Posted at 10.15.2018
TDMA stands for Time division multiple access. It is mainly a channel gain access to method that can be used for distributed medium networks as well as a digital transmitting technology that allows its users to gain access to a single radio-frequency channels with no interference. and it allocates to its users unique time slots within each route. TDMA is the common kind of service that is employed in North America. Mainly. TDMA is used in 2G cellular system(GSM, PDC, IDEN, IS-136, DECT). In cases like this a single route is divided into six time slots and each signal is using two time slot machine games. To help make the transmission possible each caller is allocated a particular time slot. TDMA offers high performance regarding capacity, courage and freedom. TDMA mainly transmit data in a buffer-and-burst method and the transmitting of any individual is non- constant.
In TDMA frame framework a data stream divided into frames and those frames split into time slot machines.
and we clarify the concept of TDMA frame structure by using a good example:-
In this case you have the TDMA structure shown designed to use seven group of frequencies that are sufficient to pay the top area that delivers the maximum distance d that is bigger than twice the utmost radius r, the radius that is being included in each transmitter. and the space of each time slots that are produced from the occurrence channels is 0. 577ms and these 8 slots make a TDMA shape of span 4. 615ms.
There are main three burst present in the TDMA:-
Normal Burst:- The transmitting of the data during the one time slot is known as a burst. and the shield time that is employed to avoid the burst suffering from the overlapping is 8. 25 parts.
In the standard Burst there are four types of bits as given below:-
Frequency Modification Burst:- FCB is mainly an unmodulated carrier which then after shift in regularity. The officer time found in the FCB is identical to that of the standard bit. It is used for regularity synchronization of the mobile channels.
Synchronization Burst:- Enough time synchronization of the mobile can be done by using synchronization burst. The payload used in this holds the FDMA frame amount (FN) and Foundation Station Individuality Code (BSIC). and the broadcasting in cases like this is with the frequency modification burst. and also broadcasting occurs on the synchronization channel.
Access Burst:- Firstly the officer burst used in this very longer as compared to the normal burst, so that it is 68. 25bit is. The mobile stations use this type of the burst for random access. In addition, it helps to gauge the undiscovered distance of any mobile train station from the tower, when the MS wants to gain access to to the new BTS.
The main drawbacks of TDMA receive as below:-
2G Systems:- Many 2G Systems derive from the TDMA. So we can say the TDMA as TDMA cellular systems such as the main examples of the TDMA cellular systems are GSM, IS-95, D-AMPS, PDC, iDEN and PHS. As regarding GSM it combines the TDMA with occurrence hopping and the wideband transmitting, to be able to minimize the interference. So regarding GSM system, base train station send the timing commands which is then helpful in the synchronization of the mobile phones that are helpful in easier transmission and decide the time. You have the guard interval regarding GSM. There is the RACH in GSM. Whenever the mobile is within the next base ststion, then the call arrived sucessfully with no delay. of course, if the mobile is situated beyond the 35 kilometres range in GSM, then the RACH used in this will get to the time slot that is in the neighboring. So there is absolutely no special technique to limit the range of the GSM cell to 35 km. So to get over this problem, the synchronization is evolved between the uplink and downlink in the base station.
3G Systems:- 3G system use the mixture of both CDMA and TDMA. So it take the advantage of both techniques. Typically the most popular 3G systems are UMTS which use CDMA instead of TDMA, and in TD-CDMA and TD-SCDMA, the TDMA is combined with CDMA and TDD.
Firstly we all know that the TDMA become a technology of the past. Regarding TDMA the info is compressed in to packets within its same bandwidth. Some important things about the TDMA receive as below:-
iDEN:- It is a Integrated Digital Enhanced Network and it is comparable to as that of the GSM technology and it is functioning at 800 MHz, 1900MHz and 1. 5 GHz in the US. It can be used to take care of the CDMA and GSM technology. It could take care of three users per channel and for the purpose of more capacity and demand, it is require the utilization of more towers which is costly.
CDMA stand s for Code Division Multiple Access which is a technology that delivered as a constant flow across larger bandwidth instead of sending a sign into packets and directed on cycles, CDMA transmissions.