2009年3月31日星期二

关于WCDMA小区重选

RSCP
We can get RSCP from Rx_AGC and Ec/Io.

RSCP=Rx_AGC+Ec/Io


WHICH VERSION OF AMSS SUPPORTS THIS PACKET?
This packet has been supported since AMSS6200 version 4.3 and higher. This packet is generated whenever cells are ranked.


REPORTING INTERVAL
This log packet 0x4005 is reported by L1 when measurements are made for cell reselection only in idle mode/Cell_FACH. This packet is generated whenever cells are ranked.

So this is really event driven, rather than timed and should follow the rules as specified in 25.304 and 25.133.

NW parameters such as the number of neighbors, various kind of neighbors, thresholds associated with serving cell or neighbor cell as well as length of DRX cycle... All that might have an influence on the freq of this log reports.


HOW TO SEE WHEN RESELECTION STARTS AND ENDS
There are 4 Event Reports that can tell you this. Create a Filtered View with Event ID 530-533 enabled.


WCDMA CELL STRUCTURE IS 10 BYTES INSTEAD OF 9
QCT has confirmed that there is bug in the ICD and it will be fixed in next release. QCT is tracking this issue through internal CR 42642.


ONLY MONITORED SET CELLS REPORTED

  • Active cells in list search (0x414F) and active set (0x4110)
  • Intra freq monitored cells in list search and cell reselection (0x4005) and neighbor set (0x4111)
  • Inter rat monitored cells in cell reselection
  • inter freq monitored cells in cell reselection when it will be available.

We don't have a packet that has everything about reselection. The very nature of Cell Reselection makes it difficult to summarize all the info in one place... (Different scenario, different RATs...). With these existing Log packets, we can achieve the primary purpose Understand reelection scenarios and debug potential issues.

IS THIS PACKET ONLY VALID IN IDLE STATE?
Yes, only in idle mode/Cell_FACH. There is an outstanding issue with the log packet - it does not work for inter-frequency in Idle mode (there is a CR already).


CAN WE INCLUDE ADDITIONAL PARAMETERS IN THIS LOG RELATED TO RESELECTION?
The cell reselection information (Qhyst, Treselection) can be found from SIB3 logging in WCDMA Signaling Messages Packet (LOG_CODE 0x412F). You will need to search for the Type3 SIB in the signaling log packets. Treselection is also logged in the diagnostic debug messages when the timer is incremented for neighbor cells. Search for the string "Tresel" in the Mobile Messages window in CAIT, or in LOG_CODE 0x1018.


RSCP UNITS
In packet description for 0x4005 units for RSCP mentioned is dB which is incorrect. It should be in dBm units.

RANK_ECIO

LENGTH
RANK_ECIO is defined in the code as...

int 16 (see below)
/* ECIO rank, range 0..-200, 0xFFFF -> not used */
int16 rank_ecio;

...and how you can see the range is [0.. -200], so an "int16" is actually needed. There is an error in the ICD RANK_ECIO's length.

EC/IO Ranking measurements
Assuming HCS is not used and performing intra-frequency measurements, if there is no penalty time in SIB 11 and Qoffmbms is not requested:
Rs = Qmeas,s + Qhysts
Rn = Qmeas,n - Qoffsets,n
This condition must be verified for t-Reselection-S seconds.

By reporting an example with a generic reference to UE log , considering neighboring cells ranking please refer below:

Qoffsets,n= 4dB

Cell 2:
RF freq = 10563
PSC = 30
ECIO = -2.0
rank_ecio = -12
RSCP = -77
rank_rscp = -81

Rn = -2 -4 = -6
-6*2 = -12 ran
king value

Why values are multiplied by 2: Ec/No values had a 0.5 granularity. When multiplying, it is reconducted to an integer values and comparison ranking move to those values, as also used in most 3GPP specs. Another example:

ECIO = -9.5
rank_ecio = -15

Rs = -9.5 + 2 = -7.5
-7.5*2 = -15

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