Logical channels are distinguished by the information they carry and can be classified in two ways. The two categories of logical channels in gsm are control channels and traf. Easily attend job interviews and college exams with these multiple choice questions. Gsm uses a variety of channels in which the data is carried. Viewing 11 posts 1 through 11 of 11 total author posts 17th august 2008 at 14. As shown in the figure there are two main types of channels in the gsm. These 8 timeslots are further broken up into logical. Depending on the quantity of information to transmit and on their consistency, several logical channels may be mapped onto one physical channel, in order to use its successive time slots as much as possible optimization of the resources number by maximizing the occupancy duration of each.
There are broadly two categories of logical channels available. The forward channel is the direction of the communication or mobiletocell downlink path. Logical channels it transports either user data during a call or signalling information for ms or base station. Cellular telephone system, gsm channels, gsm identities. May 27, 2016 this lecture is about how the logical channels are used in global system for mobiles gsm for the mobile terminating call. Jan 14, 2011 logical channels in gsm are defined by the type of information that is carried over them. This video explains the logical channels in the gsm global system for mobile and their usage. Types of channels used in gsm and there discription. Jan 11, 20 logical channels reside between rlc sublayer and mac sublayer which are layer 2 protocols in lte protocol stack. Nu tek india limited concepts of channels in gsm a company vehicle is used for several purposes in a day similarly in gsm, the timeslots are used for.
Following table lists the logical channels that are used by lte. Physical channels, logical channels, network, and operation through a thorough description of key functional sections of a gsm network and how they communicate with each other, you will learn how and why gsm is evolving into 3rd generation broadband systems including gprs, edge, and. Gsm architecture or structure defined various channels in the air interface or radio interface. Radio channels, physical channels and logical channels. Arfcn x, timeslot y, frame number n logical channels control channels traffic channels concepts of channels in gsm. Gsm, gprs, edge, channel allocation, tdma, time slot. Logical channels can be broadly divided into two types.
Logical channels the data, whether user traffic or signaling information, are mapped onto the physical channels by defining a number of logical channels. This page on gsm tutorial covers gsm logical channels and their functions. Naturally the system does use the gsm control and broadcast channels for initial set up, but all the gprs actions are carried out within the gprs logical channels carried within the pdch. They are used to transport speech, user data, high layer signally, cell specific information to name a few. Logical channels can be thought of as just different types of data that is transmitted only on certain frames in a certain timeslot. A traffic channel tch is used to carry speech and data traffic. Gsm channels part 3 call flow in gsm using logical channels. Simply put, this means in direct radio to radio communication the same frequency may be used for.
A physical radio channel is a radio frequency or pair of frequencies that is allocated by the regulatory body to an agency for communication. Use features like bookmarks, note taking and highlighting while reading introduction to gsm. Based on, as mentioned earlier, whether they carry gsm traffic ie, speech or data or. Study and learn these interview mcq questions and answers on 2g gsm logical channels and types. The video explains the orderly use of pch, rach, sdcch, sacch and tch. Logical channels reside between rlc sublayer and mac sublayer which are layer 2 protocols in lte protocol stack.
Fdma parts involves the division by frequency of the 25 mhz bandwidth in to 124 carrier frequencies also called arfcn spaced 200 khz for gsm900. This lecture is about how the logical channels are used in global system for mobiles gsm for the mobile terminating call. Cdma channels can be broadly categorized as forward channel and reverse channel. At first i will center the study in the objectives and main characteristic of. May 20, 2015 all these kinds of messages are classified in logical channels. All these kinds of messages are classified in logical channels. Study and learn these interview mcq questions and answers on 2g gsm channels, types and functionalities. Different bursts are mapped to these channels uniquely as per gsm technical specification 05. The physical channels are determined by the timeslot, whereas the logical channels are determined by the information carried within the physical channel. It is most often used in the context of a trunked radio system, where the control channel sends various data which coordinates users in talkgroups.
Every gsm gprs physical channels are mapped to one of these burst types and the mapping is described below. In the radio subsystem, the physical channel supports the logical channel based on the type of message transmitted. From the physical layer, the mac layer uses services in the form of transport channels. Umts logical channels and transport channels 3glteinfo. Broadcast control channel bcch it used for broadcasting mibssibs. Logical channels define what type of information is being transferred and transport channel defines how the information is being transferred logical channels. Gsm logical channels gsm logical channels consists of two types.
Download it once and read it on your kindle device, pc, phones or tablets. In p25 phase 1, a physical channel and logical channel are the same thing. For gsm 1800 frequency spectrum of 75 mhz bandwidth is. Introduction to physical and logical channels tel3pedia.
A physical channel may carry different messages, depending on the information that is to be sent. Traffic channels tchs are intended to carry either encoded speech or user data. Introduction to global system for mobile communication. Introduction in telecommunications a channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel. In summary, a physical radio channel is the frequency or frequency pair allocated by the regulatory body. Mapping in frequency of logical channels onto physical channels.
Control channels control channels further consists of three groups namely broadcast control channel, common control channel and dedicated control channel. A logical channel will carry information of a specific type and a number of these channels may be combined before being mapped onto the same physical channel. Two types of logical channels map onto physical channels control channels call setup, power adjustment, etc traffic channels voice or data 22. Channel types decide whether to carry traffic or signalling information. Umts channels logical,transport,physical umts channels. In gsm, these channels are separated into physical channels and logical channels. In radio communication, a control channel is a central channel that controls other constituent radios by handling data streams. Introduction to global system for mobile communication gsm. These gsm logical channels are responsible for effectively using the radio interface between a mobile and base transceiver station bts. February, 28th 2005 overview in this document i make a study of third mobiles generation systems. It is most often used in the context of a trunked radio system, where the control channel sends various data which coordinates users in talkgroups in gsm networks, control channels are divided into three categories. Aug 25, 2009 logical channels define what type of information is being transferred and transport channel defines how the information is being transferred.
Nu tek india limited channels in gsm air interface logical channels. This chapter explains the functionalities of these channels. There are two main categories of logical channels in gsm. Principles for channel allocation in gsm diva portal. Sample is95 system identifiers telcom 2720 30 is95 logical channels cdma systems define multiple channels per frequency channel pilot channel provides a reference to all signals beacon sync channel used for obtaining timing information paging channel used to page the mobile terminal when there is an. This topic has 10 replies, 1 voice, and was last updated 9 years, 3 months ago by deepak. In gsm as well, we have many different types of physical and logical channels and each of these channel types are using its own physical structure at the level of a slot burst. Logical channels the physical channels one timeslot per radio channel shown in the previous slides represent the entity transmitted through the air interface each physical channel is used totrasmit a logical channel with different functions logical channels can be divided in 2 main groups traffic channel tch. The defintion of logical channels and details of traffic channels has been discussed in the previous. For example, on one of the physical channels used for traffic, the traffic itself is transmitted using a traffic channel tch message, while a handover instruction is transmitted using a fast associated control channel facch message. The channel used in the air interface is divided into two types. The cross reference between gsm, umts, 3gpp and etsi identities can be found under.
Aug 03, 2017 in lte we have 7 logical channel in downlink and 3 logical channels in uplink. Chapter 4, by far the longest chapter in this book, covers the gsm air interface. These channels are defined by gsm architecture or structure. Every gsmgprs physical channels are mapped to one of these burst types and the mapping is described below.
Fdma parts involves the division by frequency of the 25 mhz bandwidth in to 124 carrier frequencies also called arfcn spaced 200 khz for gsm 900. In p25 phase 2, a physical channel is divided into two time slots or logical channels. Followings are the types of burst being used in gsm gprs. Followings are the types of burst being used in gsmgprs. Halfrate tchs double the capacity of a system effectively by making it possible to transmit two calls in a single channel. Physical channels, logical channels, network, and operation. To understand the mapping of the logical channels onto physical channels, it is good to understand the two dimensions in time used by the gsm frame structure for more details on the frame structure, see section 3. Logical channels in gsm are defined by the type of information that is carried over them. Different time slots will carry different logical channels, depending on the structure the bss uses. This tutorial on umts covers umts logical channels, transport channels and physical channels. A logical traffic channel in gsm is abbreviated by tch.
One topic that often causes confusion in digital radio networks is the difference between physical and logical channels. However, lte provides additional logical channels for features not yet supported by nr but likely to be introduced in upcoming releases. Logical channels reside between radio link control rlc and medium access control mac layer. In downlink there are 4 control channel which carried common channel information as well as dedicated channel information. In lte we have 7 logical channel in downlink and 3 logical channels in uplink. The above logical channels are in general present also in an lte system and used for similar functionality. There are physical and logical channels in gsm radio system.
Logical channel type in gsm as we know, every cell has several trx and every trx includes 8 timeslots i. May 26, 2016 this video explains the logical channels in the gsm global system for mobile and their usage. Logical channels tells what kind of information is transferred. Gsm logical channels free download as powerpoint presentation. Control channels for the transfer of control plane information traffic channels for the transfer of user plane. These channels assist in call terminations and sms delivery. The traffic channels are the resources available to the user for either speech or data. Based on, as mentioned earlier, whether they carry gsm traffic ie, speech or data or gsm.
As they tranverse between layers they map to other layer frames. Described are the fundamental capabilities and operation of the gsm radio channel including channel coding, modulation types, speech coding, rf power control, and mobile assisted handover. The following picture depicts the logical channel hierarchy. Physical channels, logical channels, network, and operation kindle edition by harte, lawrence. Carries user data speech and data halfrate channel tchh.
In this tutorial different types of logical channels and transport channels and their mappings are described. I understand the different types of channels common continue reading gsm logical vs physical channels. There is a variety of channels used within gprs, and they can be set into groups dependent upon whether they are for common or dedicated use. As shown in the figure, there are three types of umts channels viz. It covers fcch, sch, bcch, ccch, rach, agch, pch, cbch, sacch, sdcch and facch.