TDMA Technology
Introduction:
TDMA, or time division multiple access, is a complex innovation that necessitates exact synchronization between the transmitter & the collector. In modern portable radio frameworks, TDMA is used. Individual portable stations deliver a constant recurrence for the selective usage of time.
In most circumstances, a station does not receive the entire framework data transfer capability for a given period. However, the recurrence of the framework is divided into sub-bands, and TDMA is employed for different accesses in each sub-band. Transporter frequencies are sub-groups. This strategy is used by a portable framework that alludes to multi-transporter frameworks.
The overall structure of TDMA is Time Division Multiple Access, which uses time rather than recurrence. It is used to promote channel sharing with no resistance. The diversified customer has a comparable time allocation of the overall time available. Each client is assigned a time allotment during which the user can access the diversion, and only one client is allowed to transmit or receive in each opening. TDMA is more widely used in Europe, Japan, & Asian countries, Whereas, CDMA is widely used in South and North America. Nonetheless, the two inventions are now quite well-known all across the world.
Working of TDMA
In TDMA, users transmit quickly, each utilizing their time slot. This shuttling mechanism is so rapid that users believe they share the same RF channel. By giving every user a predetermined amount of bandwidth, TDMA enhances the amount of data transferred over the channel while allowing simultaneous talks.
North American TDMA is a variation of TDMA utilized in North America. TDMA is used in nearly every 2G cellular system, including the following:
- Advanced Digital Mobile Phone Service.
- GSM stands for Global System for Mobile Communications.
- Personal Digital Cellular (PDC)
- Improved Digital Integrated Network.
TDMA is also used in Digital Improved Cordless Telecommunications, a standard to create cordless telephone networks in Europe, Australia, South America, & Asia.
Characteristics of TDMA
- Multiple users share a single carrier frequency.
- Non-continuous transmission facilitates handoff.
- Slots in dynamic TDMA can be allocated on demand.
- Power control is less tight because of less intracellular interference than in CDMA.
- Overhead for synchronization is more significant than in CDMA.
- If the channel is "frequency selective" and creates InterSymbol interference, advanced equalization may be required for high data rates.
- More sophisticated cell breathing (borrowing resources from neighboring cells) than in CDMA.
- The complexity of frequency/slot allocation.
- Interference with other devices: pulsating power envelope.
TDMA Dynamic
Based on the traffic demand of each data stream, a dynamic time-division multiple access (dynamic TDMA) scheduling system dynamically distributes a variable number of time slots in each frame to variable bit-rate data streams. In this, dynamic TDMA is used.
- HIPERLAN/2 broadband radio access network.
- IEEE 802.16a WiMax
- Bluetooth
- Military Radios / Tactical Data Link
- TD-SCDMA
- ITU-T G.hn
- Simulation of TDMA / DTMA links
TDMA Features
TDMA is a wireless shared-medium network technology that divides a signal into different time slots to allow several users to share the same frequency channel. The users quickly transmit one after the other, each using its time slot, allowing several stations to utilize the same transmission medium while consuming only a portion of its channel capacity.
The TDMA system splits the radio airwaves into time slots only one user can transmit or receive.
- Guard time should be reduced when using TDMA features.
- Because the transmission rate is significant, adaptive equalization is required.
- Multiple users share a single carrier frequency.
- Data is transmitted in small bursts.
- The challenge of allocating frequency/slots.
- In dynamic TDMA, slots could be allocated to demand similarly.
- Power control could be more rigorous.
- Non-continuous transmission facilitates handoff.
- More difficult cell respiration.
- Interference with other devices & pulsating power envelope.
- Low battery consumption because the subscriber's transmitter could be turned off when not in use.
- A separate time slot for transmission and receiving so that duplexes are rarely required in this system.
Applications of TDMA
One type of multiple access mechanism is TDMA. First, consider the overall structure of TDMA. Users can only transmit during a specific period using a standard frequency range. It enables multiple users to communicate simultaneously on the same frequency band, each with its time slot.
- TDMA is used in digital cellular telephony.
- The Satellite Networks.
- It employs GSM, IS-136, and iDEN.
- For packet mode communication, dynamic TDMA is employed.
- GSM also uses TDMA in conjunction with FDMA. It is one of the advantages of TDMA.
- PON networks Are also used for upstream traffic from the premises to the operator.
- TDMA is also utilized in voice communication.
Benefits of Time Division Multiple Access
- TDMA can adapt to information transmission as well as voice correspondence.
- It has data transfer rates ranging from 64 kbps – 120 Mbps.
- There is no impedance in synchronous transmission.
- TDMA is a clever concept that allows a simple framework to be computerized.
- Provide a single transporter recurrence with various clients.
- A varied supported handoff is possible.
- TDMA enhances the client's battery life by interacting alone for a portion of the time during discussions.
- Piece rate flexibility
- There is no need for a recurring watch band.
- There is no need for a precise narrowband channel.
- TDMA isolates clients based on time assurances that no interference from concurrent transmissions will occur.
- TDMA enables administrators to use fax, voiceband information, SMS, and mixed media & video conferencing applications.
- TDMA provides significant investment dollars in base-station hardware, space, & support, which is essential as cell sizes shrink.
- It has a frequency range of 800/1900 MHz and is the only innovation that uses hierarchical cell topologies like Pico, micro, and macro scale.
Disadvantages of Time Division Multiple Access
As a result, if all of the time allotments in the subsequent cell are now involved, the cell may be disengaged. Similarly, if all the time allotments in a customer's cell are now implicated, the client will not receive a dial tone.
- It is vulnerable to multipath twisting. A signal from a pinnacle and get to the handset could arrive from a few directions. Therefore, the signal may have echoed off several separate structures before appearing, causing resistance.
- The focus is on organization and range arrangement.
- To a few customers, the ideal channels are rural versus city climate.
- Overhead for synchronization is significant.
- In TDMA, recurrence/opening assignments will be complicated.
- For high information rates, adaptation was critical.
- In transitory mode, this command necessitates a high maximum uplink power.
- Coordinated separation and connection recognition need signal preparation.
Distinctions between TDM & TDMA
Each user in TDM and TDMA is allotted a time slot during which their data is sent. In TDMA, however, it is released after a user has finished utilizing their time slot, and they must wait for their turn to broadcast again. Furthermore, each time a user connects to the cellular network, they may be assigned a different time. Furthermore, the multiplexed signals may originate from several sources or transmitters.
A specific time slot is permanently assigned to a user in TDM, even if they are not utilizing it. Additionally, multiplexed signals originate from the same mobile node.
Examples of TDMA
IS-136, personal digital cellular (PDC), integrated digital enhanced network (iDEN), & the second generation (2G) Global System for Mobile Communications (GSM) all make use of TDMA.
TDMA allows the radio component of a mobile station to listen & broadcast only during its designated time slot. During the remaining time, the mobile station may measure the network by detecting nearby transmitters at various frequencies. This feature enables inter-frequency handover, as opposed to code division multiple access (CDMA), which makes frequency handover problematic. Conversely, CDMA allows mobile stations to interact with up to six base stations simultaneously.
Most 2G cellular systems use TDMA, whereas 3G systems use CDMA. TDMA, on the other hand, is still relevant in modern systems. FOR EXAMPLE, coupled TDMA, CDMA, and time division duplex (TDD) are UTRA systems that allow several users to share a single time slot.
Concerning Two-Slot TDMA
TDMA, conversely, provides a proven method for achieving 6.25 kHz equivalency on 12.5 kHz repeater channels - a substantial advantage for users in increasingly congested licensed bands. Instead of two smaller slices, TDMA distributes the entire channel width into two alternate time slots. As a result, TDMA effectively doubles repeater capacity while retaining the 12.5 kHz signal's well-known RF performance characteristics. Regarding RF physics, the 12.5 kHz signal of two-slot TDMA fills the channel, propagates, and performs essentially the same as today's analog 12.5 kHz transmissions.
TDMA-based radios can deliver nearly twice the analog capacity while providing RF performance equivalent to or better than today's analog radios on a single repeater channel.
![TDMA – Technology](https://static.tutorialandexample.com/computer-networks/tdma-technology1.png)
As we see, the two-time slots can be utilized for various purposes. Most businesses contemplating TDMA-based two-way radio will aim to quadruple the voice capacity per licensed repeater channel. TDMA allows two simultaneous, independent half-duplex calls in a single 12.5 kHz repeater channel by giving 6.25 kHz equivalence.
If you're used to thinking in terms of analog radio, this two-for-one potential in two different periods may be an issue. Wouldn't the two calls clip in and out when the time slots changed, making it impossible to follow both discussions? However, remember that we live in a digital world where speech is encoded in bits. Although analogy signals indicate the actual duration of uttered syllables, digital signals can encode that duration so that significant compression is possible without sacrificing voice quality. Every TDMA time slot is only about 30 milliseconds long. The voice-to-bits technology can incorporate 60 milliseconds of digitized speech into each 30-millisecond time frame. In turn, the receiver unpacks those bits into speech in 60 milliseconds. That is why, with TDMA, two conversations can occur concurrently and fluidly across a single repeater.
Time slots vary solely in the technology, not the user's experience. Digital discussions will likely be much more straightforward than a single analog conversation over the same channel since digital technology suppresses background noise better than analog while keeping signal integrity at the farthest ends of the transmitter's range. And, because both talks use the entire bandwidth of the channel, there is no reduction in range performance or increased danger of interference with adjacent channels.
Conclusion:
We learned about TDMA technology as well as its benefits, drawbacks, and characteristics, as well as instances.