Control Channel Transmission on Shared Spectrum Using LBT
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Solution Overview
Problem
Current cellular systems, such as LTE and LTE-A, face challenges in utilizing Industrial, Scientific, and Medical (ISM) bands for control channel communication due to the need for continuous and synchronous resource allocation, which is difficult to achieve on shared spectrum bands like ISM, especially with Listen-Before-Talk (LBT) channel access methods.
Innovation Solution
The proposed solution involves transmitting control parts using the same frequency band as data parts on shared spectrum, with an indicator (Control Frame Type Indicator, CFTI) providing information on the transmission and format of control parts, allowing for efficient resource allocation and synchronization signals, even in scenarios where LBT is used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control channels use continuous and synchronous resource allocation in LTE/LTE-A systems, then control channel reliability is improved, but adaptability to shared spectrum bands (ISM bands) deteriorates
Solution Approach 1:
The patent applies dynamics by making the control channel transmission flexible and adaptive to shared spectrum conditions. The base station dynamically adjusts control channel transmission based on LBT outcomes and channel availability, rather than using fixed continuous allocation. This allows the system to adapt to the stop-and-go nature of LBT-based shared spectrum access while maintaining control channel functionality.
Solution Approach 2:
The patent changes key transmission parameters including using discontinuous transmission patterns, adjusting timing based on LBT results, and modifying resource allocation to match shared spectrum availability. These parameter changes enable control channels to operate reliably on ISM bands where continuous allocation is not feasible.
2Adaptability or versatility
If Listen-Before-Talk (LBT) channel access method is used on shared spectrum, then spectrum sharing capability is improved, but control channel transmission continuity deteriorates
Solution Approach 1:
The patent applies preliminary action by performing LBT channel sensing before control channel transmission. The base station senses the channel in advance, and only transmits control channels when the channel is determined to be free. This preliminary checking ensures that subsequent control channel transmissions can proceed without collision, maintaining continuity despite the shared spectrum environment.
Solution Approach 2:
The patent implements periodic LBT sensing intervals followed by control channel transmission when channels are available. This periodic approach to channel access creates a rhythm of sensing-transmitting that maintains control channel continuity over time while respecting shared spectrum access rules.
3Reliability
If control channels are transmitted separately from data channels, then control channel reliability is improved, but spectrum utilization efficiency deteriorates
Solution Approach 1:
The patent merges control channel and data channel transmissions by multiplexing them in the same time-frequency resources on shared spectrum. Instead of separate dedicated control channels, the system combines control and data transmissions, allowing them to share the same LBT-secured channel access. This improves spectrum utilization while maintaining reliability through joint transmission protection.
Solution Approach 2:
The patent makes the data channel serve multiple functions by carrying both data and control information. The shared channel structure allows the same transmission medium to fulfill both control and data transmission roles, improving overall spectrum efficiency while maintaining the reliability needed for control information through appropriate signaling and resource allocation.
Data Source
AI summary
Apparatus and method for communication are provided. The solution includes controlling the communication of a transceiver on shared data channels using a data channel slot including a sensing period and a data period and controlling a transceiver to communicate on common and dedicated control channels on a shared spectrum using control channel slots, each control channel slot including a downlink part and an uplink part, wherein the uplink part occurs at the same time as the sensing period of a data channel slot.