This document discusses downlink physical channels and reference signals in LTE. It describes the functions of channels like the PDCCH, PDSCH, PBCH, and reference signals. It discusses design constraints for cyclic prefix length and subcarrier spacing based on delay spread and Doppler shift. It also summarizes the radio frame structure for different bandwidths and control format indicator values, calculating overhead and peak data rates.
This document provides an overview of LTE air interface concepts including:
- Main LTE features such as frequency bands and mobility protocols.
- The LTE protocol stack including layers such as RRC, PDCP, RLC, MAC and physical.
- LTE channel types including logical, transport, and physical channels.
- Key physical channel functions like reference signals, synchronization signals, broadcast channels, and control channels.
- Uplink/downlink channel structures including time and frequency domain configurations.
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,
This document specifies 5G RRC parameters including message definitions and information elements for timers, counters, constants, and UE variables. It defines RRC messages that may be sent on different logical channels and provides descriptions of message fields. It also specifies bandwidth part configurations, measurement reporting, reconfiguration messages, and beam failure recovery resources.
The document discusses key technologies in LTE including access techniques, MIMO, scheduling, link adaptation, and HARQ. It covers OFDM and SC-FDMA used for downlink and uplink access, benefits of MIMO including improved SINR and shared SINR through modes like transmit diversity, receive diversity, and spatial multiplexing. Scheduling considers factors like CQI and aims for fairness and throughput. Link adaptation uses CQI and MCS to optimize air interface efficiency. HARQ enables recovery of errors at the MAC layer through retransmissions.
With the rise of data-intensive mobile applications, network operators must find ways to increase network capacity to meet demand. MIMO (Multiple-Input Multiple-Output) techniques, which use multiple antennas at the transmission and reception ends, have the potential to significantly boost network throughput through spatial multiplexing. However, optimizing networks for MIMO's full benefits presents challenges, as MIMO works best under rich scattering conditions and requires accurate measurement of multipath environments. Real-world RF measurements tailored for MIMO networks can help operators overcome these challenges and maximize throughput gains from MIMO without additional spectrum or infrastructure.
This document provides an overview of two fundamental mechanisms in LTE access networks: random access and buffer status reporting. It describes the random access procedure used by UEs to connect to the network, including the exchange of preambles, responses, and temporary identifiers. It also explains the buffer status reporting procedure, where UEs indicate to the base station the amount of data waiting to be transmitted so that uplink resources can be allocated. Key parameters for both mechanisms are defined in 3GPP specifications to optimize performance and control signaling in the network.
This document discusses cell coverage and ranges for LTE networks. Key points include:
- LTE aims to support cell radii up to 5 km while still enabling coverage of 100km or more, to support high-speed rail and wide-area deployments.
- Cell sizes in LTE can range from a few meters across in indoor environments to radii of 100km or more for large rural cells.
- The random access preamble formats and timing advance mechanisms in LTE are designed to support the maximum cell size of 100km radius to accommodate the largest expected propagation delays.
- A guard period duration of 700 μs supports one-way propagation delays of around 100km, allowing LTE to potentially support cell
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 an overview of LTE air interface concepts including:
- Main LTE features such as frequency bands and mobility protocols.
- The LTE protocol stack including layers such as RRC, PDCP, RLC, MAC and physical.
- LTE channel types including logical, transport, and physical channels.
- Key physical channel functions like reference signals, synchronization signals, broadcast channels, and control channels.
- Uplink/downlink channel structures including time and frequency domain configurations.
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,
This document specifies 5G RRC parameters including message definitions and information elements for timers, counters, constants, and UE variables. It defines RRC messages that may be sent on different logical channels and provides descriptions of message fields. It also specifies bandwidth part configurations, measurement reporting, reconfiguration messages, and beam failure recovery resources.
The document discusses key technologies in LTE including access techniques, MIMO, scheduling, link adaptation, and HARQ. It covers OFDM and SC-FDMA used for downlink and uplink access, benefits of MIMO including improved SINR and shared SINR through modes like transmit diversity, receive diversity, and spatial multiplexing. Scheduling considers factors like CQI and aims for fairness and throughput. Link adaptation uses CQI and MCS to optimize air interface efficiency. HARQ enables recovery of errors at the MAC layer through retransmissions.
With the rise of data-intensive mobile applications, network operators must find ways to increase network capacity to meet demand. MIMO (Multiple-Input Multiple-Output) techniques, which use multiple antennas at the transmission and reception ends, have the potential to significantly boost network throughput through spatial multiplexing. However, optimizing networks for MIMO's full benefits presents challenges, as MIMO works best under rich scattering conditions and requires accurate measurement of multipath environments. Real-world RF measurements tailored for MIMO networks can help operators overcome these challenges and maximize throughput gains from MIMO without additional spectrum or infrastructure.
This document provides an overview of two fundamental mechanisms in LTE access networks: random access and buffer status reporting. It describes the random access procedure used by UEs to connect to the network, including the exchange of preambles, responses, and temporary identifiers. It also explains the buffer status reporting procedure, where UEs indicate to the base station the amount of data waiting to be transmitted so that uplink resources can be allocated. Key parameters for both mechanisms are defined in 3GPP specifications to optimize performance and control signaling in the network.
This document discusses cell coverage and ranges for LTE networks. Key points include:
- LTE aims to support cell radii up to 5 km while still enabling coverage of 100km or more, to support high-speed rail and wide-area deployments.
- Cell sizes in LTE can range from a few meters across in indoor environments to radii of 100km or more for large rural cells.
- The random access preamble formats and timing advance mechanisms in LTE are designed to support the maximum cell size of 100km radius to accommodate the largest expected propagation delays.
- A guard period duration of 700 μs supports one-way propagation delays of around 100km, allowing LTE to potentially support cell
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
LTE TDD uses time division duplexing to separate uplink and downlink transmissions on the same frequency band. It divides each 10ms frame into uplink and downlink timeslots. Key aspects of LTE TDD include its frame structure with special subframes containing DwPTS, GP and UpPTS fields, supported frequency bands and bandwidths, and physical channels such as PDSCH, PDCCH, and PRACH that operate differently than in LTE FDD. Network planning requires consideration of uplink/downlink configuration and propagation delays between base stations and mobile stations.
LTE Physical Layer Transmission Mode Selection Over MIMO Scattering ChannelsIllaKolani1
Although LTE networks systems profits from recent advanced transmission techniques as MIMO systems, it encounters particularly two mains challenges:
MIMO channel Modeling or MIMO channel estimation .
An Optimal Dynamic MIMO transmission modes switching following the variation of MIMO Channel.
This Thesis proposes a channel model taking into account the motion of the UE first and after use this model to design an optimal transmission mode selection for 4G networks
Some questions and answers on lte radio interfaceThananan numatti
The document contains questions and answers about LTE radio interface concepts. It discusses:
- How the UE is scheduled via the PDCCH containing DCI messages for uplink/downlink scheduling.
- That PDCP is located in the eNodeB and handles encryption, header compression, and reordering at handover.
- That a resource block occupies 12 subcarriers and one time slot of 0.5ms in the frequency and time domains.
This document provides an introduction to LTE/E-UTRA technology, including both FDD and TDD modes of operation. It describes the key requirements for UMTS Long Term Evolution such as high data rates, low latency, and improved spectrum efficiency compared to previous standards. The document then covers various aspects of the LTE standard, including the OFDMA downlink and SC-FDMA uplink transmission schemes, MIMO concepts, protocol architecture, UE capabilities, and testing considerations. Abbreviations used and additional references are also provided.
The document provides an overview of LTE (Long Term Evolution) Release 8. It discusses key requirements for LTE such as supporting high data rates, low latency, and an all-IP network. It describes the network architecture including components like eNodeB, MME, S-GW, and P-GW. It also covers functionality of these components and the protocol stack consisting of PDCP, RLC, MAC, and RRC layers. Mobility management, QoS, and comparisons to other technologies like HSPA+ and WiMAX are also summarized.
The document discusses timing advances in GSM networks. It explains that timing advances are used to compensate for propagation delay between mobile stations and base transceiver stations. The base station system determines the timing advance needed based on how far away it perceives the mobile station to be. Each timing advance corresponds to a range of distances, with each subsequent timing advance representing an additional 553.5 meters in distance from the base transceiver station. The maximum distance of a cell is standardized at 37.8 kilometers to account for the round trip delay of the radio signal.
The document discusses LTE medium access control layer concepts. It describes dynamic and semi-persistent scheduling used by the eNB to allocate downlink and uplink radio resources to UEs. Semi-persistent scheduling is used for periodic traffic like VoIP to reduce signaling overhead compared to dynamic scheduling. It also discusses buffer status reporting where UEs indicate how much data they have to transmit, and scheduling requests where UEs request uplink resources from the eNB.
This document provides an overview of the LTE radio layer 2, radio resource control (RRC), and radio access network architecture. It discusses the E-UTRAN architecture including eNodeBs, home eNodeBs, and relays. It describes the user plane including bearer services, the user plane protocol stack with PDCP, RLC, and MAC layers, and security and transport functions. It also outlines the control plane including connection control and RRC states, and highlights features like interoperability, self-organizing networks, positioning, broadcasting, latency evaluations, and LTE-Advanced.
This document provides an overview of the LTE physical channel structure and procedures between the eNB and UE. It describes the LTE architecture and introduces the main physical channels including downlink channels like PBCH, PDCCH, PDSCH and uplink channels like PUSCH, PUCCH, PRACH. It explains the channel mapping and provides examples of the initial access procedure and synchronization signal transmission. Key concepts covered are radio interface protocol stacks, channel coding, multiple access, and reference signals.
The document discusses the commonalities and differences between Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD) modes in the Long Term Evolution (LTE) air interface. Key commonalities include using the same radio interface schemes, subframe formats, network architecture, and air interface protocols. Key differences are that TDD uses the same frequency band for both uplink and downlink while FDD requires paired spectrum, and TDD UEs do not need a duplex filter while FDD UEs do.
The document discusses the physical layer design of WCDMA networks. It provides an overview of WCDMA network architecture and the UMTS network model. It then describes the physical channels, transport formats, channel coding, spreading techniques and code types used in the WCDMA uplink and downlink. Key aspects covered include dedicated and common physical channels, orthogonal variable spreading factor channelization codes, scrambling codes, and transport block sets.
This document provides an overview of the key components and protocols in 3G and 4G mobile networks. It includes a high-level diagram of the overall 4G architecture and summaries of protocols like S1, X2, NAS, RRC. Key concepts covered include the PDCP, RLC, MAC and PHY layers, QoS classes, paging, attachment, handover procedures between eNodeBs and between 4G and 3G networks.
TDD & FDD Interference on TD-LTE B NetworkRay KHASTUR
1. The document discusses investigating issues with an RTWP site in region M that is experiencing interference from external sources.
2. There are two main sources of interference - a WiMAX operator using adjacent frequency bands and a local ISP using wireless MikroTik devices on the same frequency band illegally.
3. Monitoring of border sites and the highest RTWP sites was conducted to determine the direction of interference and its effects, finding it is most significantly impacting key performance indicators and the user experience.
This presentation discusses about the WCDMA air Interface used in 3G i.e. UMTS. This Radio Interface has great capability on which Third Generation of Mobile Communication is built, with backward compatibility.
The document discusses PCI (Physical Cell Identity) planning in LTE networks. It describes the cell search process where the UE detects the PCI from the PSS and SSS. The PCI is used to determine the location of reference signals and avoid interference. The document recommends strategies for PCI planning such as assigning color groups to sectors and code groups to sites to avoid conflicting PCI combinations in adjacent cells. It also discusses tools to analyze potential PCI interference and make changes to mitigate issues.
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.
The document summarizes UMTS interview questions and answers related to RRC states, radio resource control, and cell procedures. Key points include:
1) The four RRC states are Cell DCH, Cell FACH, Cell PCH, and URA PCH which define the level of connection between the UE and network.
2) Cell update procedure is used when the UE needs to notify the network of its presence in a new cell in states like Cell/URA PCH. Causes include uplink data, paging response, and cell reselection.
3) The active set defines the cells the UE is connected to, while the monitored set includes neighbors for handover. Paging is
Receive diversity uses two receive antennas at the mobile to improve signal reception on the uplink and downlink in LTE systems. Transmit diversity addresses the smaller separation between a mobile's antennas compared to a base station's antennas, using either closed-loop or open-loop techniques which provide feedback or no feedback to the transmitter, respectively. Spatial multiplexing further increases capacity by transmitting independent data streams simultaneously through multiple antennas to different users.
LTE uses OFDMA to divide available bandwidth into narrow subcarriers. A resource block in LTE consists of 12 subcarriers each with a bandwidth of 15 kHz, making the total resource block bandwidth 180 kHz. The LTE frame structure consists of 10 subframes that make up 1 frame, with each subframe being 1 ms long and consisting of 2 slots of 0.5 ms each. LTE uses either frequency division duplexing (FDD) where uplink and downlink occur on separate frequencies simultaneously, or time division duplexing (TDD) where uplink and downlink take turns in each subframe.
The document discusses Radio Resource Control (RRC) in UMTS, including RRC states, functions, and procedures. It describes the four RRC states - CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. CELL_DCH has a dedicated channel allocated, while the others do not. CELL_FACH continuously monitors a common channel. CELL_PCH and URA_PCH use discontinuous reception on a paging channel. URA_PCH location is known on the UTRAN registration area level. The document also answers questions about RRC, including differentiating RRC states, conditions for CELL_FACH
This document provides an overview of the IMS architecture from the perspective of an LTE user equipment. It describes the key components of IMS including the UE, Evolved Packet Core, and IMS core. It also discusses how IMS enables convergence across different access technologies, service types, and network functions to support multimedia services like voice and video over LTE.
3G Network Solutions is a leading trainer and consultant in the telecom industry founded in 200X in Bangalore, India. It has trained engineers from major companies and undertaken strategic projects for customers including Rohde & Schwarz, Samsung, Nokia Siemens Networks, and Vodafone. The company provides services such as protocol testing, network optimization, and training for 2G, 3G, and 4G technologies.
LTE TDD uses time division duplexing to separate uplink and downlink transmissions on the same frequency band. It divides each 10ms frame into uplink and downlink timeslots. Key aspects of LTE TDD include its frame structure with special subframes containing DwPTS, GP and UpPTS fields, supported frequency bands and bandwidths, and physical channels such as PDSCH, PDCCH, and PRACH that operate differently than in LTE FDD. Network planning requires consideration of uplink/downlink configuration and propagation delays between base stations and mobile stations.
LTE Physical Layer Transmission Mode Selection Over MIMO Scattering ChannelsIllaKolani1
Although LTE networks systems profits from recent advanced transmission techniques as MIMO systems, it encounters particularly two mains challenges:
MIMO channel Modeling or MIMO channel estimation .
An Optimal Dynamic MIMO transmission modes switching following the variation of MIMO Channel.
This Thesis proposes a channel model taking into account the motion of the UE first and after use this model to design an optimal transmission mode selection for 4G networks
Some questions and answers on lte radio interfaceThananan numatti
The document contains questions and answers about LTE radio interface concepts. It discusses:
- How the UE is scheduled via the PDCCH containing DCI messages for uplink/downlink scheduling.
- That PDCP is located in the eNodeB and handles encryption, header compression, and reordering at handover.
- That a resource block occupies 12 subcarriers and one time slot of 0.5ms in the frequency and time domains.
This document provides an introduction to LTE/E-UTRA technology, including both FDD and TDD modes of operation. It describes the key requirements for UMTS Long Term Evolution such as high data rates, low latency, and improved spectrum efficiency compared to previous standards. The document then covers various aspects of the LTE standard, including the OFDMA downlink and SC-FDMA uplink transmission schemes, MIMO concepts, protocol architecture, UE capabilities, and testing considerations. Abbreviations used and additional references are also provided.
The document provides an overview of LTE (Long Term Evolution) Release 8. It discusses key requirements for LTE such as supporting high data rates, low latency, and an all-IP network. It describes the network architecture including components like eNodeB, MME, S-GW, and P-GW. It also covers functionality of these components and the protocol stack consisting of PDCP, RLC, MAC, and RRC layers. Mobility management, QoS, and comparisons to other technologies like HSPA+ and WiMAX are also summarized.
The document discusses timing advances in GSM networks. It explains that timing advances are used to compensate for propagation delay between mobile stations and base transceiver stations. The base station system determines the timing advance needed based on how far away it perceives the mobile station to be. Each timing advance corresponds to a range of distances, with each subsequent timing advance representing an additional 553.5 meters in distance from the base transceiver station. The maximum distance of a cell is standardized at 37.8 kilometers to account for the round trip delay of the radio signal.
The document discusses LTE medium access control layer concepts. It describes dynamic and semi-persistent scheduling used by the eNB to allocate downlink and uplink radio resources to UEs. Semi-persistent scheduling is used for periodic traffic like VoIP to reduce signaling overhead compared to dynamic scheduling. It also discusses buffer status reporting where UEs indicate how much data they have to transmit, and scheduling requests where UEs request uplink resources from the eNB.
This document provides an overview of the LTE radio layer 2, radio resource control (RRC), and radio access network architecture. It discusses the E-UTRAN architecture including eNodeBs, home eNodeBs, and relays. It describes the user plane including bearer services, the user plane protocol stack with PDCP, RLC, and MAC layers, and security and transport functions. It also outlines the control plane including connection control and RRC states, and highlights features like interoperability, self-organizing networks, positioning, broadcasting, latency evaluations, and LTE-Advanced.
This document provides an overview of the LTE physical channel structure and procedures between the eNB and UE. It describes the LTE architecture and introduces the main physical channels including downlink channels like PBCH, PDCCH, PDSCH and uplink channels like PUSCH, PUCCH, PRACH. It explains the channel mapping and provides examples of the initial access procedure and synchronization signal transmission. Key concepts covered are radio interface protocol stacks, channel coding, multiple access, and reference signals.
The document discusses the commonalities and differences between Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD) modes in the Long Term Evolution (LTE) air interface. Key commonalities include using the same radio interface schemes, subframe formats, network architecture, and air interface protocols. Key differences are that TDD uses the same frequency band for both uplink and downlink while FDD requires paired spectrum, and TDD UEs do not need a duplex filter while FDD UEs do.
The document discusses the physical layer design of WCDMA networks. It provides an overview of WCDMA network architecture and the UMTS network model. It then describes the physical channels, transport formats, channel coding, spreading techniques and code types used in the WCDMA uplink and downlink. Key aspects covered include dedicated and common physical channels, orthogonal variable spreading factor channelization codes, scrambling codes, and transport block sets.
This document provides an overview of the key components and protocols in 3G and 4G mobile networks. It includes a high-level diagram of the overall 4G architecture and summaries of protocols like S1, X2, NAS, RRC. Key concepts covered include the PDCP, RLC, MAC and PHY layers, QoS classes, paging, attachment, handover procedures between eNodeBs and between 4G and 3G networks.
TDD & FDD Interference on TD-LTE B NetworkRay KHASTUR
1. The document discusses investigating issues with an RTWP site in region M that is experiencing interference from external sources.
2. There are two main sources of interference - a WiMAX operator using adjacent frequency bands and a local ISP using wireless MikroTik devices on the same frequency band illegally.
3. Monitoring of border sites and the highest RTWP sites was conducted to determine the direction of interference and its effects, finding it is most significantly impacting key performance indicators and the user experience.
This presentation discusses about the WCDMA air Interface used in 3G i.e. UMTS. This Radio Interface has great capability on which Third Generation of Mobile Communication is built, with backward compatibility.
The document discusses PCI (Physical Cell Identity) planning in LTE networks. It describes the cell search process where the UE detects the PCI from the PSS and SSS. The PCI is used to determine the location of reference signals and avoid interference. The document recommends strategies for PCI planning such as assigning color groups to sectors and code groups to sites to avoid conflicting PCI combinations in adjacent cells. It also discusses tools to analyze potential PCI interference and make changes to mitigate issues.
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.
The document summarizes UMTS interview questions and answers related to RRC states, radio resource control, and cell procedures. Key points include:
1) The four RRC states are Cell DCH, Cell FACH, Cell PCH, and URA PCH which define the level of connection between the UE and network.
2) Cell update procedure is used when the UE needs to notify the network of its presence in a new cell in states like Cell/URA PCH. Causes include uplink data, paging response, and cell reselection.
3) The active set defines the cells the UE is connected to, while the monitored set includes neighbors for handover. Paging is
Receive diversity uses two receive antennas at the mobile to improve signal reception on the uplink and downlink in LTE systems. Transmit diversity addresses the smaller separation between a mobile's antennas compared to a base station's antennas, using either closed-loop or open-loop techniques which provide feedback or no feedback to the transmitter, respectively. Spatial multiplexing further increases capacity by transmitting independent data streams simultaneously through multiple antennas to different users.
LTE uses OFDMA to divide available bandwidth into narrow subcarriers. A resource block in LTE consists of 12 subcarriers each with a bandwidth of 15 kHz, making the total resource block bandwidth 180 kHz. The LTE frame structure consists of 10 subframes that make up 1 frame, with each subframe being 1 ms long and consisting of 2 slots of 0.5 ms each. LTE uses either frequency division duplexing (FDD) where uplink and downlink occur on separate frequencies simultaneously, or time division duplexing (TDD) where uplink and downlink take turns in each subframe.
The document discusses Radio Resource Control (RRC) in UMTS, including RRC states, functions, and procedures. It describes the four RRC states - CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. CELL_DCH has a dedicated channel allocated, while the others do not. CELL_FACH continuously monitors a common channel. CELL_PCH and URA_PCH use discontinuous reception on a paging channel. URA_PCH location is known on the UTRAN registration area level. The document also answers questions about RRC, including differentiating RRC states, conditions for CELL_FACH
This document provides an overview of the IMS architecture from the perspective of an LTE user equipment. It describes the key components of IMS including the UE, Evolved Packet Core, and IMS core. It also discusses how IMS enables convergence across different access technologies, service types, and network functions to support multimedia services like voice and video over LTE.
3G Network Solutions is a leading trainer and consultant in the telecom industry founded in 200X in Bangalore, India. It has trained engineers from major companies and undertaken strategic projects for customers including Rohde & Schwarz, Samsung, Nokia Siemens Networks, and Vodafone. The company provides services such as protocol testing, network optimization, and training for 2G, 3G, and 4G technologies.
This document provides an overview of channel estimation strategies used in orthogonal frequency division multiplexing (OFDM) systems. It describes the basic types of channel estimation methods: block-type pilot channel estimation and comb-type pilot channel estimation. For block-type estimation, pilots are inserted into all subcarriers of OFDM symbols periodically. This allows estimation of the channel conditions between pilot symbols. Estimation can be done with least squares (LS), minimum mean-square error (MMSE), or modified MMSE. For comb-type estimation, pilots are inserted into certain subcarriers of each symbol, requiring interpolation to estimate data subcarriers. The document compares the implementation complexity and performance of different estimation methods.
The document discusses LTE as the de facto standard for mobile access networks. Key points include:
- LTE is designed for next generation networks and provides all-IP connectivity and consistent experience across access types.
- LTE release 8 supports peak downlink speeds up to 326 Mbps and uplink speeds up to 86 Mbps with 20 MHz bandwidth.
- LTE provides over 4x higher downlink throughput and 5x higher uplink throughput than HSPA+, improved spectrum efficiency, and supports FDD and TDD duplexing and scalable 1.4-20 MHz channel bandwidths.
The document describes CS fallback procedures for LTE networks, including an immediate-return (IR) scheme and a proposed delayed-return (DR) scheme. The IR scheme has the UE immediately return to LTE after a call is completed, while DR delays the return to avoid unnecessary CS fallbacks if another call is likely. Analytic models are developed to study the performance of IR and DR based on real network measurements. The study finds DR can reduce CS fallback costs by up to 60% compared to IR.
- Orthogonal Frequency Division Multiplexing (OFDM) is a digital multi-carrier modulation technique that divides the available bandwidth into multiple orthogonal subcarriers.
- OFDM provides advantages over traditional Frequency Division Multiplexing (FDM) by making the subcarriers orthogonal, allowing them to overlap without interference and achieving higher spectral efficiency.
- The document provides an example of how OFDM works by taking a bit stream and mapping bits in groups of four to four orthogonal subcarriers at frequencies of 1, 2, 3, and 4 Hz using BPSK modulation before combining them to generate the OFDM signal.
This document describes the process of a successful LTE handover from a source eNodeB to a target eNodeB using the X2 interface. It involves measuring signal strengths, selecting a target cell, preparing the target for handover, executing the handover by redirecting data and radio resources to the target, and completing the handover by releasing resources from the source. Key steps include establishing bearers between the target and core network elements like MME and SGW, sending a handover command to the UE, and switching the data path from source to target after handover is completed.
The document discusses various handover procedures in LTE networks, including:
1. Intra-LTE handovers using the X2 interface or S1 interface when the MME and SGW do not change.
2. Inter-MME handovers using S1 that do not change the SGW.
3. Inter-MME/SGW handovers using S1 where both the MME and SGW change.
4. Inter-RAT handovers from LTE to UTRAN Iu mode, which involve reserving resources in the target UTRAN/GERAN network during a preparation phase before executing the handover.
The document summarizes the signaling flow between an eNodeB and MME during LTE attach and default EPS bearer setup procedures. It includes: (1) UE attach, authentication and security setup; (2) Establishment of two default EPS bearers for two PDNs; (3) Release of UE context due to inactivity and reestablishment using a service request.
This document provides an overview of the LTE protocol stack, focusing on the data link layer (L2) which includes the MAC, RLC, and PDCP sublayers. It describes the architecture and functions of MAC including logical and transport channels, HARQ, scheduling, random access procedure, discontinuous reception, and more. It also covers the RLC sublayer including its different modes (TM, UM, AM) and functions like segmentation, reassembly and error correction. Finally it discusses the PDCP sublayer and its roles in header compression, security, and handover support. The document is intended to provide a systematic understanding of the LTE protocol stack for engineers working in areas like development, testing, optimization and trouble
REALIZATION OF TRANSMITTER AND RECEIVER ARCHITECTURE FOR DOWNLINK CHANNELS IN...VLSICS Design
Long Term Evolution (LTE), the next generation of radio technologies designed to increase the capacity and speed of mobile networks. The future communication systems require much higher peak rate for the air interface but very short processing delay. This paper mainly focuses on to improve the processing speed and capability and decrease the processing delay of the downlink channels using the parallel processing technique. This paper proposes Parallel Processing Architecture for both transmitter and receiver for Downlink channels in 3GPP-LTE. The Processing steps include Scrambling, Modulation, Layer mapping, Precoding and Mapping to the REs in transmitter side. Similarly demapping from the REs, Decoding and Detection, Delayer mapping and Descrambling in Receiver side. Simulation is performed by using modelsim and Implementation is achieved using Plan Ahead tool and virtex 5 FPGA.Implemented results are discussed in terms of RTL design, FPGA editor, power estimation and resource estimation.
This document discusses WCDMA channels at different levels including logical channels, transport channels, and physical channels. It provides details on:
- Logical channels describe the type of information transferred and include control and traffic channels.
- Transport channels describe how logical channels are transferred over the interface and include dedicated and common channels.
- Physical channels provide the transmission medium and are defined by specific codes. They include channels like DPDCH, DPCCH, PDSCH, PRACH, and CPICH.
- The document also discusses the radio frame structure in WCDMA and details on different physical channel types and their characteristics.
This document provides an overview of the LTE physical layer frame structure and signals for both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD). It describes the basic time and frequency units used in LTE, the uplink and downlink frame structures, reference signals, and the modulation schemes used for different physical channels. Key aspects covered include resource blocks, OFDM signal generation, uplink SC-FDMA modulation, and the use of multiple antennas and spatial multiplexing in the downlink.
The document provides an overview of LTE physical layer signals for both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD), including:
- Two frame structure types used in LTE - Type 1 for FDD using frequency separation of uplink and downlink, and Type 2 for TDD using time separation
- Key timing units like frames, subframes, slots and symbols
- Uplink and downlink reference signals, physical channels, and modulations
- Synchronization methods and differences between FDD and TDD operation
The document discusses numerology and air interface resources in 5G New Radio (NR), including:
- NR supports multiple subcarrier spacings (SCS) to accommodate different services and bands. SCS determines symbol length and impacts coverage, latency, mobility, and phase noise.
- Time domain resources include slots, subframes, and frames which are configured similarly to LTE. Symbol length depends on SCS.
- Frequency domain resources include resource blocks and bandwidth parts. Space domain resources include antenna ports and quasi-co-location.
4G-Fourth Generation Mobile Communication SystemSafaet Hossain
Seminar on "4G-Fourth Generation Mobile Communication System" at UODA Auditorium, November 16,2013.
Technical Presented by: Ahmedul Quadir, Function Tester, Ericcson, Sweeden
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.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
This document summarizes key aspects of the WCDMA physical layer:
- Spreading uses channelization codes to separate signals and scrambling codes to separate terminals and cells. Channelization codes increase bandwidth while scrambling does not affect bandwidth.
- Transport channels map data to physical channels and are multiplexed. Dedicated channels are reserved for users while common channels can be used by any user.
- In the uplink, dual channels are used to avoid audio interference from discontinuous transmission. The DPCCH carries control data and the DPDCH carries data.
- In the downlink, DPCCH and DPDCH are time-multiplexed on the DPCH using QPSK.
A Heuristic Algorithm For The Resource Assignment Problem In Satellite Teleco...Elizabeth Williams
The document proposes a heuristic algorithm for solving the resource assignment problem in satellite telecommunication networks using Demand Assigned Multiple Access (DAMA) protocol. The algorithm allows processing capacity requests with message expiration times and maximum packet loss rates using minimum bandwidth. It models the problem as a two-dimensional strip packing problem and adapts the Best Fit Decreasing heuristic to provide candidate solutions within hundreds of milliseconds, meeting the real-time response needs of such networks.
SONET-SDH is the digital infrastructure that telephone networks are largely based on today. It uses Time Division Multiplexing (TDM) and strict synchronization. Key components of SONET-SDH include SONET for North America, SDH for Europe and Japan, and STS for electrical signals. SONET-SDH was developed to replace the older Plesiochronous Digital Hierarchy (PDH) standard due to lack of scalability and synchronization issues. SONET-SDH defines a structured multiplexing hierarchy, management and protection mechanisms, and physical layer requirements to provide fault tolerance, interoperability, flexibility, and network monitoring capabilities.
SDH (Synchronous Digital Hierarchy) & Its Architectureijsrd.com
The SDH (Synchronous Digital Hierarchy) tell us about transferring large amount of data over an same optical fiber and this document gives us the information about the structure and architecture of SDH.
Comparative performance analysis of different modulation techniques for papr ...IJCNCJournal
One of the most important multi-carrier tran
smission techniques used in the latest wireless com
munication
arena is known as Orthogonal Frequency Division Mul
tiplexing (OFDM). It has several characteristics
such as providing greater immunity to multipath fad
ing & impulse noise, eliminating Inter Symbol
Interference (ISI) & Inter Carrier Interference (IC
I) using a guard interval known as Cyclic Prefix (C
P). A
regular difficulty of OFDM signal is high peak to a
verage power ratio (PAPR) which is defined as the r
atio
of the peak power to the average power of OFDM Sign
al. An improved design of amplitude clipping &
filtering technique of us previously reduced signif
icant amount of PAPR with slightly increase bit err
or rate
(BER) compare to an existing method in case of Quad
rature Phase Shift Keying (QPSK) & Quadrature
Amplitude Modulation (QAM). This paper investigates
a comparative performance analysis of the differen
t
higher order modulation techniques on that design.
The document provides an overview of the physical layer of the McWill air interface protocol. The physical layer is responsible for signal transmission and reception, coding and decoding, synchronization, channel quality evaluation, and interfacing with upper layers. It uses techniques such as OFDMA, code spreading, and adaptive modulation to provide flexibility, high capacity, and performance while combating interference. Key aspects covered include frame structure, synchronization signals, physical channels, and signal processing methods for the downlink and uplink.
The document provides an overview of LTE physical layer specifications including OFDMA frame structure, resource block structure, protocol architecture, physical channel structure and procedures, UE measurements like RSRP and RSRQ, and key enabling technologies of LTE such as OFDM, SC-FDMA, and MIMO. It describes the LTE requirements for high peak data rates, low latency, support for high mobility users, and flexible spectrum deployment.
The document provides an overview of LTE physical layer specifications including OFDMA frame structure, resource block structure, protocol architecture, physical channel structure and procedures, UE measurements like RSRP and RSRQ, and key enabling technologies of LTE such as OFDM, SC-FDMA, and MIMO. It describes the LTE requirements for high peak data rates, low latency, support for high mobility users, and enhanced broadcast services.
A Peak to Average Power Ratio (PAPR) Reduction in OFDM SystemsIRJET Journal
This document discusses peak-to-average power ratio (PAPR) reduction techniques for orthogonal frequency division multiplexing (OFDM) systems. It begins with an introduction to OFDM and the problem of high PAPR values in OFDM signals. It then describes the clipping and filtering method and parabolic peak cancellation method for PAPR reduction. It analyzes these techniques by evaluating complementary cumulative distribution function (CCDF) curves and bit error rate (BER) with the goal of minimizing PAPR while maintaining acceptable BER. Power amplifier nonlinearity is also discussed as a key factor affected by high PAPR OFDM signals.
The document discusses 5G new radio (NR) physical layer resources including numerology, time-domain resources, frequency-domain resources, and space-domain resources. It provides details on key 5G NR concepts such as subcarrier spacing, symbols, slots and frames. Cyclic prefix length is determined based on subcarrier spacing to maintain consistent overhead. Slot formats in 5G NR provide more flexibility with symbol level uplink/downlink switching compared to LTE.
This document proposes a methodology for incorporating uplink delay constraints into LTE cell planning for smart grid applications. It presents the following:
1) A semi-analytical approach is proposed to evaluate uplink transmission delays considering buffering delays before scheduling, packet transmission/retransmission delays over the air interface, and constraints from smart grid standards.
2) Analytical models are used to estimate buffering delays before scheduling based on queue length and service rate. Packet transmission delays are estimated considering packet segmentation, link adaptation, resource block allocation and retransmissions.
3) A cell planning algorithm is described that incorporates these delay metrics to validate compliance with smart grid delay constraints and determine the maximum cell range based on
The document describes the 3GPP LTE Radio Link Control (RLC) sub layer. It discusses RLC modes including transparent mode, unacknowledged mode, and acknowledged mode. For each mode it describes functions, state variables, procedures and interfaces. It also covers RLC PDU formats, configurable parameters, and transmission priority policies.
This document discusses the Packet Data Convergence Protocol (PDCP) sublayer in 3GPP LTE networks. It describes the key functions of PDCP including header compression, ciphering, integrity protection, and transmission of user and control plane data. It also explains PDCP's use of ROHC for header compression and the various PDCP protocol data unit formats used for control and user plane messages.
This document discusses the Medium Access Control (MAC) layer in 3GPP Long Term Evolution (LTE) cellular networks. It covers topics such as LTE channel architecture with physical, transport, and logical channels; functions of the MAC layer including mapping channels, error correction, priority handling, and logical channel prioritization; MAC sublayer organization in the downlink and uplink; and downlink and uplink channel types including their purposes and characteristics. Diagrams illustrate the protocol stack and channel relationships.
This document from EventHelix.com provides information about 3GPP LTE channels and the MAC layer. It describes the different logical and transport channels used in LTE, including the functions of the MAC layer such as mapping channels, error correction, and priority handling. Diagrams and explanations are provided for the downlink and uplink channel architectures, as well as the physical layer channels and signaling procedures like random access.
The document describes the LTE RRC connection setup messaging sequence between a UE (user equipment) and an eNodeB (base station). It involves the following steps:
1) The UE initiates a random access procedure by sending a random access preamble to the eNodeB.
2) The eNodeB responds with a random access response assigning the UE a C-RNTI and timing advance value.
3) The UE sends an RRC connection request message using the assigned resources with its UE identity and establishment cause.
4) The eNodeB sends an RRC connection setup message configuring radio bearers.
5) The UE responds with an RRC connection setup complete message
Three UEs (UE-A, UE-B, UE-C) initiate the random access procedure at the same time to connect to the eNodeB. UE-A and UE-B select the same preamble, resulting in a collision. UE-C selects a different preamble. The eNodeB responds to the preambles, assigning resources to UE-A and UE-C. During contention resolution, UE-A's connection request is acknowledged, while UE-B's collides and fails. UE-B then retries the random access procedure with a new preamble.
The document summarizes key System Information Blocks (SIBs) in LTE. SIB1 contains cell access parameters and scheduling of other SIBs. SIB2 contains radio resource configuration information. SIB3 contains cell reselection parameters for intra-frequency, inter-frequency, and inter-RAT cells. SIBs 4-7 provide additional cell reselection parameters. SIB10-12 contain emergency alerting information for ETWS and CMAS notifications. The SIBs convey important cell and network configuration parameters to help user equipment access the network and perform functions like cell reselection.
This document discusses various topics related to Long Term Evolution (LTE) including call flow, radio link failure, discontinuous reception (DRX), paging, scheduling, random access channel (RACH) procedure, self-organizing networks (SON), and quality of service (QoS). It provides details on the call flow process when a user equipment (UE) is powered on, performs initial cell selection and attachment, and establishes a default bearer. It also describes procedures for radio link failure, DRX, paging, scheduling, RACH, SON functions including self-configuration and optimization, and QoS with default and dedicated bearers.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
हिंदी वर्णमाला पीपीटी, hindi alphabet PPT presentation, hindi varnamala PPT, Hindi Varnamala pdf, हिंदी स्वर, हिंदी व्यंजन, sikhiye hindi varnmala, dr. mulla adam ali, hindi language and literature, hindi alphabet with drawing, hindi alphabet pdf, hindi varnamala for childrens, hindi language, hindi varnamala practice for kids, https://www.drmullaadamali.com
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
-------------------------------------------------------------------------------
Find out more about ISO training and certification services
Training: ISO/IEC 27001 Information Security Management System - EN | PECB
ISO/IEC 42001 Artificial Intelligence Management System - EN | PECB
General Data Protection Regulation (GDPR) - Training Courses - EN | PECB
Webinars: https://pecb.com/webinars
Article: https://pecb.com/article
-------------------------------------------------------------------------------
For more information about PECB:
Website: https://pecb.com/
LinkedIn: https://www.linkedin.com/company/pecb/
Facebook: https://www.facebook.com/PECBInternational/
Slideshare: http://www.slideshare.net/PECBCERTIFICATION
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
1. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
LTE PHY Fundamentals
Roger Piqueras Jover
DL Physical Channels
- DL-SCH: The DownLink Shared CHannel is a channel used to transport down-link user data or
Radio Resource Control (RRC) messages, as well as system information which are not
transported via the Broadcast CHannel (BCH).
- PBCH: The Physical Broadcast CHannel carries the Master Information Block (MIB). It consists of
a limited number of the most frequently transmitted parameters essential for initial access to
the cell. The PBCH is designed for early detection by the UE, and cell-wide coverage.
- PDSCH: The Physical Downlink Shared CHannel is the main downlink data-bearing channel in
LTE, used for all user data, as well as for broadcast system information which is not carried on
the Physical Broadcast CHannel (PBCH). It is also used for paging messages.
- PDCCH: The Physical Downlink Control CHannel is a downlink control channel used to support
efficient data transmission in LTE. A PDCCH carries a message known as Downlink Control
Information (DCI), which includes transmission resource assignments and other control
information for a UE or group of UEs. Many PDCCHs can be transmitted in a subframe.
- PCFICH: The Physical Control Format Indicator CHannel is a downlink physical channel that
carries a Control Format Indicator (CFI) which indicates the number of OFDM symbols (i.e.
normally 1, 2 or 3) used for transmission of downlink control channel information in each
subframe.
- PHICH: The Physical Hybrid ARQ Indicator CHannel is a downlink physical channel that carries
the Hybrid ARQ (HARQ) ACK/NACK information indicating whether the eNodeB has correctly
received a transmission on the Physical Uplink Shared CHannel (PUSCH). Multiple PHICHs (for
different UEs) are mapped to the same set of downlink resource elements. These constitute a
PHICH group, where different PHICHs within the same PHICH group are separated through
different complex orthogonal Walsh sequences.
Design constraints
The two basic principal physical parameters are the cyclic prefix length (Tg) and the sub-carrier spacing
(Δf). There are several design constraints to select these two parameters, and the standard tries to find a
trade-off with the optimal values holding the constraints.
2. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
First of all, Tu should be as larger than Tg as possible so the system has low overhead (Tu >> Tg). It is
important to keep in mind that Tu has to be sufficiently small to ensure that the channel does not vary
within one OFDM symbol.
Tg has to be large enough to avoid Inter Symbol Interference (ISI). This is, Tg should be larger than the
delay spread (Td) of the channel. LTE has different configurations depending on the type of channel
through which the system is transmitting (Tg > Td).
Finally, considering a mobile UE, there is going to be a deviation in frequency from the expected carrier
frequency. This is due to the Doppler Effect. This deviation in frequency will have a maximum value of
fdmax=v/λ0, being λ0 the wavelength associated to the systems carrier frequency. Note that the Doppler
Effect will be more noticeable at the further subcarriers from the DC component of the OFDM base-
band system.
In order to attenuate the effects of Inter Carrier Interference (ICI), it is required that fdmax/Δf << 1. This
implies that Δf has to be large enough to overcome ICI (Δf >> fdmax).
Recall that Tu=1/Δf, so one has to find a trade-off between Tu/Tg and Δf.
Delay spread
- Urban environment (maximum delay spread of 15μs): Among the 3 possible configurations listed
in the LTE standard, in this kind of environment the chosen parameters would be Δf=15KHz and
CP=17μs (Extended CP mode). This value of Δf is the most common one and is determined in
order to be able to serve users moving at a velocity of up to 500km/h. The chosen length of the
cyclic prefix is enough to avoid ISI.
3. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
- Indoor environment (maximum delay spread of 1μs): In this case, the chosen parameters would
be Δf=15KHz and CP=5μs (Normal parametrization). Again, the chosen value of Δf would be
enough to cover speeds of up to 500km/h and a shorter CP s enough to avoid ISI with a delay
spread of 1μs.
Mapping of reference signals
The cell-specific reference signals are pilot signals inserted into the downlink signal that are used by the
UE to perform downlink channel estimation in order to perform coherent demodulation of the
information-bearing parts of the downlink signal. These signals are modulated using QPSK to make them
resilient to noise and errors and they carry one of the 504 different cell identities. They are also
transmitted in a power boosted way (6dB more than surrounding data symbols) so they are easily
detected, received and demodulated.
It can be shown that in an OFDM-based system an equidistant arrangement of reference symbols in the
lattice structure achieves the minimum mean squared error estimate of the channel. Moreover, in the
case of a uniform reference symbol grid, a ‘diamond shape’ in the time-frequency plane can be shown to
be optimal.
The placing of these reference signals in the time-frequency lattice is constrained both in time and
frequency.
Time domain requirements:
The required spacing in the time domain between reference signals is forced by the Doppler Effect. The
maximum Doppler frequency determines how fast the channel changes in time (coherence time
τc~1/fdmax). The LTE standard considers speeds of up to 500km/h. At a carrier frequency of 2GHz, this
speed represents a maximum Doppler shift of fdmax~ 950Hz. Given Nyquist’s sampling theorem, the
minimum sampling period required to reconstruct a channel with a Doppler shift of 950Hz is
Tmin=1/(2fdmax)≈0.5ms under the above assumptions. This implies that two reference symbols per slot
are needed in the time domain in order to estimate the channel correctly.
Frequency domain requirements
The required spacing in the frequency domain between reference signals s forced by the Coherence
Bandwidth of the channel. This bandwidth can be defined in different ways depending on the degree of
decorrelation in percentage. For example, a 50% coherence bandwidth is defined as the separation in
frequency such that the cross correlation between two frequency samples of the channel is 0.5.
The coherence bandwidth of the wireless channel si directly related to the Delay Spread (δτ) of the
channel. The coherence bandwith (50% and 90%) can be approximated as Bc,90%=1/(50 δτ) and
Bc,50%=1/(5δτ). The maximum r.m.s channel delay spread considered in the standard is 991 ns,
corresponding to Bc,90%≈20KHz and Bc,50%≈200KHz.
In LTE the spacing between two reference symbols in frequency, in one RB, is 45 kHz, thus allowing
the expected frequency domain variations of the channel to be resolved. Therefore, in the frequency
direction there is one reference symbol every six subcarriers on each OFDM symbols which includes
4. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
reference symbol, but these are staggered so that within each Resource Block (RB) there is one
reference symbol every 3 subcarriers.
LTE FDD DL radio frame
a) Radio frame structure (1.4MHz BW, 1 antenna port, CFI=2)
b) Overhead and peak rate throughput (64-QAM, 5.5547 bits per symbol)
CFI=2
Given the BW of 1.4MHz, there are only 6 RBs available. For CFI=2 the structure of the frame is the same
as the one depicted in section (6.a). As can be seen above, there are 6x10=60 blocks of (1RB x 1
subframe), organized in 10 columns with 6 RB each one.
8 of the columns will be of the type a (shown above), 1 column of type a and 1 column of type c. Let’s
compute the number of resource elements used for data and the ones used for control information per
each time of column:
5. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
- Column (a): CFI + PBCH + reference + PSS/SSS= 2x12+6x12+4=100 control resource elements
12x14-100= 68 data resource elements
- Column (b): CFI + reference + PSS/SSS= 2x12+2x12+6= 54 control resource elements
12x14-54= 114 data resource elements
- Column (c): CFI + reference= 2x12+6=30 control resource elements
12x14-30= 138 data resource elements
The overhead can be calculated as:
Total control=(1 column a)x(6x100)+(1 column b)x(6x54)+(8 columns c)x(6x30)=2364 resource elements
Total resource elements=(6x12)x(10x14)=10080
Overhead (CFI=2)= 100 x (2364/10080)=23.45%
One information symbol can be allocated in each data resource element. The transmission is done by
means of 64-QAM with an average of 5.5547 bits per symbol. The peak rate thorughput is:
Total data=(1 column a)x(6x68)+(1 column b)x(6x114)+(8 columns c)x(6x138)=7716 resource elements
Peak rate= (7716 symbols x 5.5547 bits/symbol)/10ms= 4.28Mbps
CFI=3
With CFI=3, the number of data and control resource elements in each column changes as follows:
- Column (a): CFI + PBCH + reference + PSS/SSS= 3x12+6x12+4=112 control resource elements
12x14-112= 56 data resource elements
- Column (b): CFI + reference + PSS/SSS= 3x12+2x12+6= 66 control resource elements
12x14-66= 102 data resource elements
- Column (c): CFI + reference= 3x12+6=42 control resource elements
12x14-42= 126 data resource elements
Total control=1x(6x112)+1x(6x66)+8x(6x42)=3084 resource elements
Total resource elements=(6x12)x(10x14)=10080
Overhead (CFI=2)= 100 x (3084/10080)=30.59%
Total data=(1 column a)x(6x56)+(1 column b)x(6x102)+(8 columns c)x(6x126)=6996 resource elements
Peak rate= (6996 symbols x 5.5547 bits/symbol)/10ms= 3.89 Mbps
6. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
CFI=4
With CFI=4, the number of data and control resource elements in each column changes as follows:
- Column (a): CFI + PBCH + reference + PSS/SSS= 4x12+6x12+4=124 control resource elements
12x14-124= 44 data resource elements
- Column (b): CFI + reference + PSS/SSS= 4x12+2x12+6= 78 control resource elements
12x14-78= 90 data resource elements
- Column (c): CFI + reference= 4x12+6=54 control resource elements
12x14-54= 114 data resource elements
Total control=1x(6x124)+1x(6x78)+8x(6x54)=3804 resource elements
Total resource elements=(6x12)x(10x14)=10080
Overhead (CFI=2)= 100 x (3804/10080)=37.74%
Total data=(1 column a)x(6x44)+(1 column b)x(6x90)+(8 columns c)x(6x114)=6276 resource elements
Peak rate= (6276 symbols x 5.5547 bits/symbol)/10ms= 3.48 Mbps
So, the final results are as shown in the table:
Scenario CFI Overhead [%] Peak rate [Mbps]
1 2 23.45 4.28
2 3 30.59 3.89
3 4 37.74 3.48
7. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
LTE FDD DL radio frame (BW=20MHz)
a) Radio frame structure (20MHz BW, 4 antenna ports, CFI=2)
b) Overhead and peak rate throughput (64-QAM, 5.5547 bits per symbol)
Given 20MHz of available spectrum, there are 100 Resource Blocks available. Note that the 6 central
ones contain PBCH, PSS/SSS, CFI and the reference signals (for a 4 antenna port configuration) while The
remaining 94 RBs contain only CFI and the reference signals.
8. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
CFI=1
Let’s recalculate the amount of data and control block per each kind of subframe:
- Column (a): CFI + PBCH + reference + PSS/SSS= 1x12+6x12+12=96 control resource elements
12x14-96= 72 data resource elements
- Column (b): CFI + reference + PSS/SSS= 1x12+2x12+20= 56 control resource elements
12x14-64= 112 data resource elements
- Column (c): CFI + reference= 1x12+20=32 control resource elements
12x14-40= 136 data resource elements
The overhead can be calculated as:
Total control=(1 column a)x(6x96)+(1 column b)x(6x56)+(8 columns c)x(6x32) +
+ (94x10 columns c)x32=32528 resource elements
Total resource elements=(100x12)x(10x14)=168000
Overhead (CFI=2)= 100 x (32528/168000)=19.36%
One information symbol can be allocated in each data resource element. The transmission is done by
means of 64-QAM with an average of 5.5547 bits per symbol. The peak rate thorughput is:
Total data=(1 column a)x(6x72)+(1 column b)x(6x112)+(8 columns c)x(6x136) +
+ (94x10 columns c)x136=135472 resource elements
Peak rate= 4 x (135472 symbols x 5.5547 bits/symbol)/10ms= 301 Mbps
CFI=2
Let’s recalculate the amount of data and control block per each kind of subframe:
- Column (a): CFI + PBCH + reference + PSS/SSS= 2x12+6x12+8=104 control resource elements
12x14-104= 64 data resource elements
- Column (b): CFI + reference + PSS/SSS= 2x12+2x12+16= 64 control resource elements
12x14-64= 104 data resource elements
- Column (c): CFI + reference= 2x12+16=40 control resource elements
12x14-40= 128 data resource elements
The overhead can be calculated as:
Total control=(1 column a)x(6x104)+(1 column b)x(6x64)+(8 columns c)x(6x40) +
+ (94x10 columns c)x40=40528 resource elements
Total resource elements=(100x12)x(10x14)=168000
9. Roger Piqueras Jover
http://www.ee.columbia.edu/~roger/
Overhead (CFI=2)= 100 x (40528/168000)=24.12%
One information symbol can be allocated in each data resource element. The transmission is done by
means of 64-QAM with an average of 5.5547 bits per symbol. The peak rate thorughput is:
Total data=(1 column a)x(6x64)+(1 column b)x(6x104)+(8 columns c)x(6x128) +
+ (94x10 columns c)x128=127472 resource elements
Peak rate= 4 x (127472 symbols x 5.5547 bits/symbol)/10ms= 283.23 Mbps
CFI=3
Let’s recalculate the amount of data and control block per each kind of subframe:
- Column (a): CFI + PBCH + reference + PSS/SSS= 3x12+6x12+8=116 control resource elements
12x14-116= 52 data resource elements
- Column (b): CFI + reference + PSS/SSS= 3x12+2x12+16= 76 control resource elements
12x14-76= 92 data resource elements
- Column (c): CFI + reference= 3x12+16=52 control resource elements
12x14-52= 116 data resource elements
The overhead can be calculated as:
Total control=(1 column a)x(6x116)+(1 column b)x(6x76)+(8 columns c)x(6x52) +
+ (94x10 columns c)x52=52528 resource elements
Total resource elements=(100x12)x(10x14)=168000
Overhead (CFI=2)= 100 x (52528/168000)=31.27%
One information symbol can be allocated in each data resource element. The transmission is done by
means of 64-QAM with an average of 5.5547 bits per symbol. The peak rate thorughput is:
Total data=(1 column a)x(6x52)+(1 column b)x(6x92)+(8 columns c)x(6x116) +
+ (94x10 columns c)x116=115472 resource elements
Peak rate= 4 x (115472 symbols x 5.5547 bits/symbol)/10ms= 256.56 Mbps
So, the final results are as shown in the table:
Scenario CFI Overhead [%] Peak rate [Mbps]
1 1 19.36 301
2 2 24.12 283.23
3 3 31.27 256.56
We observe that, as stated in the standard, the peak bit-rate of LTE is about 300 Mbps.