Collection of GSM RNP technical problems and replies(No. 15) Internal Open 2005-03-08 Confidential Information of Huawei. No Spreading without Permission Page1, Total26 Document number Product name Applicable for Product version Drafted by Wireless Network planning Dept. Document version V1.0 Collection of GSM RNP technical problems and replies(No. 15) (For internal use only) Prepared by: Date: Reviewed by: Date: Reviewed by: Date: Approved by: Date: Huawei Technologies Co., Ltd. All rights reserved
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Collection of GSM RNP technical problems and replies(No. 15) Internal Open
2005-03-08 Confidential Information of Huawei. No Spreading without Permission
Page1, Total26
Document number Product name
Applicable for Product version
Drafted by Wireless Network planning Dept.
Document version V1.0
Collection of GSM RNP technical problems and replies(No. 15)
(For internal use only)
Prepared by: Date:
Reviewed by: Date:
Reviewed by: Date:
Approved by: Date:
Huawei Technologies Co., Ltd.
All rights reserved
Collection of GSM RNP technical problems and replies(No. 15) Internal Open
2005-03-08 Confidential Information of Huawei. No Spreading without Permission
Page2, Total26
Contents
Problem 291 3002C Traffic Statistics UL & DL Out of Balance...........................4
Problem 292 Effect of cell broadcast service on the network indexes ...................5
Problem 293 Problem during inter-BSC handovers ...............................................6
Problem 294 How is the GT800 frequency number defined in the system? ..........7
Problem 295 In which type of bit map are frequencies in EGSM/RGSM band
(1) The HOs in the table above include edge HO or inter-layer HO, exclude the
emergency HOs which might occur. The sorting for emergency HOs is done
according to the receiving level of the neighboring cells.
(2) PBGT handover does not occur because 1800 cells and 900 cells have the
different layer, but emergency HOs, edge HOs and load HOs might occur between
1800M cell and 900M cell.
(3) Edge HOs are prior to inter-layer HOs. The prerequisite for inter-layer handover is
that the serving cell does not reach the edge handover threshold.
Problem 300 The interval of HOs in dualband network
Overview Questions about the interval of HOs in dualband network
Details Q 1: How long is the interval for the initial handover under the following situation?
How to calculate it? What is the function of the parameters such as “Min interval
for TCH HOs”, “Filter length for TCH level”, and “Edge HO watch time”?
1. The parameter “Min interval for TCH HOs” in the [Handover control data
table]: 6 seconds.
A timer must be started when a new TCH channel is assigned. Handover is
possible only when the timer is expired and the parameter “Min interval for TCH
HOs” is the time limit of the timer.
2. In the [Filter Data Table], the parameter “Filter length for TCH level” is 6. This
parameter indicates the number of MRs to be used to do TCH signal strength
averaging calculation.
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3. “Edge HO watch time” is 4/3 second.
4. “Sent Frequency of preprocessed MR”: 1 time per second, 15:1 configuration.
Q 2:
How to shorten the time of the initial handover?
Q 3:
When the “Sent Frequency of preprocessed MR” is one time per second and
configured as 15:1, is it possible to change the parameter “Filter length for TCH
level” to 3 which means 3 MRs are to be sent within 3 seconds?
Answers Answer to Q1:
The time limit is the minimum interval of the initial TCH handover. That is,
handover is not to occur even when the PN criterion is satisfied. When the
session goes beyond the limit, the time limit is invalid.
“Filter length for TCH level” functions during the average of the MR. If the
parameter is 6, make average of the MRs from NO.1 to No.6 to get a filter
measurement report.
“Edge HO watch time is 4/3” indicates that three of four MRs within four
seconds must satisfy the handover demand if one survey report comes at a
second in a succession of filter MRs.
The first initial handover can be triggered only when the three terms above
are satisfied. The last two terms must be satisfied for sessions that last long.
This is the PN criterion.
Answer to Q2:
“Min interval for TCH HOs” can be shortened to 2 or 4 second, or the PN can
be set as 2/3, or the filter length is set as 4.
Answer to Q3:
Yes. The value of parameters are defined in Network Planning Data
Configuration Criteria.
Besides, when the “Sent Frequency of preprocessed MR” is one time per second
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2005-03-08 Confidential Information of Huawei. No Spreading without Permission
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and configured as 15:1, increase handover speed by following the answers to Q2
and shorten the “filter length for TCH level” because one MR is reported by BTS
every time.
Problem 301 The influence of half-rate on dualband
cooperation and traffic balance
Overview The influence of half-rate mode on dualband cooperation and traffic balance
Details The GSM 900M in Place A belongs to N manufacturer network while 1800M
belongs to Huawei Network. If half-rate is adopted for 900M network, is there any
impact on the dualband cooperation and traffic balance? How to remake the
handover strategy?
Answers 1. Generally speaking, the half-rate mode adopted for 900M does not have much
influence upon the dualband handover. When inter BSC handover in one MSC
occurs, MSC is to determine whether the full-rate or half-rate channel is assigned
according to the support capacity of MS. If the outgoing handover at 1800M
request for full rate, but only idle half-rate rather than idle full-rate channel is
avialble for target cell at 900M, and MS does not support half-rate, the outgoing
handover fails.
2. The traffic capacity increase tremendously after the half-rate mode is adopted
in 900M network. The former traffic balance strategy might be adjusted
accordingly. Meanwhile, the parameters for HO threshold and dualband
cooperation must be adjusted according to the new strategy of traffic balance.
If the traffic balance strategy demands the 900M network load the traffic as many
as possible, set the cell selection and reselection parameters and make MS stay
at 900M network when it is idle. Make the 900M to 1800M HO parameters difficult
for handover and the 1800M to 900M HO parameters easier for handover.
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If the traffic balance strategy demands that both the 900M and 1800M networks
load the traffic with 1800M system sharing more traffic, the cell selection and
reselection parameters for both networks are set freely. Meanwhile, make the
900M to 1800M HO parameters easy for handover and the 1800M to 900M
parameters difficult for handover.
Problem 302 Why does dualband handover demand A
interface support PHASE 2 or above?
Overview Why does dualband handover demand A interface support PHASE 2 and above?
Details Why does dualband handover demand A interface support PHASE 2 and above?
Answer Dualband handover demands that A interface support PHASE 2 and above because
it must support the message of “Mobile Station Classmark 3”.
The message types for A Interface PHASE1/PHASE2/PHASE2+:
ELEMENT PHASE1 PHASE2 PHASE2+
Classmark information type 2 Support Code modification of CLASSMARK 2Support Classmark information type 3 Not support new Support Classmark information type 1 Support support Support
Some messages about MS ability such as the power grade, encryption algorithm, MS
short message, multi-band capability are reported by MS CLASSMARK. MS usually
only reports classmark information type 1 or classmark information type 2 to the
network and BSC sends the information through EST IND to MSC. Classmark
information type 1 or classmark information type 2 does not specify whether MS has
multi-band capacity. The multi-band capacity of MS is sent to the network by
classmark information type 3.
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Problem 303 Does packet paging need to be sent to all the
cells in one LAC of BSC?
Overview Does packet paging need to be sent to all the cells in one LAC of BSC?
details When MS under BSC is called as packet service, SGSN sends PAGING
REQUEST to paging MS, and then PCU handles and sends the PACKET
PAGING to BSC. Then BSC send PACKET PAGING REQUEST to
corresponding cells according to the cell ID.
Question: Does packet paging need to be sent to all the cells in one LAC of BSC?
Answer Packet paging is done according to route area. Each paging is sent downward to
all the cells in the same route. Route area is the subclass of LAC. At present, the
route area is the same as LAC. In the future there can be more than one route
cells under one LAC with the development of data transactions.
There is traffic statistics of the paging times to BSC on the side of PCU.
Problem 304 A question about paging
Overview A question about paging
Details One document file specified that there must be no more than 340 TRXs under one
LAC. Another document file specified that over loading might occur if the total paging
of one LAC exceeds 50000/hour. What is the criterion for the data?
Answer The data requirement such as “there must be no more than 340 TRXs under one
LAC” and “the total paging of one LAC exceeds 50000/hour” is based on certain
terms (traffic model), the BSC processing capability and the software version of that
time. These specifications are no longer practical at the moment.
There is limit to the capacity of Um interfaces and Abis interfaces under one LAC. But
the limit is subject to the subscriber’s traffic mode, the number of subscribers, CCCH
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configuration, and the network parameters configuration. Reliable data can be
obtained through the calculation of actual data in the network.
Problem 305 How to obtain the CRH for cell reselection across
the LAC?
Overview How to obtain the CRH for cell reselection across the LAC?
Details How to obtain the CRH for cell reselection across the LAC?
Answer The CRH used for cell reselection across the LAC is the data broadcast by the
current serving cell.
The description in GSM protocol is as follows:
The calculated value of C2 for a non-serving suitable cell exceeds the value of C2
for the serving cell for a period of 5 seconds, except in the case of the new cell
being in a different location area in which case the C2 value for the new cell shall
exceed the C2 value of the serving cell by at least
CELL_RESELECT_HYSTERESIS dB as defined by the BCCH data from the
current serving cell, for a period of 5 seconds. This indicates that it is a better cell.
Problem 306 About BCCH TRX aiding
Overview About BCCH TRX aiding
Details BSC fulfills TRX aiding, which is not specified in the guide. The on-site questions is
as follows:
1. Does BSC send the configuration(such as BCCH, BSIC) of the original cell to the
new BCCH TRX (originally TCH) cell when TRX aiding occurs? Does the new
BCCH frequency and BSIC change?
2. Is the function of the cell after TRX aiding consistent with the original one? Is it
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capable of handover?
3. Describe briefly the principle of TRX aiding and the changes of the cell after the
aiding.
Answer 1. BCCH TRX aiding means that another TCH TRX provides BCCH TRX function
when one BCCH TRX is faulty. That TCH TRX maintains the original BCCH and
BSIC data. The frequency hopping MA of RF hopping remains unchanged. As for
baseband hopping, MA remove the original frequency of the TCH.
2. The function of the cell after the aiding does not change. The faulty BCCH TRX
no longer supports handover, power control and channel allocation.
3. The system will check whether the original BCCH TRX is normal or not in the next
“resource check”. If the TRX is normal, its data and functions will be resumed.
Problem 307 How to make out the No.7 link capacity on
interface A?
Overview How to make out the No.7 link capacity on interface A?
Details The capacity of interface A is dependent on the number of No.7 links configured.
According to IMSI or TMSI paging, each paging at interface A is about 50∼60 bytes. It
is counted as 60 bytes. Paging traffic is only a part of the A interface message. If 5%
of each No.7 link’s capacity is involved in paging, it can support 24,000 pieces of
paging each hour. How is it calculated?
Answer Paging on Interface A=Interface A link rate×3600/8×Interface A
Paging ratio/paging length; as the rate of each No.7 link at the interface A is 64Kbit/s,
each hour 64000*3600/8*5%/60=24,000 pieces of paging are sent.
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Problem 308 General propagation models adopted for 1800M
network by Huawei
Overview General propagation models for 1800M network by Huawei.
Details What kind of propagation models is adopted for 1800M network by Huawei
Answer 1. COST231-HaTa model expression is adopted in theoretic calculation: