Question

Summarize in your own understanding what would be the requirement in LTE design for DL and UL CoMP to work as expected.

Answer 1

Let's get to both one by one

Downlink LTE CoMP: The downlink LTE CoMP requires coordination amongst several separated eNBs transmitting to the UE.Using this element of LTE CoMP, data is transmitted to the UE simultaneously from nom of different eNBs. The aim is to improve the received signal quality and strength. And the aim of removing the interference from transmissions that are intended for other UEs.This form of coordinated multipoint places a high demand onto the backhaul network because the data to be transmitted to the UE needs to be sent to each eNB that will be transmitting it to the UE. This may easily double or triple the amount of data in the network dependent upon how many eNBs will be sending the data. In addition to this, joint processing data needs to be sent between all eNBs involved in the CoMP area.Using this concept, data to a single UE is transmitted from one eNB. The scheduling decisions as well as any beams are coordinated to control the interference that may be generated.The advantage of this approach is that the requirements for coordination across the backhaul network are considerably reduced for two reasons:UE data does not need to be transmitted from multiple eNBs, and therefore only needs to be directed to one eNB.Only scheduling decisions and details of beams needs to be coordinated between multiple eNBs.

Uplink LTE CoMP:The basic concept behind this format is to utilise antennas at different sites. By coordinating between the different eNBs it is possible to form a virtual antenna array. The signals received by the eNBs are then combined and processed to produce the final output signal. This technique allows for signals that are very low in strength, or masked by interference in some areas to be receiving with few errors. The main disadvantage with this technique is that large amounts of data need to be transferred between the eNBs for it to operate.Coordinated scheduling decisions amongst the ENBs to minimise interference. As in the case of the downlink, this format provides a much reduced load in the backhaul network because only the scheduling data needs to be transferred between the different eNBs that are coordinating with each other.