RACH Resource Allocation for Collision Reduction
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Solution Overview
Problem
The existing RACH transmission method in 3GPP RAN LTE results in increased collision rates and decreased throughput due to repeated retransmissions, leading to communication delays.
Innovation Solution
A radio communication system with a configuration that allocates separate resource blocks for pilot/UE-ID and other transmission information, prioritizing the pilot/UE-ID to reduce collision rates and prevent retransmissions by using distributed-FDMA or other multiplexing schemes like FDMA, TDMA, CDMA, and SDMA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If all transmission information is retransmitted using the RACH when collision occurs, then the RACH can be used as a contention-based channel, but the collision rate increases and throughput decreases due to repeated retransmissions
Solution Approach 1:
The transmission information is segmented into two categories: important information (pilot and UE-ID) and other information. Important information is transmitted using dedicated resource blocks with collision prevention mechanisms, while other information uses shared resource blocks. This segmentation allows the system to maintain contention-based access while protecting critical data from collision, thereby improving throughput.
Solution Approach 2:
The pilot and UE-ID are extracted from the general transmission information and allocated to dedicated resource blocks separate from other information. This extraction ensures that these critical elements are protected from collision even when other information experiences conflicts, reducing the need for complete retransmission and improving overall RACH throughput.
2Ease of operation
If transmission resources are selected randomly by mobile stations, then the RACH can operate as a contention-based channel, but collision between resource blocks increases causing retransmissions and communication delays
Solution Approach 1:
Resource blocks are segmented into dedicated resource blocks for important information and shared resource blocks for other information. Mobile stations can randomly select from shared resource blocks while dedicated resource blocks are protected from collision, maintaining ease of operation for non-critical data while ensuring reliability for critical transmissions.
Solution Approach 2:
Different quality levels of protection are applied to different parts of the transmission: dedicated resource blocks with high protection for pilot and UE-ID, and shared resource blocks with standard protection for other information. This local differentiation allows random access to remain simple while critical sections achieve high reliability.
3Quantity of substance
If the number of RACH retransmissions increases, then more information can be transmitted, but the collision rate with subsequent RACH transmissions increases creating a vicious cycle
Solution Approach 1:
Critical information (pilot and UE-ID) is extracted and placed in dedicated resource blocks that are protected from collision. This allows retransmission of other information without necessarily retransmitting the entire RACH message, breaking the vicious cycle where complete retransmission increases collision probability.
Solution Approach 2:
The RACH message is segmented into protected critical information and non-critical information. When collision occurs, only the non-critical portion needs retransmission while critical information remains intact, reducing the volume of retransmitted data and the associated collision risk, thereby improving productivity.
Data Source
AI summary
Disclosed are a radio communication system, a radio transmission device, and a Random Access Channel (RACH) transmission method capable of reducing the important information conflict probability and improving the communication system throughput in a channel transmitted at a random timing such as RACH. In a frame configuration used by the communication system, the number of slots of RACH is reduced by one and the resource for the slot is equally allocated as a resource for a pilot/User Equipment-Identification (UE-ID) of other slots. This increases the resource amount of the pilot/UE-ID. Furthermore, the resource of the pilot/UE-ID is divided into a plurality of sub slots, which are allocated as resource blocks for respective mobile stations.