This document discusses channel concepts in GSM including logical channels like BCCH, CCCH, DCCH, TCH and their usage and mapping onto physical channels. It describes different channel configurations like SDCCH/8, SDCCH/4 and combinations. SDCCH are used for call setup, SMS, location updates. The document discusses bursts, frame structures, and concepts like hyperframe, multiframe that GSM is based on.
The document discusses GSM air interface and channel mapping. It introduces GSM frequency bands, channel numbering, physical channels, and logical channels. It explains that logical channels must be mapped to physical channels, with different burst types used for different channel types during transmission. TDMA is used to allocate timeslots on each radio frequency channel for multiple users. Precise synchronization is required for the channel mapping and transmission.
The document discusses GSM-GPRS channel configuration and dimensioning. It covers:
1. Channel configuration options including combined, non-combined, and hybrid configurations and how logical channels are mapped to timeslots.
2. Signaling channel (SDCCH) dimensioning based on call setup load and location update load to determine the number of subscribers that can be supported.
3. Common control channel (CCCH) load calculation including RACH, PCH, and AGCH capacities and how they are used to page mobiles and grant channel access.
This document discusses parameters related to idle mode in GSM-GPRS networks. It describes the structure of BSS parameters including those for the BSC, BTS, handover control, power control, and adjacent cells. It then explains various aspects of idle mode including cell selection, cell reselection using criteria C1 and C2, and how parameters like cellReselectOffset and temporaryOffset can influence cell priority. It also covers cell reselection hysteresis and provides an example of how these parameters can be used in a dual-band network to optimize call setup between different layers.
Introduction
Channel Configuration
Idle Mode Operation
Protocols
Radio resources
Measurements
Power Control
HO process
Intelligent Underlay Overlay
Handover Support for Coverage Enhanchements
The extended cell
Dynamic Hotspot
Dual band GSM/DCS Network Operation
Half Rate
HSCSD
. Overview
2. Handover Causes & Priorities
3. Threshold Comparison Process
4. Target Cell Evaluation Process
5. Handover Algorithms
Power Budget (PBGT)
Level & Quality (RXLEV & RXQUAL)
Umbrella (& Combined Umbrella/PBGT)
MS Speed (FMMS & MS_SPEED_DETECTION)
6. Imperative Handovers
Distance
Rapid Field Drop (RFD) & Enhanced Rapid Field Drop (ERFD)
7. Handover Timers
Call continuity - to ensure a call can be maintained as a MS moves geographical location from the coverage area of one cell to another
Call quality - to ensure that if an MS moves into a poor quality/coverage area the call can be moved from the serving cell to a neighbouring cell (with better quality) without dropping the call
Traffic Reasons - to ensure that the traffic within the network is optimally
distributed between the different layers/bands of a network
If 2 or more handover (PC) criteria are satisfied simultaneously the following priority list
is used in determining which process is performed;
. Uplink and downlink Interference
2. Uplink quality
3. Downlink quality
4. Uplink level
5. Downlink level
6. Distance
7. Enhanced (RFD)
8. Rapid Field Drop (RFD)
9. Slow moving MS
10. Better cell i.e. Periodic check (Power Budget HO or Umbrella HO)
11. PC: Lower quality/level thresholds (UL/DL)
12. PC: Upper quality/level thresholds (UL/DL)
This document discusses selecting the appropriate capacity for a Base Station Controller (BSC) in a mobile telecommunications network. It provides the following guidelines:
1. Allow a 20% margin for additional TRXs and space for future upgrading. Minimize handovers between BSCs.
2. Calculate required capacity based on offered traffic plus a 10% margin, not installed capacity.
3. Use Erlang B calculations to determine the number of channels needed to support the traffic load at a 0.1% blocking rate.
4. Divide the number of required channels by the number supported per Ater link or interface to determine the number of links needed between the BSC and core network.
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 outlines various digital communication standards including their nominal bit rates, actual line rates, equivalent voice channels supported, and corresponding PDH, SONET, and SDH terminology. It provides a mapping between common digital communication standards like T1, E1, E3, OC-1, and others in both North America and Europe/Japan.
The document discusses GSM air interface and channel mapping. It introduces GSM frequency bands, channel numbering, physical channels, and logical channels. It explains that logical channels must be mapped to physical channels, with different burst types used for different channel types during transmission. TDMA is used to allocate timeslots on each radio frequency channel for multiple users. Precise synchronization is required for the channel mapping and transmission.
The document discusses GSM-GPRS channel configuration and dimensioning. It covers:
1. Channel configuration options including combined, non-combined, and hybrid configurations and how logical channels are mapped to timeslots.
2. Signaling channel (SDCCH) dimensioning based on call setup load and location update load to determine the number of subscribers that can be supported.
3. Common control channel (CCCH) load calculation including RACH, PCH, and AGCH capacities and how they are used to page mobiles and grant channel access.
This document discusses parameters related to idle mode in GSM-GPRS networks. It describes the structure of BSS parameters including those for the BSC, BTS, handover control, power control, and adjacent cells. It then explains various aspects of idle mode including cell selection, cell reselection using criteria C1 and C2, and how parameters like cellReselectOffset and temporaryOffset can influence cell priority. It also covers cell reselection hysteresis and provides an example of how these parameters can be used in a dual-band network to optimize call setup between different layers.
Introduction
Channel Configuration
Idle Mode Operation
Protocols
Radio resources
Measurements
Power Control
HO process
Intelligent Underlay Overlay
Handover Support for Coverage Enhanchements
The extended cell
Dynamic Hotspot
Dual band GSM/DCS Network Operation
Half Rate
HSCSD
. Overview
2. Handover Causes & Priorities
3. Threshold Comparison Process
4. Target Cell Evaluation Process
5. Handover Algorithms
Power Budget (PBGT)
Level & Quality (RXLEV & RXQUAL)
Umbrella (& Combined Umbrella/PBGT)
MS Speed (FMMS & MS_SPEED_DETECTION)
6. Imperative Handovers
Distance
Rapid Field Drop (RFD) & Enhanced Rapid Field Drop (ERFD)
7. Handover Timers
Call continuity - to ensure a call can be maintained as a MS moves geographical location from the coverage area of one cell to another
Call quality - to ensure that if an MS moves into a poor quality/coverage area the call can be moved from the serving cell to a neighbouring cell (with better quality) without dropping the call
Traffic Reasons - to ensure that the traffic within the network is optimally
distributed between the different layers/bands of a network
If 2 or more handover (PC) criteria are satisfied simultaneously the following priority list
is used in determining which process is performed;
. Uplink and downlink Interference
2. Uplink quality
3. Downlink quality
4. Uplink level
5. Downlink level
6. Distance
7. Enhanced (RFD)
8. Rapid Field Drop (RFD)
9. Slow moving MS
10. Better cell i.e. Periodic check (Power Budget HO or Umbrella HO)
11. PC: Lower quality/level thresholds (UL/DL)
12. PC: Upper quality/level thresholds (UL/DL)
This document discusses selecting the appropriate capacity for a Base Station Controller (BSC) in a mobile telecommunications network. It provides the following guidelines:
1. Allow a 20% margin for additional TRXs and space for future upgrading. Minimize handovers between BSCs.
2. Calculate required capacity based on offered traffic plus a 10% margin, not installed capacity.
3. Use Erlang B calculations to determine the number of channels needed to support the traffic load at a 0.1% blocking rate.
4. Divide the number of required channels by the number supported per Ater link or interface to determine the number of links needed between the BSC and core network.
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 outlines various digital communication standards including their nominal bit rates, actual line rates, equivalent voice channels supported, and corresponding PDH, SONET, and SDH terminology. It provides a mapping between common digital communication standards like T1, E1, E3, OC-1, and others in both North America and Europe/Japan.
The document discusses strategies for selecting IBS carriers for a second layer to increase capacity. It evaluates two options: using F1 and F2 carriers, or F1 and F3 carriers. It recommends using F1 and F2 for the project as most sites will be upgraded to three layers, and this option is simpler to set up while providing similar performance to using F1 and F3. It then covers mobility, neighbor planning, radio features, and cell ID planning considerations for the two-carrier IBS configuration.
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.
5G NR: Numerologies and Frame structure
Supported Transmission Numerologies
- A numerology is defined by sub-carrier spacing and Cyclic-Prefix overhead.
- In LTE there is only one subcarrier spacing which is 15kHz whereas in the case of 5G NR multiple subcarrier spacings are defined. Multiple subcarrier spacings can be derived by scaling a basic subcarrier spacing by an integer N.
- The numerology used can be selected independently of the frequency band although it is assumed not to use a very low subcarrier spacing at very high carrier frequencies. Flexible network and UE channel bandwidth are supported.
- The numerology is based on exponentially scalable sub-carrier spacing deltaF = 2µ × 15 kHz with µ = {0,1,3,4} for PSS, SSS and PBCH and µ = {0,1,2,3} for other channels.
- Normal CP is supported for all sub-carrier spacings, Extended CP is supported forµ=2.
- 12 consecutive sub-carriers form a physical resource block (PRB). Up to 275 PRBs are supported on a carrier.
- A resource defined by one subcarrier and one symbol is called as a resource element (RE).
This document discusses the basics of PDH (Plesiosynchronous Digital Hierarchy) and SDH (Synchronous Digital Hierarchy). It describes how E1 signals are formed by multiplexing 32 channels of 64 Kbps each. It then explains how higher order E1 signals like E2, E3, E4 are formed by multiplexing E1 signals. The document discusses some disadvantages of PDH. It also provides details of the journey from E1 to STM-1 in SDH, including the various intermediate stages of TUG2, C12, TUG3, VC12, TU12 and VC4. Finally, it highlights some key features of SDH like full synchrony and its ability to carry
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 EQC command creates a BTS in the BSDATA with the following parameters: BCF identification, BTS identification, BTS name, cell identity, frequency band in use, network colour code, BTS colour code, mobile country code, mobile network code, location area code, BTS hopping mode, hopping sequence numbers. Optional parameters include: SEG identification, SEG name, reference BTS identification, GPRS enabled, routing area code, network service entity identifier, transport type, and packet service entity identifier. After creation, the BTS is in the LOCKED state.
The document discusses the differences between SDH and PDH, as well as key aspects of SDH. SDH provides higher transmission rates up to 40 Gbit/s, simplified add and drop functions, high availability and capacity matching, reliability, and is a future-proof platform for new services compared to PDH. SDH uses synchronous multiplexing where data from multiple sources is byte interleaved at fixed locations in the frame. This allows single channels to be dropped from the data stream without demultiplexing intermediate rates as required in PDH.
This document provides an overview of Synchronous Digital Hierarchy (SDH) including its introduction, components, frame structure, and applications. SDH was developed to provide a standardized digital transmission network with vendor independence. It uses optical fiber to enable end-to-end monitoring and self-healing ring architectures for survivability. The SDH frame structure consists of sections for transport overhead (TOH), path overhead (POH), and payloads. SDH supports multiplexing of various signals like E1, DS1, and STM streams. It allows dynamic bandwidth allocation and is a platform for future services.
1. The document discusses various coverage enhancement features used in cellular networks including extended cell range, long reach timeslots, super extended cells, and smart radio concepts.
2. It provides details on the technical implementation of these features such as delayed receivers, double BCCH allocation lists, and parameters for handover control.
3. Advanced concepts like intelligent downlink diversity, interference rejection combining, and space time interference rejection combining are introduced to further improve coverage and capacity.
1) The document describes the downlink physical channels of LTE including the DL-SCH, PBCH, PDSCH, PDCCH, PCFICH, and PHICH.
2) It discusses design constraints for LTE including keeping the cyclic prefix smaller than the symbol length and larger than the delay spread to avoid overhead and interference. The subcarrier spacing must also be large enough to overcome Doppler shifts from UE motion.
3) The placement of reference signals is described, needing to be spaced at least every 0.5ms in time to track fast channels and every 6 subcarriers (45kHz) in frequency to resolve variations.
Lenovo acquired 3,800 patent families from NEC including key 3G and 4G standard essential patents for smartphones. The summary identifies three such patents held by NEC relating to 3G and 4G mobile communications standards including:
1) A patent on transmission power control that allows stable signal transmission during soft handovers.
2) A patent on a CDMA transmission system that uses different pilot signals from multiple transmission antennas.
3) A patent on generating pilot signal sequences for single carrier transmission systems using a Zadoff-Chu sequence and a mathematical formula.
This document provides an overview of telecom concepts and GSM technology. It discusses early analog cellular systems, the development of GSM standards to address limitations in analog networks, and key aspects of GSM including frequency reuse, handovers, and network architecture. The document also covers cellular concepts like frequency bands, modulation techniques, and components of the mobile station and subscriber identity module.
The document discusses GSM-GPRS network operations including:
1. Network identity parameters such as MCC, MNC, LAC, CI which allow identification of network elements and location of mobile stations.
2. Idle mode operations which include cell selection, location updating, and allow mobile stations to receive system information when not in a call.
3. Location update and handover procedures which update the network on a mobile station's location area and allow calls to be maintained as a mobile station moves between cells.
PDH and SDH are digital multiplexing techniques. PDH uses asynchronous multiplexing and operates over asynchronous networks, applying positive justification. It allows tributary clocks to differ slightly. SDH uses synchronous multiplexing and operates over synchronous networks, applying zero justification. Tributary clocks must be synchronized to a master clock. SDH was developed to simplify interconnection between network operators and expand compatibility by establishing a international standard to replace the different PDH standards.
The document discusses different types of transmission media, including guided media like twisted-pair cable, coaxial cable, and fiber-optic cable. It also discusses unguided media like radio waves, microwaves, and infrared signals. Twisted-pair cable is used for digital LANs up to 600 Mbps. Coaxial cable was used for thick and thin Ethernet. Fiber-optic cable uses glass strands to transmit data using light pulses and has very high bandwidth. Radio waves propagate through sky waves or ground waves and are used for radio, TV, and navigation. Microwaves use line-of-sight propagation for cellular networks and wireless LANs. Infrared can transmit over short ranges in a closed area
The document discusses Synchronous Digital Hierarchy (SDH) and provides details on:
1. SDH frame structure including section overhead, path overhead, pointer, and information payload areas.
2. SDH multiplexing methods allowing lower rate signals like E1, E3, E4 to be mapped and multiplexed into higher rate SDH frames like STM-1, STM-4.
3. Overhead bytes including framing bytes A1/A2, data communications channel bytes D1-D12, orderwire bytes E1/E2, parity check bytes B1/B2, and remote error indication byte M1.
The document summarizes key parameters of DVB-T2's OFDM transmission including:
1) It describes the number of carriers, IFFT size, symbol period, and bandwidth for each of DVB-T2's modes from 1K to 32K.
2) It explains that modulation patterns in DVB-T2 include QPSK, 16QAM, 64QAM, and 256QAM, with optional rotation of constellations.
3) It provides details on DVB-T2's frame structure, which begins with a P1 synchronization symbol followed by 1-16 P2 symbols carrying signaling data, and multiple payload symbols organized into physical layer pipes (PLPs).
This document provides details about the 3G-RNC 3820, including:
1. It describes the main components of the RNC 3820 including general purpose processor boards, switch core boards, timing unit boards, and special purpose boards.
2. It shows the cabinet layout including the main subrack, extension subracks, active patch panel, and fan units.
3. It provides examples of RNC 3820 node layouts with different throughput and connectivity capabilities.
The document discusses various logical channels used in GSM networks such as broadcast control channel (BCCH), common control channels (CCCH), dedicated control channels (DCCH), and traffic channels (TCH). It describes the purpose and usage of different channel types including stand-alone dedicated control channel (SDCCH), slow associated control channel (SACCH), and fast associated control channel (FACCH). The document also covers topics like burst structure, mapping of logical channels to physical channels, and usage of SDCCH in GSM networks.
The document discusses various logical channels in GSM including broadcast channels (BCH), common control channels (CCCH), dedicated control channels (DCCH), and traffic channels (TCH). It describes the purpose and usage of different channel types like FCCH, SCH, BCCH, PCH, RACH, AGCH, SDCCH, SACCH, and FACCH. It also covers topics like call setup using SDCCH, burst structure, mapping of logical channels to physical channels, and SDCCH configuration and dimensioning.
The document discusses strategies for selecting IBS carriers for a second layer to increase capacity. It evaluates two options: using F1 and F2 carriers, or F1 and F3 carriers. It recommends using F1 and F2 for the project as most sites will be upgraded to three layers, and this option is simpler to set up while providing similar performance to using F1 and F3. It then covers mobility, neighbor planning, radio features, and cell ID planning considerations for the two-carrier IBS configuration.
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.
5G NR: Numerologies and Frame structure
Supported Transmission Numerologies
- A numerology is defined by sub-carrier spacing and Cyclic-Prefix overhead.
- In LTE there is only one subcarrier spacing which is 15kHz whereas in the case of 5G NR multiple subcarrier spacings are defined. Multiple subcarrier spacings can be derived by scaling a basic subcarrier spacing by an integer N.
- The numerology used can be selected independently of the frequency band although it is assumed not to use a very low subcarrier spacing at very high carrier frequencies. Flexible network and UE channel bandwidth are supported.
- The numerology is based on exponentially scalable sub-carrier spacing deltaF = 2µ × 15 kHz with µ = {0,1,3,4} for PSS, SSS and PBCH and µ = {0,1,2,3} for other channels.
- Normal CP is supported for all sub-carrier spacings, Extended CP is supported forµ=2.
- 12 consecutive sub-carriers form a physical resource block (PRB). Up to 275 PRBs are supported on a carrier.
- A resource defined by one subcarrier and one symbol is called as a resource element (RE).
This document discusses the basics of PDH (Plesiosynchronous Digital Hierarchy) and SDH (Synchronous Digital Hierarchy). It describes how E1 signals are formed by multiplexing 32 channels of 64 Kbps each. It then explains how higher order E1 signals like E2, E3, E4 are formed by multiplexing E1 signals. The document discusses some disadvantages of PDH. It also provides details of the journey from E1 to STM-1 in SDH, including the various intermediate stages of TUG2, C12, TUG3, VC12, TU12 and VC4. Finally, it highlights some key features of SDH like full synchrony and its ability to carry
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 EQC command creates a BTS in the BSDATA with the following parameters: BCF identification, BTS identification, BTS name, cell identity, frequency band in use, network colour code, BTS colour code, mobile country code, mobile network code, location area code, BTS hopping mode, hopping sequence numbers. Optional parameters include: SEG identification, SEG name, reference BTS identification, GPRS enabled, routing area code, network service entity identifier, transport type, and packet service entity identifier. After creation, the BTS is in the LOCKED state.
The document discusses the differences between SDH and PDH, as well as key aspects of SDH. SDH provides higher transmission rates up to 40 Gbit/s, simplified add and drop functions, high availability and capacity matching, reliability, and is a future-proof platform for new services compared to PDH. SDH uses synchronous multiplexing where data from multiple sources is byte interleaved at fixed locations in the frame. This allows single channels to be dropped from the data stream without demultiplexing intermediate rates as required in PDH.
This document provides an overview of Synchronous Digital Hierarchy (SDH) including its introduction, components, frame structure, and applications. SDH was developed to provide a standardized digital transmission network with vendor independence. It uses optical fiber to enable end-to-end monitoring and self-healing ring architectures for survivability. The SDH frame structure consists of sections for transport overhead (TOH), path overhead (POH), and payloads. SDH supports multiplexing of various signals like E1, DS1, and STM streams. It allows dynamic bandwidth allocation and is a platform for future services.
1. The document discusses various coverage enhancement features used in cellular networks including extended cell range, long reach timeslots, super extended cells, and smart radio concepts.
2. It provides details on the technical implementation of these features such as delayed receivers, double BCCH allocation lists, and parameters for handover control.
3. Advanced concepts like intelligent downlink diversity, interference rejection combining, and space time interference rejection combining are introduced to further improve coverage and capacity.
1) The document describes the downlink physical channels of LTE including the DL-SCH, PBCH, PDSCH, PDCCH, PCFICH, and PHICH.
2) It discusses design constraints for LTE including keeping the cyclic prefix smaller than the symbol length and larger than the delay spread to avoid overhead and interference. The subcarrier spacing must also be large enough to overcome Doppler shifts from UE motion.
3) The placement of reference signals is described, needing to be spaced at least every 0.5ms in time to track fast channels and every 6 subcarriers (45kHz) in frequency to resolve variations.
Lenovo acquired 3,800 patent families from NEC including key 3G and 4G standard essential patents for smartphones. The summary identifies three such patents held by NEC relating to 3G and 4G mobile communications standards including:
1) A patent on transmission power control that allows stable signal transmission during soft handovers.
2) A patent on a CDMA transmission system that uses different pilot signals from multiple transmission antennas.
3) A patent on generating pilot signal sequences for single carrier transmission systems using a Zadoff-Chu sequence and a mathematical formula.
This document provides an overview of telecom concepts and GSM technology. It discusses early analog cellular systems, the development of GSM standards to address limitations in analog networks, and key aspects of GSM including frequency reuse, handovers, and network architecture. The document also covers cellular concepts like frequency bands, modulation techniques, and components of the mobile station and subscriber identity module.
The document discusses GSM-GPRS network operations including:
1. Network identity parameters such as MCC, MNC, LAC, CI which allow identification of network elements and location of mobile stations.
2. Idle mode operations which include cell selection, location updating, and allow mobile stations to receive system information when not in a call.
3. Location update and handover procedures which update the network on a mobile station's location area and allow calls to be maintained as a mobile station moves between cells.
PDH and SDH are digital multiplexing techniques. PDH uses asynchronous multiplexing and operates over asynchronous networks, applying positive justification. It allows tributary clocks to differ slightly. SDH uses synchronous multiplexing and operates over synchronous networks, applying zero justification. Tributary clocks must be synchronized to a master clock. SDH was developed to simplify interconnection between network operators and expand compatibility by establishing a international standard to replace the different PDH standards.
The document discusses different types of transmission media, including guided media like twisted-pair cable, coaxial cable, and fiber-optic cable. It also discusses unguided media like radio waves, microwaves, and infrared signals. Twisted-pair cable is used for digital LANs up to 600 Mbps. Coaxial cable was used for thick and thin Ethernet. Fiber-optic cable uses glass strands to transmit data using light pulses and has very high bandwidth. Radio waves propagate through sky waves or ground waves and are used for radio, TV, and navigation. Microwaves use line-of-sight propagation for cellular networks and wireless LANs. Infrared can transmit over short ranges in a closed area
The document discusses Synchronous Digital Hierarchy (SDH) and provides details on:
1. SDH frame structure including section overhead, path overhead, pointer, and information payload areas.
2. SDH multiplexing methods allowing lower rate signals like E1, E3, E4 to be mapped and multiplexed into higher rate SDH frames like STM-1, STM-4.
3. Overhead bytes including framing bytes A1/A2, data communications channel bytes D1-D12, orderwire bytes E1/E2, parity check bytes B1/B2, and remote error indication byte M1.
The document summarizes key parameters of DVB-T2's OFDM transmission including:
1) It describes the number of carriers, IFFT size, symbol period, and bandwidth for each of DVB-T2's modes from 1K to 32K.
2) It explains that modulation patterns in DVB-T2 include QPSK, 16QAM, 64QAM, and 256QAM, with optional rotation of constellations.
3) It provides details on DVB-T2's frame structure, which begins with a P1 synchronization symbol followed by 1-16 P2 symbols carrying signaling data, and multiple payload symbols organized into physical layer pipes (PLPs).
This document provides details about the 3G-RNC 3820, including:
1. It describes the main components of the RNC 3820 including general purpose processor boards, switch core boards, timing unit boards, and special purpose boards.
2. It shows the cabinet layout including the main subrack, extension subracks, active patch panel, and fan units.
3. It provides examples of RNC 3820 node layouts with different throughput and connectivity capabilities.
The document discusses various logical channels used in GSM networks such as broadcast control channel (BCCH), common control channels (CCCH), dedicated control channels (DCCH), and traffic channels (TCH). It describes the purpose and usage of different channel types including stand-alone dedicated control channel (SDCCH), slow associated control channel (SACCH), and fast associated control channel (FACCH). The document also covers topics like burst structure, mapping of logical channels to physical channels, and usage of SDCCH in GSM networks.
The document discusses various logical channels in GSM including broadcast channels (BCH), common control channels (CCCH), dedicated control channels (DCCH), and traffic channels (TCH). It describes the purpose and usage of different channel types like FCCH, SCH, BCCH, PCH, RACH, AGCH, SDCCH, SACCH, and FACCH. It also covers topics like call setup using SDCCH, burst structure, mapping of logical channels to physical channels, and SDCCH configuration and dimensioning.
The document discusses SDCCH (Standalone Dedicated Control Channel) configuration and usage in a GSM network. It describes:
- Possible SDCCH configurations including SDCCH/8, SDCCH/4, and combinations using 1 or 2 timeslots and TRXs.
- How logical channels like SDCCH, TCH, SACCH, and CBCH are mapped to physical timeslots and frames.
- The usage of SDCCH for functions like registration, call setup, SMS, and supplementary services.
- Parameters involved in SDCCH dimensioning like traffic estimations, congestion reasons and detection, and preventative actions.
The document discusses SDCCH (Standalone Dedicated Control Channel) configuration and usage in GSM networks. It describes possible SDCCH configurations including SDCCH/8 and SDCCH/4. It also discusses SDCCH holding times for different functions, reasons for SDCCH congestion, and methods to prevent congestion through proper dimensioning of SDCCH resources.
The document discusses various channels used in GSM networks. It describes physical channels that transfer bits between network elements and logical channels distinguished by the nature of carried information. It provides details on different types of logical channels including traffic, broadcast, common control and dedicated control channels. It also explains concepts like bursts, frames, multiframe structures and how they are used to organize speech and data on traffic channels.
The document describes the logical channels used in GSM. It discusses the 3 types of broadcast channels - FCCH, SCH, and BCCH. It also discusses the 3 common control channels - PCH, RACH, and AGCH and the 3 dedicated control channels - SDCCH, SACCH, and FACCH. It provides details on the purpose and direction (uplink vs downlink) of each channel. It also discusses traffic channels (TCH), associated control channels, and cell broadcast channels.
This document discusses BSS parameter configurations in GSM networks. It describes the channel configurations including TDMA frame structure, signaling channels like BCCH, CCCH, SDCCH, and traffic channels like TCH. It explains combined and separated signaling channel configurations and shows examples of multiframe structures for different channel types. It also covers capacity calculations for SDCCH channels and includes an Erlang B table.
This document discusses the parameters and configuration of base station subsystems (BSS) in GSM networks. It describes the channel configuration including logical and physical channels, signaling channels, traffic channels, and their organization into frames, multiframes, and hyperframes. It also provides an example calculation of SDCCH capacity for a cell with 325 subscribers, showing that 5 SDCCHs are needed to support call establishment and location update with a 1% blocking probability based on Erlang B, requiring a separate rather than combined channel configuration.
Topics covered in this presentation:
1. RF spectrum and GSM specifications
2. FDMA and TDMA
3. Digital Voice Transmission
4. Channel coding, Interleaving and Burst formatting
5. GMSK
6. Frame structure of GSM
7. Corrective actions against multipath fading
BTS functions include modulation, channel coding, interleaving, encryption, frequency hopping, frame formatting, and signal strength measurements. The CGI uniquely identifies a cell using LAI and CI. The FCCH carries frequency synchronization information. The SCH carries timing synchronization and BSIC information. The BCCH broadcasts cell information like LAI and CI. The PCH pages mobiles for calls/SMS. The RACH is used by mobiles to request resources. The AGCH sends resource grants in response to RACH requests. The SDCCH is used for location updates, call setup, and SMS. The SACCH carries signal strength measurements and timing/power control information. The FACCH can replace bursts on the SDC
ell Allocation (CA) is the subset of the total frequency band that is available for one BTS. It can be viewed as the total transport resource available for traffic between the BTS and its attached MSs. One Radio Frequency CHannel (RFCH) of the CA is used to carry synchronization information and the Broadcast Control CHannel (BCCH). This can be any of the carriers in the cell and it is known as the BCCH carrier or the c
carrier. Strong efficiency and quality requirements have resulted in a
0
rather complex way of utilizing the frequency resource. This chapter describes the basic principles of how to use this resource from the physical resource itself to the information transport service offered by the BTS.
Carrier separation is 200 kHz, which provides: • 124 pairs of carriers in the GSM 900 band • 374 pairs of carriers in the GSM 1800 band • 299 pairs of carriers in the GSM 1900 band
Using Time Division Multiple Access (TDMA) each of these carriers is divided into eight Time Slots (TS). One TS on a TDMA frame is called a physical channel, i.e. on each duplex pair of carriers there are eight physical channels.
A variety of information is transmitted between the BTS and thMS. The information is grouped into different logical channelsEach logical channel is used for a specific purpose such as paging, call set-up and speech. For example, speech is sent on the logical channel Traffic CHannel (TCH). The logical channels are mapped onto the physical channels.
The information in this chapter does not include channels specific for GPRS (General Packet Radio Service). For basic information on GPRS see chapter 14 of this documentation.
1) GSM uses paired radio frequency channels between 890-915 MHz for mobile to base station communication and 935-960 MHz for base station to mobile communication, with a 45 MHz gap between the pairs. Each channel is spaced at 200 KHz.
2) A GSM time slot is 577 microseconds long, with a burst of data transmission lasting 546.5 microseconds during each slot. This provides a data rate of approximately 33.8 kbps per time slot.
3) GSM defines different types of logical channels, including traffic channels (TCH) to carry user voice and data, and control channels like broadcast control channel (BCCH), paging channel (PCH), and dedicated
This presentation discusses GSM frame structure and logical channels. It covers GSM frequency bands and specifications, the multiple access methods of FDMA and TDMA, frame representations, and logical traffic and control channels including BCCH, CCCH, DCCH, and TCH channels. Frame structures include hyperframes, superframes, multiframes, and TDMA frames. Logical channel configurations and multiplexing of channels on timeslots are also summarized.
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 radio resource optimization parameters in GSM networks. It covers topics like idle parameter optimization, power control, handover control, radio resource administration, measurement processing, signaling channel mapping, traffic channel mapping, paging parameters, access grant channel parameters, frequency reuse, and frequency hopping techniques. Diagrams and examples are provided to illustrate concepts like TDMA frame structure, logical and physical channel organization, and capacity calculations.
This document discusses radio resource optimization parameters in GSM networks. It covers topics like idle parameter optimization, power control, handover control, radio resource administration, measurement processing, signaling channel mapping, traffic channel mapping, paging parameters, access grant channel parameters, frequency reuse, and frequency hopping techniques. Diagrams and examples are provided to illustrate concepts like TDMA frame structure, logical and physical channel organization, and capacity calculations.
The document discusses the air interface in GSM systems. It describes:
1) GSM uses TDMA to allow multiple users to share the same radio frequency by dividing each carrier into 8 time slots, with each user assigned a time slot.
2) The TDMA frame structure consists of 8 time slots of 0.577ms each, with a total frame duration of 4.615ms. Guard periods are used between time slots.
3) There are different types of logical channels including traffic channels, control channels, and broadcast channels that carry user data, signaling information, and system parameters respectively.
GSM uses a combination of FDMA and TDMA to divide up radio resources on the air interface. It defines physical channels based on frequency and timeslot, and logical channels to carry different types of data and signaling information. Logical channels include traffic channels to carry user data and various signaling channels like broadcast, common, and dedicated control channels which are used to enable network operations like cell broadcasts, paging, call setup, and handovers. Key physical channel structures include TDMA frames, multiframes, superframes, and hyperframes which are used for synchronization between base stations and mobile stations.
• -How the channel concept is used on the radio interface
• -Different burst formats in the radio interface
• -The hierarchical frame structure
• -The content sent in different logical channels
• -The mapping of the logical channels
• -Superframe and Hyperframe
• -MOBILE STATIONS ISDN NUMBER (MSISDN)
• INTERNATIONAL MOBILE SUBSCRIBER IDENTITY (IMSI)
• TEMPORARY MOBILE SUBSCRIBER IDENTITY (TMSI)
• LOCATION AREA IDENTITY (LAI)
• CELL GLOBAL IDENTITY (CGI)
• BASE STATION IDENTITY CODE (BSIC)
• PIN management
1. The document provides information on key concepts in GSM networks including call drop reasons, handover reasons, antenna parameters, signal quality metrics, interference types, logical and physical channels, and frequency bands.
2. It describes parameters related to signal quality like RX level, RX quality, BER, FER, and C/I ratio. It also covers concepts like frequency hopping, handover types, tilt, scrambling codes, and signal strength metrics in WCDMA networks.
3. The document is a reference for drive testing and troubleshooting mobile networks, outlining important factors that impact call quality and connectivity issues like call drops, handover failures, and interference.
2. Contents
Nov 17, 2003
• Channel Concepts
• Call Setup
• Burst & Multi Frames
• Mapping of Logical Channels
• Definitions of SDCCH
• Usage of SDCCH in the GSM network (BSC)
• Possible SDCCH Configuration
• SDCCH Holding Time
S. Rajshekhar Deshraj
3. Contents
Nov 17, 2003
• SDCCH Traffic Estimations
• SDCCH Congestion
• Reasons for SDCCH congestion
• How to detect SDCCH congestions
• Preventive actions to avoid SDCCH congestions
• SDCCH Dimensioning
• Parameters for SDCCH Dimensioning
• Counters & Report Analysis
S. Rajshekhar Deshraj
4. Nov 17, 2003 S. Rajshekhar Deshraj
Logical Channels
5. Broadcast Channels (BCH)
Nov 17, 2003
Frequency Correction Channel (FCCH)
•Downlink Channel
•BTS: Transmits a carrier frequency (Pure sine wave of 67.7 KHz)
This Solve 2 purpose :
a> Make sure that this is BCCH Carrier
b> To allow the MS to synchronize to the frequency
•MS: After Switch on MS Scan for this channel, since it has no
information to which frequency to use. FCCH carrier enables a mobile to
tune its frequency to that being broadcast by the BTS.
6. Broadcast Channels (BCH)
Nov 17, 2003
Syncronization Channel (SCH)
•Downlink Channels
•BTS: Transmits TDMA Frame number + Base Station
Identity Code (BSIC= NCC + BCC )
•MS: MS decodes the BSIC if the chosen BTS is GSM
Base station within a cell
7. Broadcast Channels (BCH)
Nov 17, 2003
•Broadcast Control Channel (BCCH)
•Downlink Channels
•BCCH contains the detailed Network and cell specific information
such as :
•Frequency used by Cell and its Neighboring cells.
•Frequency HSN
•Paging Groups
•LAI
•Max output power allowed in the cell
8. Common Control Channels (CCCH)
Nov 17, 2003
Paging Channel (PCH)
•Downlink Channels
• BTS: Broadcast the paging message to indicate the Incoming
Calls or Incoming SMS. Paging message also includes
the MS’s identity number IMSI/TMSI
• MS: MS listens to the PCH. If it identifies its own mobile
subscriber identity number on the PCH, it will respond.
9. Common Control Channels (CCCH)
Nov 17, 2003
Random Access Channel (RACH)
•RACH is transmitted Uplink only
•When mobile is paged , it replies on RACH requesting a
signaling channel.
•RACH can also used if the MS wants to make a contact the NW/
Originating calls
10. Common Control Channels (CCCH)
Nov 17, 2003
Access Grant Channel (AGCH)
•Downlink channel
•AGCH is answer to the RACH
•NW assigns a signaling channel (SDCCH) to the MS. This
assignment is performed on the AGCH
11. Dedicated Control Channels (DCCH)
Nov 17, 2003
Stand Alone Dedicated Control Channel (SDCCH)
•SDCCH is bi-directional Channel
•System Signaling
•Call Setup
•Authentication
•Location Update
•Assignment of Traffic channels and
•Transmission of Short messages
12. Dedicated Control Channels (DCCH)
Nov 17, 2003
Slow Associated Control Channel (SACCH)
•SACCH is transmitted in both Uplink and Downlink directions
•SACCH is associated with each SDCCH and also with TCH
•Uplink : MS Sends the averaged measurement on its own BTS and
neighboring BTS’s
•Downlink: MS receives information regarding information
concerning
•Transmit power to use
•Instructions on Timing Advance
13. Dedicated Control Channels (DCCH)
Nov 17, 2003
Fast Associated Control Channel (FACCH)
•While Calls in progress and HO is required FACCH is used
•FACCH works in Stealing mode meaning that one 20ms
segment of speech is exchanged for signaling information
necessary for the HO
Cell Broadcast Channel (CBCH)
•CBCH is used in Downlink only
•It is used to carry Short Message Service Cell Broadcast
(SMSCB) and uses the same physical channel as the SDCCH
14. Traffic Channels (TCH)
Nov 17, 2003
Traffic channels are Bi-directional logical channel that transfer the user
speech or data.
•Full Rate TCH ( TCH/F) :
•This channel carries information at a gross rate at 13Kbit/s *
* Now it is 22.8 Kbit/s with latest R9.1
•Half Rate TCH (TCH/H) :
•This Channel carried information at a gross rate at 6.5Kbit/s*
* Now it is 11.4 Kbit/s with latest R9.1
•Enhance Full Rate :
•The speech coding in EFR is still done at 13Kbit/s, but the
coding mechanism is different that is used for normal FR.
EFR gives better speech quality at the same bit rate than
normal FR.
15. Nov 17, 2003 S. Rajshekhar Deshraj
Call to an MS
More..
16. Nov 17, 2003 S. Rajshekhar Deshraj
Relationship Between Burst & Frame
Burst : Physical content of a TS is called Burst.There are 5 types of Bursts
each having 15/26 ms duration and 156.25 Bits.
Hyperframe: In GSM system every TDMA frame is assigned a fixed number,
which repeats itself in a time period of 3 HOURS 28 MINUTES 53
SECONDS 760 MILLISECONDS. This time period is referred to
as Hyperframe.
Superframe : =51x26 Multiframes. So, Duration =51x26x8x15/26=6Sec 120ms
Multiframe :There are two types of multiframe.
26 TDMA Frame Multiframe :Used to carry TCH, SACCH and
FACCH
Duration =26 x 8 x 15/26 =120ms
51 TDMA Frame Multiframe : Used to carry BCCH,CCCH,SDCCH
and SACCH.
Duration =51 x 8 x 15/26 =235.38ms
18. Bursts
Normal Bursts: This burst is used to carry information on :
•Traffic channel
•SDCCH Channel
•Broadcast Control Channel
•Paging Channel
•Access Grant Channel
•SACCH & FACCH Channel
Nov 17, 2003
1 Time slot = 156.25 bits durations (15/26 = 0.577 ms )
TB Encrypted bits Training Sequence Encrypted bits TB GP
3 57 26 57 3 8.25
F : One Stealing Bit:=0 Indicates 57bit packet contains user data or speech
:=1 Indicates burst stolen for FACCH Signalling
RxQual derived from the 26 bit midable from the TDMA frame
F F
19. Bursts
Frequency Bursts:
All 148 bits(142+6) are coded with 0. The output of GMSK Modulator is a fixed
frequency signal exactly 67.7 Khz above the BCCH carrier frequency.
Thus the MS on receiving this fixed frequency signal fine tunes to the BCCH
frequency and waits for the Sync burst to arrive after 1 TDMA Frame .i.e
=15/26*8=4.615ms
Nov 17, 2003
1 Time slot = 156.25 bits durations (15/26 = 0.577 ms )
TB TB GP
3 3 8.25
ALL ZERO 142 BITS
20. Bursts
Synchronization Bursts:
This burst is used for time synchronization of the MS
Nov 17, 2003
1 Time slot = 156.25 bits durations (15/26 = 0.577 ms )
TB TB GP
3 3 8.25
SCH DATA
39 Bits
SCH DATA
39 Bits
Extended Training Sequence
64 Bits
39Bit x 2=78 Bits :Are decoded to arrive 25-SCH control bits and that contains
the information of the NCC ,BCC & TDMA FN
64 Bits : Long training seq. of 64 Bits are identical for all BTS
21. Bursts
Access Bursts:
This burst is used only for initial access by the MS to the BTS which applies 2 cases :
•For connection setup when idle state where a CHAN_REQ message is sent using
access burst
•For HO when MS send HND_ACC message.
Nov 17, 2003
1 Time slot = 156.25 bits durations (15/26 = 0.577 ms )
TB
8
SCH Sequence RACH Data TB
41 Bits 36 Bits 3
Guard Band
68.25 Bits
36Bit Contains : BSIC+CHAN_REQ or HND_ACC
41Bit Contains : Fixed bit sequence allow BTS to recognize it is Access Burst
86.25 bits GP: Long GP enables BTS to get Propagation delay information.
22. Bursts
Dummy Bursts:
To enable the BCCH frequency to be transmitted with a constant power level, dummy
burst are inserted.
This burst is transmitted on CHGR=0 when no other type of burst is to be sent.
Thus it makes possible for MS to perform the power measurement on the BTS in order
to determine which BTS to use for initial access or which to use for HO
CCCH is replaced by the dummy page, when there is no paging message to transmit.
Nov 17, 2003
1 Time slot = 156.25 bits durations (15/26 = 0.577 ms )
TB
3
Mixed Bits Training Sequence TB Guard Band
Mixed Bits
58 26 3 8.25
58
58Bits: Coded with pseudo random bit seq. to prevent confusion with Freq correction burst
23. Mapping of Logical Channel
Method of transmitting logical channels onto physical channel is called Mapping
FCCH+SCH+BCCH+CCCH: An idle MS search for the FCH. When MS finds
the frequency correction burst it knows that this is TS 0 on CHGR=0
The cycle means F,S,B repeats after the Idle frame I.e. at Frame no 50. Cycle=51TS
Nov 17, 2003
TS=0 / CHGR=0 DOWNLINK
0 1 7 0 1 7 0 1 7
F0 F1 F2-F5 F6-9 F10 F11 F12-F15 F16-19 F20-23 F24 F25 F26-29 F30 F31 F32-F35 F36-F39 F40 F41 F42-F45 F46-49 F50
TS-0 F S BCCH CCCH F S BCCH CCCH CCCH F S CCCH F S CCCH CCCH F S CCCH CCCH I
F: FCCH 1 TS ( Use 4 Slots in each 51 TDMA Frame)
S: SCH 1 TS ( Use 4 Slots in each 51 TDMA Frame)
I: IDLE 1 TS
BCCH 4 TS
CCCH 4 TS (PCH or AGCH) Paging Block
51 TDMA Frame = 9 Paging Blocks
TS=0 / CHGR=0 UPLINK
F0 F1 F3 F3 F4 F5 F6 F7 F8 F9 F10 F46 F47 F48 F49 F50
TS-0 R R R R R R R R R R R R R R R R
R: RACH 1 TS
24. Mapping of Logical Channel
SDCCH+SACCH: Cycle=102 TS This sequence is repeated after last idle frame.
The Uplink & Downlink pattern are time shifted, so SDCCH sub channel is sent in frame 0-3 on downlink
and in frame 15-18 on uplink. The reason for this is to achieve efficient communication, by giving MS time to
calculate its answer to the request received on down link SDCCH
Nov 17, 2003
TS=2 / CHGR=0 DOWNLINK
1 2 3 1 2 3 1 2 3 7
F0-F3 F4-F7 F8-F11 F12-F15 F16-F19 F20-F23 F24-F27 F28-F31 F32-F35 F36-F39 F40-F43 F44-F47 F48 F49 F50
SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH0 SACCH1 SACCH2 SACCH3 I I I
SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH4 SACCH5 SACCH6 SACCH7 I I I
I: IDLE 1 TS
SDCCH 4 TS
SACCH 4 TS
TS=2 / CHGR=0 UPLINK
1 2 3 1 2 3 1 2 3 7
F0-F3 F4-F7 F8-F11 F12 F13 F14 F15-F18 F19-F22 F23-F26 F27-F30 F31-F34 F35-F38 F39-F42 F43-F46 F47-F50
SACCH5 SACCH6 SACCH7 I I I SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH0
SACCH1 SACCH2 SACCH3 I I I SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH4
I: IDLE 1 TS
SDCCH 4 TS
SACCH 4 TS
25. Mapping of Logical Channel
TCH+SACCH: 0&2 used by control channels. This leaves TS-1and 3-7 free for the
use by TCHs.
Repetition time (Cycle) =26 Frames .i.e. =26*8*(15/26)=120ms
Every 13th
TS contains SACCH. Downlink contains TA value and Uplink contains
measuring report.
Nov 17, 2003
TS=1 / CHGR=0 DOWNLINK
0 1 2 7 0 1 0 1 2 7
F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26
T T T T T T T T T T T T A T T T T T T T T T T T T T I
T: TCH 1 TS
A: SACCH
26. Usage of SDCCH
The SDCCH are used in some different ways in the GSM network:
• Registrations: Periodic Location Updates, IMSI Attach/Detach
• Call Setup: Immediate Assignment -> Assignment.
• SMS point-to-point: SMS messages to/from MS in Idle mode.
• Fax Setup
• Optional: USSD (Unstructured Supplementary Service Data) data
transfer. MS<->Network. Similar to SMS. Controlled by the
MSC.
Nov 17, 2003
27. Possible Configurations
SDCCH/8 : 8 Sub channels for signaling are mapped on 1 TS, this results 1 less TCH
for the cell.
SDCCH/4 (Combining BCCH and SDCCH) :4 Sub channels for signaling are mapped
on BCCH TS. As a result Paging capacity on BCCH is reduced by 1/3.
CBCH : If CBCH is active 1 sub channel of SDCCH is replaced by 1 CBCH channel.
Limitations : SDCCH/8 in a cell = Number of TRX’s
Nov 17, 2003
SDCCH TCH SDCCH TCH
SDCCH/4 4 7 4 15
SDCCH/4+CBCH 3 7 3 15
SDCCH/8 8 6 8 14
SDCCH/8+CBCH 7 6 7 14
SDCCH/4+SDCCH/8 12 6 12 14
SDCCH/4+SDCCH/8+CBCH 11 6 11 14
SDCCH/4+SDCCH/8+SDCCH/8 X X 20 13
SDCCH/4+SDCCH/8+SDCCH/8+CBCH X X 19 13
CONFIGURATIONS
1 TRX 2 TRX
HYD006A
HYD007A
30. SDCCH Congestion
Nov 17, 2003
SDCCH congestion: All SDCCH in a cell are at the same time busy for a
period of time which leads to rejection for new MS.
Reasons :
• Hanging SDCCH: Are SDCCH that are hanging busy and unusable for a
long time (many minutes or indefinite).
Hanging SDCCH are generally caused by SW faults.
• Heavily used SDCCH: SDCCH seen as continuously busy even though
they are used by different MS and thus carries traffic.
It may cause due to :
> Extreme end-user behaviors: Sport event ending, festivals or celebrations.
> Increased mean hold time of the SDCCH: Mean hold time increase from
2 to 10 seconds can give SDCCH congestion.
31. SDCCH Holding Time
Normal Location Updating = 3.5 Sec
Periodic Registration = 3.5 Sec
IMSI Attach = 3.5 Sec
IMSI Detach = 2.9 Sec (IMSI detach Indication message sent to
NW, no authentication is performed (which
normally takes 0.6Sec) & no ack is sent to MS.)
Call Setup = 2.7 Sec (MOC)
= 2.9 Sec (MTC)
Short Message Service(SMS) = 6.2 Sec (Vary depending the length of SMS)
Fax Transmission = 2.7 Sec (MOC)
= 2.9 Sec (MTC)
False Access = 1.8 Sec (when Channel req is rec’d by system ,as SDCCH
is allocated by sending Imm Ass message, and the system
waits a certain time before performing disconnection.)
Nov 17, 2003
32. SDCCH Traffic Estimations
Nov 17, 2003
Normal Location Update: Mean Holding time =3.5 Sec
No of Location update =1.0 per sub and BH
AC: Avg No of Location updates =1000X(1 X 3.5)/3600=0.972 mE/Sub
IC : No Location updating at all =1000X(0 X 3.5)/3600=0 mE/Sub
BC: 3 times the Avg no of Location updates =1000X(3 X 3.5)/3600=2.916mE/Sub
SMS: Mean Holding time =6.2 Sec
No of SMS submitted =1.0 per Sub and BH
Traffic : 1000 X (1.0 X 6.2) / 3600 =1.7 mE/sub
Call Setup: Mean Holding time =2.7 Sec(MOC) & 2.9 Sec(MTC)
Mob Originating Traffic (Incl B Ans) =0.8 BHCA
Mob Terminating Traffic (Incl B Ans) =0.4 BHCA
Traffic : 1000 X {(0.8 X 2.7)+(0.4 X 2.9)} / 3600 =0.9 mE/sub
33. Reasons for SDCCH congestion
Nov 17, 2003
Increased mean hold time of SDCCH can be caused by:
• Too low signal strength at access to the system
Due to LSS MS will be lost communication with the system, This will lead to timeout in the BSC
(RLINKT ), and thus the SDCCH is used until timeout. Increase ACCMIN.
• Congestion of TCH/TRA/RALT
Will increase CP execution time before rejecting Imm Ass. Minor increase in mean hold time expected.
• C7 problems to MSC (or TRC)
In case of C7 signalling problems (SCCP) towards MSC (and/or TRC) can lead to timeout on SCCP
connection setup. This will lead to more than 2 minutes hold time for SDCCH.
• Handover on SDCCH
Handover on SDCCH will in itself increase mean hold time on SDCCH. However minor increase is
expected.
34. Reasons for SDCCH congestion
Nov 17, 2003
• Congestion on Air-interface
Congestion on Air-interface leads to delay in communication to the MS. Can give timeout in BSC
during Imm Ass.Increases SDCCH mean hold time with more than 2 seconds.
• Congestion on Abis (LAPD link)
Congestion on Abis leads to delay in communication with BTS and MS. Can give timeout in BSC
during channel activation (TCHACTIVE). Increase SDCCH mean hold time with more than 5 seconds..
• Congestion on A-interface
Congestion on the A-interface will lead to increased mean hold time on SDCCH. Increase is unknown.
• High load in MSC/VLR or HLR
High load in MSC/VLR and/or HLR will lead to increased mean hold time on SDCCH. Increase is
unknown.
35. How to detect SDCCH congestion in the BSC
Nov 17, 2003
There is no good way to detect SDCCH congestion in real time in the
BSC!
A number of symptoms to look for:
• Increased CP Load.
• Decreased usage of TRA devices.
• Location Updates fails => Mobile terminating calls does not reach the subscriber.
• Subscriber complaints. Can not access the system.
• STS counters . Object type: CLSDCCH and CLSDCCHO.
• Seizure Supervision of LCHs (but only for Hanging SDCCHs!)
36. Preventive actions to avoid SDCCH congestion
Nov 17, 2003
• Avoid combined BCCH in cells with many SDCCHs
• Use the optional feature Adaptive Configuration of SDCCHs (ACLC)
• Use USSD (Unstructured Supplementary Service data) with care, can cause long
meanhold time on SDCCH.
• Avoid Handover on SDCCH
• Proper Dimensioning of the TCHs and TRA devices in the BSC.
• Use recommended values for Periodic Location Updates
Avoid unnecessary Periodic Location Updates :
BSC: T3212 (RLSBC) = 40 (4 hours)
MSC: BTDM (MGIDI) = 240 (4 hours)
MSC: GTDM (MGIDI) = 6 (6 minutes)
• Use Immediate Assignment on TCH.
• Increases the no of SDCCH in a Cell where SDCCH load is high
37. SDCCH Dimensioning
Nov 17, 2003
SDCCH Dimensioning is a compromise between SDCCH blocking
rate and TCH Capacity. In order to have a successful call setup
there has to be an available SDCCH as well as available TCH.
Basic SDCCH configuration:
It is recommended to choose
1 SDCCH/8 as the basic configuration for all the cells,
If LA> 2100 Erlang (500 TRX)
1 SDCCH/4 as the basic configuration for all the cells,
If LA< 2100 Erlang (500 TRX)
38. SDCCH Dimensioning
Nov 17, 2003
Automatic SDCCH dimensioning:
This can be done with optional Adaptive Configuration of Logical
Channel feature.
This feature will add extra SDCCH/8 by reconfiguring idle TCH
when SDCCH load is high, and revert back to TCH if SDCCH load
goes down.
Manual SDCCH Dimensioning :
•Monitoring SDCCH / TCH Traffic in a cell
•SDCCH/TCH load ratio
•SDCCH Grade of Service:- Max allowed TCH GOS % = 2 %
The rule of Thumb says:
SDCCH/4 : Max. SDCCH GOS =1/2 * 2= 1 %
SDCCH/8 : Max. SDCCH GOS =1/4 * 2= 0.5%
39. SDCCH Dimensioning
Nov 17, 2003
Immediate Assignment on TCH:
In case of this feature on the channel administration assigns TCH for
signaling instead of an SDCCH, based on 7 different channels
allocation strategies (CHAPs)
TCH first strategy :
Decreases the SDCCH load and enable to use SDCCH/4 in all
the cells Traffic load on TCH will in this case increases
substantially so this strategy is not recommended.
SDCCH first strategy :
SDCCH is always allocated first if available, otherwise
signaling is performed on TCH.
40. SDCCH Dimensioning
Nov 17, 2003
Example :
ASSUME: CELL=3TRX ,SDCCH Traffic =4 Erlang, Bcchtype=NCOMB.No CBCH
GOS: SDCCH/4 = 1%, SDCCH/8 =0.5% & TCH % =2%
1> When Immediate Assignment on TCH not used
Erlang B Table :To maintain 0.5 % GOS & 4 Erlang min 13 Subchannels reqd
2SDCCH/8 => TCH=(3TRX*8TS) –(1BCCH)-(2SDCCH/8)=21TCH’s
21TCH’s with 2 % GOS => 14.04 Erlang
2> When Immediate Assignment on TCH used
If we use 1SDCCH/8 only than 4 Erlangs with 8 sub channels GOS=>3 %
Congested Erlang will be =4 Erlang x 3 %=0.12Erlang
1SDCCH/8 => TCH=(3TRX*8TS) –(1BCCH)-(1SDCH/8)=22TCH’s
22TCH’s with 2 % GOS => 14.9 Erlang
Actual TCH Capacity=14.9 – 0.12 = 14.7 Erlang
TCH Capacity in the cell is increased with 0.7 Erlang
43. SDCCH Dimensioning
Nov 17, 2003
HALF RATE CAPACITY CALCULATION
Half rate will affect SDCCH dimensioning since more signaling will be
req’d when no of TCH is increased.
Important dimensioning factor is therefore the Half rate penetration
.i.e.the % of Half rate mobile in a NW.
Example: 2 TRX Cell, Half Rate Penetration =10 %, 1 SDCCH/8
TCH/F =14 support 14 Subscriber
Penetration 10% of 14 is 1.4 = 2 Subscribers (Req’d 2 Half Rate TCH/H)
Total 13 TCH/F+2TCH/H = 15 TCH required
Capacity :
Erlang B Table: 15 TCH @ 2% GOS => 9.0096 Erlang
44. SDCCH Dimensioning
Nov 17, 2003
Max Allowed SDCCH/TCH Load Ratio (Half Rate)
AC : Average Cells
BC : Border Cells
IC : Inner Cells
45. SDCCH Dimensioning
Nov 17, 2003
Dimensioning based on STS data
More accurate dimensioning is achieved by using cell statistics .i.e. STS
counters
•SDCCH Traffic
•TCH Traffic
•SDCCH/TCH Load Ratio %
•SDCCH Congestion
•TCH Congestion
•SDCCH Mean Holding Time
•Availability of SDCCH Channels
•Availability of TCH Channels
46. Parameters
Nov 17, 2003
MFRMS :This parameter defines period of transmission for PAGING REQUEST messages to the same
paging subgroup.
T3212 : Is the periodic registration timer
ACCSTATE : Activate/Deactivate the Adaptive config of logical channel feature per cell basis
CHAP :Selecting Channel Allocation profile per cell.
SLEVEL: The attempt to increase the number of SDCCH/8 will take place when allocation of an
SDCCH has failed due to congestion.
STIME :Parameter STIME determines how long the system waits before the number of SDCCH/8
added by this function is decreased when the demand for signalling channels has returned to a low
level
BTDM :Implicit detach supervision should be equal or longer than T3212 in BSC.
GTDM : is an extra Gurad time in minutes before the subscriber is set to detach.
RLINKT: Radio link time-out This parameter defines the time before an MS disconnects a call due to failure
in decoding SACCH messages. The parameter is given as number of SACCH periods (480ms).
48. STS Counters
Nov 17, 2003
CCALLS : Call attempt counter
CCONGS : Congestion counter
CTRALACC : Traffic level accumulator.
CNSCAN : Number of accumulations of SDCCH traffic level
counter.
CNDROP : Dropped connections due to Failure.
CNUCHCNT : Number of defined channels.
CAVAACC : Available channels accumulator.
CMSESTAB : Successful MS channel establishment on SDCCHs.
CTCONGS : SDCCH congestion time ( Sec)
49. Formulas
Nov 17, 2003
No. of SDCCH Attempts CCALLS
SDCCH Congestion (%) 100 X { CCONGS / CCALLS }
No. of SDCCH Connections CMSESTAB
SDCCH Establishments No
Congestion (%)
100 X {CMSESTAB / (CCALLS - CCONGS)}
SDCCH Time Congestion (%) 100 X { CTCONGS / (RPL * 60)}
SDCCH Drop (%) 100 X { CNDROP / CMSESTAB }
SDCCH Mean Holding Time
(Sec.)
RPL X 60 X {(CTRALACC/CNSCAN) / CMSESTAB }
SDCCH Traffic (Erlang) CTRALACC / CNSCAN
SDCCH/TCH Ratio (CTRALACC/CNSCAN) / ((TFTRALACC/TFNSCAN)+
(THTRALACC/THNSCAN))
52. Call Setup-Mobile Terminating Call
Nov 17, 2003
MS BTS BSC MSC
1>Paging(LAI+IMSI/TMSI)
2>Paging Command
Imsi/Tmsi+PG+TRX+CG+TN
3>Paging Req(Imsi on PCH)
4>Channel Req(On RACH)
5>Channel Reqd (Access Delay)
6>Channel Actn (MSPwr,BSPwr,TA)
7>Channel Activation Ack
8>Imm Assign Cmd(On AGCH , Freq
+TS+ SDCCH SubChannel No+TA
8>Immediate Assign
9>Estblish Ind (Paging Resp)
IMSI+MS Class
9>Conn Req (Paging Resp: BSC
add CGI)
10>Auth Req (128 bit RAND+
3bit CKSN)
10>Auth Req (128 bit RAND+3bitCKSN)
10>Auth Req (128 bit
RAND+3bitCKSN)
11>Auth Response (MS Calculate
SRES & Kc with its own Ki stored in
SIM by appling algorithm A3&A8)
11>Auth Response (SRES)
11>Auth Response (SRES)
SABM (Paging Resp:IMSI/MS Class)
UA(Paging Resp) Unnumbered Ack
Frame which confirms only 1 MS is
using Sig Channel
PCH
RACH
AGCH
SDCCH
SDCCH
Next..
53. Call Setup-Mobile Terminating Call
Nov 17, 2003
MS BTS BSC MSC
14>Setup (Req for Services I.e.
Speech/Data/Fax etc)
15>Call Confirmed
17>Channel Activation
(BSC Allocated Idle TS for Traffic)
20>Assign Comp (MS tune to TCH
and send Ind that Chan is Seized)
14>Setup
14>Setup
15>Call Confirmed 15>Call Confirmed
16>Assignment Req
(MSC send CIC to BSC)
18>Channel Activation Ack
19>Assignment Cmnd (BSC send
message on SDCCH to MS telling to go
TCH)
19>Assignment Cmnd (BSC send
message on SDCCH to MS telling to
go TCH)
20>Assign Comp (MS tune to TCH
and send Ind that Chan is Seized)
20>Assign Comp (MS tune to TCH
and send Ind that Chan is Seized)
21>RF Chann Realease
21>RF Chann Realease Ack
22>Alert (MS Send Alert to MSC as
soon as the ringing is started in MS)
22>Alert (MS Send Alert to MSC as
soon as the ringing is started in MS)
22>Alert (MS Send Alert to MSC as
soon as the ringing is started in MS)
23>Connect (When MS Sub Answer
the Conn message sent to MSC)
23>Connect (When MS Sub Answer
the Conn message sent to MSC)
23>Connect (When MS Sub Answer
the Conn message sent to MSC)
24>Connect Ack
24>Connect Ack
24>Connect Ack
SDCCH
SDCCH
SDCCH
TCH
TCH
TCH
TCH
Exit..