This document describes the design of a DS-CDMA transmitter using VHDL and an FPGA. It discusses the design of the transmitter's key components like the PN code generator and BPSK modulator. The PN code generator uses a 16-stage linear feedback shift register with a specific feedback polynomial to generate codes. The transmitter blocks were designed separately in VHDL and then combined and implemented on an FPGA board. The transmitter is capable of transmitting data at rates up to 2 Mbps using a 40 MHz carrier frequency.
The document describes overhead bytes in the Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) protocols. It explains that certain bytes, such as J0 and B1, are used for regenerator section trace and byte interleaved parity to ensure connection integrity and identify individual signals after multiplexing. Other bytes, like D1-D3 and E1, are used for embedded operations channels and orderwires. The document also describes pointer bytes H1-H3 that indicate the offset of the synchronous payload envelope and compensate for timing variations, and Maintenance overhead bytes like B2, K1-K2, and S1 that provide automatic protection switching, additional data communications, and
The document summarizes the key components and protocol architecture of a UMTS network. It describes the domains and reference points that divide a UMTS system. The radio access network (UTRAN) consists of Radio Network Subsystems (RNSs) with Node Bs and Radio Network Controllers (RNCs). The interfaces between these components, such as Iu, Iur, Iub and Uu, have user, control and transport planes with various protocols to support communication and control functions. Key responsibilities are distributed between the RNC for radio resource control and the Node B for lower-level radio access functions.
WIRELESS NETWORKS _ BABU M_ unit 3 ,4 & 5 PPT
EC 6802 WIRELESS NETWORKS PPT
POWER POINT PRESENTAION ON WIRELESS NETWORKS
BABU M
ASST PROFESSOR/ ELECTRONICS AND COMMUNICATION ENGINEERING,
RMK COLLEGE OF ENGINEERING AND TECHNOLOGY
CHENNAI, THIRUVALLUR DISTRICT
Fpga implementation of a multi channel hdlcnitin palan
This document describes the design and FPGA implementation of a multi-channel HDLC protocol transceiver. Key points:
- The transceiver contains two full-duplex channels, a 4K-byte dual-port RAM, and an interrupt management unit.
- It can automatically receive or transmit HDLC frames and provide status notifications to the CPU. Control registers allow flexible configuration of operation modes and baud rates.
- The design of the transmitter, receiver, and RAM management units are discussed. It was implemented in a Virtex FPGA and has characteristics of simplicity, flexibility, and ease of use.
This document provides an overview of RS232 and E1 communication standards. It discusses the classification of communication, RS232 data format including baud rate, transfer modes, cabling and pinouts. It then describes the E1 frame structure including timeslots and frame alignment. The document includes block diagrams of an RS232 to E1 converter.
The document discusses several digital avionics data bus systems used for exchanging data between aircraft subsystems. It describes the Ethernet, MIL-STD-1553, and ARINC 429/629 bus protocols. Ethernet uses CSMA/CD access and supports data rates up to 1 Gbps. MIL-STD-1553 is a time division multiplex bus that operates at 1 Mbps. ARINC 429 is a low-speed unidirectional bus, while ARINC 629 is a higher speed bidirectional bus that uses carrier sense multiple access.
Giga bit per second Differential Scheme for High Speed InterconnectVLSICS Design
This document summarizes a research paper on developing a high-speed transmitter for off-chip communication using differential signaling. It describes a transmitter circuit that consists of low-speed input buffers, serializers to convert parallel data to serial data, and current-mode drivers to transmit the serial data differentially over transmission lines. The serializers use a delay locked loop to generate clock phases that sample the parallel inputs and transmit each bit over the serial link for an equal duration. The current-mode drivers convert the serial data to differential current levels on the transmission line. The design is intended to increase I/O bandwidth for high-speed chip-to-chip communication.
This document discusses layer 2 switching and VLANs. It provides information on:
- How layer 2 switches break up large collision domains into smaller ones by creating separate collision domains for each switch port. This improves network performance over hub-based networks.
- The two main types of VLAN membership - static VLANs where ports are manually assigned to VLANs, and dynamic VLANs where VLAN assignments are determined automatically based on device MAC addresses.
- How VLANs simplify network management by allowing logical segmentation of broadcast domains independent of physical port locations, and improve network security by restricting communication between VLANs.
The document describes overhead bytes in the Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) protocols. It explains that certain bytes, such as J0 and B1, are used for regenerator section trace and byte interleaved parity to ensure connection integrity and identify individual signals after multiplexing. Other bytes, like D1-D3 and E1, are used for embedded operations channels and orderwires. The document also describes pointer bytes H1-H3 that indicate the offset of the synchronous payload envelope and compensate for timing variations, and Maintenance overhead bytes like B2, K1-K2, and S1 that provide automatic protection switching, additional data communications, and
The document summarizes the key components and protocol architecture of a UMTS network. It describes the domains and reference points that divide a UMTS system. The radio access network (UTRAN) consists of Radio Network Subsystems (RNSs) with Node Bs and Radio Network Controllers (RNCs). The interfaces between these components, such as Iu, Iur, Iub and Uu, have user, control and transport planes with various protocols to support communication and control functions. Key responsibilities are distributed between the RNC for radio resource control and the Node B for lower-level radio access functions.
WIRELESS NETWORKS _ BABU M_ unit 3 ,4 & 5 PPT
EC 6802 WIRELESS NETWORKS PPT
POWER POINT PRESENTAION ON WIRELESS NETWORKS
BABU M
ASST PROFESSOR/ ELECTRONICS AND COMMUNICATION ENGINEERING,
RMK COLLEGE OF ENGINEERING AND TECHNOLOGY
CHENNAI, THIRUVALLUR DISTRICT
Fpga implementation of a multi channel hdlcnitin palan
This document describes the design and FPGA implementation of a multi-channel HDLC protocol transceiver. Key points:
- The transceiver contains two full-duplex channels, a 4K-byte dual-port RAM, and an interrupt management unit.
- It can automatically receive or transmit HDLC frames and provide status notifications to the CPU. Control registers allow flexible configuration of operation modes and baud rates.
- The design of the transmitter, receiver, and RAM management units are discussed. It was implemented in a Virtex FPGA and has characteristics of simplicity, flexibility, and ease of use.
This document provides an overview of RS232 and E1 communication standards. It discusses the classification of communication, RS232 data format including baud rate, transfer modes, cabling and pinouts. It then describes the E1 frame structure including timeslots and frame alignment. The document includes block diagrams of an RS232 to E1 converter.
The document discusses several digital avionics data bus systems used for exchanging data between aircraft subsystems. It describes the Ethernet, MIL-STD-1553, and ARINC 429/629 bus protocols. Ethernet uses CSMA/CD access and supports data rates up to 1 Gbps. MIL-STD-1553 is a time division multiplex bus that operates at 1 Mbps. ARINC 429 is a low-speed unidirectional bus, while ARINC 629 is a higher speed bidirectional bus that uses carrier sense multiple access.
Giga bit per second Differential Scheme for High Speed InterconnectVLSICS Design
This document summarizes a research paper on developing a high-speed transmitter for off-chip communication using differential signaling. It describes a transmitter circuit that consists of low-speed input buffers, serializers to convert parallel data to serial data, and current-mode drivers to transmit the serial data differentially over transmission lines. The serializers use a delay locked loop to generate clock phases that sample the parallel inputs and transmit each bit over the serial link for an equal duration. The current-mode drivers convert the serial data to differential current levels on the transmission line. The design is intended to increase I/O bandwidth for high-speed chip-to-chip communication.
This document discusses layer 2 switching and VLANs. It provides information on:
- How layer 2 switches break up large collision domains into smaller ones by creating separate collision domains for each switch port. This improves network performance over hub-based networks.
- The two main types of VLAN membership - static VLANs where ports are manually assigned to VLANs, and dynamic VLANs where VLAN assignments are determined automatically based on device MAC addresses.
- How VLANs simplify network management by allowing logical segmentation of broadcast domains independent of physical port locations, and improve network security by restricting communication between VLANs.
Data Encoding for Wireless TransmissionSean McQuay
This project aims to develop a low-cost wireless transmitter/receiver pair using an inexpensive AVR microcontroller to implement error correction software. The transmitter will encode data using a forward error correction algorithm before transmission. The receiver will decode the received data and attempt to correct up to three bit errors per byte. Additionally, an addressing scheme will be implemented to allow multiple transmitters to communicate with a single receiver. The total cost of the redesigned transmitter/receiver pair is intended to remain under $10.
Multicast addresses are used to send data from one source to multiple recipients simultaneously. They can be used at both the IP layer and link layer. At the IP layer, IPv4 uses addresses between 224.0.0.0/4 and 239.255.255.255 for multicast, while IPv6 uses addresses with a prefix of ff00::/8. Specific addresses within these ranges are reserved for important network protocols. Multicast addressing schemes allow for addresses to have different scopes from the local link to global routing.
1. The PBCH is a downlink physical channel that broadcasts essential initial access parameters like system bandwidth. It occupies 72 subcarriers in the first 4 OFDM symbols of the second slot of every 10ms radio frame. The PBCH carries a 14-bit MIB that is coded at a low rate and mapped to center subcarriers.
2. The PCFICH indicates the number of OFDM symbols used for the PDCCH. It occupies 16 resource elements in the first symbol of each 1ms subframe. The PCFICH carries the CFI value which is coded to use the full 32 bits.
3. The PDCCH carries downlink control information like resource allocations using QPSK.
- The document discusses LTE physical channels, transport channels, and logical channels. It provides details on the different channels used in the downlink and uplink.
- The main physical channels described include the PBCH, PCFICH, PDCCH, PHICH, PUCCH, PUSCH, and PRACH. The transport channels include the BCH, DL-SCH, PCH, MCH, UL-SCH, and RACH. The logical channels include the BCCH, PCCH, CCCH, MCCH, DCCH, DTCH, and MTCH.
- Link adaptation procedures for the downlink and uplink are also summarized, including how CQI is used to determine the
This tutorial gives very good understanding on Protocols.After completing this tutorial,You will find yourself at a moderate level of expertise in Protocols port Number.
Circuit switched telephone networks transmit digitized voice signals over dedicated circuits, while packet switched networks divide voice signals into packets which are transmitted over shared networks. In circuit switched networks, a connection is established end-to-end for each call, while in packet switched networks multiple communications share network bandwidth through packetization. Packetization allows better utilization of bandwidth for bursty data traffic as in computer networks, while circuit switched networks ensure utilization through traffic engineering. Voice can be transmitted over packet networks by digitizing it and transmitting the voice packets alongside data packets.
This document discusses an LTE cell planning support tool called CELPLA L that was developed by NTT DOCOMO to help optimize the design of cell planning parameters for their LTE network. The tool automatically designs optimal values for key parameters like Physical Cell ID (PCI), Random Access Channel (RACH) Root Sequence (RRS), and Neighbor Relation Table (NRT). It does this through a three step process of inputting base station information, calculating the parameters, and outputting the results. The document focuses on how CELPLA L designs PCI and RACH parameters in particular. It groups sectors and assigns identifiers like local ID, cell-group ID, and hopping pattern to help determine PCI values
IRJET- Design of Virtual Channel Less Five Port NetworkIRJET Journal
This document describes the design of a virtual channel less five port network router. It discusses the need for efficient router design in Network on Chip architectures to improve communication performance. A router microarchitecture is proposed using a round robin arbiter, priority encoder, and multiplexer crossbar. The router is designed using Verilog to support five simultaneous requests. Simulation results show the round robin arbiter and priority encoder generating the necessary control signals for the crossbar to connect input and output ports. The virtual channel less router design aims to increase communication speed while reducing complexity compared to routers using virtual channels.
The document provides an overview of SAE J1939, a standard that defines how information is transferred across a network to allow vehicle ECUs to communicate. It discusses how J1939 uses Controller Area Network (CAN) protocols and frames to transmit data. Key aspects covered include physical layer specifications, arbitration processes, message priorities, and transport protocols for transmitting large amounts of data.
This document summarizes the simulation of a turbo coded orthogonal frequency division multiplexing (OFDM) system. Key points:
1) OFDM divides a wideband channel into narrowband channels to mitigate multipath fading effects. Turbo codes are added to OFDM to improve performance at high data rates.
2) Turbo codes use parallel concatenated convolutional codes for encoding and iterative decoding. Simulation shows turbo coded OFDM outperforms uncoded OFDM with lower bit error rates over both additive white Gaussian noise and Rayleigh fading channels.
3) The simulation model includes a turbo encoder, QAM modulation, IFFT/FFT, channel with noise, turbo decoder. Results show turbo coded OFDM provides much
The document provides an overview of the MCP2515 stand-alone CAN controller, including its features such as three transmit buffers, two receive buffers, and six 29-bit filters. It also outlines the target applications for the controller and describes its basic architecture, layers of the CAN protocol, message frames, bit timing, and operating modes. The controller implements the CAN 2.0B standard at 1 Mb/s and interfaces with a microcontroller through a high-speed SPI interface.
This document provides an agenda and overview of topics related to the transport layer and networking essentials. The agenda includes discussions of the transport layer, UDP overview, TCP communication process, the socket API, and tools and utilities. Specific topics that will be covered include the role and functions of the transport layer, UDP features and headers, TCP reliability mechanisms like connection establishment and termination, sequence numbers and acknowledgments, window sliding, and data loss/retransmission. The document also provides brief overviews and usage examples for common networking tools like ifconfig, nmcli, route, ping, traceroute, netstat, dig, ncat, nmap, tcpdump, and wireshark.
The document describes a method for unambiguously characterizing 4G LTE signal coverage using PBCH (Public Broadcast Channel) decoding. It explains that by decoding the PBCH bits and checking for errors, one can positively determine signal quality without knowing the original bits. This is more decisive than conventional RSSI or RSRP metrics. The document then provides details on PBCH encoding/decoding processes and how the results (PBCH OK, PBCH poor, PBCH bad) correspond to varying levels of signal coverage and user experience. Test examples demonstrate the different PBCH decoding outcomes.
PERFORMANCE EVALUATION OF CDMAROUTER FOR NETWORK - ON - CHIPVLSICS Design
This paper presents the performance evaluation of router based on code division multiple access technique (CDMA) for Network-on-Chip (NoC). The design is synthesized using Xilinx Virtex4 XC4VLX200 device. The functional behavior is verified using Modelsim XE III 6.2 C. The delay and throughput values are obtained for variable payload sizes. Throughput-Power and Delay-Power characteristics are also verified for NoC.
CCNA Routing and Switching Lesson 05 - WANs - Eric VanderburgEric Vanderburg
This document provides an overview of several WAN technologies including DSL, cable modems, ISDN, frame relay, ATM, and X.25. It describes key components and protocols used by each technology such as DSLAMs, MCNS, PPPoE, B channels, PVCs, DLCI, VPI/VCI, and more.
This document provides an overview of modern forward error correction (FEC) techniques used in satellite communications (SATCOM). It discusses the motivation for using FEC to combat various link impairments. It then reviews various FEC schemes including block codes, convolutional codes, turbo codes, and compares their performance. Turbo codes are shown to provide the best performance, approaching the theoretical Shannon limit, allowing for reduced transmitter power and bandwidth compared to older FEC schemes. The document concludes that while newer codes like turbo codes offer close to optimal performance, simpler block and convolutional codes also provide good performance for their lower complexity.
CDMA Transmitter and Receiver Implementation Using FPGAIOSR Journals
Abstract: Code Division Multiple Access (CDMA) is a spread spectrum technique that uses neither frequency channels nor time slots. With CDMA, the narrow band message (typically digitized voice data) is multiplied by a large bandwidth signal that is a pseudo random noise code (PN code). All users in a CDMA system use the same frequency band and transmit simultaneously. The transmitted signal is recovered by correlating the received signal with the PN code used by the transmitter. The DS - CDMA is expected to be the major medium access technology in the future mobile systems owing to its potential capacity enhancement and the robustness against noise. The CDMA is uniquely featured by its spectrum-spreading randomization process employing a pseudo-noise (PN) sequence, thus is often called the spread spectrum multiple access (SSMA). As different CDMA users take different PN sequences, each CDMA receiver can discriminate and detect its own signal, by regarding the signals transmitted by other users as noise- like interferences. In this project direct sequence principle based CDMA transmitter and receiver is implemented in VHDL for FPGA. Modelsim 6.2(MXE) tool will be used for functional and logic verification at each block. The Xilinx synthesis technology (XST) of Xilinx ISE 9.2i tool will be used for synthesis of transmitter and receiver on FPGA Spartan 3E. Keywords: CDMA, DSSS, BPSK, GOLD code.
The document discusses the design and analysis of a D-flip flop. It begins by introducing flip flops and their use for storing state information. It then discusses the need for a D-flip flop due to limitations in the basic SR flip flop. A D-flip flop overcomes these limitations using a gated SR flip flop with an inverter between the S and R inputs, allowing a single data input. The circuit and working of the D-flip flop are shown, noting it will store and output the data input while the clock is high.
This document provides an overview of flip-flops, which are digital circuits that function as memory elements. It describes the objectives and specific learning outcomes of understanding various types of flip-flops including JK, D, and T flip-flops. The key aspects covered include their symbols, truth tables, logic circuits, and applications in digital systems. Edge-triggered and level-triggered operations are also compared.
CDMA is a digital cellular standard that allows multiple users to access the same radio frequency channel simultaneously through the use of unique code sequences. Users are separated by spreading their transmitted signals across the frequency band using pseudo-random codes. CDMA provides advantages over other multiple access techniques like FDMA and TDMA such as increased capacity, soft handoffs between cells, and covert operation due to its noise-like signals. The IS-95 standard introduced CDMA to cellular networks and specified the use of orthogonal codes to separate signals and a 1.25 MHz channel bandwidth to support multiple simultaneous voice calls.
Data Encoding for Wireless TransmissionSean McQuay
This project aims to develop a low-cost wireless transmitter/receiver pair using an inexpensive AVR microcontroller to implement error correction software. The transmitter will encode data using a forward error correction algorithm before transmission. The receiver will decode the received data and attempt to correct up to three bit errors per byte. Additionally, an addressing scheme will be implemented to allow multiple transmitters to communicate with a single receiver. The total cost of the redesigned transmitter/receiver pair is intended to remain under $10.
Multicast addresses are used to send data from one source to multiple recipients simultaneously. They can be used at both the IP layer and link layer. At the IP layer, IPv4 uses addresses between 224.0.0.0/4 and 239.255.255.255 for multicast, while IPv6 uses addresses with a prefix of ff00::/8. Specific addresses within these ranges are reserved for important network protocols. Multicast addressing schemes allow for addresses to have different scopes from the local link to global routing.
1. The PBCH is a downlink physical channel that broadcasts essential initial access parameters like system bandwidth. It occupies 72 subcarriers in the first 4 OFDM symbols of the second slot of every 10ms radio frame. The PBCH carries a 14-bit MIB that is coded at a low rate and mapped to center subcarriers.
2. The PCFICH indicates the number of OFDM symbols used for the PDCCH. It occupies 16 resource elements in the first symbol of each 1ms subframe. The PCFICH carries the CFI value which is coded to use the full 32 bits.
3. The PDCCH carries downlink control information like resource allocations using QPSK.
- The document discusses LTE physical channels, transport channels, and logical channels. It provides details on the different channels used in the downlink and uplink.
- The main physical channels described include the PBCH, PCFICH, PDCCH, PHICH, PUCCH, PUSCH, and PRACH. The transport channels include the BCH, DL-SCH, PCH, MCH, UL-SCH, and RACH. The logical channels include the BCCH, PCCH, CCCH, MCCH, DCCH, DTCH, and MTCH.
- Link adaptation procedures for the downlink and uplink are also summarized, including how CQI is used to determine the
This tutorial gives very good understanding on Protocols.After completing this tutorial,You will find yourself at a moderate level of expertise in Protocols port Number.
Circuit switched telephone networks transmit digitized voice signals over dedicated circuits, while packet switched networks divide voice signals into packets which are transmitted over shared networks. In circuit switched networks, a connection is established end-to-end for each call, while in packet switched networks multiple communications share network bandwidth through packetization. Packetization allows better utilization of bandwidth for bursty data traffic as in computer networks, while circuit switched networks ensure utilization through traffic engineering. Voice can be transmitted over packet networks by digitizing it and transmitting the voice packets alongside data packets.
This document discusses an LTE cell planning support tool called CELPLA L that was developed by NTT DOCOMO to help optimize the design of cell planning parameters for their LTE network. The tool automatically designs optimal values for key parameters like Physical Cell ID (PCI), Random Access Channel (RACH) Root Sequence (RRS), and Neighbor Relation Table (NRT). It does this through a three step process of inputting base station information, calculating the parameters, and outputting the results. The document focuses on how CELPLA L designs PCI and RACH parameters in particular. It groups sectors and assigns identifiers like local ID, cell-group ID, and hopping pattern to help determine PCI values
IRJET- Design of Virtual Channel Less Five Port NetworkIRJET Journal
This document describes the design of a virtual channel less five port network router. It discusses the need for efficient router design in Network on Chip architectures to improve communication performance. A router microarchitecture is proposed using a round robin arbiter, priority encoder, and multiplexer crossbar. The router is designed using Verilog to support five simultaneous requests. Simulation results show the round robin arbiter and priority encoder generating the necessary control signals for the crossbar to connect input and output ports. The virtual channel less router design aims to increase communication speed while reducing complexity compared to routers using virtual channels.
The document provides an overview of SAE J1939, a standard that defines how information is transferred across a network to allow vehicle ECUs to communicate. It discusses how J1939 uses Controller Area Network (CAN) protocols and frames to transmit data. Key aspects covered include physical layer specifications, arbitration processes, message priorities, and transport protocols for transmitting large amounts of data.
This document summarizes the simulation of a turbo coded orthogonal frequency division multiplexing (OFDM) system. Key points:
1) OFDM divides a wideband channel into narrowband channels to mitigate multipath fading effects. Turbo codes are added to OFDM to improve performance at high data rates.
2) Turbo codes use parallel concatenated convolutional codes for encoding and iterative decoding. Simulation shows turbo coded OFDM outperforms uncoded OFDM with lower bit error rates over both additive white Gaussian noise and Rayleigh fading channels.
3) The simulation model includes a turbo encoder, QAM modulation, IFFT/FFT, channel with noise, turbo decoder. Results show turbo coded OFDM provides much
The document provides an overview of the MCP2515 stand-alone CAN controller, including its features such as three transmit buffers, two receive buffers, and six 29-bit filters. It also outlines the target applications for the controller and describes its basic architecture, layers of the CAN protocol, message frames, bit timing, and operating modes. The controller implements the CAN 2.0B standard at 1 Mb/s and interfaces with a microcontroller through a high-speed SPI interface.
This document provides an agenda and overview of topics related to the transport layer and networking essentials. The agenda includes discussions of the transport layer, UDP overview, TCP communication process, the socket API, and tools and utilities. Specific topics that will be covered include the role and functions of the transport layer, UDP features and headers, TCP reliability mechanisms like connection establishment and termination, sequence numbers and acknowledgments, window sliding, and data loss/retransmission. The document also provides brief overviews and usage examples for common networking tools like ifconfig, nmcli, route, ping, traceroute, netstat, dig, ncat, nmap, tcpdump, and wireshark.
The document describes a method for unambiguously characterizing 4G LTE signal coverage using PBCH (Public Broadcast Channel) decoding. It explains that by decoding the PBCH bits and checking for errors, one can positively determine signal quality without knowing the original bits. This is more decisive than conventional RSSI or RSRP metrics. The document then provides details on PBCH encoding/decoding processes and how the results (PBCH OK, PBCH poor, PBCH bad) correspond to varying levels of signal coverage and user experience. Test examples demonstrate the different PBCH decoding outcomes.
PERFORMANCE EVALUATION OF CDMAROUTER FOR NETWORK - ON - CHIPVLSICS Design
This paper presents the performance evaluation of router based on code division multiple access technique (CDMA) for Network-on-Chip (NoC). The design is synthesized using Xilinx Virtex4 XC4VLX200 device. The functional behavior is verified using Modelsim XE III 6.2 C. The delay and throughput values are obtained for variable payload sizes. Throughput-Power and Delay-Power characteristics are also verified for NoC.
CCNA Routing and Switching Lesson 05 - WANs - Eric VanderburgEric Vanderburg
This document provides an overview of several WAN technologies including DSL, cable modems, ISDN, frame relay, ATM, and X.25. It describes key components and protocols used by each technology such as DSLAMs, MCNS, PPPoE, B channels, PVCs, DLCI, VPI/VCI, and more.
This document provides an overview of modern forward error correction (FEC) techniques used in satellite communications (SATCOM). It discusses the motivation for using FEC to combat various link impairments. It then reviews various FEC schemes including block codes, convolutional codes, turbo codes, and compares their performance. Turbo codes are shown to provide the best performance, approaching the theoretical Shannon limit, allowing for reduced transmitter power and bandwidth compared to older FEC schemes. The document concludes that while newer codes like turbo codes offer close to optimal performance, simpler block and convolutional codes also provide good performance for their lower complexity.
CDMA Transmitter and Receiver Implementation Using FPGAIOSR Journals
Abstract: Code Division Multiple Access (CDMA) is a spread spectrum technique that uses neither frequency channels nor time slots. With CDMA, the narrow band message (typically digitized voice data) is multiplied by a large bandwidth signal that is a pseudo random noise code (PN code). All users in a CDMA system use the same frequency band and transmit simultaneously. The transmitted signal is recovered by correlating the received signal with the PN code used by the transmitter. The DS - CDMA is expected to be the major medium access technology in the future mobile systems owing to its potential capacity enhancement and the robustness against noise. The CDMA is uniquely featured by its spectrum-spreading randomization process employing a pseudo-noise (PN) sequence, thus is often called the spread spectrum multiple access (SSMA). As different CDMA users take different PN sequences, each CDMA receiver can discriminate and detect its own signal, by regarding the signals transmitted by other users as noise- like interferences. In this project direct sequence principle based CDMA transmitter and receiver is implemented in VHDL for FPGA. Modelsim 6.2(MXE) tool will be used for functional and logic verification at each block. The Xilinx synthesis technology (XST) of Xilinx ISE 9.2i tool will be used for synthesis of transmitter and receiver on FPGA Spartan 3E. Keywords: CDMA, DSSS, BPSK, GOLD code.
The document discusses the design and analysis of a D-flip flop. It begins by introducing flip flops and their use for storing state information. It then discusses the need for a D-flip flop due to limitations in the basic SR flip flop. A D-flip flop overcomes these limitations using a gated SR flip flop with an inverter between the S and R inputs, allowing a single data input. The circuit and working of the D-flip flop are shown, noting it will store and output the data input while the clock is high.
This document provides an overview of flip-flops, which are digital circuits that function as memory elements. It describes the objectives and specific learning outcomes of understanding various types of flip-flops including JK, D, and T flip-flops. The key aspects covered include their symbols, truth tables, logic circuits, and applications in digital systems. Edge-triggered and level-triggered operations are also compared.
CDMA is a digital cellular standard that allows multiple users to access the same radio frequency channel simultaneously through the use of unique code sequences. Users are separated by spreading their transmitted signals across the frequency band using pseudo-random codes. CDMA provides advantages over other multiple access techniques like FDMA and TDMA such as increased capacity, soft handoffs between cells, and covert operation due to its noise-like signals. The IS-95 standard introduced CDMA to cellular networks and specified the use of orthogonal codes to separate signals and a 1.25 MHz channel bandwidth to support multiple simultaneous voice calls.
CDMA allows multiple users to share the same channel by assigning each user a unique code. It spreads the user's data signal over a wider bandwidth through multiplication with a pseudo-random code. This allows different signals to be separated at the receiver through correlation with the corresponding code. Major technologies using CDMA include WiFi, Bluetooth, and GPS, which employ techniques like DSSS, FHSS, and long/short codes. Performance of 802.11 networks can be analyzed based on collision probability and throughput calculations under saturated traffic conditions. Later developments expanded CDMA capabilities with techniques like W-CDMA, TD-CDMA, and TD-SCDMA.
CDMA is a digital cellular technology that allows multiple users to access a single radio channel simultaneously through the use of unique code assignments. The document discusses CDMA network architecture, which includes mobile stations, base stations, base station controllers, mobile switching centers, home and visitor location registers, and authentication centers. It also compares CDMA to earlier multiple access technologies like TDMA and FDMA, noting advantages of CDMA like increased capacity and soft handoffs between cells using the same frequency.
Flip flops are basic memory elements that store one bit of information as a 1 or 0. Common types include RS, D, JK, T, and master-slave JK flip flops. Flip flops have two stable states and two complementary outputs. They are used as registers for storage, in frequency dividers, and digital counters. Registers consist of groups of flip flops that hold information, while shift registers can shift data in one or both directions using cascaded flip flops and clock pulses. Flip flops have applications in interfacing digital systems, as delay circuits, and for converting between serial and parallel data.
A register is a group of flip-flops that can store binary information. Registers come in various types, including shift registers and counters. A shift register contains flip-flops connected such that data shifts along the line when activated. Counters increment through a sequence of states upon each input pulse. Common types include binary counters using J-K flip-flops. Registers can have additional capabilities like parallel loading to simultaneously input multiple bits or clearing to reset the count/data.
Flip-flops are basic memory circuits that have two stable states and can store one bit of information. There are several types of flip-flops including SR, JK, D, and T. The SR flip-flop has two inputs called set and reset that determine its output state, while the JK flip-flop's J and K inputs can toggle its output. Flip-flops like the D and JK can be constructed from more basic flip-flops. For sequential circuits, flip-flops are made synchronous using a clock input so their state only changes at the clock edge.
This document discusses latches and flip-flops. It begins by explaining the difference between latches and flip-flops, noting that latches do not have a clock signal while flip-flops do. It then discusses several types of flip-flops - RS, Clocked RS, D, JK, and T - providing the definition, explanation, circuit diagram, and truth table for each. It also discusses several types of latches - SR, Gated SR, and D - providing the definition, explanation, and circuit diagram for each. The document aims to explain the key characteristics and workings of various latches and flip-flops.
This document discusses flip-flops and sequential circuits. It begins with an introduction to sequential circuits and flip-flops. There are several types of flip-flops discussed including SR flip-flops, clocked SR flip-flops, JK flip-flops, and T flip-flops. SR flip-flops can be constructed using either NAND or NOR gates. The document provides details on the logic diagrams, truth tables, and operation of SR flip-flops. It also discusses using a clock signal to control synchronous sequential circuits and provides examples of waveforms and exercises for SR flip-flops.
Design and Implementation of Low Power High Speed Symmetric Decoder Structure...Dr. Amarjeet Singh
The key objective of this project is to design a
decoder which can be used for hardware purposes.
Hardware, here accompanies with software which is more
we can discuss as a Software Defined Radio application. The
decoder implemented here offers to new radio equipment
(SDR), the flexibility of a programmable system. Nowadays,
the behavior of a communication system can be modified by
simply changing its software. Large tree decoder is made by
reusing smaller similar sub-modules. Thus the structure is
symmetric. The symmetric and regular structure of tree
decoder makes the system a less complexity one. The
structure obeys regularity and modularity concepts of VLSI
circuit, thus is easy to fabricate using cell library elements.
Design a Tree Decoder proposed architecture for SDR
application on FPGA. The Structures made here are
hardware synthesizable on FPGA board and are done in a
respective manner. The design to be implementing by using
Verilog-HDL language. The Simulation and Synthesis by
using Xilinx Vivado design suite.
FPGA Implementation of LDPC Encoder for Terrestrial TelevisionAI Publications
The increasing data rates in digital television networks increase the demands on data capacity of the current transmission channels. Through new standards, the capacity of existing channels is increased with new methods of error correction coding and modulation. In this work, Low Density Parity Check (LDPC) codes are implemented for their error correcting capability. LDPC is a linear error correcting code. These linear error correcting codes are used for transmitting a message over a noisy transmission channel. LDPC codes are finding increasing use in applications requiring reliable and highly efficient information transfer over noisy channels. These codes are capable of performing near to Shannon limit performance and have low decoding complexity. LDPC uses parity check matrix for its encoding and decoding purpose. The main advantage of the parity check matrix is that it helps in detecting and correcting errors which is a very important advantage against noisy channels. This work presents the design and implementation of a LDPC encoder for transmission of digital terrestrial television according to the Chinese DTMB standard. The system is written in Verilog and is implemented on FPGA. The whole work is then verified with the help of Matlab modelling.
Design and implementation of log domain decoder IJECEIAES
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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.
VoCoRoBo: Remote Speech Recognition and Tilt Sensing Multi-Robotic SystemSagun Man Singh Shrestha
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Turbo codes are error-correcting codes with performance that is close to the
Shannon theoretical limit (SHA). The motivation for using turbo codes is
that the codes are an appealing mix of a random appearance on the channel
and a physically realizable decoding structure. The communication systems
have the problem of latency, fast switching, and reliable data transfer. The
objective of the research paper is to design and turbo encoder and decoder
hardware chip and analyze its performance. Two convolutional codes are
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turbo encoder. The expected data from the channel is interpreted iteratively
using the two related decoders. The soft (probabilistic) data about an
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(MAP) method in the decoder chip. The performance of field-programmable
gate array (FPGA) hardware is evaluated using hardware and timing
parameters extracted from Xilinx ISE 14.7. The parallel concatenation offers
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This document summarizes the design of a low bitrate modulator using FPGA for satellite applications. It describes:
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receiver to estimate the information being sent from each transmitter. Simulation results show
that the Bit Error Rate (BER) can be decreased by using this concept comparing to the
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IMPLEMENTATION OF JOINT NETWORK CHANNEL DECODING ALGORITHM FOR MULTIPLE ACCES...cscpconf
In this paper, we consider a Joint Network Channel Decoding (JNCD) algorithm applied to a wireless network consisting to M users. For this purpose M sources desire to send information
to one receiver by the help of an intermediate node which is the relay. The Physical Layer Network Coding (PLNC) allows the relay to decode the combined information being sent from different transmitters. Then, it forwards additional information to the destination node which receives also signals from source nodes. An iterative JNCD algorithm is developed at the receiver to estimate the information being sent from each transmitter. Simulation results show that the Bit Error Rate (BER) can be decreased by using this concept comparing to the reference one which doesn’t consider the network coding.
Implementation of Algorithms For Multi-Channel Digital Monitoring ReceiverIOSR Journals
Abstract: Monitoring Receivers form an important constituent of the Electronic support. In Monitoring
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In this project, the Implementation of algorithm for multi channel digital monitoring receiver. The
implementation will carry out the channelization by the way of Digital down Converters (DDCs) and Digital
Base band Demodulation. The Intermediate Frequency (IF) at 10.7 MHz will be digitalized using Analog to
Digital Converter (ADC) with sampling frequency 52.5 MHz and further converted to Base band using DDCs.
Virtually all the digital receivers perform channel access using a DDC. The Base band data will be streamed to
the appropriate demodulators. Matlab Simulink will be used to simulate the logic modules before the
implementation. This system will be prototyped on an FPGA based COTS (Commercial-off-the-shelf)
development board. Xilinx System Generator will be used for the implementation of the algorithms.
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This document describes the design and implementation of a serial communication protocol conversion system and circular buffer in an FPGA for monitoring a Tesla meter. The system includes controllers for RS232 and RS485 serial communication, a protocol conversion unit between the two interfaces, and a circular buffer. The controllers are designed using Verilog HDL and implemented on a Spartan FPGA. Simulation and hardware results demonstrate that the system successfully converts between the RS232 and RS485 protocols in real-time and stores data in the circular buffer for offline analysis.
Efficient Design of Transceiver for Wireless Body Area NetworksIOSR Journals
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Implementation of SISO-OFDM Transmission using MATLAB on DSP Processormohan676910
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Design of Digital to Analog Voice Data Packet Conversion from Ethernet Protoc...TELKOMNIKA JOURNAL
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The design was implemented as four components consisting of frame starter unit, address matching unit,
buffer unit and DAC processing unit. The system was designed on Xilinx development board using ISE
design suite and simulated on ISIM. The test results showed that the system response was less than 40
ms. The result also showed that our proposed design only occupies 11% of number of slices and it also
requires 5% of total IOBs on Xilinx Spartan 3-E.
The document describes the design and development of an RDS (Radio Data System) encoder that the author worked on from 2011-2012 at TAKTA Company. Some key points:
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OPTICAL SWITCHING CONTROLLER USING FPGA AS A CONTROLLER FOR OCDMA ENCODER SYSTEMEditor IJCATR
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It is providing a high security for data transmission due to all data will be transmitting in binary code form. The output signals from
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receiver. In this paper, AA and 55 data were used for source 1 and source 2. It is generated sample data and sent packet data to the
FPGA and stored it into RAM. The simulation results have done by using software Verilog Spartan 2 programming to simulate. After
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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.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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A NOVEL APPROACH FOR LOWER POWER DESIGN IN TURBO CODING SYSTEMVLSICS Design
Low Power is an extremely important issue for future mobile communication systems; The focus of this paper is to implementat turbo codes for low power solutions. The effect on performance due to variation in parameters like frame length, number of iterations, type of encoding scheme and type of the interleave in the presence of additive white Gaussian noise is studied with the floating point model. In order to obtain the effect of quantization and word length variation, a fixed point model of the application is also developed.. The application performance measure, namely bit-error rate (BER) is used as a design constraint while optimizing for power and area coverage. Low power Optimization is Performed on Implementation levels by the use of Voltage scaling. With those Techniques we can reduced the power 98.5%and Area(LUT) is 57% and speed grade is Increased .This type of Power maneger is proposed and implemented based on the timing details of the turbo decoder in the VHDL model.
High speed customized serial protocol for IP integration on FPGA based SOC ap...IJMER
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A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
What is Digital Literacy? A guest blog from Andy McLaughlin, University of Ab...
Cdma
1. Digital Design of DS-CDMA Transmitter
Using VHDL and
FPGA
Khalid Eltahir Mohamed, Borhanuddin Mohd. Ali
(uofg kh@hotmaiI.com, borhan@eng.upm.edu.my)
Department of Computer and Communications Systems, Faculty of Engineering, University Putra
Malaysia (UPM), 43400 Serdang, Selangor, Malaysia
Abstract- This paper describes the Direct Sequence Code Division
Multiple Access (DS-CTDMA) wireless transmitter design using Field
Programmable Gate Array (FPGA), which has been adopted in many
wireless access technologies. Four separate blocks have been designed
using digital approach to form the transmitter circuit diagram using
the oscillator, the PN-code generator, the Parity Check, and the BPSK
modulator. The Synopsys software has been used for the design
synthesis and simulation; the Very High Speed Integrated Circuit
Hardware Description Language (VHDL) program was used for
coding and FPGA for compiling and downloading the simulaton.
The DS-CDMA wireless tansmitter was designed to trnsmit with
data rates up to 2 Mbps. Ihe transmitted signals were camed with a
40 M:Hz carrer frequency.
Keywords: DS-CDMA, tansmitter, VHDI FPGA, PNgenerator.
I. INTRODUCTION
FPGA was selected to implement this circuit. The researgh
involved two phases - simulation and synthesis of the VHDL
codes using the Synopsys package and converting the
integrated circuit of the transmitter in the FPGA compiler for
downloading on the Xilinx FPGA board.
A VHDL design begins with an ENTITY block that describes
the interface for the design. The interface defines the input and
output logic signals of the circuit. The ARCHITECTURE
block describes the internal operation of the design. Within
these blocks, there are numerous other functional blocks used
to build the design elements of the logic circuit created [8].
The source code written using the normal TEXT editor, then
saved as a VHDL file with '.vhd' extension and transferred to
any of the VHDL design compilers (DC). If the compilation
shows no error(s), the file can be simulated, synthesized and
implemented with FPGA [9].
In recent years, there has been a significant amount of research
performed in both industry and academia into the development
of CDMA systems. A clear description of a CDMA has been
elusive, since it has a different meaning to every researcher
involved in the topic [6].
The transmitter components were designed individually using
the bottom-up approach. The designs were then combined and
defined by a component declaration and port mapping.
Generally, this is an easy method although it could have had
DS-CDMA is a type of spread-spectrum communication
system in which multiple signal channels occupy the same
frequency band, being distinguished by the use of different
spreading codes [2]. CDMA communication is employed in,
for example, digital cellular telephone systems and personal
communication services. In these systems, a base station
communicates with a plurality of mobile stations, one
frequency band being used for all of the up-links from the
mobile stations to the base station, and another frequency band
being used for all of the down-links from the base station to
the mobile stations [3].
complications.
The basic transmitter circuit used was adopted from the
following digital components; flip-flops, shift registers, PN
coder and a BPSK modulator with 40 MHz DIP oscillator
providing the reference frequency [1].
This paper concentrates on the application of VHDL
simulation tool and FPGA compiler to wireless data
components. Networks operating over unlicensed bands have
recently received increased attention with the prominence of
such standards as IEEE 802.11 and Bluetooth. In 3G, the
infornation transferred is not limited to having voices, images
This paper describes the design and a circuit for pseudo
random PN coding and synchronization of a wireless
transmitter for DS-CDMA using VHDL software. The circuit
for the transmitter is comprised of basic digital components,
1-4244-0000-7/05/$20.00 02005 IEEE.
such as flip-flops, oscillators, shift registers, PN coder and a
BPSK modulator.
632
2. and digital data separately. Users will have full coverage and
mobility for 144 kbps (preferably 348 kbps) and eventually up
to 2 Mbps. With this wide bandwidth, users are able to access
the information in full multimedia form, wirelessly and with
better quality [7].
chip at half the rate as at the BPSK modulator. The Shiften
port used for shift enables or RESET. The resultant coded data
modulated using the BPSK modulator with a data rate of up to
2 Mbps.
The next section of this paper describes the PN code
generator, which is the important part of the design. The third
section of this paper presents the transmitter block diagram
with the flow chart of the program. The fourth section presents
language options in creating the design and also the simulation
and synthesize tool. Section five presents the hardware
implementation.
lI. PN CODE GENERATOR
The PN generator was used with Linear Feedback Shift
Registers (LFSRs) to provide and assign synchronization and
unique codes to the individual users across the transmission
interface [4].
The LFSR sequence goes through (2n -1) states, where n is the
number of registers in the LFSR. The contents of the registers
are shifted one position to the right per clock cycle. The
feedback from predefined registers, or taps to the leftmost
register, are XORed together. Table I presents the main
variables used in this research.
TABLE I
VARIABLES FOR LFSR DESIGN
Set value
Variable
Number of stages in the shift register, n. 16
4
Number of taps in the feedback ath.
+
f(x) = x'+ XI + X4
Position of each tap (polynomial representation)
+1
Fig. 1. Conceptual diagram of the 16-stage LFSR
The PN generator generates with chip clock signal starting for
an initial state determined by initialization data.
A flow diagram of the basic steps of the PN code generator
design is shown in Figure 2. Two major steps are explained in
this flow diagram as was just noted. Generation of the PN
code and multiplying it with the data entered were the two
main steps. When the 'data ready' is available at the input of
the PN generator the code for each bit of the data will b,e
available and waiting for data to enter. Shielen control the data
entering and shifted out of the PN generator. The coded data is
shifted serially to PN generator output bit by bit. The shilten
switch the PN generator ON until 16-bit coded data were
shifted out from the PN. Then the coded data had to wait for
2-clock cycles to start shifting again. The data was stored in
the buffer during this time.
The polynomial f (x) = X +x + x5 + x4 +1 was chosen
because it gives good autocorrelation. The polynomial could
have taken in any form, as long as it gives good cross
correlation.
Cross correlation is defined as the correlation between two
different signals. It is calculated by subtracting the
disagreements from the agreements between two different
sequences as opposed to the time-shifted replicas of the same
signal.
It is important to use a set of PN sequences with minimal cross
correlation with each other in order to reduce the effect of
adjacent channel interference. If the cross correlation is not
small, there is a possibility that the data coded from one user
can be incorrectly identified and assigned to another because
of similarity between the two keys.
Fig. 2. The flow chart of the PN code generator
III. TRANSMITTER BLOCK DIAGRAM
Figure 3 shows the block diagram of the transmitter. It
contains 7 blocks, namely, PN code generator, control block,
multiplexer, 16-bit shift register, parity bit, 1-bit shift register
and PBSK modulator. The PN generator generates a DSCDMA code, which is multiplied by the data entering the PN
generator. The Shiften port is controlled by the PN code
generator.
Figure 1 shows the conceptual diagram for the 16-stage LFSR.
Datain is an input port for the initial PN sequence, while the
Fillsel port selects the multiplexer input from either the
feedback or Datain. The registers are based on D flip-flops.
The system timed by an internal clock, which sampled the PN
633
3. 3^+-0~ .14|t
Here, the Control Block controls all the operations of the
transmitter and the timing for the transmitted bits, enabling the
multiplexer and the 16-bit shift register. The multiplexer fed
coded data from the PN code generator and parity bit. The 16bit shift register is used to shift the coded data parallel and
serial to the parity and to the BPSK modulator simultaneously.
The 16-bit coded data is shifted first to the parallel XORed
parity calculation and fed back to the multiplexer after storage
in the 1-bit shift register. The parity bit is added to the 16-bit
waiting for transmission in the 16-bit shift register. It is added
at the end of the 16-bit coded data.
This description of the design is intended to present basic
ideas behind the method and it omits details that might
obscure basic ideas. One such detail concems the nature of the
link between each step and timing. Flow chart design gives a
clear idea about the design and its steps and links. A flow
diagram showing the basic flow of the DS-CDMA wireless
transmitter is given in Figure 4. The operation is as follows:
* The coded data from the PN generator is multiplexed
immediately when it appears at the PN output.
* The coded data is delayed for 2-clock cycle at the PN
generator after each 16-clock cycle (state at previous flow
chart).
* The multiplexed data is shifted and stored at 16-bit shift
register.
* For 16 clock cycles the multiplexer multiplex the output
of the PN generator.
* For 2 clock cycles after each 16-clock cycle the
multiplexer waits to multiplex one bit from the parity
output.
. For
the initial time of simulation the data appears at the
PN output after 32-clock cycle.
* The 16-bit shift register shifted the coded data in parallel
to parity to perform 1-bit parity and stored in 1-bit shift
register.
* The data stored at the 16-bit shift register waited for 2clock cycle to start transmission through the BPSK
modulator in serial.
* The transmitted data frame contains 16-bit data with 1-bit
parity.
Lsil
t
Fig. 4. The flow chart of the DS-CDMA wireless transmitter
IV. VHDL AND FPGA COMPILER II
The VHDL source code files were already created and saved
in the same folder, all with the extension '.vhd'. These files
were for the PN code generator, parity check (including
control block, multiplexer, 16-bit shift register, parity bit and
1-bit shift register), oscillator and BPSK modulator. A toplevel design was created for the parity check files for the
whole design. Then the design was simulated and synthesized
to check its logical operation. The individual elements were
simulated using vhdlan and vhdlsim in the DOS command for
Windows NT. The FPGA Compiler 11 was used for compiling
and synthesizing the VHDL source code. The synthesis
allowed the timing factors and the other influences of the
actual FPGA devices to affect the simulation, thereby resulting
in a more thorough check before the design was committed to
the FPGA. The results of this simulation and synthesis are the
FPGA optimized chip. Test-bench files were created to test all
the above files. The purpose of a test bench is to verify the
functionality of a model or package.
Figure 5 shows the input and output ports of the transmitter
section. All transmitter components (PN code generator,
BPSK modulator, oscillator, parity, control block, 16-bit shift
register, multiplexer and 1-bit shift register) were combined at
this top-level design. The FPGA optimized chip for the
transmitter is shown in Figure 6. The final result waveform
from the created test-bench for the top-level design is shown
in Figure 7. The DS-CDMA wireless transmitter was designed
to transmit data with higher data rates. 2 MHz was selected as
the clock rate to come out with 2 Mbps data rate. The
Fig. 3. The block diagram of the DS-CDMA transmitter.
634
4. calculation for this higher rate is taken manually from the VSS
waveform.
The relationship between the frequency and the time period is:
tT
The time period used for this simulation was 250ns per half
cycle, which means 500 ns per full cycle. The data will
transmit serially through the BPSK modulator. At each clock
cycle 1-bit will be transmitted. Because of the initialization of
the transmission as shown in Figure 8 there are seen no data
(U) appear at the transmitter output. After that, the data is
transmitted continuously.
where f is the frequency and T is the period time [5]. The
clock frequency used was 2 MHz so the period is 0.5 ,us, 500
ns. For the 1st transmission, the data comes out from the BPSK
modulator after 34 clock cycles (34 clock cycle * 500 ns =
1700), as shown in Figure 9. For 2 Mbps data rate there is
2000000 bits per Is, so 2000000 clock cycles represent these
bits transmission. That means the data will come out after
(2000000 clock cycle * 500 ns = 1000000000 ns) as shown in
Figure 10. The data bits are calculated manually from the
wavefonn viewer. From the calculation, it was observed that
the transmitted data was less than 2 Mbps (1999964 bits only
come out in I s). This happens because of the lost bits during
the initial period.
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First bit appears at
the BPSK output . 1...:J
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0
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Fig.
:.. th _ 9. VSS waveform of the transmitter showing the first transnsmitted bits
appear from the BPSK after 1 7000ns
Fig. 7 VSS waveform of the VHDL top-level file of the transmitter
635
5. VI. CONCLUSION
VHDL behavioral modeling is useful in digital systems design
because the designer can model the circuit in a program that
simulates the circuit operation rather than spend time on
complex finite state machines or truth tables. This greatly
facilities and reduces the design time for a large digital
system.
TO_--...l
TATAJ
~
'MP
The simulation waveforms presented in this paper have proven
the reliability of the VHDL implementation to describe the
characteristics and the architecture of the digital transmitter.
The simulated waveforms also have shown the observer how
long the test result can be achieved by using test-bench file.
From the waveforms the digital transmitter transmitted at high
data rates of up to 2 Mbps with the BPSK modulator holding
the data during transmission. The transmitted data included a
1-bit parity that acted as error detection.
PIZ1Th
MI T'
C..........
Last bit appear at the BPSK
output after Is simulation time
-,
*-
Fig. 10. VSS waveform of the transmitter showing the end of I s time
simulation
V. HARDWARE IMPLEMENTATION
The FPGA compiler directory was used for simulation and
synthesis and downloading of the results to the XSV FPGA
board. This board, from Xilinx Virtex FPGA family board,
with a single Virtex FPGA from 50K to 800K contained two
independent banks of 512*16 SRAM for local buffering of
signals and data.
From the optimized FPGA circuit for top-level design, the
circuit of the transmitter was reduced sufficiently for
downloading to the Xilinx FPGA board. From testing, both
hardware and software components performed well and
reliably.
The first step in downloading the design to the Xilinx XSV300 FPGA board was the installation of the software. This was
to install the utility and configuration files for testing and
programming the board. The second step was to configure the
jumpers in the board. The XSV-300 Board came with shunts
on the jumpers in their default arrangement. After this, power
applied to the board from an ATX PC power supply. The next
step was to connect the board to the parallel port of the PC
through a 6-foot DB25 cable. Once the board is connected to
the PC with jumpers in their default configuration, it is now
ready for testing. The last step was to program the interface to
the board and then download the design to the board using the
gxload window of the software. Figure 11 shows the
transmitter after the final step of the downloading in the XCV300 board. The board was tested. The LEDs were used to
show the 16-bit data and 1 -bit parity check at the output of the
transmitter.
REFERENCES
[1] Chang, K., C. (1997), Digital Design and Modeling with VHDL and
Synthesis, IEEE service center, Piscataway.
[2] Cheah, J., Y, C., Practical Wireless Data Modem Design, Artech House
Publishers, Boston, London, 1999.
[3] Feher, K. (1995), Wireless Digital Communications, Prentice Hall, Inc.,
Upper Saddle River, New Jersey.
[4] Gil, H., K., PN Code Acquisition Using Nonparametric Detectors in DSCDMA Systems, Department of Electrical and Electronic, Korea
Advanced Institute of Science and Technology (KAiST), South
Korea,2000.
[51 Halsall, F., Data Commuunications, Computer Networks and Open Systems,
Addison-Wesley Publications company, Harlow, England, 1996.
[6] Jakes, W. C., Jr. (1994), Microwave Mobile Communications, J. Wiley &
Sons, New York, 1974; reprinted by IEEE Press, 1994, ISBN 0-78031069-1. http://www.cdg.org. Accessed on 2 Oct. 2001.
[71 Oianpera, T., Prasad, R., Wideband CDMA for Third Generation Mobile
Communications, Artech House Publishers, Boston, London, 1998.
[8] Rushton, A., VIDL for Logic
Chichester, England,1998.
Synthesis,
John Wiley & Sons Ltd,
[9] Zwolinski, M. (2000), Digital System Design with VHDL, Pearson
Education Ltd., England.
Fig. 1. The FPGA board after downloading the simulated and synthesizes
VHDL files of the transmitter
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