Precoded Random Access Grant Signals for 5G Beamforming
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Solution Overview
Problem
Legacy random access procedures in wireless communication systems suffer from high latency and inefficiencies, particularly in 5G networks and millimeter wave access networks, where multiple user equipment (UEs) competing for resources can lead to increased latency and interference, and the lack of prior channel information hampers beamforming in mmW networks.
Innovation Solution
The proposed solution involves broadcasting unique precoded random access grant signals with unoccupied radio network temporary identifiers and time-frequency allocations, eliminating the need for UE-transmitted preamble sequences and enabling simultaneous connection requests, which reduces the probability of collisions and allows for efficient beamforming in mmW networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If legacy random access procedure with UE-transmitted preamble sequences is used, then UEs can initiate connection requests, but latency increases and collision probability increases when multiple UEs compete for resources
Solution Approach 1:
The patent inverts the traditional random access procedure by having the network node (eNB) transmit random access grant signals instead of having UEs transmit preamble sequences. This inversion eliminates the need for UE preambles and allows the network to directly assign resources, thereby reducing latency and collision probability while improving connection establishment efficiency
Solution Approach 2:
The network node transmits random access grant signals that contain pre-assigned time-frequency resources and uplink grants before UEs need to establish connections. This preliminary allocation of resources eliminates the need for UEs to wait and retry during contention resolution, directly reducing latency and improving connection establishment efficiency
2Productivity
If multiple UEs transmit RRC connection requests on the same time-frequency resources, then resource utilization is improved, but collision probability increases and requests cannot be decoded simultaneously
Solution Approach 1:
The patent segments the random access resources by assigning different time-frequency resources to different random access grant signals transmitted by the network. Each grant signal contains unique resource allocations, which segments the previously shared resources into dedicated assignments, thereby maintaining high resource utilization while eliminating collisions and ensuring reliable decoding
3Reliability
If beamforming is used in mmW networks to alleviate path-loss, then signal quality is improved, but the procedure becomes more complex as Tx-Rx channel information is required which is not available during connection establishment
Solution Approach 1:
The network node performs preliminary beamforming configuration by transmitting random access grant signals using downlink transmit beams before UE connection establishment. The network pre-configures the beamforming parameters and transmits reference signals that enable UEs to perform uplink beamforming without requiring complex bidirectional channel estimation, thereby improving signal quality while managing complexity
Solution Approach 2:
The patent introduces reference signals and uplink grants as intermediaries that carry beamforming information from the network to the UE. These intermediaries enable the UE to configure its uplink beamforming based on network-provided parameters without requiring direct Tx-Rx channel knowledge, thus improving signal quality while reducing the complexity of beamforming configuration during connection establishment
Data Source
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AI summary
A network node for a wireless communication system includes a processor and a transceiver. The processor is configured to generate a plurality of random access grant signals. The random access grant signals include at least one unoccupied radio network temporary identifier and a resource allocation for an uplink communication request. The plurality of random access grant signals are assigned to one or more downlink transmit beams and the transceiver is configured to periodically transmit the plurality of random access grant signals on the one or more downlink transmit beams using a same time-frequency resource.