1 / 8

RachRootSequence Planning

RachRootSequence Planning. Prepared By- RAJESH KUMAR. Random access preamble transmission. First step in the random access procedure is the transmission of a random access preamble

nara
Download Presentation

RachRootSequence Planning

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RachRootSequencePlanning Prepared By- RAJESH KUMAR

  2. Random access preamble transmission • First step in the random access procedure is the transmission of a random access preamble • Indicates to the eNodeB the presence of a random access attempt and to allows the eNodeB to estimate the delay between the eNodeB and the UE • Random access preamble is transmitted on Physical Random Access Channel (PRACH) • In a first step of the random access procedure, the UE selects one preamble to transmit on the PRACH

  3. Preamble sequence generation • The preamble consists of two parts: • Preamble sequence • Cyclic prefix • In each cell, there are 64 preamble sequences available • Preamble sequences are constructed from one or several root Zadoff-Chu (ZC) sequences, by combining different cyclic shifts of each root sequence • Logical root ZC sequence index is broadcasted as part of the System Information • There are 838 different root ZC sequences used for random access and each ZC sequence consists of NZC = 839 samples • A new parameter is introduced in the current release for the Random access process:

  4. rachRootSequence Planning • It can be beneficial to plan rachRootSequence such that the same root sequences are not used in neighboring cells • If the same root sequences are used in neighboring cells, and the PRACH allocation overlaps, this will lead to an increased false alarm ratio, where a random access preamble transmitted by a UE in the neighboring cell could be detected by the eNodeB • This is mainly a problem when the random access load is high • In cells, where UEs are traversing with high speed, the restricted set of root ZC sequences should be used • It could be applicable for cells that cover railways and highways • It is not applicable in USA because speeds on railways and highways do not exceed 105 mph (limit for 1900 MHz)

  5. rachRootSequence Planning RECOMENDATION • It is recommended to set the parameter rachRootSequence to different values in neighboring cells to reduce the probability for false RACH detections • The values must differ by at least 10 between any two neighbors (and at most 827 since there is a wrap-around between the first and last value in the value range)

  6. rachRootSequence GROUPING

  7. rachRootSequence PLANNING Process • PN planning tool in Planet will be used to generate a PN plan and then convert the PN plan to the rachRootSequence plan • Best server layer will be generated • Neighbor list will be created by utilizing best server layer in Planet • A PN plan with an increment of 7 will be generated • Gives 24 groups, no reserves • rachRootSequence grouping includes 28 groups (see slide 6) • Take the first 24 groups and replace the PN Plan created in Planet with values listed on slide 6 • 4 spare groups left

  8. THANKS

More Related