A self-adaptive physical downlink control channel (PDCCH) format selecting method

Abstract

The invention provides a self-adaptive physical downlink control channel (PDCCH) format selecting method. The method comprises following steps. Firstly, a base station divides a value range of a channel quality indication CQ1 grade into multiple value intervals in advance and prescribes the PDCCH formats corresponding to value intervals. Then, the base station receives a CQ1 grade reported by UE and determines the value interval of the CQ1 grade. Finally, the base station transmits DCI information by using the PDCCH format corresponding to value interval.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an adaptive physical downlink control channel (PDCCH) format selection method. Background technique [0002] LTE is a quasi-4G system, which can increase the system capacity as much as possible and provide higher quality upload and download services. [0003] For the downlink LTE system, including Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid Automatic Repeat Request Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), Among them, the content related to the transmission rate is mainly PDCCH and PDSCH. One of these two channels carries the control information required for data reception, such as resource allocation, modulation and coding mode, redundancy version, etc.; the other carries data information content, and its correct reception will be refle...

AI Technical Summary

Problems solved by technology

[0011] 1) Control information transmission does not match data transmission;

[0012] For example, the fixed PDCCH format is 0, that is, one CCE is used to carry control information. For poor channel conditions, due to the lack of control information resources, high code rate, and high reception bit error rate, even PDSCH data can be correct under current channel conditions. Receive, but because the correct control information cannot be obtained, the PDSCH reception can only be skipped, which causes the number of data transmission bits in the current frame to be 0;

[0013] 2) Inappropriate resource expenditure;

For better channel conditions, the code rate does not need to be too low to receive PDCCH correctly, and the overhead of using 8 CCEs for each PDCCH is a waste under this condition

[0015] Therefore, the fixed PDCCH format may cause some UEs to select a small CCE length when the channel condition is poor; or select a CCE length that is too large when the channel condition is good; resulting in overhead that cannot be well matched to the current channel condition, restricting data transmission performance and system overhead

[0016] Adaptively select the CCE length according to the DCI length. Compared with the fixed CCE, it has a certain improvement. Different DCI formats are used for different transmission modes of the UE, and the PDCCH format (CCE length) is adaptively determined by using the DCI information length, which can ensure control information. The transmission code rate is basically stable, but this scheme still does not take into account the different channels of different UEs, and different channel states have a great impact on the reception of control information, so there are still two shortcomings mentioned above

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