[0042] Such as figure 1 As shown, the method for implementing downlink data transmission using an active antenna system applied to an LTE or LTE-A system includes:
[0043] Group the beams with the uplink received power greater than the preset threshold among the beams on the physical resources of the user to form the user's downlink active beam set;
[0044] According to the number of beams in the downlink activated beam set of the user, open loop diversity is used to transmit the downlink data of the user or the downlink data of the user in the downlink activated beam set; the space between the respective downlink activated beam sets of the paired users is used. The downlink data is transmitted in a division multiple access mode, where users with no intersection in the downlink activated beam sets constitute paired users.
[0045] The above method can be directed to vertical beams or horizontal beams, for example, open-loop diversity transmission is performed on the downlink vertical active beam and the downlink horizontal active beam, respectively, and can respectively solve the related interference between vertical beams and the related interference between horizontal beams.
[0046] When calculating the preset threshold, the preset threshold may be calculated according to the maximum received power on the user's beam. For example, the preset threshold is the product of the maximum received power and a coefficient, and the coefficient is a real number greater than 0 and less than 1. For example, the value of the coefficient can be 0.7.
[0047] The open-loop diversity transmission method can be the time-diversity open-loop transmission method:
[0048] (1) Realization in time domain: For different activated beams in the downlink activated beam set, the downlink time domain data of the corresponding user is sent at different time domain moments;
[0049] (2) Frequency domain realization: The user's downlink frequency domain data is rotated by different phase values for different activated beams in the downlink activated beam set and then sent.
[0050] The open-loop diversity transmission method may also be a selective open-loop transmission method: only the user's downlink data is sent on the active beam with the largest uplink received power in the downlink active beam set.
[0051] In the above method, when the number of beams in the user's downlink active beam set is greater than 1, the user's downlink data is transmitted on the beams in the downlink active beam set for open loop diversity, and when the number of beams is equal to 1, it is adopted Direct transmission, the downlink data of the user is directly transmitted on the beam in the downlink activated beam set.
[0052] When the user’s downlink activated beam set does not contain all downlink beams, it is determined whether there is a paired user of this user, and if there is, the downlink data of the paired user is transmitted in space division multiple access on the paired user’s downlink activated beam set. If it does not exist, no data is transmitted on beams other than the beams in the downlink activated beam set of this user; the number of paired users on the same physical resource is greater than or equal to 2.
[0053] The device for implementing downlink data transmission by using an active antenna system corresponding to the above method includes a beam determination module and a data transmission module.
[0054] The beam determining module is configured to group the beams whose uplink received power is greater than a preset threshold among the beams on the physical resources of the user into a downlink active beam set of the user;
[0055] The data transmission module is configured to use open loop diversity to transmit the user's downlink data or directly transmit the user's downlink data in the downlink active beam set according to the number of beams in the user's downlink active beam set; The respective downlink activated beam sets of the paired users transmit downlink data in a space division multiple access manner, where users with no intersection in the downlink activated beam sets constitute a paired user.
[0056] The device can perform processing for vertical beams or horizontal beams, such as performing open-loop diversity transmission on downlink vertical active beams and downlink horizontal active beams respectively, and can respectively solve the related interference between vertical beams and the related interference between horizontal beams.
[0057] The method for the beam determination module to calculate the preset threshold is the same as in the above method.
[0058] The data transmitting module is configured to transmit the downlink data of the user on the beams in the downlink active beam set for open-loop diversity transmission when the number of beams in the downlink active beam set of the user is greater than 1, and the number of beams When it is equal to 1, the direct transmission is adopted, and the downlink data of the user is directly transmitted on the beams in the downlink active beam set.
[0059] The data transmission module is also used to determine whether there is a paired user of this user when the downlink activated beam set of the user does not include all downlink beams, and if there is, use space division multiple access on the downlink activated beam set of the paired user The downlink data of this paired user is transmitted in the manner of. If it does not exist, no data is transmitted on beams other than the beam in the downlink active beam set of this user. The number of paired users on the same physical resource is greater than or equal to 2.
[0060] The data transmitting module is further configured to send the downlink time domain data of the user at different time domains for different activated beams in the downlink activated beam set; or, for different activated beam pairs in the downlink activated beam set The downlink frequency domain data of the user is sent after being rotated by different phase values; or, the downlink data of the user is sent only on the active beam with the largest uplink received power in the downlink active beam set.
[0061] The situation of the vertical beam will be described below through specific embodiments, such as figure 2 As shown, the processing methods for horizontal beams and other multi-beam processing methods based on the AAS system are the same, and the description will not be repeated.
[0062] In this specific embodiment, the uplink channel estimation value of each beam in the AAS system is used to determine the active beam set at each UE level. According to the beam set, the SDMA pairing and joint diversity transmission of each UE in all vertical beams in the downlink transmission process are obtained. According to the relevant algorithm principle of this method, the downlink data transmission of each UE is multiplied by the relevant weight to perform downlink data transmission. It includes steps 1, 2, and 3.
[0063] Step 1. Obtain the uplink received power of each beam.
[0064] It includes the following two steps:
[0065] a) For the LTE communication system, the uplink channel impulse response estimation matrix of the kth user is obtained by the uplink DMRS or SRS through the base station side channel estimation algorithm, expressed as:
[0066] h k = h k 1 ( 1 ) h k 1 ( 2 ) Λ h k 1 ( L ) h k 2 ( 1 ) h k 2 ( 2 ) Λ h k 2 ( L ) M M O M h k Ka ( l ) h k Ka ( l ) Λ h k Ka ( L ) - - - ( 1 )
[0067] Where K a Represents the number of vertical beams in AAS, and L represents the number of resource blocks (RE) in the LTE system bandwidth.
[0068] b) Calculate the uplink receiving energy matrix of each vertical beam according to Equation 1:
[0069] P k = P k 1 ( 1 ) P k 1 ( 2 ) Λ P k 1 ( L ) P k 2 ( 1 ) P k 2 ( 2 ) Λ P k 2 ( L ) M M O M P k Ka ( l ) P k Ka ( l ) Λ P k Ka ( L ) - - - ( 2 )
[0070] Where P represents the received power, and
[0071] Step 2. Vertical beam activation detection.
[0072] For the physical resource l occupied by the downlink traffic channel of user k (l is a set, which is a subset of all REs in the LTE system bandwidth, that is, l∈L), calculate the received power vector of the corresponding vertical beam according to equation 2. And as shown below:
[0073] P ~ k = P k 1 P k 2 M P k Ka - - - ( 3 )
[0074] among them ka=1, 2,..., Ka,
[0075] Select the maximum value of each receiving beam under the occupied physical resource l from formula (3) Then the activation threshold of the downlink diversity transmit beam can be obtained as:
[0076] P k = α · P k max - - - ( 4 )
[0077] Among them, α is the activation coefficient, and its value range is [0, 1]. Its default value can be determined according to simulation or field test. The default value in the embodiment is 0.7.
[0078] Traverse the uplink received power of all vertical beams, among which the ones greater than the activation threshold are considered to be downlink diversity transmission activated beams, and the activated vertical beam set M of the physical resource l occupied by user k is obtained.
[0079] Step 3. Downlink data transmission.
[0080] The active vertical beam set M of the physical resource l occupied by the user k is determined.
[0081] (1) The number of activated vertical beams in set M is equal to 1 (that is, only a single vertical beam is activated)
[0082] The downlink data of user k is only transmitted in the active vertical beam, and the occupied physical resource range is 1. In addition to the active vertical beam of user k, other vertical beams can use SDMA within the physical resource range l to transmit the downlink data of other paired users {p, q,...} paired with user k. The pairing requirements are: There is no intersection between the sets of activated vertical beams of the paired users. If there is no suitable paired user, no data is transmitted on other vertical beams except the active vertical beam of user k to reduce interference.
[0083] Such as image 3 As shown, the active vertical beam sets of UE1, UE2, and UE3 are vertical beams 3, 2, and 1, respectively. There is only one active vertical beam in the vertical beam sets of the three UEs, and UE1 can be directly transmitted on vertical beam 3. The downlink data of UE2 can be directly transmitted on vertical beam 2, and the downlink data of UE3 can be directly transmitted on vertical beam 1. The downlink active vertical beam sets of UE1, UE2, and UE3 do not have an intersection, and can be divided by space. In the addressing mode, the downlink data of the corresponding UE is respectively transmitted in each downlink activated vertical beam set at the same time.
[0084] (2) The number of active vertical beams in the set M is greater than one.
[0085] The downlink system that activates each vertical beam in the vertical beam set is still independent of each other, but joint open-loop diversity transmission is required between each beam. The open-loop diversity transmission in this embodiment can be, but is not limited to, time open-loop diversity. Method and selective emission method.
[0086] ①Time diversity open loop transmission method:
[0087] a) Time domain realization method:
[0088] Send the user's downlink data at different time domains for different activated vertical beams, where the transmission delay time corresponds to each activated beam one-to-one, that is, the downlink transmission time domain delay of the m-th activated beam is t m. The transmission delay time on adjacent active vertical beams is the same or different.
[0089] Assuming that the downlink time-domain transmission data is d(t), the downlink time-domain transmission data of the m-th activated beam is d(t-t m ).
[0090] Such as Figure 4 As shown, the active vertical beam concentration of UE1 includes active vertical beams 2 and 3. In the relevant downlink physical resources of UE1, time domain time diversity transmission is adopted in the active vertical beams 2 and 3, and the downlink time domain of UE1 is transmitted in beam 2. Data d(t), the downlink time domain data of UE1 is also transmitted in beam 3, but the transmission needs to be delayed at t1, that is, the downlink time domain data bit d(t-t1) of UE1 transmitted in beam 3, and beam 1 is UE1 If there is no suitable other UE to pair with UE1, no data is transmitted on beam 1.
[0091] b) Frequency domain realization method:
[0092] The downlink data of the user is rotated with different phase values for different activated beams and then sent. Different activated vertical beam groups transmit the same data, but need to be multiplied by different transmission weights. The transmission weights correspond to each activated beam one-to-one, that is, the downlink transmission time domain delay of the mth activated beam is exp(jft m ), where f is the subcarrier frequency.
[0093] Assuming that the downlink frequency domain transmission data is d(f), the downlink time domain transmission data of the m-th activated beam is d(f)·exp(jft m );
[0094] Such as Figure 5 As shown, the active vertical beam concentration of UE1 includes active vertical beams 2 and 3. Then, in the relevant downlink physical resources of UE1, the frequency domain time diversity transmission is adopted in the beam activated vertical beams 2 and 3, and the downlink of UE1 is transmitted in beam 2. Frequency domain data d(f), the downlink frequency domain data of UE1 is also transmitted in beam 3, but phase rotation is required, that is, the downlink frequency domain data bits of UE1 transmitted by beam 3 are d(f)·exp(jft 1 ), in addition, beam 1 is the inactive set of UE1, and no other suitable UE is paired with UE1, then no data is transmitted on beam 1.
[0095] ②The selective open loop transmission method is as follows:
[0096] Select a vertical beam for transmission in the active vertical beam group corresponding to the downlink physical resource of the UE. In order to receive better data on the UE side, the vertical beam with the largest uplink receiving energy in the active vertical beam group can be selected for transmission, and the active beam The other beams in the group no longer transmit data on the downlink physical resources of the UE.
[0097] Such as Image 6 As shown, the active vertical beam set of UE1 includes active vertical beams 2 and 3, and the uplink received power of active vertical beam 2 is the largest. Then the downlink data of UE1 is transmitted in beam 2 in the relevant downlink physical resources of UE1, and beam 3 The downlink data of UE1 is not transmitted on the uplink; in addition, beam 1 is the inactive set of UE1, and there is no suitable other UE to pair with UE1, then no data is transmitted on beam 1.
[0098] In addition, the above-mentioned methods based on open-loop diversity transmission and SDMA between groups can be simultaneously applied according to the active set of the UE, such as Figure 7 As shown, the active vertical beam set of UE1 includes active vertical beams 2 and 3, and the active beam set of UE2 is active vertical beam 1. In the relevant downlink physical resources, time diversity is used to transmit UE1's downlink data in beams 2 and 3. The downlink data of UE2 is directly transmitted in beam 1. In addition, the intersection of the active vertical beam sets of UE1 and UE2 is empty, and the two can be paired, then the downlink data of UE1 is sent on beam 2 and beam 3 and the downlink data of UE2 is sent on beam 1 data.
[0099] In summary, the downlink data transmission method of the LTE/LTE-A system using AAS proposed by this solution can obtain diversity gain and shaping gain without significantly increasing the computational complexity, and adopts SDMA. Reuse physical resources to improve system performance and is suitable for various channel environments, which is very conducive to engineering realization.
[0100] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other arbitrarily if there is no conflict.
[0101] Of course, the present invention can also have various other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes Both the deformations should belong to the protection scope of the appended claims of the present invention.
[0102] Those of ordinary skill in the art can understand that all or part of the steps in the above method can be completed by a program instructing relevant hardware, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a magnetic disk, or an optical disk. Optionally, all or part of the steps of the foregoing embodiments may also be implemented by using one or more integrated circuits. Correspondingly, each module/unit in the above-mentioned embodiment can be implemented in the form of hardware or software functional module. The present invention is not limited to the combination of any specific form of hardware and software.
