WCDMA abbreviations & several confusing concepts & Analysis on the reason for phone disconnection

WCDMA abbreviations
A
Aal atm Adaptation Layer ATM adapter Layer
Aal2o3 ATM adaptation layer type 2 atm adapter layer type 2
AAL5 ATM adaption layer type 5 ATM adapter layer type 5
Aich acquisition indicator channel access indicator Channel
Alcap access Link Control Application Part access Link Control Application
Amr adaptive multi-rate
ATM asynchronous transfer mode Asynchronous Transfer Mode
B
BCCH broadcast control channel broadcast Control CHannel
BCH broadcast channel
Bfn NodeB frame number counter
BMC broadcast/multicast control protocol
BSc Base Station Controller
Bsc6800 Huawei RNC model Huawei RNC Model
BSS Base Station Subsystem
C
CA-ICH channel assignment indication channel allocation indication Channel
CBC cellbroadcastcenter residential Broadcast Center
CBS Cell Broadcast Service community broadcast service
CC call control Call Control
Ccch common control channel public control channel
CCH common transport channel
Cctrch coded composite transport channel encoding Compound transmission channel
CFN connection frame number
CN core network
Cpch common packet channel public group Channel
CPCs common part convergence sublayer public part aggregation sub-layer and public aggregation sub-Layer
CPICH common pilot channel public channel
CRC cyclic redundancy check (method)
Crnc Controlling RNC control RNC
C-RNTI cell radio network temporary identifier cell wireless network temporary identifier
CS circuit-switched circuit switch
Csich cpch status indication channel cpch status indication Channel
D
Dcch dedicated control channel dedicated Control CHannel
Dch dedicated channel
DPC destination (signaling) point code destination signaling point code
Dpcch dedicated physical control channel
Dpch dedicated physical channel
Dpdch dedicated physical data channel
Drnc drift RNC
DRNs drift RNS
Drx discontinuous interval tion discontinuous reception
DSCH downlink shared channel downstream shared channel
F
Fach forward access channel
FDD Frequency Division Duplex frequency duplex
Fer frame error rate Frame Error Rate
G
GPRS General Packet Radio Service general grouping wireless service
GSM Global System for Mobile Communications Global Mobile Communication System
GTP-U user plane part of GPRS tunnelling protocol GPRS tunnel protocol user part
I
IE information element Information Unit and elements
Imsi International Mobile Station identity international mobile station ID
IP Internet protocol, Internet Protocol
ISUP integrated services digital network user part/ISDN User Part
ITU-T International Telecommunication Union-Telecommunication Standardization Sector International Telecommunication Union-Telecommunications Standards Department
IU Iu interface interfaces between CN and RNC
Iur IUR interface: interface between RNC and RNC
L
Lai Location & nbsp; area identity location code
M
Mac Medium Access Control Media Access Control
MiB master information block primary information block
MM mobility management
MS Mobile Station (mobile)
MSC mobileswithingcenter mobile exchange center
MSU message signalling unit message signaling Unit
MTP message transfer part message transmission
Mtp3 message transfer part Layer 3 layer 3 message transmission
N
NAS non-access stratum non-access layer
NBAP NodeB Application Part Protocol
NNI network node interface (network-to-Network) network node interface
NodeB WCDMA base station
O
OAM operation administration and maintenance operation management and maintenance
OPC originating point code source message point code
P
Pcch paging channel (Logical Channel) Paging channel (Logical Channel)
Pccpch primary common control physical channel primary public control physical channel
PCH paging Channel
PCP power control preamble power control prefix
Pcpch physical common packet channel public group physical channel
Pcpich primary common pilot channel main public channel
PDCP packet data convergence protocol group data aggregation Layer Protocol
PDP Packet Data Protocol (information) package data protocol
Pdsch physical downlink shared channel
Pich paging indicator Channel
Plmn publiclandmobile Network Public Land Mobile (Communication) Network
Prach packet Random Access Channel group random access channel
PS packet switched group switch
Psch physical shared channel
PSTN Public Switched Telephone Network Public Switch Telephone Network
Q
QoS quality of service
R
RAB radio access bearer Wireless Access bearer
Rach random access channel Random Access Channel
Ranap Radio Access Network Application Part Wireless Access Network Application Part
RB Radio Bearer wireless bearer
Rfn RNC frame number counter
RNC radio network controller wireless network controller
RNS radio network subsystem wireless network subsystem
Rnsap radio network Subsystem Application Part wireless network Subsystem Application Part Protocol
Rnti radio network temporary identity temporary wireless network ID
RRC radio resource control wireless resource control
Rtwp received ed total Wide Band Power total bandwidth received
S
SAAL signaling ATM Adaptation Layer ATM signaling Adaptation Layer
Sabp service area broadcast protocol service area broadcast Protocol
SAR segmentation and reassembly segmentation and reorganization, segmentation and reorganization
SCCP Signaling connection and control part Signaling connection control part
Sccpch secondary common control physical channel assists in public control of physical channels and "slave" public control of physical Channels
Sch synchronization Channel Synchronous Channel
Scpich secondary common pilot channel from public channel
SDU service data unit business data unit
Sgsn Serving GPRS Support Node service GPRS Support Node
SI service indicator business indicator code
SIB system information block system Message Block
Sif signaling information field
SiO2 service information octet Business Information octet bits (bytes)
Sir signal-interference ratio Signal-to-dry ratio
SlS Signaling Link selection Signaling Link Selection
Srgsignalling Radio Bearer signaling wireless bearer
Srnc serving RNC service RNC
Srns serving RNS service RNS
SS7 signaling system number 7 7 Signaling
Coordination functions of specific services
Ssch secondary synchronization Channel
Sscop service specific connection oriented protocol connection protocol for specific services
SSCs service specific convergence sublayer specific aggregation child Layer
SSN sub-system number subsystem number
STC signaling transport converter signaling transfer Conversion Layer
Sttd Space Time Transmit Diversity
T
TB Transport Block
TBS transport block set
TDD Time Division Duplex
TFC transport format combination Transmission Format combination
Tfci transmit format combined indicator sends format combination indication
TFI transport Format Indicator Transmission Format indication
Toa Time of Arrival arrival time
Toawe Time of Arrival window endpoint arrives at the end of the time window
Toaws Time of Arrival window startpoint arrival time window start point
TPC transmit power control
TTI transmission time interval transmission interval, transmission interval, Transmission Interval
U
UE user equipment user Device
UMTS Universal Mobile Telecommunication Services/Universal Mobile Telecommunications System general mobile telecommunication business/General Mobile Communication System
Uni logical user-network interface logical User Network Interface
Up user plane
Ura utran registration area
U-RNTI UTRAN radio network temporary identifier UTRAN wireless network temporary identifier
Utran umts Terrestrial Radio Access Network UMTS land Wireless Access Network
UU Uu interface between UE and UTRAN
V
VP Video Phone
W
WCDMA Wideband CDMA broadband CDMA

Several confusing concepts
1. Symbols
1.1 signal symbol
1. C: carrier power
2. EC: the energy of the QR code.
3. EB: Bit energy in the business channel. The relationship between EC and 95 and 1X is EB = EC + w/R (db)
4. IOR: The concept in do, which refers to the power spectral density of useful signals.
1.2 noise disturbance symbol
1. I: Total interference power, including thermal noise, excluding useful signal power.
2. IO: interference power spectrum density, including thermal noise. It is mainly used in combination with EC on the pilot channel to form EC/Io.
3. No: thermal noise power spectral density. The formula is 10lg (KT) + NF. (CDMA system engineering manual p652) Such & #61486; EB/NO can be interpreted as the ratio of the total energy (including pilot, DRC and ACK) stored ed per antenna from that mobile during an information bit to thermal noise PSD. (80-h0447-1, X4 p10)
4. nt: noise power spectrum density, including thermal noise and interference. (NT. The specified tive noise power spectral density at the sector RF input ports.) limit PP2 C. s0032. "Fig 2.3.1 demonstrates the reverse traffic channel per versus total & #61486; EC, P/NT per antenna (OR & #61486; EC, p/no per antenna at 0% loading in which situation Nt = no ). "" due to the assumed geometry, IOR/NT saturates while ior/no-> ∞. "in 80-h0447-1, X4
5. IOC: interference power spectral density of other residential areas and users, excluding hot noise.
Note: Noise (rather than hot noise) generally refers to hot noise and interference.
1.3 ratio symbol
1. EC/IO: the EC/IO of the pilot channel. The SNR of 95 and 1X is equal to that of the Pilot Channel.
2. EC/NT: Same as EC/Io, but used to use EC/Io.
3. Eb/NT: The demodulation threshold. It is the same as EB/NO in the absence of interference. Otherwise, it is smaller than Eb/No.
4. Eb/No: it is the same as EB/NT when there is no interference (0 load in reverse direction), and increases with the increase of load (interference.
5. c/I: Load-to-dry ratio
6. SNR: signal noise ratio, snrreq = (EB/no)/(W/R ).
7. ior/IOC: Used in evdo to indicate the ratio of useful signal spectral density to interference spectral density.
8. ior/(IOC + NO): Used in the evdo forward direction. It refers to the ratio of useful signal spectral density to noise spectral density, which is equal to C/I, SNR, and integrated EC/Io.
2. Relationship between Symbols
2.1 signal symbols
1. c and EC: C are the carrier power, EC is the code piece energy, and the relationship between them in CDMA is c = W * EC. (W indicates the bitrate ).
2. Bits of EB and EC: 95 and 1X business channels, EB = EC + w/R (db ).
3. ior and EC: IOR are the power spectral density of useful signals. They are a comprehensive value, and the product of bandwidth W is the total power. From this point of view, it is the same as the value, why not use EC, the main reason is that the EC values in the forward direction of a time slot in do are different. Therefore, IOR is equivalent to a comprehensive EC, or an average of the forward EC.
2.2 interference symbols
1. Io and NT: both are noise spectral density. The thermal noise spectral density and interference spectral density are the same. Io focuses on interference, While NT focuses on noise.
2. nt and no: NT indicates the thermal noise spectral density and interference spectral density, while no indicates the thermal noise spectral density.
3. I and I: I is the total interference power (including thermal noise), and I/O is the interference spectral density (including thermal noise). The relationship between the two is I = W * IO, where W is the bandwidth.
4. Io and IOC: Io is the interference spectral density that includes hot noise, and IOC is the interference spectral density that does not include hot noise. IO = IOC + NO
2.3 ratio symbol
1. EC/Io, EC/NT, SNR, C/I, IOR/(NO + IOC)
EC/Io and EC/NT are the same as SNR and C/I and IOR/(NO + IOC.
2. Eb/NT and EC/Io, EC/NT, SNR, C/I, IOR/(NO + IOC)
EB/NT is the upper ratio plus W/R (db ).
The reason for the disconnection is not determined by the mechanism alone. There are many reasons for the disconnection in the CDMA network. from a global perspective, the disconnection is mainly caused by forward interference, insufficient coverage, unbalanced frontend and backend links, limited service channel power, and access and switching conflicts. Through signaling analysis, you can easily determine the direct cause of disconnection. However, to identify the underlying cause of disconnection and determine the solution, you need to carefully analyze the road test data. We usually observe the features before and after the test from the road test data, for example, changes in transmission power, reception power, guide EC/Io, transmission power adjustment value (tx_gain_adj), guide Pn, and signaling interaction before and after a mobile device goes off, then, we analyze these features to find out the real cause of the disconnection.

1. Disconnection caused by forward interference

Based on whether the duration of the forward interference exceeds the preset value of the fading timer, the value is 5 S (t5m), which can be divided into long-forward interference and short-term forward interference.

A. Long forward interference

& #61548; Features

& #61557; the reception power of the mobile station is continuously increasing, and the EC/IO of the pilot signal is continuously decreasing, lower than-15db;

& #61557; Forward fer increase;

& #61557; the range of the transmit power adjustment value tx_gain_adj of the mobile station remains flat;

& #61557; after the above phenomenon lasts for 5 S (t5m), the mobile station will soon initialize on another pilot or enter the long-time search mode (drop-off ).

& #61548; Analysis

& #61557; the mobile station receives an increasing power while the EC/IO of the pilot signal keeps decreasing, indicating that there is a strong interference source on the forward link;

& #61557; the quality of the forward link is seriously reduced, causing the mobile station to fail to be demodulated. The fer increases. When the mobile station receives 12 bad frames consecutively, the Mobile Station closes the transmitter, start the fading timer (t5m), ignore the reverse Closed Loop function control, and the tx_gain_adj amplitude remains flat;

& #61557; because the duration of the forward interference exceeds the preset value of the fading timer for 5 S (t5m), the mobile device fails to receive two good frames until the fading timer expires, failed to reset the fading timer. The fading timer expires, the mobile device is initialized, and a disconnection occurs;

& #61557; if the mobile station is deprecated and soon initialized on another pilot station, the disconnection is caused by a switchover failure. The interference source is the available pilot signal in the CDMA system, it is a self-interference of the CDMA system. The switchover may fail due to the following reasons;

& #61607; the mobile station does not send the frequency guide strength measurement message (psmm) containing the available frequency guide to the base station or it is very slow to send. The possible cause is that the search window is too small, the t_add value is too high, or the mobile station's pilot search is too slow. As a result, the mobile station does not detect the available pilot signal. Adjustable Parameters include search_win_a, search_win_n, search_win_r, t_add, and pilot_inc;

& #61607; the mobile station sends a message (psmm) containing the available guide to the base station, but the base station does not detect it. The possible cause is that the performance of the reverse link is reduced, and the reverse Fer is too high, which leads to an error or loss of the Guide strength measurement message (psmm;

& #61607; the base station receives a message for measuring the frequency conductivity (psmm) containing the available guide sent by the Mobile Station ), however, no switching indication message (HDM) or extended switching indication message (ehdm) containing the available pilot was sent to the mobile station ). The possible cause is that the pilot frequency is not in the list of adjacent sets (you can modify the list of adjacent sets and add the pilot frequency to the list of adjacent sets ), or there is a problem with the switchover permit algorithm (for example, if the number of soft switches allowed is too small, the number of soft switches has reached the maximum allowed value, and the adjustment can be made to increase the number of soft switches allowed );

& #61607; the base station sent a switch indication message (HDM) or extended switch indication message (ehdm) to the mobile station, but the mobile station did not detect it. The possible cause is an error or loss of the previous High fer enable switch indication message (HDM) or extended switch indication message (ehdm;

& #61607; excessive network load and high switching rate lead to insufficient resources. Possible causes include: t_drop is too low, and t_tdrop is too large.

& #61557; if the mobile station goes into the long-time search mode after it goes off, the interference source may be from outside the CDMA system, rather than the available pilot signal in the CDMA system, this requires detection of the forward spectrum, identification and elimination of interference sources.

B. Short-term forward interference

& #61548; Features

& #61557; the reception power of the mobile station is continuously increasing, and the EC/IO of the pilot signal is continuously decreasing, which is lower than-15db, but the duration is very short, the value of the fading timer cannot exceed 5 S (t5m), and the receiving power of the mobile station begins to decrease, and the EC/IO of the pilot signal starts to rise again, the fading timer is restored to-15db or above before it expires;

& #61557; fer increase;

& #61557; the transmission power adjustment value of the mobile station tx_gain_adj is flat. After the pilot signal is restored to-15 dB or above, the transmission power adjustment value of the mobile station is still flat;

& #61557; after the above phenomenon lasts for 5 S (t5m), the mobile station reinitializes on the same pilot.

& #61548; Analysis

After the pilot signal is restored to-15 dB or above, the transmission power adjustment value of the mobile station tx_gain_adj is still flat, which indicates that the transmitter of the mobile station is not started, that is to say, the Mobile Station fails to receive two good frames consecutively, and the fading timer is still timing. This is because the base station's disconnection mechanism has been enabled. After the base station fails to receive the reverse signal from the Mobile Station, it considers that it has stopped sending signals to the Business Channel. As the forward signal has been restored, after the fading timer expires, the mobile device is initialized on the same guide.

2. Disconnection caused by insufficient coverage

Based on the value of 5 S (t5m) for whether the overwrite duration exceeds the fading timer duration, it is divided into long-time overwrite and short-time overwrite.

A. Long term coverage is insufficient.

& #61548; Features

& #61557; the mobile station receives power and the EC/IO of the pilot signal at the same time, and the mobile station receives power close to-dBm or lower, the EC/IO of the pilot signal is lower than-15db;

& #61557; the transmission power of the mobile station increases, and the maximum value is generally reached;

& #61557; fer increase;

& #61557; the range of the transmit power adjustment value tx_gain_adj of the mobile station remains flat;

& #61557; after the above phenomenon lasts for 5 S (t5m), the mobile device is initialized and enters the long search mode, it may take a long time for the mobile station to find the network again (either on the same pilot or on the new pilot ).

& #61548; Analysis

& #61557; because the mobile station receives power and the EC/IO of the pilot signal decreases at the same time, it can be determined that the coverage is insufficient;

& #61557; the quality of the forward link is seriously reduced, causing the mobile station to fail to be demodulated. The fer increases, the Mobile Station closes the transmitter, starts the fading timer (t5m), and ignores the reverse closed-loop power control, tx_gain_adj is flat;

& #61557; after the fading timer expires, the mobile device is initialized. However, due to insufficient coverage, it takes a long time to search for the timer to re-capture the network.

B. Short-term coverage is insufficient.

& #61548; Features

& #61557; the mobile station receives power and the EC/IO of the pilot signal at the same time, and the mobile station receives power close to-dBm or lower, the EC/IO of the pilot signal is lower than-15db, but the duration is very short. The value of the fading timer cannot exceed 5 S (t5m ), then the receiving power and the EC/IO of the pilot signal of the mobile station began to increase, and the EC/IO of the leading frequency signal was restored to-15db after the fading timer expired;

& #61557; the transmission power of the mobile station increases, and the maximum value is generally reached;

& #61557; fer increase;

& #61557; the transmission power adjustment value of the mobile station tx_gain_adj is flat. After the pilot signal is restored to-15 dB or above, the transmission power adjustment value of the mobile station is still flat;

& #61557; after the above phenomenon lasts for 5 S (t5m), the mobile station is initialized on the same pilot.

& #61548; Analysis

After the coverage improves and the pilot signal is restored to-15 dB or above, the range of tx_gain_adj, which indicates that the transmitter of the mobile station is not started, that is to say, the Mobile Station fails to receive two good frames consecutively, and the fading timer is still timing. This is because the base station's disconnection mechanism has been enabled. After the base station fails to receive the reverse signal from the Mobile Station, it considers that it has stopped sending signals to the Business Channel. As the forward signal has been restored, after the fading timer expires, the mobile device is initialized on the same guide.

3. Disconnection caused by unbalanced reverse links

& #61548; Features

& #61557; the receiving power and guide signal EC/IO of the mobile station are both strong, and the transmit power of the Mobile Station reaches the maximum;

& #61557; fer increase;

& #61557; the range of the transmit power adjustment value tx_gain_adj of the mobile station remains flat;

& #61557; after the above phenomenon lasts for 5 S (t5m), the mobile station is initialized on the same pilot.

& #61548; Analysis

& #61557; the receiving power and guide signal EC/IO of the mobile station are both strong, indicating that the forward link is good, while the output power of the mobile station has reached the maximum, which indicates that the reverse link is very poor. This indicates that the reverse link is seriously unbalanced. The reasons for this are:

& #61607; strong interference with the reverse link;

& #61607; too many users cause reverse link blocking, mainly because CDMA is a self-interference system (the coverage area can be reduced by reducing the antenna gain or adjusting the antenna's downtilt angle and direction angle, to reduce the number of users );

& #61607; the pilot power sent by the base station is too high.

& #61557; because the reverse link is poor, after a period of time, the base station's disconnection mechanism starts, the base station abandons the reverse Business Channel and stops sending forward business signals, at this time, the forward FER of the mobile station becomes very high. When the mobile station receives 12 bad frames consecutively, the Mobile Station closes the transmitter and starts the fading timer (t5m). The tx_gain_adj amplitude remains flat;

& #61557; because the forward signal is good, after the fading timer expires, the mobile device is initialized on the same guide.

4. Disconnection caused by limited transmit power of business channels

& #61548; Features

& #61557; the transmitting power, receiving power and the EC/IO of the mobile station remain flat, and the transmitting power of the mobile station is not up to the maximum, the receiving power of the Mobile Station and the EC/IO of the pilot signal are both strong enough, both above the threshold value;

& #61557; the range of the transmit power adjustment value tx_gain_adj of the mobile station remains flat for 5 S (t5m), and the mobile station is initialized on the same guide;

& #61548; Analysis

& #61557; the receiving power of the Mobile Station and the EC/IO of the Pilot Channel are all above the threshold, and the transmit power of the mobile station is not up to the maximum, in addition, the EC/IO of the mobile station's receiving power, transmitting power, and pilot channel are flat, without deteriorating or increasing, it indicates that the disconnection is caused by limited power of the forward or reverse business channels;

& #61557; the power of the base station's forward business channel has a certain range. This range is set on the base station side. If this range is set improperly, the transmit power of the forward business channel will be limited, as a result, the signal of the forward business channel is too weak, and the mobile station cannot be successfully demodulated, resulting in disconnection.

& #61557; the power of the reverse Business Channel of the mobile station is limited by the reverse closed loop power control. If the outer ring power control settings of the base station are unreasonable, the target value of the closed loop power control EB/No is not large enough, the transmit power of the reverse business channel is limited. As a result, the base station receives too weak signals from the reverse Business Channel. As a result, the base station gives up the reverse Business Channel and stops sending forward business signals, resulting in disconnection.

& #61557; in this case, check whether the power range setting of the base station's forward business channel and the outer ring power control setting of the base station are reasonable.

5. Disconnection caused by access and switch conflicts

& #61548; Features

& #61557; In the is-95 system, the call is dropped immediately after the call is established;

& #61557; the reception power of the former mobile station is continuously increasing, and the EC/IO of the pilot signal is continuously decreasing, which is lower than-15db. The transmission power adjustment value of the mobile station is 5 S (t5m) internal flat;

& #61557; after the disconnection, the mobile station is initialized on a new pilot.

& #61548; Analysis

The above features show that the mobile station enters the switching zone during the access process. Because the is-95 system does not allow switching during the access process, the mobile station cannot demodulated the forward signal, the transmitter is disabled, causing disconnection. In the CDMA system, switching is allowed during the access process, so there is no conflict between access and switching.

The above section analyzes several typical deutation situations based on bad frames. In addition, the above analysis methods can be combined with signaling interactions, analyze the underlying reasons for the failure.