Some Special Antenna Technologies and Scheduling Mode for LTE
Special Antenna Technologies
MIMO and Beam Forming are critical features in determining the actual link budget required for the Operator’s network. However, these two features are also critical features from a capacity perspective as they can also improve the efficiency of frequency reuse and reduce the intra-frequency interference within the same cell as well as neighbor cells.
The separate antenna related technology in uplink, which is focusing on capacity improvement. This feature is called Uplink Virtual MIMO and it achieves uplink throughput by allocating same RB for different uplink users. Uplink Virtual MIMO can increase overall uplink spectral efficiency and hence increasing the overall uplink throughput. It is similar to a feature called CSM for WiMAX.
The network will carefully select two users with the following characteristics:
- Highly uncorrelated in the Uplink
- Offer the best capacity improvement to the cell after combining
- Highest Max PF air output when the 2 users are combined together
These selection criteria will allow users with the most uplink data need and most uncorrelated to be chosen first. Since those two users are highly uncorrelated, they can be easily removed from each other’s overall signal.
Scheduler is one of the key RRM algorithms designed to maximize the radio resource usage and capacity availability while meeting the QoS (Quality of Service) requirements of different applications and users in both uplink and downlink. Because different operators may have different traffic mixes and strategies of utilizing their resources, the scheduler is flexible and configurable in order to meet various goals.
The design goals of the scheduler include maximization and/or guarantee of the following:
- Cell throughput
- Cell edge user throughput
- VoIP capacity
- QoS satisfaction rate for various services.
Scheduling algorithm enables the system to decide the resource allocation for each UE during each TTI. Scheduler algorithm can bring the following benefits:
- Flexible selection for the scheduling algorithm
- Flexible configuration for QoS priority parameters
- Strong QoS guarantee mechanism for different services
- Optimal tradeoff among throughput, fairness, and the QoS