PRACH Open Loop Power Control Parameters
AICH PRACH
z
Timing relationship of PRACH and AICH
AICH PRACH 1 access slot τp-a τp-m τp-p Pre- amble Pre- amble Message part Acq. Ind.
z After UE transmit the first Preamble on PRACH, it will wait for the corresponding AI (Acquisition Indicator) on the AICH. The timing relationship of PRACH and AICH is shown in above figure.
z There will be 3 parameters used to define the timing relationship:
τp-p: time interval between two PRACH preambles. τp-pis not a fixed value, it is decided by selecting access slot of PRACH preambles,
Here τp-phas one restriction, it must be longer than a minimum value τp-p min , namelyτp-p≥τp-p min.
τp-a: time interval between PRACH preamble and AICH Acquisition Indicator. If UE sends the PRACH preamble, it will detect the responding AI afterτp-atime. τp-m: time interval between PRACH preamble and PRACH message part. If UE
sends the PRACH preamble and receives positive AI from the AICH, it will send the message part after τp-mtime.
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PRACH Open Loop Power Control Parameters
z
AICHTXTIMING
Parameter name: AICH transmission timing
Content:
When AICHTXTIMING = 0,
τ
p-p,min= 15360 chips,τ
p-a= 7680 chips,τ
p-m= 15360 chips When AICHTXTIMING = 1,
τ
p-p,min= 20480 chips,τ
p-a= 12800 chips,τ
p-m= 20480 chips
The recommended value is 1
z Parameter AICHTXTIMING is used to define the set of τp-p min, τp-a, τp-m.
z AICHTXTIMING
Parameter name: AICH transmission timing Value range：0,1
Content:
When AICHTXTIMING = 0,
τp-p,min= 15360 chips, τp-a= 7680 chips, τp-m= 15360 chips
When AICHTXTIMING = 1,
τp-p,min= 20480 chips, τp-a= 12800 chips, τp-m= 20480 chips
Recommended value: 1
Set this parameter through ADD AICH, query it through LST AICH, and modify it needs de-activated the cell through DEA CELL. After the old configuration of AICH is deleted through RMV AICH , a new AICH can be established through ADD AICH
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PRACH Open Loop Power Control
z
Power Ramping for Preamble Retransmission
Power Ramp Step
Power Offset Pp-m Preamble_Initial _Power Message part Pre- amble Pre- amble …… Pre- amble Pre- amble ＃1 ＃2 ＃3 ＃N
z After UE transmit the first Preamble,
If no positive or negative AI on AICH is received after τp-atime,
UE shall increase the preamble power by POWER RAMP STEP, and retransmit the preamble.
This ramping process stops until the number of transmitted preambles has reached the MAX PREAMBLE RETRANSMISSION within an access cycle, or when the maximum number of access cycles has reached MAX
PREAMBLE LOOP.
If a negative AI on AICH is received by the UE after τp-atime,
which indicates rejection of the preamble, the UE shall wait for a certain “Back-off Delay” and re-initiate a new random access process.
When a positive AI on AICH is received by UE after τp-atime,
it will transmit the random access message after the uplink access slot of the last preamble.
The transmit power of the random access message control part should be
POWER OFFSET higher than the power of the last transmitted preamble.
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PRACH Open Loop Power Control Parameters
z
POWERRAMPSTEP
Parameter name: Power increase step
The recommended value is 2, namely 2dB
z
PREAMBLERETRANSMAX
Parameter name: Max preamble retransmission
The Recommended value is 20
z POWERRAMPSTEP
Parameter name: Power increase step Value range : 1 to 8
Physical Value Range: 1 to 8 dB
Content: The power increase step of the random access preambles transmitted before the UE receives the acquisition indicator in the random access process. Recommended value: 2
Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and modify it through MOD PRACHUUPARAS
z PREAMBLERETRANSMAX
Parameter name: Max preamble retransmission Value range : 1 to 64
Content: The maximum number of preambles transmitted in a preamble ramping cycle.
Recommended value: 20
Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and modify it through MOD PRACHUUPARAS
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PRACH Open Loop Power Control Parameters
z
MMAX
Parameter name: Max preamble loop
The recommended value is 8
z
NB01MIN / NB01MAX
Parameter name: Random back-off lower / upper limit
The recommended value: 0 for both NB01MIN / NB01MAX
z MMAX
Parameter name: Max preamble loop Value range: 1 to 32
Content: The maximum number of random access preamble loops. Recommended value: 8
Set this parameter through ADD RACH, query it through LST RACH, and modify it first de-activated the cell through DEA CELL, then MOD RACH.
z NB01MIN / NB01MAX
Parameter name: Random back-off lower / upper limit Value range: 0 to 50
Content: The lower / upper limit of random access back-off delay. The recommended value: 0 for both NB01MIN / NB01MAX
Set this parameter through ADD RACH, query it through LST RACH, and modify it first de-activated the cell through DEA CELL, then MOD RACH.
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PRACH Open Loop Power Control Parameters
z
POWEROFFSETPPM
Parameter name: Power offset
The default value:
-3dB for signalling transmission;
-2dB for service transmission.
z POWEROFFSETPPM
Parameter name: Power offset Value range: -5 to 10dB
Content: The power offset between the last access preamble and the message control part. The power of the message control part can be obtained by adding the offset to the access preamble power.
The recommended value of this parameter is -3dB for signalling transmission , and that -2dB for service transmission
Set this parameter through ADD PRACHTFC, query it through LST PRACH, and modify it de-activated the cell through DEA CELL . After the old configuration of PRACH is deleted through RMV PRACHTFC , a new parameters can be established through ADD PRACHTFC
z The PRACH message also consists of control part and data part, here the POWER
OFFSET is the difference between the PRACH preamble and the message control part.
z The PRACH message uses GAIN FACTOR to set the power of control / data part: GAIN FACTOR BETAC ( βc ) is the gain factor for the control part.
GAIN FACTOR BETAD ( βd ) is the gain factor for the data part.
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Contents
2.
Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power Control
2.4 Uplink Dedicated Channel Open Loop Power Control
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