Study on Cell-specific Reference Signals (CRS) interference mitigation for homogenous deployments of LTE
The objectives of this Study Items are:
● Identify the partial traffic loading levels and other realistic system level parameters (e.g. traffic and interference models including interference level, time offset between cells and frequency offset between cells) and performance metrics for studying the feasibility of CRS IM in a synchronized homogenous network assuming:
- 3GPP Case 1 as a starting point
- non-colliding CRS between serving and dominant aggressor/interfering cells and
- non-colliding CRS between dominant aggressor/interfering cells
- The homogeneous deployment and relevant system parameters should reuse as much as possible those defined in the Rel-11 performance study of MMSE-IRC
● Identify the baseline receiver which can be used for evaluating the gain of CRS IM in a synchronized homogenous network considering:
- Reuse of CRS IM receiver assumed for Release 11 FeICIC.
- Reuse of MMSE-IRC receiver as the baseline receiver. MMSE-IRC does not differentiate CRS or data interference when suppressing them and was assumed for Release 11 work item on interference rejection combining.
● Agree on interference levels, interference models and simulation parameters for link level evaluations.
● Evaluate the system level and link level gains of CRS IM with respect to the baseline MMSE-IRC receiver in a synchronized homogenous network deployment under the various loading levels identified.
- Gains of CRS IM from 1 and 2 aggressor cells CRS shall be evaluated and compared.
- Modeling of realistic CRS IM receiver for system level performance evaluation should be clarified and agreed if possible
● Investigate UE complexity tradeoffs e.g. tradeoff between number of interferers to cancel and the number of transmit antenna ports.
● The introduction of CRS IM based receiver requirements for homogenous deployments will only use the existing Release 11 signaling of CRS assistance information.
Note 1: Interference from neighboring cells’ PDSCH is not the focus of this study item. Any interference from data, which varies according to the traffic loading level, is assumed to be suppressed in the same way as in Rel-11 with the baseline MMSE-IRC receivers.
Note 2: Non-colliding CRS is prioritized and will be studied first while colliding CRS is not precluded. But the study will focus only on UE demodulation aspects.