Intercell Uplink Interference Control via Non-Serving Relative Grants
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Solution Overview
Problem
In wireless communication networks, particularly in UMTS networks, UEs in the CELL_FACH state lack dedicated physical channels, leading to uplink interference issues due to the inability to engage in soft handover, especially in heterogeneous networks where varying technologies cause interference challenges.
Innovation Solution
Implementing a method for managing intercell interference by allowing UEs in the CELL_FACH state to listen to a shared E-RGCH channel for non-serving relative grant signals from neighbor cells, enabling them to adjust their uplink transmission rates and power to mitigate interference, thereby controlling intercell interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UEs in CELL_FACH state transmit uplink without soft handover capability, then uplink transmission can be initiated, but intercell interference occurs at neighbor cells
Solution Approach 1:
The patent implements a feedback mechanism where the neighbor cell monitors uplink interference from CELL_FACH UEs and sends non-serving relative grant signals back to control their transmission rates. This closed-loop feedback allows the system to maintain uplink transmission capability while dynamically adjusting to prevent interference at neighbor cells.
Solution Approach 2:
The patent introduces an intermediary control mechanism using the shared E-RGCH channel and non-serving relative grant signals as a mediator between the transmitting UE and the affected neighbor cell. This intermediary allows indirect control of UE transmission behavior without requiring direct UE-neighbor cell communication or soft handover capability.
2Adaptability or versatility
If UEs camp on serving cell adjacent to neighbor cell without soft handover, then UE can operate in CELL_FACH state, but uplink interference occurs at neighbor cell
Solution Approach 1:
The system maintains CELL_FACH operation flexibility by implementing a feedback loop where the neighbor cell monitors interference and sends non-serving relative grant signals through the shared E-RGCH channel. This allows UEs to remain in CELL_FACH state while their transmission behavior is dynamically controlled based on neighbor cell interference conditions.
Solution Approach 2:
The patent enables UEs to self-adjust their uplink transmission characteristics by having them monitor the shared E-RGCH channel for non-serving relative grant signals from neighbor cells. UEs autonomously modify their transmission rates based on these signals without requiring network reconfiguration or handover procedures.
3Duration of action of stationary object
If cell reselection procedures are slow in CELL FACH, then UE can maintain current serving cell, but serving cell may not be strongest downlink cell causing interference
Solution Approach 1:
The patent addresses the slow cell reselection issue by implementing continuous feedback through non-serving relative grant signals on the E-RGCH channel. This feedback mechanism allows real-time adjustment of uplink transmission parameters based on current interference conditions, effectively compensating for the inability to quickly reselect to the strongest downlink cell.
Solution Approach 2:
The system dynamically changes transmission parameters (uplink rate and power) based on feedback from neighbor cells rather than relying on frequent cell reselection. This parameter adjustment approach allows UEs to adapt to changing channel conditions and interference scenarios without requiring slow cell reselection procedures.
4Productivity
If UEs transmit uplink to serving cell while neighbor cell is stronger, then uplink transmission can proceed, but uncontrollable interference exists at neighbor cell
Solution Approach 1:
The patent implements feedback control where the affected neighbor cell monitors uplink transmissions and sends non-serving relative grant signals to UEs causing interference. This feedback loop makes interference controllable by dynamically adjusting UE transmission rates based on real-time neighbor cell conditions, rather than allowing uncontrollable interference.
Solution Approach 2:
The system takes preliminary anti-action by having UEs monitor the shared E-RGCH channel for non-serving relative grant signals before and during uplink transmissions. This allows UEs to proactively adjust their transmission behavior to prevent interference at neighbor cells before the interference problem arises, rather than reacting after interference occurs.
Data Source
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AI summary
Wireless user equipment (UE) operating in a wireless communication system may operate in a state, for example, the CELL_FACH state in UMTS, that does not allow for soft handoff from one cell to another. This inability to engage in soft handover may lead to intercell interference at a non-serving cell when the UE transmits on its uplink in close proximity to the non-serving cell. Therefore, provided in the present disclosure is method of wireless communication, which includes receiving a neighbor cell identification set indicating one or more neighbor cells, receiving a relative grant channel resource index corresponding to a relative grant channel shared by at least one of the one or more neighbor cells, detecting intercell interference associated with a user equipment (UE) in the one or more neighbor cells, and transmitting a non-serving relative grant message to the UE on the relative grant channel.