Gugal Emeka Ijere February 20, at 7: In some aspect, you may say this is a kind of wasting resources. Why are the durations of the TTIs all common, or equal? Combined processing of the redundant transmissions over multiple subframes leads to a better probability of detection of the bundlijg block. Should it be always like this i.
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Gugal Emeka Ijere February 20, at 7: In some aspect, you may say this is a kind of wasting resources. Why are the durations of the TTIs all common, or equal?
Combined processing of the redundant transmissions over multiple subframes leads to a better probability of detection of the bundlijg block. Should it be always like this i. Maybe that exists as well. Bundllng 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. A single RLC PDU is transmitted as multiple redundancy versions in consecutive subframes using a single common allocation.
Thanks for the chart on explaining it visually. Altamont April 16, at 2: This way we are avoiding delay and reducing control plane overhead at mac layer. TTI bundling is used to achieve successful transmissions from power limited terminals. Or is equally applicable to both? This could for example happen at the edge yti a cell when the terminal has to send high power but is limited by the power capability of the terminal.
Normally, a transport block is converted to multiple redundancy versions after coding and the first redundancy version is sent in a subframe.
This way the chances of successfully decoding the bits improve every time. Tt, in a case where the communication is for time critical communication and UE is in the area of poor coverage e. Thus, with limited power, the UE has a better chance of a successful transmission with lesser latency using the TTI bundling method.
This triggers the eNB to transmit the various redundancy versions of the same transport block in consecutive subframes or TTIs giving rise to the name TTI bundling.
What would be the advantages and drawbacks of TTI bundling compared to this other solution if it is possible to implement? Eric November 29, at 8: The process as shown in Figure 3 is typically triggered by UE informing the eNB about its power limitations at the present state. In case the bundle is not received correctly, it is repeated in the same way as an ordinary transmission of a packet.
The simple answer is to increase the possibility of data reception at the destination. The purpose of TTI Bundling is to improve cell edge coverage bunling in-house reception for voice. About Sekhar Sekhar joined Award Solutions inand has over 16 years of experience in wireless telecommunication industry with mobile cellular, digital communications technologies.
Just enable a ttiBundling IE as shown below. Vicky January 15, at.
The data block in a bundle of TTIs, where the chunk of each bundle up to 4 chunks , is modulated with different redundancy versions within the same HARQ identity. The resource allocation during this operation is restricted to a certain number of PRB and transport block size TBS in order to improve the probability of decoding at lower data rates. The mechanism to transmit same packets four times in one scheduling instance expands the coverage by increasing the uplink transmission reliability with a better success rate gain. In addition, it guarantees that VoLTE packets are transmitted at cell-edge when resources are limited to improve the latency in bad radio conditions.
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In particular it was seen to improve VoLTE speech quality. Quite a bit of thinking ahead because we were far away from VoLTE in practice back then. Just a quick recap on how TTI bundling works: Instead of one transmission, TTI bundling transmits 4 different redundancy versions of a packet in the uplink direction, i. This way, the network can combine the four transmissions and thus cope with more transmission errors. But when I was recently doing some drive testing in the US in very rural areas, I noticed that TTI-bundling actually got activated occasionally. And it was direly needed indeed as the base station sites were so far apart from each other that handovers regularly occurred at an incredibly low signal level of dBm. To set that into context, in urban environments, LTE handovers are done somewhere between and dBm, i.
TTI Bundling for better HARQ and Latency
LTE TTI Bundling in the Wild