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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TTI Bundling in FDD and TD-LTE

bunrling The channel coding used in LTE enables easy generation of the multiple redundancy versions from which the transmissions in the TTI bundle are generated. Or only in UL? So the basic idea of TTI bundling is to improve performance of VoIP applications at cell edge and therefore it happens only in uplink Hope this helps. We will first explore the motivation bundking TTI Bundling and then compare it with other techniques. Adnan Basir April 17, at 2: Vicky January 15, at Altamont April 16, at 2: Bhavesh Thakker February 21, at Or is there any misunderstanding from my side?

Should it be always like this i. What would be the advantages let drawbacks of TTI bundling compared to this other solution if it is possible to implement?

LTE TTI Bundling

For services like VoIP this means bad end user experience. Check the following figure to understand the concept of TTI. Newer Post Older Post Home. 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 bund,ing conditions. In ttii the bundle is not received correctly, it is repeated in the same way as an ordinary transmission of a packet. Emeka Ijere February 20, at 7: Sekhar joined Award Solutions inbundlint has over 16 years of experience in wireless telecommunication industry with mobile cellular, digital communications technologies.


Latency is also reduced as no waiting time is required between the retransmissions.

How LTE Stuff Works?: TTI Bundling

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. Or is equally applicable to both?

Winnie Bundilng August 4, at 4: 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. TTI bundling is used to achieve successful transmissions from power limited terminals.

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 bundlijg illustration at the beginning.

Rachel Johnson October 13, at Normally, a transport block is converted to multiple redundancy versions after coding and the first redundancy version is sent in a subframe.


There is one drawback however, that it can result in delay and too much control overhead in case of bnudling radio conditions if the sender has to attempt many transmissions. Typical case of TTI Bundling can be illustrated as shown below. The reciever will combine the previously recieved erroneous data with newly attempted data by the sender.

Rakshith KN July 5, at 8: According to this statement, the PHICH timing for all the case illustrated above the answer is same as follows.

Therefore, in a case where the communication is bundlingg time critical communication and UE is in the area of poor coverage e. In some aspect, you may say this is a kind of wasting resources. There must be some technical reason why they are not varied.

Then Why we need this kind of method? Unknown April 25, at There might be retransmissions of each of those transport blocks which will also potentially increase the control signaling overhead. Isn’t it too much waste of subframes? 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. Now bujdling may have another question.

A single RLC PDU is transmitted as multiple redundancy versions in consecutive subframes using a single common allocation. Eric November 29, at 8: