Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
Assignment Topic. Current wireless communication technologies. Presented by. 1. ... operational range of ZigBee application is 10-20 m. C) Antennas.
Typology: Summaries
1 / 40
This page cannot be seen from the preview
Don't miss anything!
! A) Layered Stacks Figure 1 : ZigBee stack ! Layered like OSI (Open System for Interconnection) model as can be seen in Figure 1
! Compose of Application Layer, Network layer (routing) , MAC (Medium Access Control) , PHY (Physical Layer) , Radio. ! It minimizes the time for which the radio is on to reduce the power use. ! The ZigBee stack defines the multiply accumulate and PHY of the protocol. ! MAC and PHY define the RF (Radio Frequency) and communications components of neighboring devices. ! On the other hand, include a network layer, an application layer and a SSP (Security Service Provider). ! The PHY defines radio characteristics and supports the 2.45GHz and 868/915MHz radio bands. ! The MAC layer is responsible for single-hop data communication between neighboring devices which supports association/disassociation and MAC-level security. Also provides a reliable link between two devices. ! A ZigBee stack provides all the functionality required by the Zigbee specification so that manufacturers can focus on developing their product applications. ! B) Protocols ! The protocols build on algorithm to construct a low speed ad-hoc network of nodes and minimize the time radio is on and reduce power ! C) Standards ! It provides for the connectivity of simple fixed and mobile devices. ! Based on the IEEE (Institute of Electrical and Electronics Engineers) 802.15.4-2003 standard for wireless home area network which define the characteristics of the physical and MAC layer. ! It also defines the network layer specifications and provides structure for application program in application layer. ! It was created to address the market need for a cost- effective, standard-based wireless networking solution that
! A) Transmit Power ! It is between 0 dBm (1 mWatt) and 3 dBm (2 mWatts) ! It requires radios to have a minimum output power of -3dBm or 0.5 mWatts. ! Reducing the transmitter output power to the minimum necessary for a reliable communication link will help reduce the interference to other wireless node. ! B) Receive Thresholds ! Receive sensitivity limit approximately -85 dBm for the 2. GHz band.
! In the receiver path, the required sensitivity is defined as a threshold input signal power of the receiver that yield less than 1 percent PER (Packet Error Rate). ! The minimum sensitivity is -92 dBm for the 868/915 MHz bands. ! The ZigBee receiver should be able to receive an input level up to -20 dBm. With the transmit power of 0 dBm, the typical operational range of ZigBee application is 10-20 m. ! C) Antennas ! It is independent antennas not shared antennas. ! The PCM (Pulse Code Modulation)-ZigBee uses a SMA (Security Monitoring and Automation) connector for the most flexible cabling and antennas options. ! A dipole omni-directional or yagi antenna can be used. ! D) Distance ! ZigBee is meant to offer short distance low-speed transmissions that employ very little power. ! Its distance is approximately 50 m.
! As shown in Table 2, for the lower bands, it will employ BPSK (Binary Phase Shift Keying) modulation. While the highest band, it will employ OQPSK (Offset-Quadrature-Phase-Shift- Keyed). OQPSK ! The 2.4-GHz band, in which ZigBee transceivers are most commonly deployed, uses the OQPSK modulation scheme. ! This is a derivation of traditional QPSK (Quadrature Phase Shift Keying) and is used because it requires less power than similar schemes while achieving the same level, or better, of throughput. ! It takes four values of the phase (two bits) at a time to construct a QPSK symbol.
! ZigBee protocols are intended for use in embedded applications requiring low data rates and low power consumption. ZigBee's current focus is to define a general-purpose, inexpensive, self-organizing mesh network that can be used for industrial control, embedded sensing, medical data collection, smoke and intruder warning, building automation, home automation, etc. The resulting network will use very small amounts of power so individual devices might run for a year or two using the originally installed battery. Typical application that user can use in these areas include:
! ZED (ZigBee End Device) : Contains just enough functionality to talk to the parent node (either the coordinator or a router); it cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC.
! Not only ZigBee is extensively used in several countries, but it is also widely used in Thailand. The reason that ZigBee is chosen by user following: ! It is low cost allows the technology to be widely deployed in wireless control and monitoring applications. ! The low power-usage allows longer life with smaller batteries. ! The mesh networking provides high reliability and more extensive range.
! To use ZigBee technology , users need to have ZC , ZR and ZED which cost about 2000 Baht for ZC , 6000 Baht for ZR and 150 Baht for ZED
! Baseband is the physical layer of the Bluetooth which manages physical channels and links apart from other services similar to error correction. ! ACL is Asynchronous Connection-Less physical link for transmitting data over the physical channels. ACL link provides a packet switched connection between the master and all the active slaves. ! SCO is Synchronous Connection-Oriented physical link for voice-like information. It is a symmetric, point-to-point link between the master and a specific slave. It is like a circuit- switched connection. ! Link Manager essentially handles link set-up, security and control. It provides services like authentication, encryption control and power control. ! L2CAP is the Logical Link Control and Adaptation Layer protocol. It resides in the data link layer and provides connection-less and connection-oriented data services to upper layer coding technique for RF (Radio Frequency). ! SDP is Service Discovery Protocol for applications to discover which services are available and to determine the characteristics of those available services. ! RFCOMM (Radio Frequency Communication) is a simple transport protocol, with between two Bluetooth devices. ! TCP (Transmission Control Protocol) provides a reliable connection between devices at the transport layer with IP (Internet Protocol) in the network layer. IP provides protocol multiplexing and connections based on IP addresses. ! Jini technology provides simple mechanisms which enable devices to plug together to form an impromptu community. Each device provides services that other devices in the community may use. ! WAP is Wireless Access Protocol is a standard for providing Internet communications and advanced telephony services
on digital mobile phones, pagers, personal digital assistants and other wireless terminals. These can be shown in Figure 2 ! B) Protocols ! The Bluetooth standard requires a basic level of communication in order to connect each other over airwaves, at the correct frequencies, correct channel and correct destination. Thus, a specific protocol has been created by establish the rule by which all devices need to abide. Most protocols are included to be form of protocol stack. ! Bluetooth based on low-cost transceiver microchips in each device. According to the devices use a radio in communications system, they do not have to be in line of sight of each other. ! C) Standards ! There are 3 norms for Bluetooth standard following ! IEEE (Institute of Electrical and Electronics Engineers) 802.15.1 defines Bluetooth 1.x, which can reach speeds of 1 Mbps; ! IEEE 802.15.2 recommends practices for using the 2.4 GHz frequency band (the frequency also used by Wi-Fi (Wireless Fidelity) ). However, this standard has not yet been approved; ! IEEE 802.15.3 is a standard currently being developed, which would offer broadband speed (20 Mbps) with Bluetooth; ! IEEE 802.15.4 is a standard currently being developed for use with low-speed Bluetooth applications. ! D) Standard Organisations ! Standard organisation, Bluetooth SIG, is formed
! A) Spectrum ! Bluetooth employs a transmission technique called frequency hopping spread spectrum which chops up the data being sent and transmits chunks of it on up to 79 bands (1 MHz each) in the range 2402-2480 MHz. This is in the globally unlicensed ISM
! Class 1 1mW – 100 mW ! Class 2 0.25mW – 2.5 mW ! Class 3 1mW ! B) Receive Thresholds ! Receive threshold is inverse from transmit power. The more transmit power, the lower receive threshold. In theory, the receiver threshold defines a minimum level of signal where the receiver starts to function. Receiver sensitivity quantifies the ability of a receiver to respond to weak signal levels. Typically uses -70dBm ! C) Antennas ! It is dependent antenna which seems that Bluetooth shares same antennas ! The Bluetooth antenna provides powerful performance in all directions. ! As Bluetooth uses such a high frequency (in the 2.4GHz range) the antennas can be made small while still maintaining efficiency. For everyday experimentation, a 1/4 wavelength piece of wire would do. For more professional setup, a dipole antenna would be better. ! D) Distance ! Class 3 : The lowest power, the max. range of this is 10m (30 feet) ! Class 2 : Max range is about 50m (150ft) ! Class 1 : Max range is about 100m (300ft)
! The modulation in Bluetooth is GFSK (Gaussian Frequency Shift Keying) which is a type of FSK (Frequency Shift Keying) modulation that uses a Gaussian filter to smooth positive/ negative frequency deviations, which represent a binary 1 or 0.
For basic data rate Bluetooth the minimum deviation is 115 kHz. A GFSK modulator is the same as FSK modulator except the baseband data pulse(-1,1) go to the FSK modulator, they need to pass through the Gaussian filter first in order to make the pulse smoother to limit the spectral bandwidth. With GFSK, frequency increases and decreases slowly, but with FSK, it jumps very quickly.
! A) Error Detection ! Two techniques that is used for detect error in Bluetooth following: ! -FEC (Forward Error Correction) is the technique which appends the additional bits to data in which a number can be detected and corrected. ! -ARQ (Automatic Repeat Request) is done by using feedback channel from the receiver to transmitter. Whenever the receiver detects an error, a signal would be feedback to transmitter. ! B) Error Correction ! Three types of error correction are implemented in Bluetooth systems,
! To use Bluetooth technology users have to has a Bluetooth USB modem and a device that can support Bluetooth technology which will cost about 1000 Baht and 20000 Baht for device such as Laptop.
! A) Layered Stacks Figure 3 : Wireless Lan stack ! IEEE (Institute of Electrical and Electronics Engineers) 802.11 define the PHY (Physical Layer) and MAC (Medium Access Control) based on CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). These can be illustrated in Figure 3 ! B) Protocols ! Use the Ethernet protocol and CSMA/CA for path sharing and include an encryption method ! C) Standards ! There are several standards for Wireless Lan hardware but can divide in to 4 major part
