Selective E-DPCCH Transmission for Uplink Capacity
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Solution Overview
Problem
The additional power required for transmitting the enhanced dedicated physical control channel (E-DPCCH) significantly reduces the overall capacity of the reverse channel, especially in applications with low data rates or unfavorable path loss conditions, and introduces overhead due to its constant transmission, even when the transport format combination remains unchanged.
Innovation Solution
E-DPCCH is transmitted selectively only when the transport format combination of the enhanced dedicated physical data channel (E-DPDCH) changes or when acknowledgments from NodeBs indicate successful decoding, and is turned off otherwise, with the option to resume transmission when the format changes or maximum retransmissions are reached, and a new-transmission flag is used to simplify decoding at NodeBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If E-DPCCH is transmitted continuously to ensure NodeBs can decode the channel correctly, then reliability of control channel decoding is improved, but power consumption increases and capacity of the reverse channel decreases
Solution Approach 1:
The patent implements discontinuous transmission of E-DPCCH by transmitting control information only in periodic intervals rather than continuously. The E-DPCCH is transmitted selectively based on whether transport format combination changes occur, thereby reducing power consumption while maintaining adequate decoding reliability through periodic updates.
Solution Approach 2:
The patent extracts and transmits only the necessary control information (E-TFCI and RSN bits) rather than continuous control channels. By taking out only the essential elements needed for decoding and transmitting them selectively when format changes occur, the system reduces overall power consumption while maintaining decoding reliability.
2Measurement precision
If E-DPCCH is transmitted continuously to provide complete control information, then decoding accuracy at NodeB is improved, but overhead on the reverse channel increases
Solution Approach 1:
The patent extracts only the essential control elements (E-TFCI for transport format combination and RSN for redundancy version) from the control channel and transmits them selectively. This extraction approach provides sufficient decoding accuracy while significantly reducing the quantity of control overhead on the reverse channel compared to continuous E-DPCCH transmission.
Solution Approach 2:
The patent applies partial action by transmitting E-DPCCH only when necessary (when transport format combination changes) rather than continuously. This partial transmission provides adequate decoding accuracy for the critical information while minimizing the overhead burden on the reverse channel.
3Reliability
If E-DPCCH transmission is maintained for low data rate applications, then control information is reliably delivered, but capacity for data transmission is reduced
Solution Approach 1:
The patent implements periodic transmission of E-DPCCH based on transport format combination changes rather than continuous transmission. For low data rate applications where format changes are infrequent, this periodic approach maintains reliable control information delivery while freeing up significant capacity for actual data transmission.
Solution Approach 2:
The patent makes the E-DPCCH transmission dynamic by adjusting its presence based on whether transport format combination changes occur. This dynamic approach adapts to different data rates and application requirements, maintaining control reliability when needed while maximizing data channel capacity during stable transmission periods.
Data Source
AI summary
In a UMTS wireless communication system, the enhanced dedicated physical control channel (E-DPCCH) that is usually always transmitted together with the enhanced dedicated physical data channel (E-DPDCH) on the uplink from a UE to a NodeB is instead only transmitted when a predetermined “start criterion” is met and is turned off when a predetermined “stop criterion” is met until a “start criterion” is later met again. The UE starts transmitting E-DPCCH whenever the corresponding E-DPDCH transport format combination is different from the previous one in the same HARQ process or some other “start criterion” is met. Multiple mechanisms can be used to decide when the UE should switch off E-DPCCH transmission after the transport format combination of E-DPDCH has changed.