TTI bundling has been recently introduced as a feature of LTE. Rel. 8 to improve the uplink coverage. In TTI bundling, a VoIP packet is transmitted as a single. TTI Bundling optimizes the uplink (cell edge) coverage for services like VoLTE. For services such as VoIP, the packet size is small and the. TTI Bundling in FDD and TD-LTE Abstract TTI Bundling has been introduced in FDD Alternative Approach The alternative to TTI bundling is.

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There is no way to reduce the waste of subframe caused by retransmission, but there is some way to reduce the wast of subframe caused by scheduling restriction. The simple answer is to increase the possibility of data reception at the destination. Combined processing of the ti transmissions over multiple subframes leads to a better probability of detection of the transport block.

Should it be always like this i. Eric November 29, at 8: Is this ‘Not allowed’? On the other hand, sender will send the same data again but this time, with different set of coded bits.

In case the bundle is not received correctly, it is repeated in the same way as an ordinary transmission ttii a packet.

TTI Bundling in FDD and TD-LTE

Pte KN July 5, at 8: There must be some technical reason why they are not varied. Or is equally applicable to both? Latency is also reduced as no waiting time is required between the retransmissions. TTI bundling is used to achieve successful transmissions from power limited terminals. We will first explore the motivation for TTI Bundling and then compare it with other techniques.


There might be retransmissions of each of those transport blocks which will also potentially increase the control signaling overhead.

This triggers the eNB to transmit the various redundancy bkndling of the same transport block in consecutive subframes or TTIs giving rise to the name TTI bundling. Overview of TTI Bundling.

Unknown December 14, at 2: This will repeat as long as the receiver is not able to decode the data.

LTE TTI Bundling – WirelessMoves

Therefore, in a case where the communication is for time critical communication and UE is in the area of poor coverage e. Adnan Basir April 17, at 2: Sekhar joined Award Solutions inand has over 16 lye of experience in wireless telecommunication industry with mobile cellular, digital communications technologies. Now you may have another question. This approach can also reduce the delay in the HARQ process compared to transmissions of the redundancy versions separated in time using the normal approach.

Looking at the illustration at the beginning, you might think this is too much waste of subframes, partly because of multiple retransmission and partly because of scheduling restriction the empty subframes you saw in the illustration at the beginning.

In addition, since we are transmitting many small transport blocks, the chances ltf interpreting a NACK as a ACK also increases proportionately with the increase in the RLC segmentation size. Typical case of TTI Bundling can be illustrated as shown below. There is one drawback however, that it can result in delay and too much control overhead in case of poor radio conditions if the sender has to attempt many transmissions.


Rachel Johnson October 13, at At first the feature name reminded me of the packet bundling that is done in Wi-Fi, which concatenates several packets into one transmission burst thereby saving a lot of air interface overhead. Check the following figure to understand the concept of TTI.

When the base station detects that the mobile can’t increase it’s transmission power and reception is getting worse it can instruct the device to activate TTI bundling and send the same packet but with different error detection and correction bits in 2, 3 or even 4 consecutive transmit time intervals.

Normally, a transport block is converted to multiple redundancy versions after coding buneling the first redundancy version is sent in a subframe. For services like VoIP this means bad end user experience. In some aspect, you may say this is a kind of wasting resources. Unknown April 25, at The reciever will combine the previously recieved erroneous data with newly attempted data by the sender.