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WHAT IS THE USER PLANE (UP) LATENCY IN LTE ?

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First of all understand the path and structure of user plane (UP). The diagram is shown below. Ideally for UP latency the transmission of an IP packet with 0 bytes of payload , should experience a one way User Plane latency of less than 5 msec. Therefore the round trip UP latency ought to be […]

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HOW IS CELL SEARCH PERFORMED IN LTE FDD ? LIST THE MAIN STEPS BRIEFLY.

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Cell search is the process of identifying and obtaining downlink synchronization to cells so the broadcast information from the cell can be detected. This procedure is used both at initial access and at handover. In order to perform cell search both in FDD, UE has to perform the following 5 steps. 1. Measure Reference Signals […]

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WHAT IS THE CONTROL PLANE (CP) LATENCY IN LTE ?

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First you need to understand the definition of control plane. The path shown below is termed as control plane. Control plane latency to go from Idle mode (camped state) to connected mode (active state) is expected to be less than 100 ms. For example: MME-Idle to MME-Connected.

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HOW CAN LTE TDD EFFICIENTLY CO-EXIST WITH OTHER LTE OR LEGACY UTRA TDD NETWORKS?

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In the frequency arrangements currently considered in 3GPP, several TDD carriers possibly belonging to different operator can be allocated next to each other. To handle interference between UL and DL of adjacent carriers, on the eNodeB side, one may at least use filtering to reduce interference between UL and DL on adjacent carriers. Some guard […]

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WHAT ARE THE REQUIRED GUARD PERIODS BETWEEN UL AND DL FOR LTE TDD MODE OF OPERATION?

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In LTE, the UL is synchronous which means that the eNodeB controls the transmission timing. Due to the round-trip propagation delay, the transmission start in the UE depends on the UE – eNodeB distance in order to get all uplink receptions aligned in the base station receiver. In FDD, timing alignment messages are sent by […]

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