to
timing at the terminal via simple time domain process- the central subcarriers in an equidistant manner. This is
ing. To facilitate the detection, the synchronization
sequence should have large peak to side-lobe ratio
(PSR). The PSR of a sequence is defined as the ratio
between the peak to the side-lobes of its aperiodic
autocorrelation function.
An important design consideration for the syn-
chronization channel is coverage. One primary fac-
tor that affects coverage is the peak-to-average
power ratio (PAPR) of the synchronization
(a)
sequence, since this limits the maximum transmit
power of the cell. Hence, a synchronization
sequence that yields low PAPR is desirable.
Design of Synchronization Channel
In this section, we first describe P-SCH and S-SCH sym-
bol structures, and then discuss the synchronization
sequence design. (b)
FIGURE 3 P-SCH symbol structure with repetitive pattern: (a) 2
P-SCH Symbol Structures repetitions; (b) 4 repetitions.
The goal of P-SCH is to facilitate the timing and fre-
quency offset detection. To achieve the goal, three P-
SCH symbol structures have been proposed: repetitive
pattern, symmetrical-and-periodic pattern, and non-
repetitive pattern.
A P-SCH symbol structure with time domain repeti-
tive blocks was proposed in [5], [6]. In the example
shown in Figure 3, the P-SCH symbol in the time
domain contains K ( K = 2 or 4) blocks of equal
length, and the cyclic prefix (CP) is attached at the
FIGURE 4 P-SCH symbol structure with symmetrical-and-periodic pattern.
beginning of the P-SCH symbol.
As shown in Figure 4, a P-SCH symbol structure
with a symmetrical-and-periodic pattern was pro-
posed in [7] as an alternative to the P-SCH symbol
structure with a repetitive pattern. Block B in Figure 3
is symmetrical (reverse) to block A.
A P-SCH symbol structure with a non-repetitive
pattern, as shown in Figure 5, was proposed in [9].
Unlike the P-SCH symbol with a repetitive pattern
which is discussed above, the P-SCH symbol with a FIGURE 5 P-SCH symbol structure with non-repetitive pattern.
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4. pattern in the time domain. According to the property of
THE GOAL OF P-SCH IS TO FACILITATE THE DFT, the symmetrical-and-periodic pattern can be gener-
TIMING AND FREQUENCY OFFSET DETECTION. ated when a real synchronization sequence is used.
THERE ARE THREE P-SCH SYMBOL STRUCTURES: In the time domain method, on the other hand, a
REPETITIVE PATTERN, SYMMETRICAL-AND-PERIODIC time domain synchronization sequence is precoded by
a DFT and then mapped to localized (consecutive) sub-
PATTERN, AND NONREPETITIVE PATTERN.
carriers of the same symbol. Finally, a P-SCH symbol is
generated after IDFT.
shown in Figure 6. Using the frequency domain mapping, The example in Figure 7 illustrates the method, in
any complex frequency domain synchronization which sequences AN/4 and B N/4 , and an appropriate
sequence can be used to generate the K repetition blocks training pattern vector a = [1 −1 1 1] are used to
generate symmetrical-and-periodic P-SCH symbol
[ AN/4 − B N/4 AN/4 B N/4 ] , as proposed in [8] and
shown in Figure 4. In the frequency domain implemen-
tation, only a real number sequence can be used for
the P-SCH symbol structure with a symmetrical-and-
periodic pattern. With time domain implementation, a
complex number sequence can be used.
S-SCH Symbol Structure
The design of S-SCH needs to supports a sufficient
number of hypotheses to carry the following informa-
tion: 510 cell IDs (jointly with P-SCH symbols) and the
number of transmit antennas used for broadcast
channel (1 bit). Suppose that three different P-SCH
sequences are used in the system, hence the S-SCH
FIGURE 6 Generation of P-SCH symbols in the frequency domain needs to support 340 (i.e., 2 × 510/3) hypotheses.
approach [5], [6].
Since there are at most 76 subcarriers can be used for
S-SCH, the only solution to support such a large num-
ber of hypotheses is to use a fixed equal-distant inter-
leaving of two short sequences with length G, say
SG (1) and SG (2), as shown in Figure 8 [13]. With this
structure, the number of supported hypotheses is the
product of numbers of different SG (1) and SG (2),
which approximately equals to G 2 .
Since there are more than one P-SCH symbols in a
radio frame as shown in Figure 2, P-SCH symbols can
only provide symbol timing but not frame timing
(due to ambiguity of multiple same P-SCH symbols).
Two different S-SCH symbols can be generated by
FIGURE 7 Generation of P-SCH symbols in the time domain approach.
swapping the frequency locations of SG (1) and SG (2).
Upon detection of an S-SCH symbol, the terminal can
obtain the frame timing as well.
Synchronization Sequence Design
In order to meet the synchronization sequence design
considerations discussed above, we examine the PAPR
and PSR of several candidate sequences. The candidate
sequences include Gold, Golay [10], and generalized
chirp like (GCL) [2] sequences. The Gold and Golay
sequences and their PAPR and sequence detection
properties are well known; On the other hand, the GCL
sequence and its properties are less known. Therefore,
we provide details of the GCL sequence here. A GCL
FIGURE 8 Generation of S-SCH symbols. sequence is defined as:
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5. exp −j 2πu k(k+1) ,
2N G N G is odd,
su (k) = k 2 (1) IN ORDER TO MEET THE SYNCHRONIZATION
exp −j 2πu 2N G , N G is even,
SEQUENCE DESIGN CONSIDERATIONS, THE PAPR
AND PSR OF THREE CANDIDATE SEQUENCES ARE
where u is the sequence index, N G is the sequence length, CONSIDERED: GOLD, GOLAY, AND GENERALIZED
k = 0, 1, …, N G − 1, and u = 1, …, N G − 1. Furthermore,
CHIRP LIKE (GCL) SEQUENCES.
the GCL sequence has constant amplitude zero auto-cor-
relation (CAZAC) property when N G is prime. It is shown
in [4] that the DFT/IDFT output of a CAZAC sequence is Step 1: By processing the P-SCH symbols, OFDM sym-
still a CAZAC sequence. Therefore, the IDFT output of the bol timing and the carrier frequency offset are detected.
frequency domain GCL sequence has a constant envelope Depending on the P-SCH symbol structure, one of three
(i.e., PAPR of 0 dB) as well. In practice, a pulse shaping methods of timing and frequency offset detection can be
filter will be applied to the transmitted signals and will used: auto-correlation, cross-correlation, or hybrid detec-
increase the PAPR of GCL sequence to about 4 dB. tion. Note that these detection methods can be applied to
One key property of the GCL sequence is that the both time and frequency domain synchronization
sequence index can be detected using one common dif- sequences.
ferential encoding based correlator. First, the frequency Auto-correlation based detection: This method can be
domain GCL sequence is differentially encoded, and applied to P-SCH symbols with repetitive or symmetrical-
then the output of the differential encoder is trans- and-periodic pattern. The received signal is multiplied by
formed by IDFT, which in turn becomes the Kronecker its conjugate after a delay of one repetition block and
delta function. In this way, the GCL sequence index can summed over one repetition block. The search window
be detected using one common correlator, instead of a slides along in time as the receiver searches for a P-SCH
bank of correlators. symbol. MMSE-type detection is used to obtain the
The PAPR and PSR properties of all three candidate
sequences are summarized in Table 1. Among the three,
only the GCL sequence meets both of the design criteria TABLE 1 PAPR and PSR properties for different sequences.
discussed above: best PAPR and high PSR.
Therefore, in the 3GPP LTE study the GCL sequence
Sequence Length PAPR† (dB) PSR
and its variations were widely adopted in many P-SCH
Gold 31 5.4 1.04
and S-SCH proposals. For example, the GCL sequence Golay 32 2.8 2.91
was applied to a P-SCH symbol with a repetitive pattern GCL 31 0 2.98
generated by the frequency domain method in [5], [6]. †: PAPR before pulse shaping filter.
The Frank sequence, which is a special case of the GCL
sequence as established in [12], was used for a P-SCH
symbol with a repetitive pattern generated by the time
domain method in [8]. It was also used for a P-SCH sym-
bol with a non-repetitive pattern in [9]. For a P-SCH
symbol with a symmetrical-and-periodic pattern gener-
ated in the frequency domain [7], the Golay sequence
was used. The Frank sequence can be used if a P-SCH
symbol with a symmetrical-and-periodic pattern is gen-
erated by the time domain method. The Zadoff-Chu
sequence [13], which is a special case of GCL sequence,
was used in [13] to generate S-SCH symbols.
Cell Search Procedure
In the WCDMA UMTS system, a common P-SCH is used for
the terminal to obtain the timing. Cell group ID is
obtained from processing of the S-SCH. Then, the terminal
further processes a cell-specific scrambling code via the
common pilot channel to detect the cell ID within the
group. This is called hierarchical cell search. Cell search
in the 3GPP LTE systems follows a similar hierarchical
procedure as well, performed in the three steps summa-
rized in Figure 9. FIGURE 9 Hierarchical cell search procedure.
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6. downlink P-SCH symbol timing. The sample timing
TABLE 2 Simulation parameters. with the largest peak in the block-wise auto-correlator
output is selected as the P-SCH symbol timing. The fre-
Synchronization channel BW 1.25 MHz quency offset can be estimated easily from the output
Carrier frequency 2 GHz of the auto-correlation as well. The advantages of this
FFT Size 128
Total number of used subcarrier 64 method are its low complexity and reliable estimation
Frank sequence length 16 of frequency offset. However, its main drawback is its
Length of cyclic prefix (samples) 9 large timing estimation error at low SNR.
Number of sync symbols per frame 2
Channel Model 6-path Typical Cross-correlation based detection: This method
Urban can be applied to any P-SCH symbol structure. In
Vehicle speed 120 km/hr this method, the transmitted P-SCH sequence is used
Carrier frequency offset ±5 ppm
to correlate the received P-SCH signals. The cross-
correlation metric is used to obtain the timing and
frequency offset. It is known that cross-correlation
detection suffers in the presence of frequency offset.
To mitigate this problem, the cross-correlation can
be partitioned into M parts [9]. The advantage of the
method is its reliable estimation of timing. However,
its main drawbacks are higher complexity compared
to auto-correlation based detection.
Hybrid detection: This method can be applied to P-
SCH symbols with repetitive or symmetrical-and-peri-
odic pattern. First, the coarse timing and frequency
offset are estimated by using auto-correlation detec-
tion. The received signal is then compensated with the
estimated phase, and cross-correlation is performed
to obtain a refined timing offset estimate. Hybrid
detection combines the advantages of auto- and cross-
correlation based detection and has a lower complexi-
ty compared to cross-correlation based detection.
Step 2: The S-SCH symbols are processed in the fre-
quency domain to detect the cell ID group (one out of
170), frame timing and cell-specific information (such
FIGURE 10 Correlated peaks for timing detection.
as number of antennas used by BCH).
Step 3: A one-to-one mapping between 3 P-SCH
sequences (one of the 3 Cell IDs in each Cell ID group)
and downlink reference signals are applied in the sys-
tem. By processing the downlink reference signals, the
cell ID (one out of 3) is derived within the cell ID group
obtained in the step 2.
Performance Results
The performance of the different P-SCH structures pro-
posed in [5]–[9] for 3GPP LTE systems is simulated
and compared. The simulation parameters are summa-
rized in Table 2. We assumed that the accumulation
length for the first and second steps of the cell search
is two radio frames (20 ms).
For different P-SCH symbols proposed in [5]–[9],
the correlated peaks for timing detection using corre-
sponding detection methods (e.g., auto-correlation or
cross-correlation based detection) are shown and
compared in Figure 10.
FIGURE 11 Detection probabilities for different methods and P-SCH The P-SCH symbol with 2 repetitions generates a
symbol structures. peak plateau of the same length as the cyclic prefix.
28 ||| IEEE VEHICULAR TECHNOLOGY MAGAZINE | JUNE 2007
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7. In contrast, the P-SCH symbol with 4 repetitions gener-
ates a peak with steep roll off. No plateau is observed. ONLY THE GENERALIZED CHIRP LIKE SEQUENCE
The P-SCH symbol with symmetrical-and-periodic struc- MEETS BOTH OF THE DESIGN CRITERIA OF BEST
ture yields an impulse-shaped timing metric but with PEAK-TO-AVERAGE POWER RATIO AND HIGH PEAK
two side-lobes. The non-repetition pattern yields the TO SIDE-LOBE RATIO.
same impulse-shaped timing metric without side-lobes.
The overall performance metric of cell search is the
cell miss detection probability, which combines the
results of all steps of the cell search procedure. A cell
search is considered to be successful if the acquired
timing falls within the duration of the cyclic prefix, the For the P-SCH symbols with either a non-repetitive or
frequency offset is corrected, and the cell ID is identi- a symmetrical-and-periodic pattern, low cell miss detec-
fied. If any of these conditions is not met, a miss detec- tion probability can be achieved with a short accumula-
tion has occurred. tion length of two radio frames at low SNR (e.g., around
The miss detection probabilities of the auto-correlation, −3 dB). Therefore, the synchronization channel design is
cross-correlation, and hybrid detection methods are plot- considered to be sufficient to support the proper opera-
ted and compared in Figure 11. In this section, we com- tion of 3GPP LTE systems.
pare the performance of the following detection methods:
■ Cross-correlation detection with M-parts (M = 2) using Conclusions
non-repetitive P-SCH symbols, denoted as “CC M = 2 [A]”; In this article, we have reviewed the cell search issue in
■ Auto-correlation detection using P-SCH symbols with 4 the 3GPP LTE systems. Design considerations for both
repetitions, denoted as “AC [A − A A A]”; primary and secondary synchronization channels are dis-
■ Auto-correlation detection using P-SCH symbols with a cussed. We discussed and evaluated synchronization
symmetrical-and-periodic structure, denoted as channel solutions proposed in 3GPP LTE standardization.
“AC [A − B A B]”; The performance of these solutions is simulated and pre-
■ Hybrid detection using P-SCH symbols with 4 repeti- sented. The proposed synchronization channel design is
tions, denoted as “HD [A − A A A]”; shown to be sufficient to support the proper operation of
■ Hybrid detection using P-SCH symbols with a sym- 3GPP LTE systems.
metrical-and-periodic structure, denoted as
“HD [A − B A B]”;
As shown in Figure 11, the auto-correlation based References
1. 3rd Generation Partnership Project, Technical Specification Group Radio Access
detection has a 3–6 dB performance degradation com- Network, Physical Layer Aspects for Evolved UTRA (Release 7), 3GPP TR25.814
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(timing) only. Ericsson.
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