WCDMA uses code division multiple access (CDMA) to allow multiple users to access the network simultaneously over the same frequency band. It uses orthogonal variable spreading factor codes and a scrambling code to discriminate between users. Power control is crucial to WCDMA to manage interference levels, maximize capacity, and ensure sufficient signal quality for all users. Tight power control allows the reuse of frequencies in each cell, improving spectral efficiency.
This document provides summaries of key concepts in GSM RF including:
1) GSM PLMN services including bearer, tele, and supplementary services.
2) GSM 900 and DCS 1800 uplink and downlink frequency ranges.
3) Ciphering and authentication processes to encode transmissions and verify identities.
4) Equalization, interleaving, and other techniques used to extract signals and spread data across timeframes.
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.
This document discusses Ethernet networking concepts like CSMA/CD, collision domains, Ethernet frames, and switch operation. It explains that switches reduce collision domains by connecting multiple ports and forwarding traffic based on MAC addresses, thereby also reducing broadcast domains. The document also provides information on basic switch configuration and other data link layer protocols like wireless Ethernet, PPP, ATM, DOCSIS, and DSL.
WCDMA uses spread spectrum technology to allow multiple users to access the same frequency band simultaneously. It spreads user data over a wide bandwidth through multiplication with unique spreading codes. At the receiver, the desired user's signal is recovered through correlation with the same spreading code. WCDMA employs RAKE receivers to combine signals from different propagation paths using maximal ratio combining for improved reception. Power control is used to manage interference between users communicating over the same frequency channel.
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.
Synchronization is important in telecommunication networks to avoid data errors. All node clocks must be synchronized to the master clock to minimize errors. The TimeSource 3600 GPS receiver provides precise timing synchronization at the picosecond level for telecom networks. It can be monitored using TimeScan Craft and TimeScan NMS software to ensure the network maintains precise synchronization.
This document discusses Time Division Multiplexing (TDM) and Synchronous Digital Hierarchy (SDH) basics. It provides information on how TDM converts analog signals to digital signals and multiplexes them. It then explains how SDH was developed to overcome limitations of Plesiochronous Digital Hierarchy (PDH) by employing synchronous transmission and simpler add/drop functionality. The document outlines the frame structure and overhead bytes of STM-1, and defines the common network elements in SDH including Terminal Multiplexer, Add/Drop Multiplexer, Cross-connect, and Regenerator.
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
This document provides summaries of key concepts in GSM RF including:
1) GSM PLMN services including bearer, tele, and supplementary services.
2) GSM 900 and DCS 1800 uplink and downlink frequency ranges.
3) Ciphering and authentication processes to encode transmissions and verify identities.
4) Equalization, interleaving, and other techniques used to extract signals and spread data across timeframes.
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.
This document discusses Ethernet networking concepts like CSMA/CD, collision domains, Ethernet frames, and switch operation. It explains that switches reduce collision domains by connecting multiple ports and forwarding traffic based on MAC addresses, thereby also reducing broadcast domains. The document also provides information on basic switch configuration and other data link layer protocols like wireless Ethernet, PPP, ATM, DOCSIS, and DSL.
WCDMA uses spread spectrum technology to allow multiple users to access the same frequency band simultaneously. It spreads user data over a wide bandwidth through multiplication with unique spreading codes. At the receiver, the desired user's signal is recovered through correlation with the same spreading code. WCDMA employs RAKE receivers to combine signals from different propagation paths using maximal ratio combining for improved reception. Power control is used to manage interference between users communicating over the same frequency channel.
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.
Synchronization is important in telecommunication networks to avoid data errors. All node clocks must be synchronized to the master clock to minimize errors. The TimeSource 3600 GPS receiver provides precise timing synchronization at the picosecond level for telecom networks. It can be monitored using TimeScan Craft and TimeScan NMS software to ensure the network maintains precise synchronization.
This document discusses Time Division Multiplexing (TDM) and Synchronous Digital Hierarchy (SDH) basics. It provides information on how TDM converts analog signals to digital signals and multiplexes them. It then explains how SDH was developed to overcome limitations of Plesiochronous Digital Hierarchy (PDH) by employing synchronous transmission and simpler add/drop functionality. The document outlines the frame structure and overhead bytes of STM-1, and defines the common network elements in SDH including Terminal Multiplexer, Add/Drop Multiplexer, Cross-connect, and Regenerator.
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
SDH (Synchronous Digital Hierarchy) is a transport network standard that uses synchronous framing and multiplexing to transmit synchronous and asynchronous signals. It defines a framework for digital signal transmission with standardized bit rates and multiplexing structures. SDH uses regenerators, multiplexers, and cross-connects to combine and route lower-rate tributary signals into higher-rate aggregate signals for transmission over longer distances. Overhead bytes in the frames provide functions like monitoring, maintenance, and control of network elements.
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 Synchronous Digital Hierarchy (SDH) and its advantages over Plesiochronous Digital Hierarchy (PDH). It describes some key components of SDH including section overhead bytes, path overhead bytes, virtual containers, tributary units, and administrative units. It also provides definitions and functions of various overhead bytes used for frame alignment, error monitoring, data communication, and other purposes in SDH networks.
This document summarizes various communication techniques including spread spectrum, multiple access techniques, and modulation schemes. It discusses frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS), code division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), frequency division multiple access (FDMA), time division multiple access (TDMA). It provides examples and explanations of how each technique works including the use of pseudorandom codes and orthogonal codes. Quiz questions at the end ask about how FHSS works, the most popular 3G technique, and the technique used for 4G.
Throughput calculation for LTE TDD and FDD systemsPei-Che Chang
This document discusses the calculation of throughput for LTE TDD and FDD systems. It explains that LTE systems have configurable channel bandwidth and modulation schemes, unlike fixed CDMA systems. The document then provides an example calculation of throughput for a 20 MHz bandwidth LTE FDD system using 100 resource blocks, 64QAM modulation, and 4x4 MIMO. It calculates the downlink throughput as approximately 300 Mbps and uplink as 75 Mbps after accounting for overhead. Similar calculations are shown for LTE TDD systems using different frame configurations.
Nec neo microwave equipment introductionAdnan Munir
The document introduces the NEC NEO Microwave equipment, including PASOLINK NEO. It discusses microwave communication concepts and applications in mobile networks. It provides an overview of PASOLINK equipment, including the indoor and outdoor units. Key specifications of the indoor unit such as interface cards and configuration are described. The document also covers performance parameters of the outdoor unit such as modulation modes and operating frequencies.
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.
The document provides an overview of the Global System for Mobile communications (GSM) including its history, architecture, key components, and technical aspects. It describes GSM concepts such as cellular structure and multiple access techniques. It also outlines the roles of core network elements like the HLR, VLR, MSC, BSC, BTS, and identifies interfaces between them. Finally, it covers topics like channel structure, encryption, and mobility management in GSM.
1. The document describes the specifications of the NEC PASOLINK NEO IP Transport, including its frequency bands from 6 to 52 GHz, modulation types from QPSK to 128QAM, and transmission capacities from 10 to 150 Mbps.
2. It has two interface options - a 4 port Fast Ethernet interface with 8 E1 ports, and a 3 port Fast Ethernet with 1 Gigabit Ethernet port and 1 E1 port.
3. Key features include scalability through software upgrades, flexible system configurations, port-based and tag-based VLAN support, QoS functions, and link aggregation on Gigabit Ethernet interfaces.
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.
Code division multiple access (CDMA) allows all terminals to send signals simultaneously over the same frequency by assigning each terminal a unique spreading code. The receiver can isolate a particular sender's signal by correlating the received signal with the known spreading code. CDMA offers advantages like higher capacity and integration of encryption due to the use of spreading codes, though receivers are more complex.
The document discusses different methods for establishing channels in radio technologies: FDMA uses different frequencies for each user; TDMA uses different time slots on the same frequency; W-CDMA uses unique code patterns to distinguish each user on the same frequency. It also describes the UMTS frame format and power control mechanisms in UMTS, including inner loop power control which adjusts transmission power based on comparisons to Eb/Nt objectives, and outer loop power control which estimates Eb/Nt objectives based on measured frame error rates.
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.
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.
1) The document discusses the installation and commissioning of a Nokia Flexi EDGE BTS. It provides an overview of the GSM system and BTS functions.
2) It describes the various components of the Nokia Flexi EDGE BTS including the EDGE System Module (ESMA), Dual TRX Module (EXxA), Dual Duplexer Module (ERxA), and Wideband Combiner (EWxA).
3) The commissioning process involves 12 steps like hardware installation, software configuration, RF parameter checks, traffic tests and O&M integration to activate the BTS in the live network.
The document discusses Synchronous Digital Hierarchy (SDH) and its advantages over earlier transmission systems. It describes the evolution from analog to digital transmission and the standards of Plesiochronous Digital Hierarchy (PDH) and SDH. The key aspects of SDH covered are its frame structure, equipments used, network topologies supported, and advantages such as availability of high speed standards and efficient multiplexing.
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 the mapping and multiplexing of asynchronous 2048 kbps tributaries onto an STM-1 frame. It describes how the 2048 kbps signal is mapped into a VC-12 container by adding justification bytes and then into a TU-12. Multiple TU-12s carrying different tributaries are multiplexed into a TUG-2. Several TUG-2s are then multiplexed into a TUG-3, which is further multiplexed into a VC-4 container along with other TUG-3s. The VC-4 is then multiplexed with an AU-4 and pointers to form an STM-1 frame for transmission.
WCDMA uses an OSI model with 7 layers. The lower 3 layers - physical, data link, and network layers - are most important for WCDMA. The physical layer uses different physical channels to transmit data over the air interface. Logical channels define how data is transferred, transport channels define how data is transmitted, and physical channels carry payload data and define signal characteristics. There are three types of channels - logical, transport, and physical - that work together to transmit various types of control and traffic data between the UE and base station.
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.
SDH (Synchronous Digital Hierarchy) is a transport network standard that uses synchronous framing and multiplexing to transmit synchronous and asynchronous signals. It defines a framework for digital signal transmission with standardized bit rates and multiplexing structures. SDH uses regenerators, multiplexers, and cross-connects to combine and route lower-rate tributary signals into higher-rate aggregate signals for transmission over longer distances. Overhead bytes in the frames provide functions like monitoring, maintenance, and control of network elements.
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 Synchronous Digital Hierarchy (SDH) and its advantages over Plesiochronous Digital Hierarchy (PDH). It describes some key components of SDH including section overhead bytes, path overhead bytes, virtual containers, tributary units, and administrative units. It also provides definitions and functions of various overhead bytes used for frame alignment, error monitoring, data communication, and other purposes in SDH networks.
This document summarizes various communication techniques including spread spectrum, multiple access techniques, and modulation schemes. It discusses frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS), code division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), frequency division multiple access (FDMA), time division multiple access (TDMA). It provides examples and explanations of how each technique works including the use of pseudorandom codes and orthogonal codes. Quiz questions at the end ask about how FHSS works, the most popular 3G technique, and the technique used for 4G.
Throughput calculation for LTE TDD and FDD systemsPei-Che Chang
This document discusses the calculation of throughput for LTE TDD and FDD systems. It explains that LTE systems have configurable channel bandwidth and modulation schemes, unlike fixed CDMA systems. The document then provides an example calculation of throughput for a 20 MHz bandwidth LTE FDD system using 100 resource blocks, 64QAM modulation, and 4x4 MIMO. It calculates the downlink throughput as approximately 300 Mbps and uplink as 75 Mbps after accounting for overhead. Similar calculations are shown for LTE TDD systems using different frame configurations.
Nec neo microwave equipment introductionAdnan Munir
The document introduces the NEC NEO Microwave equipment, including PASOLINK NEO. It discusses microwave communication concepts and applications in mobile networks. It provides an overview of PASOLINK equipment, including the indoor and outdoor units. Key specifications of the indoor unit such as interface cards and configuration are described. The document also covers performance parameters of the outdoor unit such as modulation modes and operating frequencies.
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.
The document provides an overview of the Global System for Mobile communications (GSM) including its history, architecture, key components, and technical aspects. It describes GSM concepts such as cellular structure and multiple access techniques. It also outlines the roles of core network elements like the HLR, VLR, MSC, BSC, BTS, and identifies interfaces between them. Finally, it covers topics like channel structure, encryption, and mobility management in GSM.
1. The document describes the specifications of the NEC PASOLINK NEO IP Transport, including its frequency bands from 6 to 52 GHz, modulation types from QPSK to 128QAM, and transmission capacities from 10 to 150 Mbps.
2. It has two interface options - a 4 port Fast Ethernet interface with 8 E1 ports, and a 3 port Fast Ethernet with 1 Gigabit Ethernet port and 1 E1 port.
3. Key features include scalability through software upgrades, flexible system configurations, port-based and tag-based VLAN support, QoS functions, and link aggregation on Gigabit Ethernet interfaces.
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.
Code division multiple access (CDMA) allows all terminals to send signals simultaneously over the same frequency by assigning each terminal a unique spreading code. The receiver can isolate a particular sender's signal by correlating the received signal with the known spreading code. CDMA offers advantages like higher capacity and integration of encryption due to the use of spreading codes, though receivers are more complex.
The document discusses different methods for establishing channels in radio technologies: FDMA uses different frequencies for each user; TDMA uses different time slots on the same frequency; W-CDMA uses unique code patterns to distinguish each user on the same frequency. It also describes the UMTS frame format and power control mechanisms in UMTS, including inner loop power control which adjusts transmission power based on comparisons to Eb/Nt objectives, and outer loop power control which estimates Eb/Nt objectives based on measured frame error rates.
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.
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.
1) The document discusses the installation and commissioning of a Nokia Flexi EDGE BTS. It provides an overview of the GSM system and BTS functions.
2) It describes the various components of the Nokia Flexi EDGE BTS including the EDGE System Module (ESMA), Dual TRX Module (EXxA), Dual Duplexer Module (ERxA), and Wideband Combiner (EWxA).
3) The commissioning process involves 12 steps like hardware installation, software configuration, RF parameter checks, traffic tests and O&M integration to activate the BTS in the live network.
The document discusses Synchronous Digital Hierarchy (SDH) and its advantages over earlier transmission systems. It describes the evolution from analog to digital transmission and the standards of Plesiochronous Digital Hierarchy (PDH) and SDH. The key aspects of SDH covered are its frame structure, equipments used, network topologies supported, and advantages such as availability of high speed standards and efficient multiplexing.
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 the mapping and multiplexing of asynchronous 2048 kbps tributaries onto an STM-1 frame. It describes how the 2048 kbps signal is mapped into a VC-12 container by adding justification bytes and then into a TU-12. Multiple TU-12s carrying different tributaries are multiplexed into a TUG-2. Several TUG-2s are then multiplexed into a TUG-3, which is further multiplexed into a VC-4 container along with other TUG-3s. The VC-4 is then multiplexed with an AU-4 and pointers to form an STM-1 frame for transmission.
WCDMA uses an OSI model with 7 layers. The lower 3 layers - physical, data link, and network layers - are most important for WCDMA. The physical layer uses different physical channels to transmit data over the air interface. Logical channels define how data is transferred, transport channels define how data is transmitted, and physical channels carry payload data and define signal characteristics. There are three types of channels - logical, transport, and physical - that work together to transmit various types of control and traffic data between the UE and base station.
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 discusses WCDMA RF optimization processes, policies, and case studies. It describes the three steps of the WCDMA RF optimization process: single station check, base station group optimization, and whole network optimization. It then discusses common RF problems, analysis, and optimization policies for issues like call drops, discontinuity, and access failures. Finally, it presents five case studies of WCDMA network optimization including issues like handover problems, coverage gaps, high site interference, and neighbor cell list configuration errors.
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.
UMTS system architecture, protocols & processesMuxi ESL
This document provides an overview of UMTS system architecture and protocols. It discusses:
- The logical architecture of UTRAN including RNC and Node-B elements.
- Interfaces between network elements are clearly specified to allow interoperability between equipment from different manufacturers.
- The main functions of the RNC include radio resource management, call management, and connection to the core network.
- Protocols in UTRAN include RRC for radio resource control, RLC for radio link control, and MAC for medium access control.
The document is a seminar report on Wideband Code Division Multiple Access (WCDMA) technology. It discusses the basics of WCDMA, including that it uses code division multiple access to separate users and spread signals over a wide 5MHz bandwidth. It also covers WCDMA specifications, generation, spreading principles, power control, handovers, and advantages such as service flexibility and spectrum efficiency.
This document provides a rough guide to understanding 3G/HSPA concepts for RF engineers. It begins with general information on 3G networks and UMTS. It then discusses technical concepts such as spreading codes, scrambling codes, and processing gain. It explains how spreading spreads the baseband signal over the frequency band and hides it below the noise floor, allowing recovery via despreading. The document also covers HSPA technologies and their advantages over prior 3G standards.
HSPA is a mobile telecommunications protocol that extends 3G networks by improving data transmission rates. It consists of HSDPA for faster downloads and HSUPA for faster uploads. HSPA was designed for non-real time data and increases peak rates to 14Mbps down and 5.8Mbps up. It achieves these improvements through technologies like shorter transmission time intervals, link adaptation, advanced modulation schemes, and MIMO antennas. The architecture introduces new channels like HS-DSCH for user data and HS-SCCH for control information. Subsequent evolutions like HSPA+ and DC-HSDPA have further increased speeds through higher order modulation and dual-cell connections.
Long Term Evolution (LTE) is the next generation of mobile broadband technology that provides higher data rates and network throughput compared to 3G. LTE networks use OFDM and SC-FDMA for downlink and uplink, respectively, along with MIMO and an all-IP architecture to improve performance. The network elements include eNBs, SGWs, PDN GWs and MMEs. For operators, LTE provides an opportunity to increase ARPU through new applications and services while decreasing CCPU through an all-IP infrastructure. Mass deployment of LTE is expected to begin around 2012, with LTE Advanced enabling data rates up to 1 Gbps.
OFDM is a high-speed wireless transmission technology that divides the available spectrum into multiple orthogonal subcarriers. It is implemented as OFDMA to support multi-user communication. OFDM provides advantages over single carrier transmission by combating inter-symbol interference and frequency selective fading. It works by encoding data over multiple carrier frequencies, with spacing between carriers chosen so that the carriers are orthogonal to each other. This allows high data rates without overlapping signals at a receiver.
This document summarizes various communication techniques including spread spectrum, multiple access techniques, and modulation schemes. It discusses frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS), code division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), frequency division multiple access (FDMA), time division multiple access (TDMA). It provides examples and explanations of how each technique works including the use of pseudorandom codes and orthogonal codes. Quiz questions at the end ask about how FHSS works, the most popular 3G technique, and the technique used for 4G.
CDMA systems use code division multiple access (CDMA) to allow multiple users to access the network simultaneously using the same frequency band. CDMA uses spreading codes to distinguish between users, allowing signals to overlap in both time and frequency. Key aspects of CDMA include soft handoff which provides better call quality during handoffs, rake receivers which mitigate multipath interference, and intelligent vocoders which provide high quality voice compression. CDMA networks also use power control and simple network planning to provide better coverage than comparable systems while using less infrastructure. The cdma2000 1x standard provided increased data speeds and backward compatibility with earlier CDMA networks.
The document discusses key concepts in 3GPP Long Term Evolution (LTE) including Orthogonal Frequency Division Multiplexing (OFDM), why OFDM was chosen for the LTE downlink, the difference between OFDM and OFDMA, how Single Carrier Frequency Division Multiple Access (SC-FDMA) is used in the LTE uplink instead of OFDM due to its lower peak-to-average power ratio, and how multiple-input multiple-output (MIMO) techniques can increase channel capacity, robustness and coverage for LTE. It provides high-level explanations of LTE physical signals, channels and how they are modulated and mapped in the time-frequency domain.
Here you are an interesting explanation about HSPA Technology. The High Speed packet Access is the combination of two technologies, one of the downlink and the other for the uplink that can be built onto the existing 3G UMTS or W-CDMA technology to provide increased data transfer speeds.
The original 3G UMTS / W-CDMA standard provided a maximum download speed of 384 kbps.
The document discusses the structure and characteristics of GPS signals. It covers topics like signal requirements, encoding methods, modulation techniques, and digital signal processing. Key points:
- GPS signals are transmitted from satellites on two carrier frequencies (L1 and L2) which are modulated by pseudo-random codes and navigation data.
- The signals use phase modulation to encode information in the carrier phase. Receivers use correlation and filtering techniques to recover the codes, data, and carrier signals.
- After the introduction of anti-spoofing in 1994, various methods like squaring, cross-correlation and Z-tracking were developed to still allow civilian use of the encrypted P-code signal.
The document provides an overview of LTE and its evolution from previous cellular standards. It discusses the targets of LTE including high data rates up to 100 Mbps, low latency, high spectral efficiency, and flexibility in spectrum and bandwidth. It also describes the EPS architecture with E-UTRAN, EPC, and the air interface structure of LTE including OFDMA in the downlink and SC-FDMA in the uplink. Key layers like the PHY, MAC, and RLC layers are also summarized.
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.
The document contains 20 questions and answers related to GSM interview questions. Some key points covered include:
1) The channel used to transmit random access signals is the CCCH.
2) The combination of channels that make up the main BCCH is FCH+SCH+BCH+CCCH.
3) The value range of the Timing Advance in GSM is 0-63.
4) With one paging message using IMSI, 2 MS can be paged.
5) Directed Retry handover refers to a handover from SDCCH to TCH.
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
Pmit lecture 03_wlan_wireless_network_2016Chyon Ju
The document discusses requirements and specifications for wireless local area networks (WLANs). It notes that the IEEE 802 committee develops standards for wired and wireless networking, including 802.11 for WLANs. The document then describes several 802.11 specifications such as 802.11, 802.11a, 802.11b, and 802.11g that define transmission speeds and frequencies for WLANs. It also discusses modulation techniques like BPSK and QPSK used in wireless communications.
Positioning techniques in 3 g networks (1)kike2005
Independent Study Presentation on Positioning Techniques in 3G Networks. The presentation discusses [1] positioning parameters in 3G networks such as RSCP, RSS, RTT, and AoA; and [2] positioning techniques including enhancements to the basic Cell ID method, OTDOA methods using IPDL and CVB, the Database Correlation Method using power delay profiles, and the Pilot Correlation Method using pilot signal measurements. Simulation results are presented showing the accuracy of some of these techniques.
UMTS uses WCDMA technology which allows all cells to reuse the same frequency band by differentiating users through the use of unique scrambling codes. It provides benefits like improved voice quality, higher data rates up to 384kbps, and new multimedia services. UMTS network architecture utilizes scrambling codes to distinguish between base stations and user equipment on the downlink and uplink respectively, enabling frequency reuse across all cells.
This document discusses communication networks and data transmission. It covers the basic components of a transmission system including transmitters that encode digital data and receivers that decode the signals back into data. It describes different transmission mediums and the impairments they can cause. It also explains techniques used for encoding data like line coding and modulating signals for bandpass channels. Finally, it discusses multiplexing techniques like frequency division multiplexing and time division multiplexing that allow multiple signals to be transmitted over the same communication channel.
Spread spectrum is a communication technique that spreads a narrowband communication signal over a wide range of frequencies for transmission then de-spreads it into the original data bandwidth at the receive.
UMTS is the 3G cellular standard proposed by ETSI to evolve GSM and GPRS networks. It uses WCDMA as its air interface and includes the following key aspects:
- A complete system architecture with standardized interfaces to allow interoperability between vendors.
- A UTRAN subsystem comprising Node B base stations and RNC controllers to handle radio functionality using WCDMA.
- A core network subsystem including elements like MSC, SGSN, GGSN to support both circuit switched and packet switched services.
- WCDMA uses CDMA with variable spreading factors to provide different data rates. It employs channelization codes, scrambling codes and modulation like QPSK.
The document discusses multiple access techniques for satellite communications. It describes frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA divides the available radio spectrum into narrow frequency channels. TDMA divides each radio channel into time slots. CDMA allows all users to access the full bandwidth at all times by using orthogonal spreading codes. The document provides examples of these different multiple access techniques and compares their approaches.
The document contains 20 questions and answers related to GSM interview questions. Some key points:
1) The channel used to transmit random access signals is the BCCH (Broadcast Control Channel).
2) The combination of channels that make up the main BCCH is FCH+SCH+BCH+CCCH (Frequency Correction Channel + Synchronization Channel + Broadcast Control Channel + Common Control Channel).
3) The value range for the Timing Advance (TA) parameter in GSM is 0-63.
3 sentences.
This document provides an overview of LTE vs 3G technologies. It discusses LTE's motivations including higher data rates and spectral efficiency. It covers MIMO definitions and how to calculate LTE and 3G throughput. It also compares the architectures, access technologies, physical resources, frames, and channels of LTE, 3G, and 2G. Key aspects of LTE performance are highlighted such as scalable bandwidth and flat IP architecture.
2. Multiple Access Technology
User Frequency
Time
Power
Traffic channels: different users
are assigned unique code and
transmitted over the same
frequency band at the same
time, for example, WCDMA and
CDMA2000
Traffic channels: different frequency
bands are allocated to different
users,for example, AMPS and TACS
Traffic channels: different time slots
are allocated to different users, for
example, DAMPS and GSM
Frequency
Time
Power
Frequency
Time
Power
FDMA
TDMA
CDMA
User
User
User
User
User
3. Duplex Spacing: 190 MHz
FDD
Time
Frequency
Power
5 MHz 5 MHz
Code Multiplex
UL DL
UMTS USER 1
UMTS USER 2
Time
Frequency
Power
TDD
5 MHz
Code Multiplex
&
Time Division
666.67 µs
DL
UL
DL
DL
UL
UMTS USER 2
UMTS USER 1
Multiple Access Technology
• WCDMA: FDD or TDD
Uplink: 1920 MHz - 1980 MHz
Downlink: 2110 MHz - 2170 MHz
Each carrier is 5 MHz width.
4. Binary data to transmit 0 1 0 0 1 0Binary data to transmit 0 1 0 0 1 0
The faster is the bit rate, the more the energy is spread on the spectrumThe faster is the bit rate, the more the energy is spread on the spectrum
+ a
- a
a2
T0
s(t)
T0
1/T0 2/T0
Frequency
Time
0 1 0 0 1 0
+ a
- a
a2
T1
s(t)
T1
1/T1 2/T1
Frequency
NRZ
coding
Time
0 1 0 0 1 0
Power
spectrum
Spread Spectrum Principle
• 1 - Time - Frequency Duality
5. Tbit
Tchip
Data sequence
spreading sequence
transmitted sequence
a2
Tbit = Ebit
1/Tbit
Tchip = Echip
1/Tchip
Frequency
a2
Tchip
1/Tchip
+a
-a
-1
+1
-a
+a
x
=
Data
sequence
Transmitted
signal
Spreading sequence generator
Modulation
x(t)
Power spectrum
Spread Spectrum Principle
• 2 – Transmission (Spreading)
6. Tbit
Tchip
Data sequence
spreading sequence
received sequence
a2
Tbit = Ebit
Power spectrum
1/Tbit
Tchip = Echip
1/Tchip
Frequency
a2
Tchip+a
-a
-1
+1
-a
+a
x
=
1/Tchip
Received
signal
Data
sequence
Spreading sequence generator
Demodulation
x(t)
Spread Spectrum Principle
• 3 – Reception (Dispreading)
11. WCDMA Principles
• Multiplexing users data
Power spectrum
User 1
User 2
User 3
User 4
User 5
Spreading
Code 1
Code 2
Code 3
Code 4
Code 5
Composite signal
5 MHz
Codes discriminate users
15. Scrambling codeScrambling code
Channelization code 1Channelization code 1
Channelization code 2Channelization code 2
Channelization code 3Channelization code 3
User 1 signal
User 2 signal
User 3 signal
BTS
Code Multiplexing
• 1 - Downlink Transmission on a Cell Level
16. BTS
Scrambling code 3
User 3 signal
Channelization code
Scrambling code 2
User 2 signal
Channelization code
Scrambling code 1
User 1 signal
Channelization code
Code Multiplexing
• 2 - Uplink Transmission on a Cell Level
17. Functions and Features of the Scrambling and
Channelization Codes
Channelization (Orthogonal) code Scrambling (Pseudorandom) code
Purpose
Uplinks: Distinguish physical data
(DPDCH) and control channels
(DPCCH).
Down links: Distinguish the down
links of different users in the same
cell.
Uplinks: Distinguish terminals
Down links: Distinguish cells
Length
4~256 chips (1.0-66.7 us)
The down links contain 512 chips
Uplinks: 10 ms = 38400 chips or
=66.7 us = 256 chips
Down links: 10 ms = 38400 chips
Code cluster
OVSF (Orthogonal Variable Spreading
Factor)
Long 10 ms code: Gold code
Spreading
spectrum
Yes, transport bandwidth is added.
No, transport bandwidth is not
affected.
21. Interference level
Example: 2 UEs at the
same distance from the
BTS using 2 data rates
Eb/No
require
d
SF=128
Service provided: Speech
Interference level
Eb/No
require
d
SF=8
Service provided: Data 144
User 2 needs more power for the
UL & DL for the same quality as
user 1
UE2
UE1
Speech 8 kbps Data 144 kbps
The higher the SF, the less power requiredThe higher the SF, the less power required
BTS
Received power
Received power
Coverage Limits (1)
22. SF = 128
Speech 8 kbps Data 64 kbps Data 384 kbps
BTS
SF = 32
SF = 4
Coverage Limits (2)
23. Receiver sensitivity (x kbps)
BS Receiver
Maximum Noise Floor
Lowest Despread Signal
BTS
UE1
x kbps x kbps
UE2 UE3
x kbps
Eb/No
Processing
Gain
Uplink Limits (1)
The transmission medium is a resource that can be subdivided into individual channels according to different criteria that depend on the technology used. Here’s how the three most popular radio technologies establish channels: FDMA (Frequency Division Multiple Access) each user is on a different frequency A channel is a frequency. TDMA (Time Division Multiple Access) each user is on a different window in time (“time slot”) A channel is a specific time - slot on a specific frequency. WCDMA (Wide-band Code Division Multiple Access) Each user uses the same frequency all the time, but it is mixed with different distinguishing code patterns. A channel is a unique (set of) code pattern(s).
The possibility to operate in either FDD or TDD mode is allowed for efficient utilization of the available spectrum according to the frequency allocation in different regions. FDD and TDD are defined as follows: FDD A duplex method whereby the u plink and d ownlink transmissions use 2 separate frequency bands: Uplink : 1920 MHz - 1980 MHz Downlink : 2110 MHz - 2170 MHz Each carrier is 5 MHz wid e and the u plink channel is 190 MHz away from the d ownlink. So there are up to 12 pairs of carriers. TDD A duplex method whereby the u plink and d ownlink transmissions are carried over same frequency using synchronized time intervals. The carrier still use s a 5 MHz band. FDD mode is the preferred mode for macro-cellular applications. TDD mode is the preferred mode for the unpaired part of the spectrum. Because each time - slot can be assigned a different direction, the TDD mode offers a great flexibility to manage duplex and asymmetric traffic. The TDD spectrum will be used for low mobility coverage in urban areas.
The information to transmit is a succession of bits, i.e. “0” or “1”. Bits, unlike electrical signal s have no physical existence. It is the purpose of data modulation (example above: NRZ used in UMTS) to give a physical existence to the virtual bits. When looking at the power spectrum of a succession 0 and 1 coded with NRZ modulation, we can see that the spectrum is composed of lobes that cut the frequency axis at multiple s of the bit period T. The main part of the power (90%) is located in the first lobe which has a maximum value for f = 0 of a 2 T = Eb. Nevertheless, the remaining parts are consuming spectrum as the theoretical spectrum is infinite. So, the faster the modulation is (the smaller T is ), the more the energy is spread o ver the frequency domain.
Spreading the spectrum consists in artificially increasing the modulation rate (chip rate) in order to spread the energy of the information signal on a wide frequency band without modifying the data rate. The number of chips per bit is called the Spreading Factor (SF) and defines the data service required for the user: For UMTS: Bit Rate x SF = 3.84 Mchip/s (Chip Rate) The following table shows examples of data services and associated Spreading Factors:
To be able to perform the de - spreading operation, the receiver must not only know the sequence used to spread the data signal, but the spreading sequence of the received signal and the locally - generated spreading sequence must be synchronized. This synchronization must be accomplished at the beginning of reception and maintained until the whole signal has been received.
To be able to perform the de - spreading operation, the receiver must not only know the sequence used to spread the data signal, but the spreading sequence of the received signal and the locally - generated spreading sequence must be synchronized. This synchronization must be accomplished at the beginning of reception and maintained until the whole signal has been received.
To be able to perform the de - spreading operation, the receiver must not only know the sequence used to spread the data signal, but the spreading sequence of the received signal and the locally - generated spreading sequence must be synchronized. This synchronization must be accomplished at the beginning of reception and maintained until the whole signal has been received.
To be able to perform the de - spreading operation, the receiver must not only know the sequence used to spread the data signal, but the spreading sequence of the received signal and the locally - generated spreading sequence must be synchronized. This synchronization must be accomplished at the beginning of reception and maintained until the whole signal has been received.
In a multi-path environment, the original transmitted signal is reflected by obstacles such as buildings or mountains, and the receiver has to treat several copies of the signal with different delays. Actually, from each multi-path point of view, other multi- path signals are considered as interference and are partially suppressed after de - spreading thanks to the processing gain. However, a further benefit is obtained if several multi-path signals are combined together using a rake receiver. The rake receiver has multiple fingers (4 to 8), each for a multi-path component. In each finger, the received signal is de - spread by the code which is time aligned with the delay of the multi-path signal. After despreading, the signals are combined using either equal gain or maximum ratio combining. This technique provides a more stable transmission channel. Rake receivers are used in the uplink and the downlink. In addition to multi-path combination the rake receiver is used by the UE to communicate with several cells (macro - diversity) . A trade-off has to be made between the multi-path gain and the capacity loss due to the use of multiple channels. Another receiver, which has been under study for a certain time now, works in a totally different way. MUD (Multi-User Detection) removes the unwanted multiple access signals through a complex algorithm. Its goal is to cancel the intra-cell interference. By so doing, an increased capacity and coverage are expected. Also, this would cancel the near-far problem, but power control would still be needed to limit inter-cell interference. This receiver is a bit more complex than the rake receiver.
All WCDMA users occupy the same frequency at the same time. Frequency and time are not used as discriminators. WCDMA operates by using CODES to discriminate between users. The receiver will ‘hear’ all the transmitter signals mixed together . B ut by using the correct code sequence , it can decipher the required transmission channel and the rest is background noise. Spreading sequences are actually unique streams of 1 and -1 which compose the code associated with a user. Therefore, users are discriminated thanks to spreading codes . Many code channels are individually “spread” with their associated “code” and then added together to create a “composite signal”. In the receiver, the composite signal is correlated with a replica of the code used to spread the data to be recover ed . Thus, low cross-correlation between the desired users and the interfering users is important to suppress multiple access interference. Good auto-correlation properties are required for initial synchronization and to reliably separate multi-path components. Remark : The correlation between two bit strings of the same length is defined as the “degree of similarity” between them: When the correlation is determined between two copies of the same string, it is called auto-correlation . When the correlation is determined between any two same length strings, it is called cross-correlation .
User A after spreading spreading sequence = +1 -1 +1 -1 = +a -a +a -a User B after spreading spreading sequence = +1 -1 -1 +1 = +b -b -b +b The signals will be added together and received as: (+a +b) (-a -b) (+a -b) (-a +b) The r eceiver reapplies the sequence spreading sequence = +1 -1 +1 -1 therefore +1x(+a +b) = +a +b -1x (-a -b) = +a +b +1x(+a -b) = +a -b -1x(-a +b) = +a -b therefore +a +a +a +a = 4a +b +b -b -b = 0 100% of the results are ‘a’ and 0% are ‘b’, so we assume ‘a’. If we apply the spreading code for user B to the same received signal we will receive a result in favor of ‘b’.
At the receiver, as the codes are different and are known, only the power of the intended user is de-spread. After despreading (decoding), correct data recovery requires a given value for the Eb to No ratio. Under this Eb/No ratio the noise will generate too many errors. The noise is mainly generated by the other users transmitting at the same time and at the same frequency but using different spreading codes. Therefore, in order not to cross this maximal noise level, all the users have to share their power: In WCDMA the Time-Frequency plane is not divided among the mobile subscribers as is done in TDMA or FDMA. So the common shared resource is power. The de-spreading process gives processing gain proportional to the bandwidth of the spreading signal. The larger the s preading f actor, the larger the gain. This means that by using a larger s preading f actor, we can reduce the power (and therefore the background noise). Thanks to this property, spread signals can operate at negative signal - to - noise ratios provided that they possess enough gain. Example: The narrow-band signal requires an Eb/No of 12 dB to achieve a certain bit - error rate performance. What is the required Ec/No, knowing that the processing gain is 20 dB?
WCDMA interference come s mainly from nearby users. Transmit power on all users must be tightly controlled so their signals reach the base station at the same signal level. This way, interferences are controlled and the famous near-far problem is alleviated. Power control is also done in the downlink to decrease the inter-cell interference. The Eb/No target is set for every service, and for each environment. Every constructor tries to have the lowest Eb/No target possible. For example, it could be worth 6.1 dB for 12.2 kbps speech in the downlink, in a dense urban area.
A mobile station or UE is surrounded by BSs ( Base Station ) , all of which transmitting on the same WCDMA frequency. It must be able to discriminate between the different cells of different b ase s tations and listen to only one set of code channels. Therefore two types of codes are used: Channelization The user data are spread synchronously with different channelization codes. The orthogonality properties of OVSF enable the UE to recover each of its bits without being disturbed by other user channels. Scrambling S crambling is used for b ase s tation and UE identification. It reduces the interference with neighboring cells since the same channelization codes are used . It is important to maintain good cross correlation characteristics between the different scrambling codes in order not to decode an interferer. O nce allocated to the U E s , t hese codes, remain the same during the whole communication. Otherwise, the b ase s tation must be notified of the change. Similar to the re-use of frequency in GSM, scrambling codes are necessarily re-used.
The WCDMA system must be able to uniquely identify each UE that may attempt to communicate with a B S . The different uplink code channels are distinguished by different UE scrambling codes. They may be scrambled by either long or short scrambling codes. Orthogonality from channelization codes is lost because there is no longer synchronous transmission. Nevertheless UE scrambling codes reintroduce some kind of reduced orthogonality thanks to their good cross-correlation properties.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.
The channelization codes are OVSF ( Orthogonal Variable Spreading Factor ) codes that preserves the orthogonality between a user’s different physical channels. The OVSF codes can be defined using a code tree. In the code tree the channelization codes are uniquely described as C ch , SF , k , where SF is the Spreading Factor of the code and k the code number, 0 k SF-1. A channelization sequence codes one user bit. As the chip rate is constant, the different length s of code enable different user data rates to be coded . The length of an OVSF code is an even number of chips and the number of codes is equal to the number of chips. The codes generated within the same layer constitute a set of orthogonal codes. Furthermore, any two codes of different layers are orthogonal except when one of the two codes is a father code of the other. For example C 4 , 3 is not orthogonal with C 1 , 0 and C 2 , 1 , but is orthogonal with C 2 , 0 . Each s ector in each b ase s tation is transmitting WCDMA d ownlink t raffic c hannels with up to 512 code channels. Exercise: Find code C ch , 8 , 3 and code C ch , 16 , 15 OVSF shortage Scrambling enables neighboring cells to use the same channelization codes. This allows the system to use a maximum of 512 OVSF in each cell. Notice that the use of an OVSF forbid the use of the other codes of its branch. This considerably reduces the number of available codes especially for fast rate service. This may lead to OVSF shortage. For such a case, secondary scrambling codes are allocated to cells and enable to re-use the same OVSF in the same cell.
Orthogonality means that there is no correlation between codes, so, C k presence does not affect C j energy. OVSF codes are completely orthogonal for zero delay. For other delay s they have very bad cross-correlation properties, and thus they are suitable only for synchronous applications. If the synchronization at To is not respected then there is no orthogonality anymore ==> C j and C k interfere.
For a given noise level, as the processing gain is smaller for a high rate user data, the acceptable path loss is lower and therefore so is the range of the cell.
The radius of a cell varies with the SF ( Spreading Factor ) and, as we will see, the noise level or, as a matter of fact, the number of active subscribers in the cell. The figures are given for a traffic load of 50% of the maximum traffic acceptable in the cell.
Consider UE 1 transmitting at the boarder of the cell. That is to say UE 1 transmits at full power and is received at the minimum power to access the cell (equal to the receiver sensitivity). After de - spreading, decoding UE 1 needs a noise level lower than the maximum noise floor fixed by the processing gain and the Eb/No. For so long as the interference generated by users UE 2 and UE 3 do es not cross this floor, UE 1 is correctly decoded.
Consider a BTS transmitting with UE1, UE2 and UE3. The further the UE is, the more power is needed from the BTS to be able to reach it. When UE4 asks for an access, the BTS doesn’t have not enough power capacity to add the power intended for UE4 although they are very close to each other. In th is case, the UE can be handed over to another BTS (if possible), or the system can degrade the quality of communication for the other UEs in order for the BTS to be able to reach it.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.
In order to satisfy the request of UE4, UE1 is handed over to another cell if th is is possible. If not, the access to UE4 could be denied.