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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The channel coding used in LTE enables easy generation of the multiple redundancy versions from which the transmissions in the TTI bundle are generated.

Typical case of TTI Bundling can be illustrated as shown below.

TTI Bundling in FDD and TD-LTE – Sekhar – Expert Opinion – LTE University

In addition, since we are transmitting many small transport blocks, the chances of interpreting a NACK as ttj ACK also increases proportionately with the increase in the RLC segmentation size.

This will repeat as long as the receiver is not able to decode the data. Now you may have another question.

The simple answer is to increase the possibility of data reception at the destination. Emeka Ijere February 20, at 7: There might be retransmissions of each of those transport blocks which will also potentially increase the control signaling overhead.

Magdalena Mieczkowska November 18, at 7: We will first explore the motivation for TTI Bundling and then compare it with other techniques. Or is equally applicable to both? DJ May 29, at 3: Or is there any bundlin from my side?

Ok here is what I understand Since UE has very limited power in uplink 23dbm LTE this means that at cell edge there can be many re transmissions in uplink due to poor radio thi. But the real implementation and optimization may not as easy as it sound. 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 bundlnig 2, 3 or even 4 consecutive transmit time intervals.


The process as shown in Figure 3 is typically triggered by UE informing the eNB about its power limitations at the present state. Winnie Lee August 4, at 4: This could for example happen at the edge of a cell when the terminal has to send high power but is limited by the bundlihg capability of the terminal. In some aspect, you may say this is a kind of wasting resources.

Then Why we need this kind of method? Re transmission means control plane overhead and specially the delay which is not acceptable for services like VoIP.

So the basic idea of TTI bundling is to improve performance of VoIP applications at cell bundljng and therefore it happens only in uplink Hope this helps. Is this ‘Not allowed’? Why are the durations of the TTIs all common, or equal? Isn’t it too much waste of subframes?

All about Wired and Wireless Technology: TTI Bundling

Check the following figure to understand the concept of TTI. Adnan Basir April 17, at 2: Rakshith KN July 5, at 8: The advantage over sending the packet in a single TTI and then detecting that it wasn’t received correctly which in turn would lead to one or more retransmissions is that it saves a lot of signaling overhead. Just enable a ttiBundling IE as shown below.

The purpose of TTI Bundling is to ote cell edge coverage and in-house reception for voice.

LTE TTI Bundling

Altamont April 16, at 2: Maybe that exists as well. As shown in Figure 4, TTI thi enables up to 4 redundancy versions of the same transport block to be sent in 4 consecutive subframes. According to this statement, the PHICH timing for all the case illustrated bundlnig the answer is same as follows. Overview of TTI Bundling. Sekhar joined Award Solutions inand has over 16 years of experience in wireless telecommunication industry with mobile cellular, digital communications technologies.


In case the bundle is not received correctly, it is repeated in the same way tle an ordinary transmission of a packet. What would be the advantages and drawbacks of TTI bundling compared to this other solution if it is possible to implement? That is true, but this kind of normal retransmission mechnism cause a certain time delay e.

Latency is also reduced as no waiting time is required between the retransmissions. This way the chances of successfully decoding the bits improve every time. Rachel Johnson October 13, at A single RLC PDU is transmitted as multiple bundliing versions in consecutive subframes using a single common allocation. One drawback of this method is the potential overhead increase due to RLC segmentation due to multiple RLC headers needed.

For services like VoIP this means bad end user experience.

The reciever will combine the previously recieved erroneous data with newly attempted data by the sender. There is one drawback however, that it can result in delay and too much control overhead in case of poor radio conditions ttti the sender has to attempt many transmissions.

Thus, with limited power, the UE has bubdling better chance of a successful transmission with lesser latency using the TTI bundling method. Vicky January 15, at Newer Post Older Post Home. This way we are avoiding delay and reducing control plane overhead at mac layer. Unknown April 25, at