A method for calculating the resource capacity of PDCCH of LTE network

Abstract

The application discloses a kind of LTE network PDCCH resource capacity calculation method, belong to information transmission technical field, PDCCH resource capacity includes the number of bits that can be used for PDCCH, the number of REG that can be used for PDCCH, the number of CCE that can be used for PDCCH;First, based on the number of REG that can be used for PDCCH, the number of bits that can be used for PDCCH and the number of CCE that can be used for PDCCH are calculated by the number of REG that can be used for PDCCH, the number of bits that can be used for PDCCH, the number of CCE that can be used for PDCCH are calculated according to the number of REG that can be used for PDCCH.The PDCCH resource capacity calculation method presented in the application is more in line with 3GPP protocol specification.

Description

Technical Field

[0001] This invention belongs to the field of information transmission technology, specifically relating to a method for calculating the PDCCH resource capacity of an LTE network. Background Technology

[0002] The Physical Downlink Control Channel (PDCCH) of LTE networks carries control information, including key information such as resource allocation, modulation and coding schemes, and redundancy versions for user downlink data transmission. It is a crucial guarantee for high-speed and stable downlink data transmission. Due to the limited time and frequency resources in LTE networks, the time and frequency resources available for PDCCH are also limited. PDCCH resource capacity can be represented by the number of Control Channel Elements (CCEs), Resource Element Groups (REGs), and bits. The number of CCEs and bits can be calculated from the number of REGs; therefore, the number of REGs available for PDCCH characterizes its resource capacity. Parameters such as the number of antenna ports, channel bandwidth, cyclic prefix, and number of PHICH groups all affect PDCCH resource capacity. Researching and analyzing the calculation method of PDCCH resource capacity is crucial for wireless network capacity analysis and ensuring high-speed and stable downlink data transmission for users. It also provides important guidance for the development of 4G physical layer protocol signal simulation devices.

[0003] Existing solutions, based on the 3GPP protocol's description of PDCCH resource composition, focus on calculating the number of REGs that make up the PDCCH. PDCCH resources are concentrated in the control area symbols of each subframe in the 4G network physical layer frame structure. Within these OFDM symbols, resource elements available for composing REGs cannot be elements of the Cell-Specific Reference Signal (CRS). Simultaneously, the Physical Control Format Indicator Channel (PCFICH) and the Physical Hybrid Repeat Indicator Channel (PHICH) also require REG resources. Therefore, the actual REG resources available for the PDCCH are the remaining REGs formed by removing the resource elements occupied by CRS, PCFICH, and PHICH from all resource elements in the control area symbols.

[0004] The resource elements occupied by CRS are related to the number of antenna ports and the cyclic prefix. Furthermore, the arrangement of these resource elements is related to the number of control area symbols, and the maximum number of control area symbols is determined by the channel bandwidth. PCFICH occupies a fixed 4 REGs, while the REGs occupied by PHICH are related to the number of PHICH groups. Therefore, the relationship between parameters such as channel bandwidth, number of antenna ports, cyclic prefix, number of PHICH groups, and the number of REGs available for PDCCH is quite complex and requires detailed analysis.

[0005] While the current scheme has analyzed the relationship between parameters such as channel bandwidth, number of antenna ports, cyclic prefix, number of PHICH groups and the number of REGs available for PDCCH, it does not fully comply with the 3GPP protocol and has problems such as unclear parameter relationships and mismatched calculation results.

[0006] Because many parameters affect the number of REGs available for PDCCH, such as channel bandwidth, number of antenna ports, cyclic prefix, and number of PHICH groups, the relationship between these parameters and the number of REGs available for PDCCH is quite complex. Furthermore, different duplex modes in 4G networks need to be considered. Therefore, existing technical solutions have oversights, leading to problems such as unclean calculation methods and mismatched calculation results under certain parameter conditions.

[0007] In summary, the current scheme for calculating PDCCH resource capacity has the following shortcomings: 1. When four antenna ports are not considered, the first two OFDM symbols require every three resource elements to be reserved for reference signals (or unused resource elements corresponding to reference signals on other antenna ports). 2. The number of REGs available for PDCCH does not change when the number of antenna ports is 2 or 4. According to the 3GPP protocol, the number of REGs available for PDCCH is not exactly the same when the number of antenna ports is 2 and 4. 3. The calculation results also do not conform to the TS36.211 protocol description for TDD duplex mode and extended cyclic prefix. According to the 3GPP protocol, different duplex modes mainly affect the calculation of the number of PHICH groups, thus affecting the PDCCH resource capacity. Summary of the Invention

[0008] To address the aforementioned issues, this invention proposes a method for calculating the PDCCH resource capacity of an LTE network. It focuses on analyzing the relationship between the number of REGs available for PDCCH and parameters such as channel bandwidth, number of antenna ports, cyclic prefix, and number of PHICH groups, and provides a calculation formula.

[0009] The technical solution of the present invention is as follows:

[0010] A method for calculating the PDCCH resource capacity of an LTE network, wherein the PDCCH resource capacity includes the number of bits available for PDCCH, the number of REGs available for PDCCH, and the number of CCEs available for PDCCH; firstly, the number of REGs available for PDCCH is calculated based on the channel bandwidth, the number of antenna ports, the cyclic prefix, and the number of PHICH groups; then, the number of bits available for PDCCH and the number of CCEs available for PDCCH are calculated based on the number of REGs available for PDCCH.

[0011] Furthermore, the calculation method differs depending on the channel bandwidth size when calculating the number of REGs available for the PDCCH. The specific calculation process is as follows:

[0012] (1) When the channel bandwidth is greater than 10 RBs, the calculation method differs depending on the number of antenna ports, as follows:

[0013] When the number of antenna ports is 1 or 2:

[0014] The number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + (number of control area symbols - 1) * number of resource blocks per time slot * 3;

[0015] When the number of antenna ports is 4:

[0016] When the control region symbol is 1 or 2, the number of REGs available for PDCCH = number of control region symbols * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3;

[0017] When the control area symbol is 3, the number of REGs available for PDCCH = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3;

[0018] (2) When the channel bandwidth is no more than 10 RBs and the number of control area symbols is less than 4, the calculation method for the number of REGs that can be used for PDCCH is exactly the same as when the channel bandwidth is greater than 10 RBs.

[0019] (3) When the channel bandwidth is no more than 10 RBs and the number of control area symbols is 4, the calculation method will be different depending on the number of antenna ports or the cyclic prefix. Specifically:

[0020] When the number of antenna ports is 1 or 2 and the regular cyclic prefix is ​​used, the number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 3 * number of resource blocks per time slot * 3;

[0021] When the number of antenna ports is 1 or 2 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH is = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3;

[0022] When the number of antenna ports is 4 and the regular cyclic prefix is ​​used, the number of REGs available for PDCCH is = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3;

[0023] When the number of antenna ports is 4 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH is = [3 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3.

[0024] Furthermore, each CCE consists of 9 REGs, so the number of CCEs available for PDCCH = floor(number of REGs available for PDCCH / 9), where floor() is the floor function.

[0025] Furthermore, each RE transmits one PDCCH symbol and each symbol is 2 bits, so the number of bits available for PDCCH = the number of REGs available for PDCCH * 8.

[0026] The beneficial technical effects of this invention are as follows:

[0027] 1. This invention proposes a detailed and specific method for calculating PDCCH resource capacity. It focuses on analyzing the calculation method of REG number applicable to PDCCH under different channel bandwidth, number of antenna ports, cyclic prefix, and number of PHICH groups, and provides a method for calculating CCE number and bit number from REG number.

[0028] 2. The LTE network PDCCH resource capacity method proposed in this invention integrates existing solutions, not only realizing all the functions of existing solutions but also solving their shortcomings, such as unclear calculation methods in some parameter scenarios and mismatches between calculation results and 3GPP protocol descriptions. Specifically, this invention proposes a PDCCH resource capacity calculation method when the number of antenna ports is 4, analyzes the differences between the PDCCH resource capacity calculation methods when the number of antenna ports is 2 and 4, and is applicable to TDD duplex mode and extended cyclic prefix scenarios. Compared with existing solutions, the PDCCH resource capacity calculation method proposed in this invention is more in line with 3GPP protocol specifications. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method for calculating the PDCCH resource capacity of the LTE network according to the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] This invention proposes a method for calculating the PDCCH resource capacity of an LTE network. According to the 3GPP protocol, the control area of ​​the LTE network physical layer includes the Physical Control Format Indicator (PEC) channel, Physical Hybrid Transmission Indicator (PHI) group, and PDCCH. The PEC channel occupies a fixed 4 REGs, each PHICH group occupies 3 REGs, and the remaining resource elements (REs), after deducting those used for cell-specific reference signals, are grouped into a REG of 4 REs. The RE resource location of the cell reference signal is related to parameters such as the number of antenna ports, channel bandwidth, and cyclic prefix. By analyzing the number of REGs under different channel bandwidths, antenna ports, and cyclic prefixes, a closed-form expression for the number of REGs available for PDCCH is obtained, thus revealing a closed-form relationship between PDCCH resource capacity and parameters such as the number of antenna ports, channel bandwidth, cyclic prefix, and number of PHICH groups.

[0032] like Figure 1 As shown, the PDCCH resource capacity includes the number of bits available for PDCCH, the number of REGs, and the number of CCEs. The number of bits and CCEs available for PDCCH can be calculated from the number of REGs available for PDCCH. Therefore, once the number of REGs available for PDCCH is determined, the available PDCCH resource capacity can be determined. Thus, this invention focuses on analyzing the method for calculating the number of REGs available for PDCCH.

[0033] According to the 3GPP protocol, a REG contains 4 Resource Elements (REs), and these 4 REs reside on the same OFDM symbol. Therefore, regardless of whether the number of antenna ports is 1, 2, or 4, the number of REGs on the same OFDM symbol is the same. The following details the method and analysis process for calculating the number of REGs available for PDCCH based on parameters such as channel bandwidth, number of antenna ports, cyclic prefix, and number of PHICH groups.

[0034] 1. When the channel bandwidth is greater than 10 RBs, the maximum number of control area symbols is 3; at this time, the calculation method of the number of REGs is given according to the different number of antenna ports.

[0035] 1.1 When the number of antenna ports is 1 or 2:

[0036] Based on the description of the resource element location of CRS in TS36.211, the number of REGs in different control area symbols within a resource block (RB) frequency domain can be determined. OFDM symbol 0 has 2 REGs per RB, while symbols 1 and 2 have 3 REGs per RB.

[0037] Therefore, in OFDM symbol 0, the number of REGs available for PDCCH equals the number of resource blocks per time slot * 2; in OFDM symbols 1 and 2, the number of REGs available for PDCCH equals the number of resource blocks per time slot * 3. PCFICH occupies a fixed 4 REGs, and each PHICH group occupies 3 REGs.

[0038] Therefore, the number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + (number of control area symbols - 1) * number of resource blocks per time slot * 3.

[0039] 1.2 When the number of antenna ports is 4:

[0040] Based on the description of the resource element location of CRS in TS36.211, the number of REGs in different control area symbols within a single RB frequency domain can be determined. OFDM symbols 0 and 1 each have 2 REGs, while symbol 2 has 3 REGs per RB. Therefore:

[0041] 1) When the control region symbol is 1 or 2, the number of REGs available for PDCCH = number of control region symbols * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3;

[0042] 2) When the control area symbol is 3, the number of REGs available for PDCCH = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3.

[0043] 2. When the channel bandwidth is no more than 10 RBs, the maximum number of control area symbols is 4. If the number of control area symbols is less than 4, the number of REGs that can be used for PDCCH is the same as when the channel bandwidth is greater than 10 RBs.

[0044] 3. When the channel bandwidth is no more than 10 RBs and the number of control area symbols is 4, if the extended cyclic prefix is ​​used, there will only be 2 REGs on symbol 3.

[0045] 3.1 When the number of antenna ports is 1 or 2 and the cyclic prefix is ​​normal, the number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 3 * number of resource blocks per time slot * 3.

[0046] 3.2 When the number of antenna ports is 1 or 2 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH is = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3.

[0047] 3.3 When the number of antenna ports is 4 and the regular cyclic prefix is ​​used, the number of REGs available for PDCCH is = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3.

[0048] 3.4 When the number of antenna ports is 4 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH is = [3 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3.

[0049] The number of REGs available for PDCCH can be used to further calculate the number of CCEs and bits available for PDCCH. Each CCE consists of 9 REGs, therefore the number of CCEs available for PDCCH = floor(number of REGs available for PDCCH / 9), where floor() is the floor function. Each RE transmits one PDCCH symbol and each symbol is 2 bits, therefore the number of bits available for PDCCH = number of REGs available for PDCCH * 8.

[0050] This invention relates to a method for calculating the number of REGs available for use in a PDCCH using four antenna ports. Based on a detailed analysis of the 3GPP protocol, this invention reveals that with four antenna ports, the first two OFDM symbols require every three resource elements to be reserved for reference signals (or unused resource elements corresponding to reference signals on other antenna ports). This leads to the conclusion that within a single RB frequency domain, only two REGs are available on the first two OFDM symbols within the control area. This results in a method for calculating the number of REGs usable in the PDCCH.

[0051] This invention also applies the calculation of the number of REGs available for the PDCCH when the number of antenna ports is 2 and 4. Combining the 3GPP protocol's description of antenna ports, this invention analyzes the impact of different channel bandwidths and cyclic prefixes on the number of REGs available for the PDCCH when the number of antenna ports is 2 and 4, thus deriving a method for calculating the number of REGs available for the PDCCH. Compared with existing solutions, the method proposed in this invention for calculating the number of REGs available for the PDCCH when the number of antenna ports is 2 and 4 is more in line with the 3GPP protocol specifications.

[0052] This invention's method is applicable to TDD duplex mode and extended cyclic prefix scenarios. According to 3GPP protocol specifications, the number of PHICH groups in TDD duplex mode and extended cyclic prefix scenarios has a different calculation method than in FDD duplex mode and TDD duplex mode with a regular cyclic prefix scenario. Furthermore, the number of PHICH groups affects the calculation of the number of REGs available for PDCCH. The method proposed in this invention follows 3GPP protocol specifications when calculating the number of PHICH groups in TDD duplex mode and extended cyclic prefix scenarios. Based on the number of PHICH groups in TDD duplex mode and extended cyclic prefix scenarios, and combined with parameters such as channel bandwidth and the number of antenna ports, the method proposed in this invention can be used to calculate the number of REGs available for PDCCH. Therefore, compared with existing solutions, the method proposed in this invention for calculating the number of REGs available for PDCCH in TDD duplex mode and extended cyclic prefix scenarios is more in line with 3GPP protocol specifications.

[0053] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for calculating the PDCCH resource capacity of an LTE network, characterized in that, PDCCH resource capacity includes the number of bits available for PDCCH, the number of REGs available for PDCCH, and the number of CCEs available for PDCCH. First, the number of REGs available for PDCCH is calculated based on the channel bandwidth, the number of antenna ports, the cyclic prefix, and the number of PHICH groups. Then, the number of bits available for PDCCH and the number of CCEs available for PDCCH are calculated based on the number of REGs available for PDCCH. The calculation method differs depending on the channel bandwidth size when calculating the number of REGs available for PDCCH. The specific calculation process is as follows: (1) When the channel bandwidth is greater than 10 RBs, the calculation method is different depending on the number of antenna ports, as follows: When the number of antenna ports is 1 or 2: The number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + (number of control area symbols - 1) * number of resource blocks per time slot * 3; When the number of antenna ports is 4: When the control region symbol is 1 or 2, the number of REGs available for PDCCH = number of control region symbols * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3; When the control area symbol is 3, the number of REGs available for PDCCH = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3; (2) When the channel bandwidth is no more than 10 RBs and the number of control area symbols is less than 4, the calculation method for the number of REGs that can be used for PDCCH is exactly the same as when the channel bandwidth is greater than 10 RBs; (3) When the channel bandwidth is no more than 10 RBs and the number of control area symbols is 4, the calculation method will be different depending on the number of antenna ports or the cyclic prefix, as follows: When the number of antenna ports is 1 or 2 and the cyclic prefix is ​​normal, the number of REGs available for PDCCH = [number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 3 * number of resource blocks per time slot * 3; When the number of antenna ports is 1 or 2 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3; When the number of antenna ports is 4 and the regular cyclic prefix is ​​used, the number of REGs available for PDCCH is = [2 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + 2 * number of resource blocks per time slot * 3; When the number of antenna ports is 4 and the extended cyclic prefix is ​​used, the number of REGs available for PDCCH is = [3 * number of resource blocks per time slot * 2 - 4 - number of PHICH groups * 3] + number of resource blocks per time slot * 3.

2. The method for calculating the PDCCH resource capacity of an LTE network according to claim 1, characterized in that, Each CCE consists of 9 REGs, therefore the number of CCEs available for PDCCH = floor(number of REGs available for PDCCH / 9), where floor() is the floor function.

3. The method for calculating the PDCCH resource capacity of an LTE network according to claim 1, characterized in that, Each RE transmits one PDCCH symbol and each symbol is 2 bits, so the number of bits available for PDCCH = the number of REGs available for PDCCH * 8.

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