LTE eNB Scheduling via MAC CE for PDCCH Cost Reduction
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Solution Overview
Problem
The Long Term Evolution (LTE) system faces limitations in handling capacity due to the inefficiency of Physical Downlink Control Channel (PDCCH) signaling, particularly when transmitting a large number of small data packets, leading to reduced system capacity and increased costs.
Innovation Solution
The proposed solution involves using Media Access Control (MAC) protocol data units (PDU) with MAC control elements (CE) to allocate uplink resources in advance, reducing the reliance on PDCCH signaling by predicting subsequent uplink data transmission and carrying uplink resource allocation information in downlink MAC PDUs, allowing for efficient scheduling of uplink data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PDCCH signaling is used to schedule each transport block, then each user can receive dedicated scheduling, but the system handling capacity is limited due to the small number of available PDCCH resources
Solution Approach 1:
The patent combines multiple scheduling operations into a single PDCCH signaling by introducing the Scheduling Information Field (SIF) that can indicate multiple resource allocations, modulation and coding schemes, and other scheduling parameters for different transport blocks within one PDCCH message, thereby reducing the total number of PDCCH signals needed while maintaining dedicated scheduling capability
Solution Approach 2:
The PDCCH signaling is enhanced to perform multiple scheduling functions simultaneously through the SIF structure, which can convey resource allocation information for both uplink and downlink, indicate hybrid ARQ processes, and specify transmission parameters for multiple transport blocks, making a single PDCCH signal serve universal scheduling purposes
2Adaptability or versatility
If dynamic scheduling is adopted with PDCCH signaling for each transport block, then real-time scheduling flexibility is achieved, but the cost of PDCCH signaling increases significantly when transmitting many small packets
Solution Approach 1:
The patent implements semi-persistent scheduling where resource allocations are pre-configured through RRC signaling, and subsequent transmissions use these pre-configured resources without requiring new PDCCH signals for each transport block, thereby reducing PDCCH signaling cost while maintaining scheduling flexibility through dynamic adjustments when needed
Solution Approach 2:
The scheduling mechanism uses periodic resource allocations where resources are assigned at regular intervals based on traffic patterns, reducing the frequency of PDCCH signaling events while maintaining the ability to dynamically adjust scheduling when traffic conditions change, thus lowering overall signaling cost
Data Source
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AI summary
The present invention relates to a scheduling method of evolved NodeB, an evolved NodeB in a long term evolution system and the long-term evolution system. The method comprises an eNB sends a downlink media access controlprotocol data unit, MAC PDU, for transmitting downlink data, the downlink MAC PDU carries an media access control control element, MAC CE, the MAC CE carries the uplink resource allocation information for indicating an uplink resource to a user device; the eNB receives an uplink MAC PDU sent by the UE according to the uplink resource allocation information. Through using the MAC CE in the MAC PDU for downlink data transmission to perform scheduling, PDCCH cost is effectively saved, especially in the case of there are large amount of small packets to transmit, thus the capacity of the system is increased as much as possible.