Here I write on 3GPP Services Classification and EUTRAN Capacity Limiting Factors for LTE.
3GPP Services Classification
Being a data centric technology, LTE has well defined classifications for Quality of Service. In general, there are two main classes of service type, with Guaranteed Bit rate vs with Non Guaranteed Bit rate.
RT (Real Time) services are characterized by the short time response between the communicating parts and they generally required an acceptable GBR. These services have strict requirements regarding packet delay and jitter.
As an example of this kind of service we can mention Voice over IP (VoIP). On the other hand, NRT (Non-Real Time) services do not have tight requirements concerning packet delay although high packet delays are unacceptable.
Hence, NRT normally is Non-GBR services. However, when transmitting NRT services the major constraint is the information integrity, i.e., information loss is not tolerable. Therefore, applications of this type must have error-correction or recovery mechanisms. Web browsing is an example of an NRT service.
The table below shows the relative priority, expected error rate and delay for each QoS class.
From a EUTRAN design perspective, how customer chooses the proportion and combination of these different services will be translated into bits per second requirement for the customer network.
Although the dynamic nature of E-UTRAN capacity limiting factors as listed below will affect the final user throughput and capacity, it is essential that the network is dimensioned properly in the design stage to reduce the impact of services offer booking and short term surges in services due to unexpected events.
EUTRAN Capacity Limiting Factors
In general, the following are the major factors that will contribute towards the limitation of EUTRAN capacities:
- Operating Frequency band
- RF Coverage – RSRP
- Impact of Interference on Capacity
- Signal Interference Noise Ratio and Adaptive Coding
- Radio (Transmitter) Power Availability
- Spectrum Bandwidth Availability
- Channel Card (LPPB) Processing Capacity
- S1/X2 Capacity
- Application of Special Antenna Technologies (MIMO/BF/Virtual MIMO)
- Scheduling Mode
- Actual Cell Site Placement in Relation to Traffic
- UE Capability
- User Traffic Mix and Call Modeling
- Time Slot Allocation for Uplink and Downlink – TDD specific
