5/25/2018 BSS DRX Buffer and Paging

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From: Voutilainen Timo (EXT-Embe/Oulu)Sent: 03 May, 2002 10:09

Paging buffer size is calculated the same way in all Nokia BTS products.One must also understand that slots in this buffer equal the actual availablePCH blocks in air if. Therefore when BTS receives a paging commandfrom BSC the paging command is first analyzed (for example the BSC may setthe paging group for Paging Command) and the Paging message is then put intopaging buffer (actually we talk about DRX-buffer) into the actual slot that equa

lsthe paging group calculated...The buffer size is based on a lead time which is the time during which themessage must be scheduled into air if.gsm_buffer_area = max_paging_group * ( 1 + pch_blocks_gsm_drx / max_paging_group)

max_paging_group = ((CCCH3/9 - BS_AG_BLKS_RES) * BS_PA_MFRMS.... CCCH3/9 means that for combined BCCH there are 3 available PCH-blocks and fornon-combined there are 9 available PCH-blocks.pch_blocks_gsm_drx =

((10 * (9 - BS_AG_BLKS_RES ) * 1000 * 1000 * pa_max_lead_time )

div (51*4615 ) + 5) div 10 for non-combined CCCH and((10 * (3 - BS_AG_BLKS_RES ) * 1000 * 1000 * pa_max_lead_time)

div (51*4615 ) + 5) div 10 for combined CCCH"In existing BTS SW the maximum lead-time value (pa_max_lead_time) is also defined for traditionalGSM paging messages. The maximum lead-time value for a GSM paging message is a configurable parameter in the BTS configuration file and it canbe from 1 up to 10 seconds with one seconds intervals. The default value is 5 seconds. "

So this gsm_buffer_area is the amount of blocks available for GSM-paging messages.If TMSI is used in Paging Commands then it is possible to pack max 4 Paging mess

agesinto one air if message --> maximum number of paging message that fit into gsm areaof our DRX-buffer = 4 * gsm_buffer_area.But we must remember that even if the buffer is not full, it can happen that thePagingCommand doesn't fit into BTS's buffer (if the calculated paging group(s) are already full).

For paging messages that are scheduled GPRS-wise (DRX parameters included) thegprs_paging_buffer_space = 4* number_of_pch_blocks * 64number_of_pch_blocks = (CCCH3/9 - BS_AG_BLKS_RES))So, even though the GSM pages and GPRS pages are put into the same buffer (DRX-

buffer)in BTS, the GPRS pages can be inserted into a wider range due to longer lead time 15seconds.

5/25/2018 BSS DRX Buffer and Paging

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