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Showing posts from August, 2014

Double BA Lists in GSM

The Double BA Lists feature is defined per cell. This means that it is possible to have double lists in one cell and a single list in another cell. A single list corresponds to having the same list in idle mode and in active mode. The Absolute Radio Frequency Channel Numbers (ARFCNs) to be measured on by an MS in a cell shall be included in the BA list and they are defined by the parameter MBCCHNO . Only ARFCNs for the neighboring cells BCCH frequencies shall be defined (serving cells BCCH frequency can also be included if separate idle mode and active mode BA lists are used). With the parameter LISTTYPE it is possible to determine whether the list is for idle mode or active mode, or both. Basically up to 32 measurement frequencies can be defined in the BA list. If UTRAN neighbors are registered in the cell, then the maximum number of frequencies in the BA list is 31. The following restrictions will apply according to the global system type and the list type. Note that if the list t...

Dynamic Half Rate Allocation (DHA)

The DHA feature optimizes the usage of capacity when the cell load is high, whilst offering the best possible speech quality when the cell load is low. This is achieved by allocating FR or HR TCHs in accordance with the cell load, at the time when a new TCH shall be selected due to assignment and most types of handovers. At high cell load HR TCHs have precedence and at low cell load FR TCHs have precedence. The feature is invoked if the parameter DHA is ON.   The parameter is set on cell level. The feature is not invoked at immediate assignment if using a TCH. Then it is the setting of the parameter CHAP that controls whether FR and/or HR may be used To trigger the functionality it must also be checked that the DL signal strength measured by the MS is not too low. If the signal strength is below DHASSTHRASS (if during assignment) or DHASSTHRHO (if during handover) then dynamic HR allocation evaluation will not be performed. This signal strength check can be activated a...

Log-Normal Fade Margins

The Log-normal fade margin is incorporated in to the link budget calculation to ensure coverage reliability, and there are three environmental cases to consider: · Outdoor fade margin · Indoor fade margin · In-vehicle fade margin Outdoor Fade Margin The outdoor standard deviation α 0 , depends on the terrain: dense urban, urban, or suburban and may change very slightly with frequency. The outdoor standard deviation, α 0 , ranges from 5 dB (rural) to 12 dB (dense urban) with a typical value of 8 dB (suburban) Radio Wave Propagation A Indoor Fade Margin If an MS is inside a building, the received signal is attenuated as it passes through the exterior of the building. Building penetration loss, L bp is subject to random variation. We denote the standard deviation of the building penetration loss as α bp . The standard deviation, α , used to compute the indoor fade margin accounts for the outdoor environment, as well as the random variation of the building penetration...

Cell level Traffic Load Counters for EDGE Evolution

TBFDCDLCAP :  Number of downlink TBFs where the MS is capable of using dual carriers. TRAFDCDLTBF :   Number of downlink TBFs, in EGPRS mode, reserved on dual carriers. MAXDCTSDL :  Maximum possible number of time slots reservable for MSs on downlink TBFs in EGPRS mode, reserved on dual carriers. MUTILDCDL :  Sum of percentage shares of reserved time slots for all EGPRS mode downlink TBFs reserved on dual carriers related to the maximum possible reservable time slots. TRAFEEVOSCAN :  Number of scans for the counters in this object type. This counter is only valid for counters in object type TRAFEEVO. TSDCDL:  Number of time slots with one or more uplink or downlink TBFs currently reserved on dual carriers.

Tower Mounted Amplifiers TMA

A Tower Mounted Amplifier (TMA) has a low noise figure and some gain. If it is mounted as closely as possible to the receive antenna, it can improve uplink sensitivity at the antenna, thus increasing the cell radius. There will be an improvement if the radio link is truly noise limited. If the system is uplink interference limited, there will be no improvement using a TMA. A TMA can degrade performance if the gain is set too high. There will be intermodulation effects due to larger signals, such as terminals close to the base station. Best results are achieved when the TMA gain is used to compensate for the feeder loss.

Frequency Reuse Patterns in GSM

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Proper frequency planning is essential in the development of a quality cellular system. Due to the limited amount of available RF spectrum, the scarcity of channels available to each operator, and the fact that most available frequencies are non-contiguous for most operators, frequencies must be reused throughout the system to increase network capacity. The frequencies are assigned such that there is minimal cochannel and adjacent channel interference between sites. Frequency reuse is based on hexagonal cell groupings called clusters. The size of the cluster will determine how the cluster is repeated throughout the network, i.e. the reuse pattern. The frequency reuse patterns are designated as N/F. Where N is the number of cell sites in a cluster and F is the number of frequency groups within a cluster. Ericsson uses 7/21 and 4/12 reuse patterns. The cluster patterns  In a 7/21 plan, there are 7 cell sites (A, B, . . . , G) and 21 frequency groups (A1, A2, A3, . . . , G1, G2,...

BER ( Bit Error Rate )

The environmental effects on the received signal produce interference and impairments in the form of Bit Error Rate (BER) . BER is defined as the ratio of the number of incorrect bits received versus the total number of bits. BER is estimated by the RBS on the reverse-link and by the MS on the forward-link. IS-136 does not state explicitly how the BER should be estimated but does specify the recommended accuracy for BER estimations. BER measures the effects of radio environment-introduced impairments which are discussed in the Speech Quality and Link Budget documents in this RF module.                           Coding of Estimated   BER Class BER BER Interval (%) 0 BER% < 0.01 1 0.01 ≤ BER% < 0.1 2 0.1 ≤   BER% < 0.5 3 0.5 ≤   BER% ...

GPRS/EGPRS Traffic Load counters for the uplink per cell

TRAFFULGPRSSCAN Total number of scans (accumulations). TBFULGPRS Accumulated number of Basic and GPRS mode UL TBFs (active users), for all types of traffic, including effective streaming PDCH and PDCH used for EIT, in the cell. TBFULEGPRS Accumulated number of EGPRS mode UL TBFs (active users), for all types of traffic, including effective streaming PDCH and PDCH used for EIT, in the cell. ULBPDCH Accumulated number of B-PDCH that carried one or more UL TBFs of any mode in the cell (a B-PDCH used on the UL). Valid for all types of traffic, including effective streaming PDCH and PDCH used for EIT. ULGPDCH Accumulated number of G-PDCH that carried one or more UL TBFs of any mode in the cell (a G-PDCH used on the UL). Valid for all types of traffic, including effective streaming PDCH and PDCH used for EIT. ULEPDCH Accumulated number of E-PDCH that carried one or more UL TBFs of any mode in the cell (an E-PDCH used on the UL). Valid for all types of traffic, includi...

Ericsson Counter : GPRS/EGPRS Traffic Load counters for the downlink per cell.

TRAFFDLGPRSSCAN Total number of scans (accumulations). TBFDLGPRS Accumulated number of Basic and GPRS mode DL TBFs (active users), for all types of traffic, including effective streaming PDCH and PDCH used for EIT, in the cell. TBFDLEGPRS Accumulated number of EGPRS mode DL TBFs (active users), for all types of traffic, including effective streaming PDCH and PDCH used for EIT, in the cell. DLBPDCH Accumulated number of B-PDCH that carried one or more DL TBFs of any mode in the cell (a B-PDCH used on the DL). Valid for all types of traffic, including effective streaming PDCH and PDCH used for EIT. DLGPDCH Accumulated number of G-PDCH that carried one or more DL TBFs of any mode in the cell (a G-PDCH used on the DL). Valid for all types of traffic, including effective streaming PDCH and PDCH used for EIT. DLEPDCH Accumulated number of E-PDCH that carried one or more DL TBFs of any mode in the cell (an E-PDCH used on the DL). Valid for all types of traffic, includi...

Ericsson Counter : Hierarchical Cell Structure

HOTOHCS  :  Number of handover attempts due to HCS. LOCEVAL:   Accumulated number of locating evaluations. BRHILAYER :  Accumulated number of locating evaluations where HCS ranking differs from basic ranking. TIMEHCSOUT :  Accumulated time in seconds when the servings cells  channel availability is below or equal to HCSOUT. Please, note that the counter is only stepped it the feature HCS Traffic Distribution is active. HOATTHR :  Number of handover attempts at high handover rate. HOSUCHR :  Number of successful handovers at high handover rate

Ericsson Counter: handovers between underlaid and overlaid subcell

HOAATOL :  Number of handover attempts from underlaid to overlaid subcell. The corresponding counter for handover to underlaid subcell is called HOAATUL . HOSUCOL :  Number of successful assignment attempts to overlaid subcell. The corresponding counter for underlaid subcell is called HOSUCUL . HOATTULMAXIHO :  Number of handover attempts from overlaid to underlaid subcell due to maximum number of intra-cell handovers in overlaid subcell. HOSUCULMAXIHO :  Number of successful handover attempts from overlaid to underlaid subcell due to maximum number of intra-cell handovers in overlaid subcell. HOATTOLMAXIHO :   Number of handover attempts from underlaid to overlaid subcell due to maximum number of intra-cell handovers in underlaid subcell. HOSUCOLMAXIHO :   Number of successful handover attempts from underlaid to overlaid subcell due to maximum number of intra-cell handovers in underlaid subcell.

EBS (Event Based Statistics)

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The data in this database will act as a complement to the STS database but it is of more detailed character than the STS statistics. The data can either be stored in the database or in a Bulk Copy format file that can be distributed to other postprocessing tools. The monitors (counters) that can be stored must be activated in the GUI by the user, the user must have the correct authority to perform this action. The user must also select if the counters are to be collected for all cells in a specific BSC or several/all BSCs. The user can schedule the start and stop of data storage. The aggregation time, i.e. how often data is accumulated, can be decided by the user. The data can later be postprocessed and reports can be created from monitors stored as counters by using the Business Objects tool. EBS and STS data can preferrably be combined into the same Business Objects report. Note:   In order to combine STS and EBS data in the same report, it is important that the data is sto...

R-PMO (Realtime Performance MOnitoring)

R-PMO was the first application that was introduced in the family. Its main purpose is to present data in real-time. Realtime is achieved by letting the event data stream continuously to the OSS from the BSCs,and updating the OSS GUI once every minute. The performance data that can be evaluated in real-time includes traffic load, service quality, hand over, GPRS/EGPRS cell reselection performance, GPRS/EGPRS data throughput and more. The measures are called Monitors. The monitors are combined into reports. Several pre-defined Ericsson Standard Reports for both circuit switched and packet switched traffic performance monitoring are available. The user can also assemble monitors into own reports by using drag and drop. A wide range of filters can be used on monitors, depending on the nature of the monitor. As an example the performance information for circuit switched traffic can be filtered per MS manufacturer and type, and the dropped calls can be filtered per drop reason.

FFAX (Find Faulty Antenna eXpert)

The purpose of FFAX is to provide an efficient way to remotely identify RF paths and antenna installations that are not performing according to expectations. This is done by monitoring the difference in received signal strength from different RX paths in the BTS. FFAX in OSS is applicable for the uplink and requires the BSS feature Find Faulty Antenna Data (FFAD). FFAX enables managing of cell sets to monitor, presentation of results in real-time and database storage functionality. For each reported TRX, key values are presented representing the accumulated receiver signal strength difference, during the measurement period, and when relevant an indication of the most likely fault or no fault found. The report will be updated every minute, and can be viewed in table as well as graph format (sliding window displaying data for the last hour). This is ideal during site visits where results of changes to the RF paths can be immediately seen in OSS.

BTS Fault Alarm

Types of Fault Map Internal Class 1A Internal to BTS, affecting MO, within MO Internal Class 1B Internal to BTS, affecting MO, within MO environment Internal Class 2A Internal to BTS, not affecting MO, within MO External Class 1 External to BTS and affecting MO External Class 2 External to BTS not affecting MO The alarm slogan is the description of the current alarm situation for an MO or TG. The alarm slogans 'BTS INTERNAL' and 'BTS EXTERNAL' each describe more than one alarm situation. The remaining alarm slogans each describe a unique alarm situation. This section describes how each alarm slogan should be interpreted. TGC FAULT No active TGC application exists in the Transceiver Group. PERMANENT FAULT A managed object is classified as being permanently faulty when fault situations have occurred, and have been cleared, a certain number of times within ...