QoS Class Identifier (QCI)

The need for supporting a broader variety of applications requiring higher bandwidth and lower latency led 3GPP to alleviate the existing QoS principles with the introduction for EPS of a QoS Class Identifier (QCI).
LTE provides different QoS for a given application by putting it into the different bearer . each bearer has its own QCI (QoS Class Identifier) which introduce a particular service for a particular application. as far as I know 9 different QCIs have been defined in LTE based on priority,packet loss and delay.

 

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The QoS architecture in EPC enables a number of important capabilities for both operators and users:

VoIP support with IMS: QoS is a crucial element for providing LTE/IMS voice service.
Enhanced application performance:Applications such as gaming or video can operate more reliably.
More flexible business models:With flexible, policy-based charging control, operators and third-parties will be able to offer content in creative new ways. For example, an enhanced video stream to a user could be paid for by an advertiser.
Congestion control: In congestion situations, certain traffic flows (e.g., bulk transfers, abusive users) can be throttled down to provide a better user experience for others.

Congestion Indicators for EUL

Congestion Indicators for EUL

Iub overload problems are solved by flow control for Enhanced Uplink highspeed data services. For EUL increased delay is measured internally and thedata flow from RBS in UL is throttled according to measurements recorded,therefore there is no congestion as such but rather the transmission rate of thedata is slowed down in the uplink direction when potential overload is detected.There are counters which can be used to monitor when the Iub tends towardscongestion for EUL services. When that happens it should be considered toexpand the Iub capacity for EUL services.

 

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• Iub Limiting EUL Performance
• EUL Frame Loss
• EUL Dynamic Delay of Frames

HSDPA Frame Loss

These counters relating to frame loss are available on the RBS to monitor HighSpeed data service in the downlink direction.

IubDataStreams::pmHsDataFramesLostSpiXX
- the number of HSdata frames lost, destroyed and errored over Iub in the RBS. There areseparate counters for each of the priority classes.

IubDataStreams::pmHsDataFramesReceivedSpiXX
- the totalnumber of HS data frames correctly received over Iub in the RBS. Thereare separate counters for each of the priority classes.

The XX suffix represents the priority class and can range from 00 to 15.The counters can be used to indicate data loss rate for the HS service.High frame loss will indicate potential congestion problems. RecommendedPerformance Indicator for this is:



Frame Loss Rate on the path from SRNC to RBS

Find more HSDPA Counters at www.telecomfunda.com/forum

VoLTE + Wi-Fi = LTE Femto

This week, Kineto announced it now supports the GSMA’s VoLTE profile (IMS voice & SMS) in its Smart Wi-Fi client. Smartphones with the Smart Wi-Fi client will now be able to receive the mobile operator’s voice/SMS service (VoLTE) when attached to Wi-Fi.
I have always believed LTE and Wi-Fi were two sides of the same coin – both are high-speed, low-latency flat IP networks. LTE covers the macro/outdoor world, and Wi-Fi is by far the dominant in-building wireless technology. Marrying the two technologies into a seamless experience delivers a compelling experience for mobile subscribers.
In the move to LTE, mobile operators are adopting VoLTE, an IMS/SIP-based voice and SMS profile that replaces (replicates?) the existing circuit voice/SMS services used in GSM/UMTS networks.

UE Measurements

Intra-frequency measurements: measurements on downlink physical channels at the same frequency as the active set. A measurement object corresponds to one cell.

Inter-frequency measurements: measurements on downlink physical channels at frequencies that differ from the frequency of the active set. A measurement object corresponds to one cell.

Inter-RAT measurements: measurements on downlink physical channels belonging to another radio access technology than UTRAN, e.g. GSM. A measurement object corresponds to one cell.

Traffic volume measurements: measurements on uplink traffic volume. A measurement object corresponds to one cell.

Quality measurements: Measurements of downlink quality parameters, e.g. downlink transport block error rate. A measurement object corresponds to one transport channel in case of BLER. A measurement object corresponds to one timeslot in case of SIR (TDD only).

UE-internal measurements: Measurements of UE transmission power and UE received signal level.

UE positioning measurements: Measurements of UE position.The UE supports a number of measurements running in parallel. The UE also supports that each measurement is controlled and reported independently of every other measurement.

Cyclic Delay Diversity

Cyclic Delay Diversity (CDD) is a simple approach to introduce spatial diversity to an Orthogonal Frequency Division Multiplexing (OFDM) based transmission scheme that itself has no built-in diversity. It also can be regarded as a Space-Time Code (STC).

But in contrast to that there is no additional effort in the receiver necessary, since the different codewords result in a changed channel impulse response in the receiver. They insert virtual echos and thus increase the frequency selectivity of the channel seen by the receiver. Cyclic Delay Diversity (CDD) is a diversity scheme used in OFDM-based telecommunication systems, transforming spatial diversity into frequency diversity avoiding intersymbol interference.

RSRP and RSRQ

In cellular networks, when a mobile moves from cell to cell and performs cell selection/reselection and handover, it has to measure the signal strength/quality of the neighbor cells. In LTE network, a UE measures two parameters on reference signal: RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality).

RSRP is a RSSI type of measurement. It measures the average received power over the resource elements that carry cell-specific reference signals within certain frequency bandwidth. RSRP is applicable in both RRC_idle and RRC_connected modes, while RSRQ is only applicable in RRC_connected mode. In the procedure of cell selection and cell reselection in idle mode, RSRP is used.

RSRQ is a C/I type of measurement and it indicates the quality of the received reference signal. It is defined as (N*RSRP)/(E-UTRA Carrier RSSI), where N makes sure the nominator and denominator are measured over the same frequency bandwidth.

The carrier RSSI (Receive Strength Signal Indicator) measures the average total received power observed only in OFDM symbols containing reference symbols for antenna port 0 (i.e., OFDM symbol 0 & 4 in a slot) in the measurement bandwidth over N resource blocks. The total received power of the carrier RSSI includes the power from co-channel serving & non-serving cells, adjacent channel interference, thermal noise, etc.

The RSRQ measurement provides additional information when RSRP is not sufficient to make a reliable handover or cell reselection decision. In the procedure of handover, the LTE specification provides the flexibility of using RSRP, RSRQ, or both.