This document proposes a new dynamic power control algorithm with variable quality of service (QoS) for different substreams in CDMA systems. It aims to minimize transmitter power while maintaining reliable communication. The algorithm assigns different power levels to each traffic type/substream to provide unequal error protection. It uses a combination of open-loop power control to compensate for slow fading and closed-loop power control using power control bits transmitted every 1.25ms to adjust power based on measured signal quality and compensate for fast fading. This allows supporting variable QoS while transmitting the minimum necessary power for each substream to reduce interference for other users.
This document discusses parameters related to power control in GSM networks, including:
1. Maximum transmit power of MS (MSTXPWRMX) which defines the maximum power a mobile station can transmit at.
2. Received level threshold of downlink power increment (LDR) which defines the threshold at which the base station will increase its transmit power if the downlink signal is too weak.
3. Received level threshold of uplink power increment (LUR) which defines the threshold at which the base station will increase the mobile station's transmit power if the uplink signal is too weak.
4. Received quality threshold of downlink power increment (LDR) which defines the threshold for downlink
Enhancement of power quality by DVR using "ANN Technique" under unbalanced an...ijceronline
The paper discusses the voltage control of a critical load bus using dynamic voltage restorer (DVR) in a distribution system. The critical load requires a balanced sinusoidal waveform across its terminals preferably at system nominal frequency of 50Hz .It is assumed that the frequency of the supply voltage can be varied and it is different from the system nominal frequency. The DVR is operated such that it holds the voltage across critical load bus terminals constant at system nominal frequency irrespective of the frequency of the source voltage. In case of a frequency mismatch, the total real power requirement of the critical load bus has to be supplied by the DVR. Proposed method used to compensate for frequency variation, the DC link of the DVR is supplied through an uncontrolled rectifier that provides a path for the real power required by the critical load to flow .A simple frequency estimation technique is discussed which are Discrete Fourier transform (DFT), ANN controller. The present work study the compensation principle and different control strategies of DVR used here are based on DFT, and ANN Controller .Through detailed analysis and simulation studies using MATLAB. It is shown that the voltage is completely controlled across the critical load.
Iaetsd design and analysis of low-leakage high-speedIaetsd Iaetsd
This document summarizes and compares different domino circuit designs for wide fan-in OR gates. It describes 8 different domino circuit techniques: 1) Standard Footless Domino, 2) Conditional-Keeper Domino, 3) High-Speed Domino, 4) Leakage Current Replica Keeper Domino, 5) Controlled Keeper by Current-Comparison Domino, 6) Diode Footed Domino, 7) Diode-Partitioned Domino, and 8) Wide Fan-In OR gate Current Comparison Domino. It simulates these circuits in 180nm, 130nm, and 90nm technologies and compares their power, propagation delay, energy, and energy-delay product performance.
The third order LLCL filter is gaining more attractive in grid connected PV inverter in terms of material cost saving than LCL filter. Several active and passive damping techniques prevail in mitigating the resonance problem for maintaining the grid power quality standards. In this paper an improved passive damping is examined with reduction of power loss for the LLCL filter. Particularly, it reduces the switching ripple much better than LCL filter, with a decrease in volume of the inductance. The filter design is also developed for the operation of stiff grid. Mathematical operations and transfer function are derived with frequency response for the accuracy of the filter design. In addition, comparative analysis of passive and improved passive damping control is proposed. The control strategy is improved with feedback linearization in order to avoid the glitches in inverter control and is verified with prototype grid connected PV inverter.
Handover is the process of transferring an ongoing call or data session from one cell to another. It involves measurement preprocessing, threshold comparisons, target cell list generation, and handover signaling. Key aspects of measurement preprocessing include measuring signal quality and level values on the serving and neighbor cells, averaging these values, and distinguishing between full and subset measurements when discontinuous transmission is used. The results are used to detect when handover criteria are met and determine the best target cell.
Performance Evaluation of OFDM and Single Carrier Modulation in Broadband Wir...XIAOGENG YUAN
This document compares the performance of OFDM and single carrier modulation with frequency domain equalization (SC-FDE) in broadband wireless systems using computer simulation. It finds that both systems can achieve similar bit error rate performance when forward error correction is applied. OFDM has a higher peak-to-average power ratio than SC-FDE, but the peak power of OFDM signals can be reduced to around 6.5dB higher than the average power using a peak power reduction method. QPSK modulated SC-FDE shows around 3-8% higher power efficiency at the power amplifier compared to QPSK-OFDM with peak power reduction, while 64QAM SC-FDE achieves similar power efficiency as 64QAM-OF
Research Inventy: International Journal of Engineering and Scienceresearchinventy
This document summarizes a research paper that presents the design of a digitally controlled current-mode DC-DC converter integrated circuit. Key points:
- A charge-pump digital-to-analog converter (CP-DAC) is used to link the digital voltage control loop to the analog current control loop. This allows a reconfigurable digital compensator without sampling the inductor current.
- Experimental results show the converter achieves a response time of 4 microseconds for a 200mA load step using a 0.18um CMOS process. The active area of the controller is small at 0.077mm^2.
- Analysis is presented on limit-cycle oscillations in current-mode control with mixed-
Comparative Study and Performance Analysis of different Modulation Techniques...Souvik Das
Make a comparative study and performance analysis of different modulation
techniques which shows graphically and comparatively results like Bandwidth,
Energy and Power Efficiency of AM, DSB-SC, SSB and SSB-SC
This document discusses parameters related to power control in GSM networks, including:
1. Maximum transmit power of MS (MSTXPWRMX) which defines the maximum power a mobile station can transmit at.
2. Received level threshold of downlink power increment (LDR) which defines the threshold at which the base station will increase its transmit power if the downlink signal is too weak.
3. Received level threshold of uplink power increment (LUR) which defines the threshold at which the base station will increase the mobile station's transmit power if the uplink signal is too weak.
4. Received quality threshold of downlink power increment (LDR) which defines the threshold for downlink
Enhancement of power quality by DVR using "ANN Technique" under unbalanced an...ijceronline
The paper discusses the voltage control of a critical load bus using dynamic voltage restorer (DVR) in a distribution system. The critical load requires a balanced sinusoidal waveform across its terminals preferably at system nominal frequency of 50Hz .It is assumed that the frequency of the supply voltage can be varied and it is different from the system nominal frequency. The DVR is operated such that it holds the voltage across critical load bus terminals constant at system nominal frequency irrespective of the frequency of the source voltage. In case of a frequency mismatch, the total real power requirement of the critical load bus has to be supplied by the DVR. Proposed method used to compensate for frequency variation, the DC link of the DVR is supplied through an uncontrolled rectifier that provides a path for the real power required by the critical load to flow .A simple frequency estimation technique is discussed which are Discrete Fourier transform (DFT), ANN controller. The present work study the compensation principle and different control strategies of DVR used here are based on DFT, and ANN Controller .Through detailed analysis and simulation studies using MATLAB. It is shown that the voltage is completely controlled across the critical load.
Iaetsd design and analysis of low-leakage high-speedIaetsd Iaetsd
This document summarizes and compares different domino circuit designs for wide fan-in OR gates. It describes 8 different domino circuit techniques: 1) Standard Footless Domino, 2) Conditional-Keeper Domino, 3) High-Speed Domino, 4) Leakage Current Replica Keeper Domino, 5) Controlled Keeper by Current-Comparison Domino, 6) Diode Footed Domino, 7) Diode-Partitioned Domino, and 8) Wide Fan-In OR gate Current Comparison Domino. It simulates these circuits in 180nm, 130nm, and 90nm technologies and compares their power, propagation delay, energy, and energy-delay product performance.
The third order LLCL filter is gaining more attractive in grid connected PV inverter in terms of material cost saving than LCL filter. Several active and passive damping techniques prevail in mitigating the resonance problem for maintaining the grid power quality standards. In this paper an improved passive damping is examined with reduction of power loss for the LLCL filter. Particularly, it reduces the switching ripple much better than LCL filter, with a decrease in volume of the inductance. The filter design is also developed for the operation of stiff grid. Mathematical operations and transfer function are derived with frequency response for the accuracy of the filter design. In addition, comparative analysis of passive and improved passive damping control is proposed. The control strategy is improved with feedback linearization in order to avoid the glitches in inverter control and is verified with prototype grid connected PV inverter.
Handover is the process of transferring an ongoing call or data session from one cell to another. It involves measurement preprocessing, threshold comparisons, target cell list generation, and handover signaling. Key aspects of measurement preprocessing include measuring signal quality and level values on the serving and neighbor cells, averaging these values, and distinguishing between full and subset measurements when discontinuous transmission is used. The results are used to detect when handover criteria are met and determine the best target cell.
Performance Evaluation of OFDM and Single Carrier Modulation in Broadband Wir...XIAOGENG YUAN
This document compares the performance of OFDM and single carrier modulation with frequency domain equalization (SC-FDE) in broadband wireless systems using computer simulation. It finds that both systems can achieve similar bit error rate performance when forward error correction is applied. OFDM has a higher peak-to-average power ratio than SC-FDE, but the peak power of OFDM signals can be reduced to around 6.5dB higher than the average power using a peak power reduction method. QPSK modulated SC-FDE shows around 3-8% higher power efficiency at the power amplifier compared to QPSK-OFDM with peak power reduction, while 64QAM SC-FDE achieves similar power efficiency as 64QAM-OF
Research Inventy: International Journal of Engineering and Scienceresearchinventy
This document summarizes a research paper that presents the design of a digitally controlled current-mode DC-DC converter integrated circuit. Key points:
- A charge-pump digital-to-analog converter (CP-DAC) is used to link the digital voltage control loop to the analog current control loop. This allows a reconfigurable digital compensator without sampling the inductor current.
- Experimental results show the converter achieves a response time of 4 microseconds for a 200mA load step using a 0.18um CMOS process. The active area of the controller is small at 0.077mm^2.
- Analysis is presented on limit-cycle oscillations in current-mode control with mixed-
Comparative Study and Performance Analysis of different Modulation Techniques...Souvik Das
Make a comparative study and performance analysis of different modulation
techniques which shows graphically and comparatively results like Bandwidth,
Energy and Power Efficiency of AM, DSB-SC, SSB and SSB-SC
10 17sep 8310 10079-1-ed pulse density (edit ari)IAESIJEECS
Switched mode power supply (SMPS) converter is a dc-dc power electronic converter which is used to step up or step down the dc output voltage. A dimmable driver circuit for Light Emitting Diode (LED) lamp for automotive lighting with dimming feature is used in this paper. A flyback converter is used as a driver circuit operated in discontinuous conduction mode to perform dimming control of LEDs. High overall circuit efficiency is achieved by regulating the current through the LED lamps using pulse density modulation scheme. The LED driver circuit design and operating principle is discussed in detail. A gentle current control feature is achieved by pulse density modulation technique. The high performance driver circuit is designed for 25 W LED lamps.
This document summarizes key radio parameters in GSM networks. It describes parameters for network identification like CGI and BSIC, which help identify cells and distinguish neighboring base stations. It also covers system control parameters for random access, including MAXRETRANS, Tx_Integer, and AC. Finally, it discusses cell selection parameters and network function parameters that control aspects like paging and location updating.
Power Quality Enhancement in Power Distribution system using Artificial intel...sundar balan
The document summarizes a research paper that models an artificial neural network (ANN) controlled dynamic voltage restorer (DVR) for power quality enhancement in a power distribution system. Key points:
1) A DVR with a voltage source inverter and LC filter is designed to compensate for voltage sags and harmonics in the distribution system and protect sensitive loads.
2) The DVR is controlled using both a proportional-integral controller and an ANN controller trained offline with data from the PI controller.
3) Simulation results in MATLAB/Simulink show the DVR restores the load voltage under different fault conditions like 3-phase faults and line-to-ground faults with both controllers. The
DESIGN AND ANALYSIS OF 2 GHz 130nm CMOS CASCODE LOW NOISE AMPLIFIER WITH INTE...csijjournal
This work, illustrates the development of 2 GHz Low Noise Amplifier (LNA) interfaced with square truncated edge-fed right circularly polarized patch antenna. The LNA is simulated on Agilent ADS platform with TSMC 130nm RF CMOS process. The development of cascode amplifier and its optimization has been further exemplified. The developed LNA is tuned for 2 GHz and the performance is tuned for high stability factor of 4, Gain of 19 dB which is essential for any mobile device, Noise Figure (NF) of 1.15 dB with a P1dB point at -9 dBm. Further a truncated patch antenna with right circular polarization has been simulated on EMpro. The antenna has a gain of 6.1 dB in the azimuth plane. The simulated system can be further integrated to form the RF front end of TDD2000 LTE standard mobile device.
Multiplexing is a technique where multiple users can use the same medium simultaneously with minimal interference. There are four main types of multiplexing: space division, frequency division, time division, and code division.
Time division multiplexing involves all senders using the same frequency but transmitting at different time intervals with guard spaces between transmissions to avoid interference. Precise synchronization is required between users.
Frequency shift keying and phase shift keying are digital modulation techniques used to convert digital data to analog signals for transmission. In frequency shift keying, two different frequencies represent binary 1 and 0, while in phase shift keying a 180 degree phase shift represents a change between 1 and 0.
A Modern Technique of Deduction in Leakage Current in Resonant Bi-directional...IJMTST Journal
This Paper Presents A whole New resonant twin active bridge(DAB) topology, that uses a tuned inductor-capacitor-inductor(LCL) network. As compared to ancient DAB topologies, the planned topologies significantly reduced the bridge current, lowering every physical phenomenon and alter losses and conjointly VA rating associated with the bridges. The performance of the DAB is investigated using a mathematical model at a lower place varied operational conditions. Experiment results of a model is reduced the outflow current of the circuit. are presented with discussion to demonstrate the improved performance of the LCL DAB topology. Result clearly that the planned DAB Topology provide higher efficiency over an oversized vary of every input voltage and as compared to ancient DAB topology
This document discusses the key concepts of frequency modulation (FM) covered in Chapter 5. It explains that in FM, the carrier frequency varies proportionally to the amplitude of the modulating signal, while the carrier amplitude remains constant. The chapter covers the principles of both FM and phase modulation (PM), including modulation index, sidebands, bandwidth, and noise suppression properties. Bessel functions are used to calculate the amplitudes of the carrier and sidebands for different modulation indexes. The chapter compares FM and AM modulation techniques and explains how FM provides better noise suppression using limiter circuits and pre-emphasis filtering.
The document contains information about the course EC6501 Digital Communication including the units covered in the course and their brief descriptions. It discusses topics like sampling and quantization, waveform coding, baseband transmission, digital modulation schemes and error control coding. It provides the course outcomes listing the highest cognitive level for each outcome. The subsequent sections provide more details about digital modulation formats including ASK, PSK, FSK and their generation and detection. It also discusses coherent and non-coherent receivers along with their probability of error analysis.
This document discusses various digital modulation and multiplexing techniques. It begins by explaining the differences between analog and pulse modulation. It then discusses key concepts like sampling, quantization, and the sampling theorem. It provides details on pulse amplitude modulation (PAM) including flat top and natural PAM. The document also covers pulse code modulation (PCM), differential PCM (DPCM), delta modulation, and adaptive delta pulse code modulation. It defines line coding and discusses time division multiplexing (TDM) and frequency division multiplexing (FDM).
Power Efficiency Improvement in CE-OFDM System With 0 dB IBO for Transmission...CSCJournals
Orthogonal frequency division multiplexing (OFDM) OFDM has been adopted for high speed data transmission of multimedia traffic such as HomePlug A/V and Mobile WiMax. However, OFDM also has a drawback of a high PAPR (peak-to-average-power-ratio). Due to this high PAPR amplifier usually does not act in dynamic range. One potential solution for reducing the peak-to-average power ratio (PAPR) in an OFDM system is to utilize a constant envelope OFDM (CE-OFDM) system. Furthermore, by utilizing continuous phase modulation (CPM) in a CE-OFDM system, the PAPR can be effectively reduced to 0 dB, allowing for the signal to be amplified with a power efficient non-linear power amplifier with Input Back-Off (IBO) of 0 dB. This paper describes a CE-OFDM based modem for Power Line Communications (PLC) over the low voltage distribution network. Relying on a preliminary characterization of a PLC network, a complete description of the modem is given. Also CE-OFDM is compared with conventional OFDM under HomePlug 1.0 in the presence of power amplifier nonlinearities, considering different values of IBO.
Energy Efficient Design of Multiplexer Using Adiabatic logicIJEEE
the increasing prominence of portable systems and the need to limit the power consumption in very high density VLSI chips have led to rapid and innovative developments in low power design during the recent years. The CMOS technology provides circuits with very low static power dissipation, during the switching operation currents are generated, due to the discharge of load capacitances that cause power dissipation increasing with the clock frequency. The adiabatic technique prevents such losses, the charge does not flow from the supply voltage to the load capacitance and then to ground, but it flows back to a trapezoidal or sinusoidal supply voltage and can be reused.In this paper a low 2:1 multiplexer is designed using positive feedback adiabatic logic. The design is simulated at .12µm technology using Microwind 3.1. Simulated results shows that proposed design saves 38% energy as compare to conventional CMOS design.
High-Performance of Domino Logic Circuit for Wide Fan-In Gates Using Mentor G...iosrjce
IOSR journal of VLSI and Signal Processing (IOSRJVSP) is a double blind peer reviewed International Journal that publishes articles which contribute new results in all areas of VLSI Design & Signal Processing. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced VLSI Design & Signal Processing concepts and establishing new collaborations in these areas.Design and realization of microelectronic systems using VLSI/ULSI technologies require close collaboration among scientists and engineers in the fields of systems architecture, logic and circuit design, chips and wafer fabrication, packaging, testing and systems applications. Generation of specifications, design and verification must be performed at all abstraction levels, including the system, register-transfer, logic, circuit, transistor and process levels.
The document presents a new robust load frequency controller for a two area interconnected power system to reduce deviations in frequency and tie line power due to different load disturbances. It develops a dynamic model of the system using integral control and evaluates the system responses. Simulation results in MATLAB/Simulink are provided to study the impact of changing parameters like inertia constant, integration constant, and turbine constant on the frequency deviation and tie line power flow deviation.
This document describes the simulation of a dynamic voltage restorer (DVR) using PI control with fuzzy logic to mitigate voltage sags. A DVR is connected between a distribution system and critical load to inject compensating voltages during faults. The control system uses PI controllers for the dq components of load voltage with additional fuzzy logic control. Simulation results under different fault conditions show the DVR maintains the load voltage, demonstrating its effectiveness in compensating voltage sags. Total harmonic distortion is also improved by increasing the DC link voltage of the DVR. The PI with fuzzy logic control provides faster response compared to conventional controllers.
CDMA is a technique that allows multiple users to access the network using the same frequency band at the same time. It works by spreading each user's signal across the entire bandwidth using unique codes. This allows signals to overlap without interfering with each other. Key advantages of CDMA include larger network capacity, less transmit power per user, seamless handoffs between cells, no need for frequency planning, high tolerance of interference, and multiple diversity techniques. A typical CDMA network can support 400 subscribers per sector using 1.25MHz of spectrum, allowing a cell with 6 sectors to support up to 2,400 subscribers on a single frequency channel.
Qualitative Analysis of Darlington Feedback Amplifier at 45nm TechnologyjournalBEEI
The transistors are the key element of present communication system having high data rate. Some applications need high gain by using very low frequency, and then transistors are used. Amplifier is the key element in many applications of present high data rate communication system such as low noise amplifier (LNA), broadband amplifier, distributed and power amplifier. The Darlington pair amplifier is analyzed for high frequency performance and related effect of bandwidth. Broadband feedback Darlington pair amplifier is designed with enhanced gain, bandwidth and slew rate. This paper presents the comparison of single stage and three stage feedback Darlington feedback amplifier with reference to gain, bandwidth and slew rate. This paper is simulated on cadence analog design environment at GPDK 45nm technology. This paper shows that increase in gain, bandwidth and slew rate of three stage Darlington feedback amplifier can show better stability over the single stage Darlington feedback amplifier.
This document provides an overview of Chapter 6 from the textbook "Principles of Electronic Communication Systems". The chapter covers FM circuits, including frequency modulators, phase modulators, and frequency demodulators. Section 6-1 describes different types of frequency modulator circuits such as varactor diodes, reactance modulators, and voltage-controlled oscillators. Section 6-2 discusses phase modulator circuits that use varactors, transistors, and tuned circuits. Section 6-3 reviews common frequency demodulator or detector circuits like slope detectors, pulse-averaging discriminators, and quadrature detectors.
This chapter of the textbook provides an overview of fundamental electronics concepts including gain, attenuation, decibels, tuned circuits, filters, and Fourier theory. It discusses how circuits manipulate signals through gain and attenuation. Key aspects covered include calculating gain and attenuation in decibels, the fundamentals of reactive components like capacitors and inductors in tuned circuits, the characteristics of series and parallel resonant circuits, and the basic types of passive and active filters. The chapter aims to review these essential electronics topics as background for further communication systems principles discussed in later chapters.
Benchmarks, performance, scalability, and capacity what's behind the numbersJustin Dorfman
Baron Schwartz gave a presentation on analyzing database performance beyond surface-level metrics and benchmarks. He discussed how ideal benchmarks provide full system specifications and metrics over time to understand response times and throughput. Little's Law and queueing theory can predict concurrency, response times, and capacity given arrival rates and service times. While tools like Erlang C model queues, the assumptions must be validated. True scalability is nonlinear due to bottlenecks, and debunking performance claims requires examining raw data.
The document discusses power control in 3G networks. It describes the need for power control to address the near-far effect in cellular systems and reduce interference. There are two main types of power control: inner loop power control, which operates fast to compensate for fading and distance, and outer loop power control, which operates slower to maintain signal quality. Inner loop power control can be open-loop, where the transmitting device adjusts its power, or closed-loop, where the receiving device provides feedback to adjust transmission power.
This document discusses capacity planning for GSM networks. It covers topics like trunking, traffic theory including traffic intensity, grade of service, busy hour, and request rate. It describes how to dimension traffic channels and SDCCH channels based on factors like traffic intensity and grade of service. It also discusses connectivity planning between network elements like MSC, BSC, transcoder, and BTS. It provides details on air interface, Abis interface between BSC and BTS, and different LAPD modes for signaling concentration over Abis. The objective is to estimate the optimal number of resources needed to meet performance requirements based on traffic analysis and engineering principles.
10 17sep 8310 10079-1-ed pulse density (edit ari)IAESIJEECS
Switched mode power supply (SMPS) converter is a dc-dc power electronic converter which is used to step up or step down the dc output voltage. A dimmable driver circuit for Light Emitting Diode (LED) lamp for automotive lighting with dimming feature is used in this paper. A flyback converter is used as a driver circuit operated in discontinuous conduction mode to perform dimming control of LEDs. High overall circuit efficiency is achieved by regulating the current through the LED lamps using pulse density modulation scheme. The LED driver circuit design and operating principle is discussed in detail. A gentle current control feature is achieved by pulse density modulation technique. The high performance driver circuit is designed for 25 W LED lamps.
This document summarizes key radio parameters in GSM networks. It describes parameters for network identification like CGI and BSIC, which help identify cells and distinguish neighboring base stations. It also covers system control parameters for random access, including MAXRETRANS, Tx_Integer, and AC. Finally, it discusses cell selection parameters and network function parameters that control aspects like paging and location updating.
Power Quality Enhancement in Power Distribution system using Artificial intel...sundar balan
The document summarizes a research paper that models an artificial neural network (ANN) controlled dynamic voltage restorer (DVR) for power quality enhancement in a power distribution system. Key points:
1) A DVR with a voltage source inverter and LC filter is designed to compensate for voltage sags and harmonics in the distribution system and protect sensitive loads.
2) The DVR is controlled using both a proportional-integral controller and an ANN controller trained offline with data from the PI controller.
3) Simulation results in MATLAB/Simulink show the DVR restores the load voltage under different fault conditions like 3-phase faults and line-to-ground faults with both controllers. The
DESIGN AND ANALYSIS OF 2 GHz 130nm CMOS CASCODE LOW NOISE AMPLIFIER WITH INTE...csijjournal
This work, illustrates the development of 2 GHz Low Noise Amplifier (LNA) interfaced with square truncated edge-fed right circularly polarized patch antenna. The LNA is simulated on Agilent ADS platform with TSMC 130nm RF CMOS process. The development of cascode amplifier and its optimization has been further exemplified. The developed LNA is tuned for 2 GHz and the performance is tuned for high stability factor of 4, Gain of 19 dB which is essential for any mobile device, Noise Figure (NF) of 1.15 dB with a P1dB point at -9 dBm. Further a truncated patch antenna with right circular polarization has been simulated on EMpro. The antenna has a gain of 6.1 dB in the azimuth plane. The simulated system can be further integrated to form the RF front end of TDD2000 LTE standard mobile device.
Multiplexing is a technique where multiple users can use the same medium simultaneously with minimal interference. There are four main types of multiplexing: space division, frequency division, time division, and code division.
Time division multiplexing involves all senders using the same frequency but transmitting at different time intervals with guard spaces between transmissions to avoid interference. Precise synchronization is required between users.
Frequency shift keying and phase shift keying are digital modulation techniques used to convert digital data to analog signals for transmission. In frequency shift keying, two different frequencies represent binary 1 and 0, while in phase shift keying a 180 degree phase shift represents a change between 1 and 0.
A Modern Technique of Deduction in Leakage Current in Resonant Bi-directional...IJMTST Journal
This Paper Presents A whole New resonant twin active bridge(DAB) topology, that uses a tuned inductor-capacitor-inductor(LCL) network. As compared to ancient DAB topologies, the planned topologies significantly reduced the bridge current, lowering every physical phenomenon and alter losses and conjointly VA rating associated with the bridges. The performance of the DAB is investigated using a mathematical model at a lower place varied operational conditions. Experiment results of a model is reduced the outflow current of the circuit. are presented with discussion to demonstrate the improved performance of the LCL DAB topology. Result clearly that the planned DAB Topology provide higher efficiency over an oversized vary of every input voltage and as compared to ancient DAB topology
This document discusses the key concepts of frequency modulation (FM) covered in Chapter 5. It explains that in FM, the carrier frequency varies proportionally to the amplitude of the modulating signal, while the carrier amplitude remains constant. The chapter covers the principles of both FM and phase modulation (PM), including modulation index, sidebands, bandwidth, and noise suppression properties. Bessel functions are used to calculate the amplitudes of the carrier and sidebands for different modulation indexes. The chapter compares FM and AM modulation techniques and explains how FM provides better noise suppression using limiter circuits and pre-emphasis filtering.
The document contains information about the course EC6501 Digital Communication including the units covered in the course and their brief descriptions. It discusses topics like sampling and quantization, waveform coding, baseband transmission, digital modulation schemes and error control coding. It provides the course outcomes listing the highest cognitive level for each outcome. The subsequent sections provide more details about digital modulation formats including ASK, PSK, FSK and their generation and detection. It also discusses coherent and non-coherent receivers along with their probability of error analysis.
This document discusses various digital modulation and multiplexing techniques. It begins by explaining the differences between analog and pulse modulation. It then discusses key concepts like sampling, quantization, and the sampling theorem. It provides details on pulse amplitude modulation (PAM) including flat top and natural PAM. The document also covers pulse code modulation (PCM), differential PCM (DPCM), delta modulation, and adaptive delta pulse code modulation. It defines line coding and discusses time division multiplexing (TDM) and frequency division multiplexing (FDM).
Power Efficiency Improvement in CE-OFDM System With 0 dB IBO for Transmission...CSCJournals
Orthogonal frequency division multiplexing (OFDM) OFDM has been adopted for high speed data transmission of multimedia traffic such as HomePlug A/V and Mobile WiMax. However, OFDM also has a drawback of a high PAPR (peak-to-average-power-ratio). Due to this high PAPR amplifier usually does not act in dynamic range. One potential solution for reducing the peak-to-average power ratio (PAPR) in an OFDM system is to utilize a constant envelope OFDM (CE-OFDM) system. Furthermore, by utilizing continuous phase modulation (CPM) in a CE-OFDM system, the PAPR can be effectively reduced to 0 dB, allowing for the signal to be amplified with a power efficient non-linear power amplifier with Input Back-Off (IBO) of 0 dB. This paper describes a CE-OFDM based modem for Power Line Communications (PLC) over the low voltage distribution network. Relying on a preliminary characterization of a PLC network, a complete description of the modem is given. Also CE-OFDM is compared with conventional OFDM under HomePlug 1.0 in the presence of power amplifier nonlinearities, considering different values of IBO.
Energy Efficient Design of Multiplexer Using Adiabatic logicIJEEE
the increasing prominence of portable systems and the need to limit the power consumption in very high density VLSI chips have led to rapid and innovative developments in low power design during the recent years. The CMOS technology provides circuits with very low static power dissipation, during the switching operation currents are generated, due to the discharge of load capacitances that cause power dissipation increasing with the clock frequency. The adiabatic technique prevents such losses, the charge does not flow from the supply voltage to the load capacitance and then to ground, but it flows back to a trapezoidal or sinusoidal supply voltage and can be reused.In this paper a low 2:1 multiplexer is designed using positive feedback adiabatic logic. The design is simulated at .12µm technology using Microwind 3.1. Simulated results shows that proposed design saves 38% energy as compare to conventional CMOS design.
High-Performance of Domino Logic Circuit for Wide Fan-In Gates Using Mentor G...iosrjce
IOSR journal of VLSI and Signal Processing (IOSRJVSP) is a double blind peer reviewed International Journal that publishes articles which contribute new results in all areas of VLSI Design & Signal Processing. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced VLSI Design & Signal Processing concepts and establishing new collaborations in these areas.Design and realization of microelectronic systems using VLSI/ULSI technologies require close collaboration among scientists and engineers in the fields of systems architecture, logic and circuit design, chips and wafer fabrication, packaging, testing and systems applications. Generation of specifications, design and verification must be performed at all abstraction levels, including the system, register-transfer, logic, circuit, transistor and process levels.
The document presents a new robust load frequency controller for a two area interconnected power system to reduce deviations in frequency and tie line power due to different load disturbances. It develops a dynamic model of the system using integral control and evaluates the system responses. Simulation results in MATLAB/Simulink are provided to study the impact of changing parameters like inertia constant, integration constant, and turbine constant on the frequency deviation and tie line power flow deviation.
This document describes the simulation of a dynamic voltage restorer (DVR) using PI control with fuzzy logic to mitigate voltage sags. A DVR is connected between a distribution system and critical load to inject compensating voltages during faults. The control system uses PI controllers for the dq components of load voltage with additional fuzzy logic control. Simulation results under different fault conditions show the DVR maintains the load voltage, demonstrating its effectiveness in compensating voltage sags. Total harmonic distortion is also improved by increasing the DC link voltage of the DVR. The PI with fuzzy logic control provides faster response compared to conventional controllers.
CDMA is a technique that allows multiple users to access the network using the same frequency band at the same time. It works by spreading each user's signal across the entire bandwidth using unique codes. This allows signals to overlap without interfering with each other. Key advantages of CDMA include larger network capacity, less transmit power per user, seamless handoffs between cells, no need for frequency planning, high tolerance of interference, and multiple diversity techniques. A typical CDMA network can support 400 subscribers per sector using 1.25MHz of spectrum, allowing a cell with 6 sectors to support up to 2,400 subscribers on a single frequency channel.
Qualitative Analysis of Darlington Feedback Amplifier at 45nm TechnologyjournalBEEI
The transistors are the key element of present communication system having high data rate. Some applications need high gain by using very low frequency, and then transistors are used. Amplifier is the key element in many applications of present high data rate communication system such as low noise amplifier (LNA), broadband amplifier, distributed and power amplifier. The Darlington pair amplifier is analyzed for high frequency performance and related effect of bandwidth. Broadband feedback Darlington pair amplifier is designed with enhanced gain, bandwidth and slew rate. This paper presents the comparison of single stage and three stage feedback Darlington feedback amplifier with reference to gain, bandwidth and slew rate. This paper is simulated on cadence analog design environment at GPDK 45nm technology. This paper shows that increase in gain, bandwidth and slew rate of three stage Darlington feedback amplifier can show better stability over the single stage Darlington feedback amplifier.
This document provides an overview of Chapter 6 from the textbook "Principles of Electronic Communication Systems". The chapter covers FM circuits, including frequency modulators, phase modulators, and frequency demodulators. Section 6-1 describes different types of frequency modulator circuits such as varactor diodes, reactance modulators, and voltage-controlled oscillators. Section 6-2 discusses phase modulator circuits that use varactors, transistors, and tuned circuits. Section 6-3 reviews common frequency demodulator or detector circuits like slope detectors, pulse-averaging discriminators, and quadrature detectors.
This chapter of the textbook provides an overview of fundamental electronics concepts including gain, attenuation, decibels, tuned circuits, filters, and Fourier theory. It discusses how circuits manipulate signals through gain and attenuation. Key aspects covered include calculating gain and attenuation in decibels, the fundamentals of reactive components like capacitors and inductors in tuned circuits, the characteristics of series and parallel resonant circuits, and the basic types of passive and active filters. The chapter aims to review these essential electronics topics as background for further communication systems principles discussed in later chapters.
Benchmarks, performance, scalability, and capacity what's behind the numbersJustin Dorfman
Baron Schwartz gave a presentation on analyzing database performance beyond surface-level metrics and benchmarks. He discussed how ideal benchmarks provide full system specifications and metrics over time to understand response times and throughput. Little's Law and queueing theory can predict concurrency, response times, and capacity given arrival rates and service times. While tools like Erlang C model queues, the assumptions must be validated. True scalability is nonlinear due to bottlenecks, and debunking performance claims requires examining raw data.
The document discusses power control in 3G networks. It describes the need for power control to address the near-far effect in cellular systems and reduce interference. There are two main types of power control: inner loop power control, which operates fast to compensate for fading and distance, and outer loop power control, which operates slower to maintain signal quality. Inner loop power control can be open-loop, where the transmitting device adjusts its power, or closed-loop, where the receiving device provides feedback to adjust transmission power.
This document discusses capacity planning for GSM networks. It covers topics like trunking, traffic theory including traffic intensity, grade of service, busy hour, and request rate. It describes how to dimension traffic channels and SDCCH channels based on factors like traffic intensity and grade of service. It also discusses connectivity planning between network elements like MSC, BSC, transcoder, and BTS. It provides details on air interface, Abis interface between BSC and BTS, and different LAPD modes for signaling concentration over Abis. The objective is to estimate the optimal number of resources needed to meet performance requirements based on traffic analysis and engineering principles.
The document discusses various propagation mechanisms that affect radio signals, including reflection, diffraction, scattering, and their effects on signal strength over distance. It also covers propagation models like free space path loss, two-ray ground reflection model, and log-distance path loss for estimating average received signal power at a given distance. Fresnel zones and knife-edge diffraction are explained as factors in signal propagation around obstructions. Log-normal shadowing is described as a statistical model to account for variations from the average path loss.
This document discusses in-building wireless solutions. It explains that high-speed wireless connectivity is increasingly common in indoor spaces like workplaces, airports and hospitals. However, outdoor cellular coverage is often insufficient indoors due to building materials blocking signals. This creates a need for dedicated in-building wireless solutions to provide seamless connectivity and meet growing demand. The document outlines the key steps to planning and implementing a robust in-building wireless solution, including surveying, planning, installation, testing and ongoing maintenance.
This document discusses mobile radio propagation and propagation models. It begins by introducing how radio channels are random and time-varying. It then covers the free space propagation model and how received power decreases with distance. Reflection, diffraction, and scattering are described as the main propagation mechanisms. The two-ray ground reflection model is presented to model propagation over large distances. Diffraction is explained using the knife-edge diffraction model. Fresnel zones and diffraction gain are also defined.
cellular concepts in wireless communicationasadkhan1327
The document discusses the concept of frequency reuse in cellular networks. It explains that a limited radio spectrum is used to serve millions of subscribers by dividing the network coverage area into cells and reusing frequencies across spatially separated cells. Each cell is allocated a portion of the total available frequencies, and neighboring cells are assigned different frequencies to minimize interference. The frequency reuse factor is defined as the ratio of the minimum distance between co-channel cells to the cell radius. Larger frequency reuse factors provide better isolation between co-channel cells but reduce network capacity. The document also covers additional topics like different channel assignment strategies, handoff methods, interference calculation and optimization of frequency reuse networks.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
CDMA 1x Introduction to Power Control Issue2.1Tempus Telcosys
One of the aims of the CDMA1X system is to maximize the number of its users. If each mobile station (MS) adjusts its transmitter power to minimize the signal noise received by the base transceiver station (BTS), the capacity of the system is maximized. Higher power brings higher interference and results in more capacity loss. Power control can adjust the transmission power of the MS and BTS, aiming to minimize the interference
After learning this course, you will learn the following:
The importance of the power control of the CDMA system
Categories and calculating theories of the power control
Data configuration of the power control
Chapter 1 Goals and Principles of Power Control
Chapter 2 Categories and Arithmetic of Power Control
Chapter 3 Data Configuration of Power Control
Each couple of customers is in a same room.
Each couple of customers speaks a language different from that spoken by other couples.
If the noise becomes louder, all the customers will raise their voices.
If the noise is too louder, the customers may go to other rooms.
The customer who speaks too loudly will affect the communication of others.
The transmission power of the control BTS and MS must ensure that the signal sent to the receiver through the complicated radio space can meet the threshold of correct demodulation.
When the first principle is satisfied, the transmission power of the BTS and MS is required to be lowered as much as possible to decrease the interference between users and best optimize the network performance.
The transmission power of the MS near the BTS is lower than that of the MS far from the BTS and of the MS in the fading areas.
Power control strategies are used in GSM and CDMA networks to optimize signal strength and minimize interference. In GSM, the base station and mobile station adjust their transmitted power based on measurement reports to maintain a desired signal quality and strength. The power control aims to save power, reduce interference, and increase network quality. It includes uplink and downlink power control performed independently. Power control regulates the signal power in steps of 2 dB and takes three periods or 480 ms to provide feedback from when a command is sent. This process helps control interference levels and prolongs battery life in cellular networks.
Optimization channal contral power in live umts networkThananan numatti
Abstract— The proposed approach to improvement on the
UMTS (Universal Mobile Telecommunications System)
network radio, there are many ways we propose another way of
reducing power control channel slightly to provide improved
signal quality, which is a measure of quality is EcIo (energy per
bit) / (Own cell interference +. Noise density) principle when the
power control channel down a bit to make the quality better,
because the denominator less energy than ever before, and open
the extra capacity in the network in the body, this is the reason
for the optimization this principle can be applied in a live
network.
It is important to maintain signal quality are durable and
resistant to interference. Probability to the good benefits for
imply network must be physical tuning coverage complete before
and area dense urban or urban is good to the imply this
parameter. For area rural should not imply because the cell edge
a foot print coverage is too large . However this paper presents a science so that the results can be applied to real work.
This document discusses key WCDMA wireless technologies including power control, handover, and RAKE receivers. It provides details on:
- Power control including inner loop power control to maintain signal quality and outer loop power control to set thresholds based on quality of service. Both uplink and downlink power control are discussed.
- Handover types including soft handover which maintains service continuity and hard handover which interrupts service. Softer handover between sectors is also mentioned.
- The general handover flow including measurement, reporting, and the RNC deciding whether to initiate a handover based on reports and algorithms.
This document discusses key WCDMA wireless technologies including power control, handover, and RAKE receivers. It provides details on:
- Power control including inner loop power control to maintain signal quality and outer loop power control to set thresholds based on quality of service. Both uplink and downlink power control are discussed.
- Handover types including soft handover which maintains service continuity and hard handover which interrupts service. Softer handover between sectors is also mentioned.
- The general handover flow including measurement, reporting, and the RNC deciding whether to initiate a handover based on reports and algorithms.
This paper proposes a single-bit ADC system based Proportional and Integral (PI) controller to maintain a desired level of power transfer efficiency in Capacitive Power Transfer (CPT) systems. In this paper, a simple single-bit ADC system i.e., Single-Bit Modulator (SBM) is considered as an alternative to the commonly used multi-bit ADC systems. Unique features of employing SBM are 1) its ability to convert analog signals into single-bit signals and 2) its easy integrability in digital chips with linear variable differential transformers (LVDTs) such as FPGAs. A SBM based PI (SBM-PI) controller is designed to judicially interface with the single-bit output of SBM. The proposed (SBM-PI) controller guarantees less hardware resources, latency and regulates the output voltage to provide the desired power transfer efficiency. The behavior of SBM-PI controller is compared to that of a conventional multi-bit controller, with the results of both controllers being identical. The effectiveness of the proposed controller with SBM is further demonstrated using the experimental prototype of CPT by implementing a SBM-PI controller using $16$ MHz ATmega8 microcontroller. The experimental results from a laboratory prototype illustrate that SBM-PI controller successfully regulates the output voltage of CPT to control the power flow.
This document discusses cellular network planning and optimization, specifically for WCDMA radio resource management (RRM). It covers several key topics:
Quality of Service (QoS) in UMTS is achieved through a system of bearers that negotiate bandwidth and latency requirements between network elements. Radio access bearers connect the user equipment to the core network.
RRM functions like admission control, power control, handover control, and packet scheduling work to guarantee QoS, maintain coverage, and optimize cell capacity in WCDMA networks. Power control is a critical RRM mechanism that uses fast and outer loop techniques to control transmission power and mitigate interference.
This document discusses optimizing bit loading in broadband power line communication networks. It describes using a greedy bit loading technique to maximize the raw bit rate given available transmission power constraints. The performance of bit loading is analyzed under different system parameters like load conditions, available power, and target error probability. Results show that raw bit rates increase with higher available power and decrease with higher load conditions and lower target error probabilities. Maximum raw bit rates of around 180 Mbps were achieved for the analyzed network model.
ETDCC: Energy-Efficient Transmission Scheme for Dynamic Climatic Conditions i...TELKOMNIKA JOURNAL
In this paper, an energy-efficient transmission scheme for dynamic climatic conditions (ETDCC)
has been proposed in wireless sensor networks (WSNs). This scheme is based on IEEE802.15.4 standard.
In this method, open-loop and closed-loop feedback systems are used for snowfall variation. An open-loop
system is utilized for snowfall-aware link quality compensation and estimation. However, closed-loop system
aids to split the network into two logical regions, resulting the overhead of total control packets is minimized.
According to link quality changes due to snowfall variation, the transmitting power is decided on the basis of
current number of neighbor nodes and threshold power loss for each region. The simulated results depict
that the proposed scheme with reduced control packets overhead adjusts transmitting power level (Plevel) to
compensate link quality. This scheme based on threshold level is compared with the conventional approach
that comprises the division of regions without threshold level.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
- The document compares using two types of smart loads (SLQ and SLBC) for primary frequency control on power systems with high renewable penetration.
- SLBC uses back-to-back converters to provide independent and flexible control of active and reactive power, while SLQ uses reactive compensation.
- Case studies on a 4 generator system and 39 bus New England grid show SLBC more effectively regulates frequency for both over and under-frequency events compared to SLQ.
- SLBC maintains performance for loads near unity power factor where SLQ is ineffective, and requires comparable converter ratings to SLQ for under-frequency events but much less for over-frequency events.
Engineer EMERSON EDUARDO RODRIGUES PRESENTA UNA NUEVA VERSION
THERE ONE NEW ONE PRESENTATION FOR 2G AND 3G ENGINEERING FOR LTE AND PSCORE ENGINEER
ITS VERY SUITABLE FOR YOUR RESEARCH AT ALL LEVELS OF RF ENGINEERING AND PS CS
The document describes transmission diversity functionality in base station systems. It allows base station sites with combined control unit (CU) pairs to apply transmission diversity to keep up with capacity requirements and operate in adjustable modes. Transmission diversity mode provides double power and half capacity using a master and slave CU pair. Later, slave CUs can be released from pairs and become single CUs for additional base station sites if more are installed.
Joint impacts of relaying scheme and wireless power transfer in multiple acce...journalBEEI
This paper considers ergodic capacity of energy harvesting (EH) based cellular networks. Such a network employs non-orthogonal multiple access (NOMA) together with relaying scheme to serve two far users. In this system model, relay is facilitated power splitting (PS) protocol to implement energy harvesting (EH). To examine capacity, expressions of signal to noise ratio (SNR) need be computed to achieve capacity. Power allocation factors are different for two users in such system and hence performance gap happens to distinguish requirements for separated users. It can be confirmed that the proposed paradigm exhibits maximal achievable capacity in some scenarios of setting parameters. To confirm exactness of the analytical expressions and show advantages of the proposed EH-NOMA, simulation results are performed in terms of ergodic capacity.
This document provides an overview of Wideband Code Division Multiple Access (WCDMA) technology. It discusses the basics of WCDMA including that it uses direct sequence spread spectrum technology and differentiates users through the use of spreading codes. It also describes key aspects of WCDMA such as power control, handovers between cells, and current market adoption of WCDMA networks. The document aims to inform readers about the specifications and advantages of the 3G wireless standard known as WCDMA.
1. The document describes a five-level cascaded H-bridge inverter used as a distribution static compensator (DSTATCOM) to compensate for reactive power and harmonics in a power system.
2. A DSTATCOM is connected in shunt with the distribution system and uses a voltage source converter to generate a set of three-phase output voltages that can be adjusted to control the exchange of active and reactive power with the system.
3. The five-level cascaded H-bridge inverter topology reduces device voltage stress and output harmonics. Level shifted pulse width modulation and phase shifted pulse width modulation techniques are investigated for controlling the DSTATCOM.
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.
ATC for congestion management in deregulated power systemBhargav Pandya
This document discusses congestion management in deregulated power systems through enhancement of available transfer capacity (ATC) using flexible AC transmission system (FACTS) devices. It proposes a new set of AC sensitivity factors called AC power transfer congestion distribution factors (ACPTCDF) to calculate ATC and identify the most congested transmission line. FACTS devices like UPFC can then be optimally placed to enhance ATC and relieve transmission congestion while maintaining system security and stability constraints. The document provides background on deregulation, open access, congestion management, ATC calculation methodology, and the role of various FACTS technologies to improve power transfer capability.
Low frequency ac transmission for power systems by Aamir SaleemAamir Saleem
Voltage instability is one of the major issue in
HVAC power network operating at 50 Hz frequency due to
limited power transfer capability and distance limit. The stable
operation of power system must be kept within limits to
increase the efficiency of power transmission system. In this
research Low Frequency AC (LFAC) transmission system has
been proposed as a new power transmission technology to
reduce the losses of transmission network and controlling the
reactive power using Flexible AC transmission device. A
LFAC Transmission lines operates at 16.7Hz frequency for
transmission of power from source to load and use two
Frequency converters at source and load side. The normal
operation of power system depends on the reactive power
flowing through the power transmission lines, which can be
adjusted by a flexible AC transmission device; Static
synchronous compensator. LFAC transmission lines with
STATCOM controller improve the Power system voltage
stability under various disturbances and enhance the power
transmission capability as compare to HVAC transmission.
The simulations are done in Matlab Simulink 2017a .The
Output of Matlab Simulink model shows that voltage will
become Stable and reactive power is compensated for best
performance for power system.
Similar to Cdma Dynamic Reverse Link Power Control (20)
Low frequency ac transmission for power systems by Aamir Saleem
Cdma Dynamic Reverse Link Power Control
1. CDMA dynamic reverse link power control with variable quality of service
Sunjeev Kumar gupta, Ranjit kumar karma
Department Of Electronics and Computer
Kathmandu Engineering College, Kathmandu, Nepal
ABSTRACT
For wireless communication systems, In this paper, we propose new dynamically
iterative power control algorithms have been power control with QOS for different substreams
proposed to minimize the [2]. For this, we study first the embedded trellis
transmitter power while maintaining reliable coded modulation for UEP on which punctured
communication between mobiles and base convolutional codes have been applied for reliability
stations. A digital cellular radio code- of a substreams increased through migration from
division multiple-access (CDMA) system can only high rate to low rate code. But we found difficulties
support a finite number of users before the to provide trellis equivalent of variable rate
interference plus noise power density, I0, received at convolution code by varying constellation size so
the cellular base station causes an unacceptable proper solution is to perform UEP by using a fixed
frame-error rate. Once the maximum interference rate trellis code & varying power. This makes
level is reached, new arrivals should be blocked. In beneficial to transmit the minimum power necessary
a power-controlled CDMA system, the base station to support the given QOS for a substream as this
can direct mobiles to reduce their power and data creates least interference to other users.
rate to reduce interference and allow more users on
the system. In current IS-95 systems, forward link 2. NECESSITY OF POWER CONTROL
power control is far less powerful than reverse link
power control. Thus, this paper presents an All users in CDMA share the same RF band
algorithm to focus on the current IS-95 reverse link through the use of PN codes, each user looks like
power control but in a more general sense, it random noise to other users. So power of each
presents a systematic approach to the designing of a individual user therefore must be carefully
power control unit. In this paper, we present a controlled so that no one user is unnecessarily
power control algorithm, which simultaneously interfering with others who are sharing the same
minimizes interference & also provides variable band. Under no power control the MS nearer to the
QOS contracts for different traffic types in a CDMA BS transmits higher power than the MS far from the
system by assigning different power levels to each BS transmits lower power. This makes greater
traffic type. enjoyment to the MS nearer to the BS than others.
This is the classic near-far problem in SSMA
1. INTRODUCTION system.
Power control is implemented to overcome
A substream of the individual user (concept near-far problem & to maximize capacity by the
similar to internet protocol defines flow headers to action of controlled transmitted power from each
support variable QOS across different applications) user such that received power of each user is equal
consist of one media type (audio or video).The to one other.
substream abstraction enhances network efficiency
by only the appropriating more resources.
Substrems are variable rate & multiplexed into one
aggregate stream for each user. Sum of substream
bit rates for any user don‟t exceed total bit rate of
that user‟s stream [1]. Each stream then undergoes
channel coding, modulation & power control before
being assigned a spreading code & transmitted.
Different substream consists of audio, video & data
all have different unequal error protection so that
higher efficiency is made for protecting must
significant bits than to least significant bits.
Fig.1 Power Controlled System
2. One problem that has to be immediately identical to reverse path loss. So better Closed Loop
solved in power control is initial mobile transmit Power Control (CLPC) is forwarded to compensate
power which can‟t be controlled by the BS.So the for power fluctuation due to fast reyleigh fading
best solution is the MS to attempt to transmit a involving both BS & MS. CLPC continues measures
series of access probe i.e. a series of transmissions the link quality along with OLPC & its contribution
of progressively higher power. This process is in reverse link (uplink) is as follow:
continued until the BS acknowledgment & step size BS continuously monitors Eb/No on
for the access probe correction is specified by reverse link.
system parameter PWR_Step. If Eb/No is too high (exceeding certain
Knowing received power & ERP of BS, threshold) then BS commands MS to
MS would know how much it needs to transmit decrease it‟s transmit power & vice versa.
power to compensate path loss [3]. But in reality, The power control commands are in the
MS neither know ERP of BS nor received power form of power control bits & amount of
contributed by the neighboring BS, So generic power up & down per PCB is normally
assumptions of initial power transmission of MS in +1dB or -1dB.
decibels:
Ptinitial=-Pr – 73 + NOM_ PWR + INIT_PWR. Since, CLPC is combated Rayleigh fading, MS
Where NOM_PWR & INIT_PWR are the response to these PC commands must be very fast
adjustments factors. These adjustment factors are .So Power Control Bits (PCBS) are directly sent
broadcasted by MS in access parameter message. over traffic channel by robbing some bits from
traffic channel.
Fig.3 PCBS are multiplexed directly onto
baseband system at 19.2 Kbps
The PCBS are integrated into traffic
channel by robbing selected bits from baseband
Fig 2 Initial transmit power stream. The stream of PCBS at 800 bps is Power
Control Sub channel (PCS). Since the rate of PCB
2.1. POWER CONTROL PROCESS transmission is 800 bps, a PCB is sent once every
(1/800) second or 1.25 ms. Since PCB is sent every
After initial power transmission, two methods 1.25 ms, each traffic channel frame is divided into
open loop & closed loop power control in (20 ms/1.25 ms) or 16 segments called Power
proceeded. After a call is established & as MS Control Groups (PCGS). Since each PCG is 1.25 ms
moves around within cell, path loss between MS & in duration & baseband is at a rate of 19.2 Kbps then
BS will continue to change, so received power at each PCG contains (19.2 *1000)*(1.25*1000) OR
MS will change & open loop power control will 24 bits.
continue to monitor MS received power Pr & adjust In a closed loop section, for example BS
MS transmit power. measures Eb/No in PCG7, decide in PCG8 for
Pr= -Pr -73 + NOM_PWR + INIT_PWR + (sum inserting 0 or 1 & transmit decided 0 or 1 during
of all access probe correction). PCG9 on forward traffic channel. This process is
Open Loop Power Control (OLPC) is used to repeated for every power control group in the frame
compensate for slow-varying & log-normal [4]. The PCG can be inserted in any one of 1 st 16
shadowing effects but inadequate to compensate fast positions. The exact location of PCB in PCG is
Rayleigh fading coz of frequency dependency & determined by decibel value of four most significant
works under assumption of forward path loss is bits of decimator output.
3. Fig 4 Closed loop power control using PCBS
Closed loop power control has inner loop & outer
loop.
Fig 5 Schematic CLPC
Inner loop decides the power up & down decision
by threshold decision. Outer loop makes
dynamically adjusted to maintain an acceptance
FER. This CLPC is also assisted by the soft handoff
process.
3. PROPOSED CONTROL SYSTEM Fig 6 Reverse link PC functions carried out by BS.
The reverse link power control with the On the MS side, it receives forward link
multiple co-ordinations of substreams leading the signal. It recovers PCB & based on PCB, makes a
variable quality of service scheme is shown a below. decision (closed loop decision) to power up/down
The fig. 6 shows high level schematic of the system by (1 dB).This correction is combined with open
considered. The subsystems for each user are loop terms & combined result is fed to transmitter
statically multiplexed into one stream (How this is so that it can transmit at the power (proper) level.
done in accordance with the substreams‟ different
delay bounds will not be described in this
paper).The stream then undergoes channel coding,
modulation & power control before being assigned a
code & transmitted. BS demodulates & estimate
FER of reverse link, this information on reverse link
frame quality is fed into threshold which adjusts
(Eb/No) based on received frame quality. The PCB
are multiplied onto forward traffic channel &
transmitted to MS [5].
4. - If feasible, how do we allocate power to each
substream?
- Hoe do we decide if we can admit a new stream
without violating the reliability guarantees for
streams in progress?
In this paper we don‟t consider the reliability
requirement of a substream by its desired E/I
(remains for future work)
Let
K= No of substreams.
(Eb/No)= E/I required by substream I, i= 1,
2……K.
βi = 1, if substream I is transmitting during the
current time slot
0, otherwise
xi = Power assigned to substream I given that it
is transmitting during current time slot
P = Total Power
N = Spreading Code Processing Gain
σi2 = Intercell interference experienced by
stream i.
The E/I experienced by substream „i‟ is
given by the expression
Nxi
E/I= ………Eq. (1)
( i k xk )
k i
We wish to minimize total power subject to
constraints that E/N for every substream is satisfied
i.e. minimize
k
P k xk ……….Eq. (2)
k 1
such that
Nxi
( i k xk )
≥ E N
b
oi
..........Eq. (3)
k i
For i=1....k
xi ≥0 and (Eb ) >0 ............Eq. (4)
N
The Eq. (4) can be expressed in the form of linear
program matrix as
Fig.7 Reverse link Power Control functions carried
1
N
- Eb
No 1 2
- Eb N
o1 k
out by MS.
A= - Eb
No 2 1
1
N
- E
b
N
o2 k
4. POWER CONTROL ALGORITHM
Before PC, each of the substrams has its
Eb
-
No k 1
- Eb No 2
k
1
N
own desired reliability requirement, we wise to .........Eq. (5)
address three issues [6]:
- How to determine if the set of requirement is
feasible or not?
5. xi
1 Eb
2
No 1
[2]K.S. Gilhousen et al, “On the capacity of a
cellular CDMA system,”IEEE Trans. Vehicular
X= , b= , Technology, vol. 40, no. 2, pp. 303-312,
x
k
2 Eb
1
No k
May1991.
[3]Theodore S. Rapport,” Wireless Communication,
Principles & Practice,”2nd Edition, Published in
c = 1 k .........Eq. (6) New Delhi, 2005.
The above equations are modified as: [4]Samuel C. Yang,” CDMA RF Signal
Minimize cx such that Engineering,” London, ISBN 0-89006-991-
Ax ≥ b, x ≥ 0 .......Eq. (7) 3.1998.
The Eq. (7) is solved optimally for finding closed [5]Qualcomm Inc., “Compatibility Standard for
form optimal solution to the system. Dual-Mode Wideband Spread Spectrum Cellular
A feasible solution to the system Ax=b, x ≥ 0 is System,” TIA/EIA/IS- 95, July 1993.
obtained by considering following assumptions: [6]Google search as www.power control algorithm
xi = i i i2 P ......Eq. (8)
class based power control algorithm in cdma.html.
Where
α=
E N , i=1....k
b
N E
o
i ......Eq. (9)
b
N oi
And total transmitted power
k
k k k2
P= k 1 ......Eq. (10)
k
1 k k
k 1
From Eq. (10), 0≤ P≤ ∞ if and only if
k
k k < 1 ......Eq. (11)
k 1
If Eq.(11) holds true, then x ≥ 0 and Eq. (8) & (9)
represent a finite.
Now from Eq.(1) & (11), under comparison , βk is
constant integer so, x<<1≈ 0 provides unique
solution to the system [Ax ≈ 0].
5. CONCLUSION
Dynamically PC algorithm performs the
task of closed loop power control as well as QOS
improvement Substream concept enhances network
efficiency as well as combating of both near far
problem & self -jamming/anti-jamming problem. It
reduces the MS transmission power & the capacity
of the system enhances but system becomes more
complex in the case of substream division.
6. REFERENCES
[1]Research documents from University of
California at Berkeley, Berkeley, CA94720
published by Louis C. Yun and David G.
Messerschmitt.