community for readers. Mobile Cellular Communication covers all the important aspe. by. Gottapu Sasibhushana Rao ebook, pages. Mobile Cellular Communication covers all the important aspects of cellular and mobile communications from the Internet to signals, access protocols and cellular . Wireless communication has become a ubiquitous part of modern life, from global cises are provided and a solutions manual is available for instructors.
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Cellular Mobile Communication Gottapu Sasibhushana Rao. Mobile Cellular Mobile Communication pdf · Read Online Cellular Mobile Communication pdf . Mobile Cellular. Communication. Gottapu Sasibhushana Rao. Professor and Head. Department of Electronics and Communication Engineering. In , AM mobile communication systems for municipal police radio In , FM mobile communications for the first public mobile telephone service.
The current cellular location of the phone i. TU D A billing relationship with a mobile phone operator. This is usually either where services are paid for in advance of them being consumed prepaid , or where bills are issued and settled after the service has been consumed postpaid. A mobile phone that is GSM compliant and operates at the same frequency as the operator.
Most phone companies sell phones from third-party manufacturers.
A Subscriber Identity Module SIM card, which is activated by the operator once the billing relationship is established. Personal information such as contact numbers of friends and family can also be stored on the SIM by the subscriber. Every SIM card contains a secret key, called the Ki, which is used to provide authentication and encryption services.
This is useful to prevent theft of service, and also to prevent "over the air" snooping of a user's activity. The network does this by utilising the Authentication Center and is accomplished without transmitting the key directly. When a phone contacts the network, its IMEI may be checked against the Equipment Identity Register to locate stolen phones and facilitate monitoring.
TDMA It can be easily adapted to the transmission of data and voice communication. TDMA offers the ability to carry data rates of 64 kbps to Mbps expandable in multiples of 64 kbps. This enables operators to offer personal communication-like services including fax, voiceband data, and short message services SMSs as well as bandwidth-intensive applications such as multimedia and videoconferencing.
Frequency hopping is a feature that is optional within the GSM system. It can help reduce interference and fading issues, but for it to work, the transmitter and receiver must be synchronised so they hop to the same frequencies at the same time. The encryption process is synchronised over the GSM hyperframe period where a counter is used and the encryption process will repeat with each hyperframe.
However, it is unlikely that the cellphone conversation will be over 3 hours and accordingly it is unlikely that security will be compromised as a result.
Multiframes are then constructed into superframes taking 6. These consist of 51 traffic multiframes or 26 control multiframes.
As the traffic multiframes are 26 bursts long and the control multiframes are 51 bursts long, the different number of traffic and control multiframes within the superframe, brings them back into line again taking exactly the same interval.
Traffic multiframe: The Traffic Channel frames are organised into multiframes consisting of 26 bursts and taking ms. In a traffic multiframe, 24 bursts are used for traffic. These are numbered 0 to 11 and 13 to One of the remaining bursts is then used to accommodate the SACCH, the remaining frame remaining free. The actual position used alternates between position 12 and Control multiframe: This always occurs on the beacon frequency in time slot zero and it may also occur within slots 2, 4 and 6 of the beacon frequency as well.
This multiframe is subdivided into logical channels which are time-scheduled. TDMA systems. It is therefore important to address them correctly. The IMSI is a unique identity allocated to each subscriber to allow correct identification over the radio path and through the network and is used for all signaling in the PLMN.
All network-related subscriber information is connected to the IMSI. The TMSI is used for the subscribers confidentiality on the air interface. The MSISDN is a number, which uniquely identifies a mobile telephone subscription in the public switched telephone network numbering plan. These are the digits dialed when calling a mobile subscriber. The IMEI is consisted with followings; x x x x.
A MSRN is used during the call setup phase for mobile terminating calls. Each cell is identified by cell identity CI. Wireless Communication Assignment of a traffic channel Call confirmation, call accepted, and call release. The process that occurs during the handover intra BSC as follows: During the call, MS will measure the strength and quality of the signal on the TCH and the signal strength from the neighboring cell. MS to evaluate and assess the average for each cell.
MS send the results to the BTS measurements every two times in one second cell not only on their own but also the results of measurements from the BTS neighboring cell. In the BSC, the function is activated when the placement is required to handover to another cell.
BSC will ask the BTS for a long time to send a message to MS with information about the frequency, time slot, and the output power for the change. MS choose a new frequency handover and access to the appropriate time slot. MS send a "HO complete message. The chosen HO ref.
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The BTS will acknowledge that the activation has been made. Handover bursts - When the MS has changed to the new channel, it will send handover bursts on the new channel. The information content is the HO ref. The bursts are as short as the access bursts. On the detection of the handover bursts, and check of HO ref.
Handover complete - Now the MS is ready to continue the traffic and will send a handover complete message, which will be addressed to the old BSC as clear a command. Handing over a GSM call is a complicated procedure. The following call flows analyze the different steps involved in a inter-MSC handover: The source BSC analyzes the signal quality measurement reports and initiates a handover.
The source MSC releases the radio resources for the call. Note that the call is still routed via the source MSC. A GSM network is a bearer data communication protocol families.
User plane ,Control plane,Management plane The user plane defines protocols to carry connection oriented voice and user data. At the radio interface Um, user plane data will be carried by the logical traffic channel called TCH.
The control plane defines a set of protocols for controlling these connections with signalling information, for example signalling for connection setup. Such signalling data is carried over logical control channels called D-channels Dm-. As the control channels often have spare capacities, also user data, the packet oriented SMS data, is transported over these channels see Figure gsm8.
All logical channels, however, will be finally multiplexed onto the physical channel. Management of network element configuration and network element faults are examples of management plane functionality. The basic GSM bearer service, Circuit Switched Data CSD , simply consists of transmitting and receiving signals representing data instead of voice across the air interface. Modems are used for the conversion between data bit streams and modulated radio signals.
Data transmission is either transparent or non-transparent. Networking layer operations Connection management Mobility management Radio resource management. The number of customers requiring such services is increasing exponentially, and there is a demand for integration of a variety of multimedia services.
The range of services includes short messaging, voice, data, and video. Consequently, the bit rate required for the services varies widely from just 1. Furthermore, supporting such a wide range of data rates with flexible mobility management increases network complexity dramatically. The CDMA is a digital modulation and radio access system that employs signature codes rather than time slots or frequency bands to arrange simultaneous and continuous access to a radio network by multiple users.
Contribution to the radio channel interference in mobile communications arises from multiple user access, multipath radio propagation, adjacent channel radiation and radio jamming.
The spread spectrum systems performance is relatively immune to radio interference. However, CDMA still has a few drawbacks, the main one being that capacity number of active users at any instant of time is limited by the access interference.
Furthermore, Near-far effect requires an accurate and fast power control scheme. The first cellular CDMA radio system has been constructed in conformity with IS95 specifications and is now known commercially as cdmaOne.
IN Fig 6. There is increasing demand for data traffic over mobile radio.
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The mobile radio industry has to evolve the current radio infrastructures to accommodate the expected data traffic with the efficient provision of high-speed voice traffic. The GPRS operation is supported by new protocols and new network nodes: GPRS supports quality of service and peak data rate of up to GPRS packetises the user data and transports it over 1 to 8 radio channel timeslots using IP backbone network.
Bandwidth is limited to 1. The system is intended to provide voice and low bit rate data service using circuit-switching techniques. Data rate varies from 1. Forward base station to mobile and reverse mobile to base station link structures are different and each is capable of distinctive capacity. Forward transmission is coherent and synchronous while the reverse link is asynchronous. The 'chanellisation' in each link is achieved by using chip orthogonal codes, including provision for pilot, synchronisation, paging, and network access.
Consequently, the number of active users able to simultaneously access the network is limited by the level of interference, service provisions and the number of 'channels' available. In ISB, an active mobile always has a fundamental code channel at 9. Thus W-CDMA is capable of offering the transmission of voice, text, data, picture still image and video over a single platform.
However, in addition to the drawbacks arising from the mobile environment and multiple access interference, high bit rate transmission causes Inter-symbol interference ISI to occur. The ISI therefore has to be taken into account during transmission. The UTRAN consists of a set of radio network subsystem comprising a radio controller and one or more node base station. The network controller is responsible for the handover decisions that require signalling to the user equipment.
Each subsystem is responsible for the resources of its set of cells and each node B has one or more cells. Each channel state is associated with either a prob- ability of transmission success or a transmission rate. In such systems, the transmitter typically has partial informa- tion concerning the channel states, but can deduce more by probing individual channels, e.
The main goal of this work is to derive op- timal strategies for determining which channels to probe in what sequence and which channel to use for transmission.
For both problems, we derive key structural proper- ties of the corresponding optimal strategy. In particular, we show that it has a threshold structure and can be de- scribed by. We further show that the opti- mal CDT strategy can only take on one of three structural forms. This strategy is shown to be optimal for a number of cases of practical interest.
Wireless Communication 6. Unit-7 Wireless Modulation Techniques and Hardware 7. RBS antenna systems Combining and distribution unit example Typical antenna configurations Hybrid combiner Duplex filter. The authenticator is a network device, such as an Ethernet switch or wireless access point; and the authentication server is typically a host running software supporting the RADIUS and EAP protocols.
The authenticator acts like a security guard to a protected network. The supplicant i. An analogy to this is providing a valid visa at the airport's arrival immigration before being allowed to enter the country. With If the authentication server determines the credentials are valid, the supplicant client device is allowed to access resources located on the protected side of the network.
Wireless LANs have gone through rapid changes with respect to their security architecture in recent years. Another view has been to address the security of the airwaves which has been demonstrated to be extremely vulnerable. This paper traces the evolution and development of this new WLAN security architecture.
Initialization On detection of a new supplicant, the port on the switch authenticator is enabled and set to the "unauthorized" state. In this state, only Initiation To initiate authentication the authenticator will periodically transmit EAPRequest Identity frames to a special Layer 2 address on the local network segment.
If authentication is successful, the authenticator sets the port to the "authorized" state and normal traffic is allowed, if it is unsuccessful the port remains in the "unauthorized" state. When the supplicant logs off, it sends an EAPOL-logoff message to the authenticator, the authenticator then sets the port to the "unauthorized" state, once again blocking all nonEAP traffic. TS Fig 8. Wireless Communication Bluetooth is a wireless technology standard for exchanging data over short distances using short-wavelength radio transmissions in the ISM band from MHz from fixed and mobile devices, creating personal area networks PANs with high levels of security.
Created by telecom vendor Ericsson in , it was originally conceived as a wireless alternative to RS data cables.
It can connect several devices, overcoming problems of synchronization. Bluetooth is managed by the Bluetooth Special Interest Group, which has more than 17, member companies in the areas of telecommunication, computing, networking, and consumer electronics.
The SIG oversees the development of the specification, manages the qualification program, and protects the trademarks. To be marketed as a Bluetooth device, it must be qualified to standards defined by the SIG.
Bluetooth uses a radio technology 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; centered from to MHz in the range 2,, Originally Gaussian frequency-shift keying GFSK modulation was the only modulation scheme available; subsequently, since the introduction of Bluetooth 2. Bluetooth is a packet-based protocol with a master-slave structure. One master may communicate with up to 7 slaves in a piconet; all devices share the master's clock.
Packet exchange is based on the basic clock, defined by the master, which ticks at Two clock ticks make up a slot of s; two slots make up a slot pair of s. In the simple case of single-slot packets the master transmits in even slots and receives in odd slots; the slave, conversely, receives in even slots and transmits in odd slots. Packets may be 1, 3 or 5 slots long but in all cases the master transmit will begin in even slots and the slave transmit in odd slots. Bluetooth provides a secure way to connect and exchange information between devices such as faxes, mobile phones, telephones, laptops, personal computers, printers, Global Positioning System GPS receivers, digital cameras, and video game consoles.
It was principally designed as a low-bandwidth technology. Communication and connection. Older pre Bluetooth dongles, however, have limited capabilities, offering only the Bluetooth Enumerator and a less-powerful Bluetooth Radio incarnation. Bluetooth is a standard wire-replacement communications protocol primarily designed for low power consumption, with a short range power-class-dependent, but effective ranges vary in practice; see table below based on low-cost transceiver microchips in each device.
At any given time, data can be transferred between the master and one other device except for the little-used broadcast mode. The master chooses which slave device to address; typically, it switches rapidly from one device to another in a round-robin fashion.
Since it is the master that chooses which slave to address, whereas a slave is in theory supposed to listen in each receive slot, being a master is a lighter burden than being a slave. Being a master of seven slaves is possible; being a slave of more than one master is difficult. The Bluetooth Core Specification provides for the connection of two or more piconets to form a scatternet, in which certain devices simultaneously play the master role in one piconet and the slave role in another.
A master Bluetooth device can communicate with a maximum of seven devices in a piconet an ad-hoc computer network using Bluetooth technology , though not all devices reach this maximum. The devices can switch roles, by agreement, and the slave can become the master for example, a headset initiating a connection to a phone will necessarily begin as master, as initiator of the connection; but may subsequently prefer to be slave.
These profiles include settings to parametrize and to control the communication from start. Adherence to profiles saves the time for transmitting the parameters anew before the bidirectional link becomes effective. There are a wide range of Bluetooth profiles that describe many different types of applications or use cases for devices. A typical Bluetooth mobile phone headset. Wireless control of and communication between a mobile phone and a handsfree headset.
This was one of the earliest applications to become popular. Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system Wireless Bluetooth headset and Intercom. Wireless networking between PCs in a confined space and where little bandwidth is required. Wireless communication with PC input and output devices, the most common being the mouse, keyboard and printer.
Transfer of files, contact details, calendar appointments, and reminders between devices with OBEX. Replacement of previous wired RS serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices.
For controls where infrared was often used. For low bandwidth applications where higher USB bandwidth is not required and cable-free connection desired. Sending small advertisements from Bluetooth-enabled advertising hoardings to other, discoverable, Bluetooth devices.
Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem. Short range transmission of health sensor data from medical devices to mobile phone, set-top box or dedicated telehealth devices.
Personal security application on mobile phones for prevention of theft or loss of items. The protected item has a Bluetooth marker e. If the connection is broken the marker is out of range of the phone then an alarm is raised.
This can also be used as a man overboard alarm. A product using this technology has been available since Bluetooth vs. Wi-Fi is intended as a replacement for cabling for general local area network access in work areas. This category of applications is sometimes called wireless local area networks WLAN. Bluetooth was intended for portable equipment and its applications.
The category of applications is outlined as the wireless personal area network WPAN. Bluetooth is a replacement for cabling in a variety of personally carried applications in any setting and also works for fixed location applications such as smart energy functionality in the home thermostats, etc. Wi-Fi is a wireless version of a common wired Ethernet network, and requires configuration to set up shared resources, transmit files, and to set up audio links for example, headsets and hands-free devices.
Wi-Fi uses the same radio frequencies as Bluetooth, but with higher power, resulting in higher bit rates and better range from the base station. The MacBook Pro, shown, also has a built in Bluetooth adaptor. The technology is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones i. Bluetooth protocols simplify the discovery and setup of services between devices.
The protocol operates in the license-free ISM band at 2. IN Page Implementations with versions 1. Version 2. Technically, version 2. The ZigBee network layer natively supports both star and tree typical networks, and generic mesh networks.
Every network must have one coordinator device, tasked with its creation, the control of its parameters and basic maintenance. Within star networks, the coordinator must be the central node.
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Both trees and meshes allows the use of ZigBee routers to extend communication at the network level. The specification goes on to complete the standard by adding four main components: Besides adding two high-level network layers to the underlying structure, the most significant improvement is the introduction of ZDOs.
These are responsible for a number of tasks, which include keeping of device roles, management of requests to join a network,. ZigBee is a low-cost, low-power, wireless mesh network standard. The low cost allows the technology to be widely deployed in wireless control and monitoring applications.
Low power-usage allows longer life with smaller batteries. Mesh networking provides high reliability and more extensive range. ZigBee chip vendors typically sell integrated radios and microcontrollers with between 60 KB and KB flash memory.
ZigBee is targeted at applications that require a low data rate, long battery life, and secure networking. Applications include wireless light switches, electrical meters with in-home-displays, traffic management systems, and other consumer and industrial equipment that requires short-range wireless transfer of data at relatively low rates.
ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE standard for personal area networks. ZigBee devices are often used in mesh network form to transmit data over longer distances, passing data through intermediate devices to reach more distant ones.
Any ZigBee device can be tasked with running the network. ZigBee is not intended to support powerline networking but to interface with it at least for smart metering and smart appliance purposes.
Because ZigBee nodes can go from sleep to active mode in 30 ms or less, the latency can be low and devices can be responsive, particularly compared to Bluetooth wake-up delays, which are typically around three seconds.
Application profiles. It is an enhancement of the ZigBee Smart Energy version 1 specifications, adding services for plug-in electric vehicle PEV charging, installation, configuration and firmware download, prepay services, user information and messaging, load control, demand response and common information and application profile interfaces for wired and wireless networks.
It is being developed by partners including: Specifications under development o ZigBee Smart Energy 2. The ZigBee RF4CE specification lifts off some networking weight and does not support all the mesh features, which is traded for smaller memory configurations for lower cost devices, such as remote control of consumer electronics.
Configurable functionality A number of network properties can be pre-configured. The network is initialised by the Co-ordinator, at which time these configuration values are taken into account.
These properties determine the maximum size in terms of the maximum number of nodes and shape of the network, and are as follows: Network Depth: The depth of a device in a network is the number of nodes from the root of the network tree the Co-ordinator to the device.
The maximum network depth is then the maximum number of hops from the Co-ordinator to the most distant device in the network. This determines the overall diameter for the network.
Note that a Star network has a network depth of 1. Number of Children: Each Router in the network can have a number of child devices attached to it.
These may be either Routers or End Devices. The Co-ordinator specifies the maximum number of child devices allowed per Router. Number of Child Routers: In addition to the number of children per Router, a limit is put on how many of these children may be Routers themselves.
The Co-ordinator uses the above information during initialisation to allocate blocks of network addresses to the branches of the network tree.
In turn, the Routers use it to allocate subsets of these address blocks to their children. Forming a ZigBee Network: The Co-ordinator is responsible for starting a ZigBee network. Network initialisation involves the following steps:. The Co-ordinator first searches for a suitable radio channel usually the one which has least activity.
This search can be limited to those channels that are known to be usable - for example, by avoiding frequencies in which it is known that a wireless LAN is operating. The PAN ID can be pre-determined, or can be obtained dynamically by detecting other networks operating in the same frequency channel and. At this stage, the Co-ordinator also assigns a network short address to itself. Usually, this is the address 0x The Co-ordinator then finishes configuring itself and starts itself in Co-ordinator mode.
It is then ready to respond to queries from other devices that wish to join the network. Joining a ZigBee Network: Once the network has been created by the Co-ordinator, other devices Routers and End Devices can join the network. Both Routers and the Coordinator have the capability to allow other nodes to join the network. The join process is as follows: The new node first scans the available channels to find operating networks and identifies which one it should join.
The node may be able to see multiple Routers and a Co-ordinator from the same network, in which case it selects which one it should connect to. Usually, this is the one with the best signal. The node then sends a message to the relevant Router or Co-ordinator asking to join the network. Typically, a Router or Co-ordinator can be configured to have a time-period during which joins are allowed. The join period may be initiated by a user action, such as pressing a button.
An infinite join period can be set, so that child nodes can join the parent node at any time. Message Propagation: The way that a message propagates through a ZigBee network depends on the network topology. However, in all topologies, the message usually needs to pass through one or more intermediate nodes before reaching its final destination. The message therefore contains two destination addresses: Address of the final destination Address of the node which is the next hop Page The way these addresses are used in message propagation depends on the network topology, as follows: Route Discovery Mechanism: The mechanism for route discovery between two End Devices involves the following steps: A route discovery broadcast is sent by the parent Router of the source End Device.
This broadcast contains the network address of the destination End Device. All Routers eventually receive the broadcast, one of which is the parent of the destination End Device. The parent Router of the destination node sends back a reply addressed to the parent Router of the source. The message is routed along the tree. The message is routed along an already discovered mesh route, if one exists, otherwise the Router initiates a route discovery.
Once this is complete, the message will be sent along the calculated route. If the Router does not have the capacity to store the new route, it will direct the message along the tree. FORCE route discovery: If the Router has the route capacity, it will initiate a route discovery, even if a known route already exists.
If the Router does not have the route capacity, it will route the message along the tree. Use of this option should be restricted, as it generates a lot of network traffic. Route Discovery Options There are three options related to route discovery for a mesh network the required option being indicated in the message:. Route Discovery: The ZigBee stack network layer supports a route discovery facility in which a mesh network can be requested to find the best available route to the destination, when sending a message.
Route discovery is initiated when requested by a data transmission request. Star Topology: All messages are routed via the Co-ordinator. Both addresses are needed and the next hop address is that of the Co-ordinator. Tree Topology: A message is routed up the tree until it reaches a node that can route it back down the tree to the destination node. Both addresses are needed and the initial next hop address is that of the parent of the sending node. The parent node then resends the message to the next relevant node - if this is the target node itself, the final destination address is used.
The last step is then repeated and message propagation continues in this way until the target node is reached. Mesh Topology: In this case, the propagation path depends on whether the target node is in range: The message propagation continues in this way until the target node is reached.
As the reply travels back through the network, the hop count and a signal quality measure for each hop are recorded. Each Router in the path can build a routing table entry containing the best path to the destination End Device.
Eventually, each Router in the path will have a routing table entry and the route from source to destination End Device is established. Note that the corresponding route from destination to source is not known the route discovered is unidirectional. There are two types of discovery, Device and Service Discovery: Device Discovery: Device Discovery involves interrogating a remote node for address information.
The retrieved information can be either:. If the node being interrogated is a Router or Co-ordinator, it may optionally supply the addresses of all the devices that are associated with it, as well as its own address.
In this way, it is possible to discover all the devices in a network by requesting this information from the Co-ordinator and then using the list of addresses corresponding to the children of the Co-ordinator to launch queries about their child nodes. Service Discovery: Service discovery involves interrogating a remote node for information about its capabilities.
This information is stored in a number of descriptors on the remote node, and includes: The device type and capabilities of the node Node Descriptor The power characteristics of the node Node Power Descriptor Information about each application running on the node Simple Descriptor Page Device and Service Discovery: The ZigBee specification provides the facility for devices to find out information about other nodes in a network, such as their addresses, which types of applications are running on them, their power source and sleep behaviour.
This information is stored in descriptors on each node, and is used by the enquiring node to tailor its behaviour to the requirements of the network. Discovery is typically used when a node is being introduced into a user-configured network, such as a domestic security or lighting control system. Once the device has joined the network, its integration into the network may require the user to start the integration process by pressing a button or similar.
The first task is to find out if there are any other devices that it can talk to. For example, a device implementing the switch conforming to the HCL profile tries to find devices containing HCL load controllers to which it could potentially send its switch state information the process of associating the switch with a particular load controller is handled by the binding process.
The choice of best path is usually the one with the least number of hops, although if a hop on the most direct route has a poor signal quality and hence a greater chance that retries will be needed , a route with more hops may be chosen.
Requests for these descriptors are made by a device during its configuration and integration into a ZigBee network. Uses ZigBee protocols are intended for embedded applications requiring low data rates and low power consumption. The resulting network will use very small amounts of power individual devices must have a battery life of at least two years to pass ZigBee certification. ZigBee Co-ordinator ZC: The most capable device, the Co-ordinator forms the root of the network tree and might bridge to other networks.
There is exactly one ZigBee Co-ordinator in each network since it is the device that started the network originally the ZigBee LightLink specification also allows operation without a ZigBee Co-ordinator, making it more usable for over-the-shelf home products. As well as running an application function, a Router can act as an intermediate router, passing on data from other devices.
Contains just enough functionality to talk to the parent node either the Co-ordinator 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. Introduction to wireless telecommunication systems and Networks, History and evolution Different generations of wireless cellular networks 1 G, 2 g,3 G and 4 G networks.
Flag for inappropriate content. Related titles. Jump to Page. Search inside document. Wireless Communication Subject Code: IN Introduction to wireless telecommunication systems and Networks, History and evolution Different generations of wireless cellular networks 1G, 2g,3G and 4G etworks. Wireless Telecom Systems and networks, Mullet: Thomson Learning TU D TS. EN TS. Early AM wireless systems CI TS The early wireless transmitter consists of inductance and capacitance which is used to tune the output frequency of the spark gap.
Typical early wireless transmitter The transmitter signal propagates through the air to a receiver which is located at some distance. CI Amplitude modulation is used for low frequency radio broadcasting the AM include quadrature amplitude modulation which is used for high speed data transmission at RF frequencies. IN TS. IN Signalling System No.
IN Page 10 TS. CI Fig 1. IN Fig 1. IN "2. CI TS Fig 1. TS The fourth generation has been defined but we are not in it, yet. CI TS The subscriber device must be able to sample , digitize and process audio and other multimedia signals, transmit and receive RF signals, process system control messages and provide the power needed to operate the complex electronics subsystems.
TU D Fig 2. IN Page 22 TS. IN Page 26 TS. IN Page 28 TS. Simplex and duplex Each cellular base station is allocated a group of radio channels within a small geographic area called a cell. The total number of available radio channels EN TS. IN minimize interference Channel assignment strategy fixed channel assignment dynamic channel assignment Fixed channel assignment each cell is allocated a predetermined set of voice channel any new call attempt can only be served by the unused channels the call will be blocked if all channels in that cell are occupied Dynamic channel assignment channels are not allocated to cells permanently.
Cell Fundamentals Reuse number Frequency reuse distance The reuse distance can be calculated by using the equation: Wireless Communication 06EC81 Split congested cell into smaller cells. IN Page 35 TS. IN Page 36 TS.The TRC consists of subsystems that perform transcoding and rate adaptation which can be either stand alone or combined. The Traffic Channel frames are organised into multiframes consisting of 26 bursts and taking ms.
Handoff must ensure that the drop in the measured signal is not due to momentary fading and that the mobile is actually moving away from the serving base station. This is used to maintain synchronisation of the different scheduled operations with the GSM frame structure.
The 'chanellisation' in each link is achieved by using chip orthogonal codes, including provision for pilot, synchronisation, paging, and network access. There are no discussion topics on this book yet. Earlier, he was a postdoctoral fellow and part-time professor at the Department of Electronics and Communication Engineering, Concordia University, Montreal, Canada.
Pranathi Reddy marked it as to-read Mar 07, IN Page 36 TS.
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