WO2015184884A1 - 基于小区间协作的异构网服务小区选择方法及装置 - Google Patents

基于小区间协作的异构网服务小区选择方法及装置 Download PDF

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WO2015184884A1
WO2015184884A1 PCT/CN2015/074516 CN2015074516W WO2015184884A1 WO 2015184884 A1 WO2015184884 A1 WO 2015184884A1 CN 2015074516 W CN2015074516 W CN 2015074516W WO 2015184884 A1 WO2015184884 A1 WO 2015184884A1
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cell
user
ffr
rate
users
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PCT/CN2015/074516
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English (en)
French (fr)
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王绍鹏
秦洪峰
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中兴通讯股份有限公司
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Priority to EP15803147.6A priority Critical patent/EP3200507B1/en
Priority to US15/513,764 priority patent/US10015730B2/en
Publication of WO2015184884A1 publication Critical patent/WO2015184884A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0009—Control or signalling for completing the hand-off for a plurality of users or terminals, e.g. group communication or moving wireless networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/16—Discovering, processing access restriction or access information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/20—Selecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This paper relates to the field of digital communications, and in particular to a heterogeneous network serving cell selection scheme based on a carrier aggregation (Carrier Aggregation) system.
  • Carrier Aggregation Carrier Aggregation
  • the heterogeneous network can improve the system performance by improving the topology of the network, it becomes one of the research hotspots of mobile communication.
  • the heterogeneous network consists of a network-planned high-power macro base station and a low-power node with autonomous placement under its coverage.
  • the low-power nodes include a home base station, a pico-cell, and a relay station, which can implement hotspot coverage and cells.
  • the traffic is shunted to obtain the cell splitting gain. Due to the different power and coverage of different types of base stations and the autonomous placement of low-power nodes, the interference problems of control channels and traffic channels of different base stations are very prominent. Heterogeneous networks face enormous technical challenges.
  • inter-cell interference coordination technology is adopted to solve the interference problem caused by it, that is, eICIC (enhanced inter-cell interference coordination schemes).
  • eICIC is one of the key technologies in LTE-A. It is used to improve cell edge coverage and achieve range extension (RE) for cell traffic offload.
  • eICIC is mainly divided into two categories: the first type is eICIC based on carrier aggregation technology, and the second is based on time-domain ABS (almost blank subframes).
  • the ABS implements service silence by configuring an ABS subframe in the interfering cell, and the interfered cell uses these ABS subframes to provide services for users who are originally interfered in the cell, thereby achieving coordination of inter-cell interference.
  • Carrier aggregation is one of the key technologies of LTE-A. In addition to providing high-speed services on the large bandwidth formed by aggregation, it can also achieve frequency domain interference avoidance of heterogeneous networks at the component carrier (CC) resolution level. Assume that the bandwidth of a heterogeneous network consists of two component carriers: f1 and f2. In order to achieve interference coordination between the macro base station and the pico base station, f1 and f2 may be respectively allocated to users of the macro base station and the pico base station, thereby achieving interference avoidance of the user traffic channel and the control channel. Alternatively, the cell center user of the pico base station may allocate the same component carrier as the macro cell, and the edge user allocates a component carrier different from the macro base station.
  • CC component carrier
  • the disadvantage of this scheme is that it can only be adopted by LTE-A users. Not compatible with LTE users.
  • the application of all the above technologies has an important premise, that is, the problem of user service cell selection in a cell is first solved.
  • the cellular mobile communication network all users have a home serving cell, providing users with services such as broadcasting and service transmission.
  • the user's serving cell selection is based on measurements of received signal strength.
  • the transmit power of the newly added node is much lower than that of the macro base station, the serving cell selection method based on the received signal strength will cause the coverage of these nodes to be small, and the cell splitting gain is not maximized.
  • RE Range Extension
  • path loss algorithm The core idea of the RE algorithm is to add a bias value (offset value) greater than 0 to the received power RSRP (Reference Signal Receiving Power) of the low power node in the traditional serving cell selection algorithm, and the RSRP compensation value for the macro cell.
  • the bias is 0, thereby lowering the threshold of the low power node and increasing the probability that the UE selects the low power node as the serving cell.
  • RSRP Reference Signal Receiving Power
  • the above method makes the coverage of the low power node significantly increased, and can even be similar to the macro cell.
  • the downlink SINR signal to interference and noise ratio
  • the spectrum utilization rate of the cell is lowered.
  • inter-cell interference coordination can be further performed in the airspace, such as Coordinated Multi-Point (CoMP), and the adjacent cell to the edge user through the interaction of mobile user channel information between adjacent cells.
  • CoMP Coordinated Multi-Point
  • a certain interference avoidance strategy or multiple cells are jointly transmitted to mobile users, thereby improving coverage of edge users and coverage of high data transmission rates, reducing interference of edge users, and improving cell throughput.
  • COMP can be used as an enhancement to the eICIC technology described above, and further gains in system capacity over the gain obtained by eICIC.
  • cell selection and interference management are two independent processes.
  • the cell selection increases the number of low-power node users through load balancing, and the interference management is used to solve the problem of inter-cell interference increase.
  • the complexity of the interference management algorithm will increase sharply, and the effectiveness of the interference management algorithm will be reduced, thereby affecting the low-power nodes.
  • the number of users has increased.
  • Embodiments of the present invention provide a heterogeneous network serving cell selection method and apparatus based on inter-cell cooperation to improve system capacity of a low power node.
  • an embodiment of the present invention discloses a heterogeneous network serving cell selection method based on inter-cell cooperation, and the method includes:
  • the central node in the heterogeneous network obtains the candidate users in each cell in the heterogeneous network, and selects a whole network among the candidate users in all the cells in the heterogeneous network according to the preset candidate user selection criterion.
  • the foregoing method further includes:
  • Each of the cell sites in the heterogeneous network selects an alternate user in the cell in the cell according to the preset candidate user selection criterion, and reports the candidate user in the selected cell to the central node.
  • Base station Each of the cell sites in the heterogeneous network selects an alternate user in the cell in the cell according to the preset candidate user selection criterion, and reports the candidate user in the selected cell to the central node. Base station.
  • the candidate user selection criterion includes one or a combination of the following:
  • the maximizing system rate criterion refers to:
  • R m (q)/R m (j) the user whose rate ratio R m (q)/R m (j) is the largest is selected as an alternative user, where R m (q It is the rate that the user m obtains in the cell q after the reselection, and R m (j) is the rate that the user m obtains in the current serving cell j.
  • determining a rate ratio R m (q)/R m (j) of the cell reselection of the user according to the following process:
  • the rate that each user obtains in each cell is determined according to the following formula:
  • R m (q*) is the rate at which the user m is taken in the cell q*;
  • Time indicates that the cell q* is the serving cell of the user m.
  • Time indicates that the cell q* is not the serving cell of the user m, and M is the total number of users supported under the cell q*;
  • the degree of freedom recovery criterion is:
  • the user with the largest number of beam closures in the number of beam closures of all users is selected as the candidate user.
  • the process of determining the number of beam closures of the user is as follows:
  • K is the number of download waves in the cell q
  • SINR k,m,q is the signal to interference and noise ratio of the user m in the block fading scenario on the cell q download wave k;
  • the frequency reuse criterion refers to:
  • the user with the largest FFR is selected as the candidate user.
  • the FFR of the user is calculated according to the following formula:
  • FFR FFR 1 ⁇ P 1 +FFR 2 ⁇ P 2 +FFR 3 ⁇ P 3 +...+FFR Q ⁇ P Q
  • P 1 , P 2 , ... P Q are weighting coefficients.
  • the embodiment of the invention further discloses a heterogeneous network serving cell selection device based on inter-cell cooperation, comprising:
  • the candidate user selection module is configured to obtain an alternate user in each cell in the heterogeneous network, and select one of the candidate users in all cells in the heterogeneous network according to the preset candidate user selection criterion. Alternative users within;
  • the cell reselection module is configured to initiate a cell reselection process when an alternate user in the entire network is to perform a reselection operation.
  • the candidate user selection criterion includes one or a combination of the following:
  • the maximizing system rate criterion refers to:
  • R m (q)/R m (j) the user whose rate ratio R m (q)/R m (j) is the largest is selected as an alternative user, where R m (q It is the rate that the user m obtains in the cell q after the reselection, and R m (j) is the rate that the user m obtains in the current serving cell j.
  • the candidate user selection module is configured to:
  • the rate that each user obtains in each cell is determined according to the following formula:
  • R m (q*) is the rate at which the user m is taken in the cell q*;
  • Time indicates that the cell q* is the serving cell of the user m.
  • the time cell q* is not the serving cell of the user m, and M is the total number of users supported under the cell q*;
  • the degree of freedom recovery criterion refers to:
  • the user with the largest number of beam closures in the number of beam closures of all users is selected as the candidate user.
  • the candidate user selection module is configured to determine a number of beam closure times of the user in the spatial domain beam joint selection algorithm in the set time, including:
  • K is the number of download waves in the cell q
  • SINR k,m,q is the signal to interference and noise ratio of the user m in the block fading scenario on the cell q download wave k;
  • the frequency reuse criterion refers to:
  • the user with the largest FFR is selected as the candidate user.
  • the candidate user selection module is configured to calculate the FFR of the user according to the following formula:
  • FFR FFR 1 ⁇ P 1 +FFR 2 ⁇ P 2 +FFR 3 ⁇ P 3 +...+FFR Q ⁇ P Q
  • P 1 , P 2 , ... P Q are weighting coefficients.
  • the foregoing apparatus further includes:
  • the reporting module is configured to: when the device is a coordinated cell base station in the heterogeneous network, select an candidate user in the cell according to the preset candidate user selection criterion according to the preset candidate user selection criterion, and prepare the candidate in the selected cell. The selected user is reported to the central node base station.
  • the embodiment of the present invention further provides a computer readable storage medium, where the storage medium stores a computer program, where the computer program includes program instructions, when the program instruction is executed by the base station device, enabling the device to perform the foregoing inter-cell based cooperation.
  • the technical solution of the embodiment of the present invention combines cell selection and interference management, reduces the complexity of the interference management algorithm, improves the effectiveness of the interference management, and improves the system capacity of the low power node.
  • Figure 1 is a schematic diagram of a heterogeneous network
  • FIG. 2(a) is a block diagram showing an implementation of a central node base station for heterogeneous network serving cell selection based on inter-cell cooperation according to an embodiment of the present invention
  • 2(b) is a block diagram showing an implementation of a cooperative base station i for heterogeneous network serving cell selection based on inter-cell cooperation according to an embodiment of the present invention
  • 2(c) is a block diagram showing an implementation of a cooperative base station j for heterogeneous network serving cell selection based on inter-cell cooperation according to an embodiment of the present invention
  • FIG. 3 is a flowchart of implementing a heterogeneous network serving cell selection based on inter-cell cooperation according to an embodiment of the present invention
  • FIG. 4 is a flowchart of implementing a cell selection algorithm based on inter-cell cooperation according to another embodiment of the present invention.
  • FIG. 5 is a block diagram of a heterogeneous network serving cell selection apparatus based on inter-cell cooperation according to an embodiment of the present invention.
  • the existing cell selection methods are based on signal strength (RE algorithm) or interference (path loss method).
  • RE algorithm signal strength
  • path loss method path loss method
  • the low-power nodes introduced in the heterogeneous network adopt multi-antenna technology. If the interference and airspace information of the neighboring cells are simultaneously considered in the serving cell selection, a better cell splitting gain can be obtained, but the existing methods are all These factors are not considered.
  • the inventor of the present application proposes that the serving cell of the edge user can be dynamically selected by the Dynamic Cell Selection (DCS) technology, and the number of users can be improved by the cell diversity gain; Combined with interference management, the complexity of the interference management algorithm is reduced, and the effectiveness of interference management is improved, thereby improving the system capacity of the low power node.
  • DCS Dynamic Cell Selection
  • the embodiment provides a method for selecting a heterogeneous network serving cell based on inter-cell cooperation, where the heterogeneous network is composed of a macro cell and a plurality of low-power base stations under the coverage thereof, such as a home base station and a pico base station.
  • the carrier aggregated by the base station includes a plurality of component carriers CC 1 , CC 2 , . . . , CC K .
  • the method mainly includes:
  • the central node in the heterogeneous network obtains the candidate users in the cells in the heterogeneous network, and selects one of the candidate users in all the cells in the heterogeneous network according to the preset candidate user selection criterion.
  • Alternative user
  • the process in which the central node base station acquires the candidate users in the cells in the heterogeneous network is that each cell base station in the heterogeneous network selects a candidate in the cell according to the preset candidate user selection criterion according to the preset. The user then reports the candidate user in the selected cell to the central node base station.
  • the candidate user selection criteria according to the central node base station and each cell base station include at least one or more of the following criteria:
  • the maximizing system rate criterion refers to the rate ratio R m (q)/R m (j) among the rate ratios R m (q)/R m (j) of all users' cell reselections.
  • the user selects an alternate user, where R m (q) is the rate that the user m takes in the reselected cell q, and R m (j) is the rate at which the user m gets in the current serving cell j.
  • the rates obtained by the users involved in the present embodiment in each cell refer to the average rate values in a certain period of time.
  • the above formula calculates the calculation method of the weighting rate when the rate m mq (q*) obtained by the user m in the q* cell is calculated.
  • the degree of freedom recovery criterion refers to: the number of beam closures of all users in the spatial domain beam joint selection algorithm in the statistical setting time, and the user with the largest number of beam closure times is selected as the candidate user.
  • the rate of the mth user is defined as:
  • the system combining rate made by Q cells is:
  • the frequency reuse criterion refers to: the average soft frequency reuse factor FFR of all users in the carrier beam joint selection algorithm in the statistical setting time, and the user with the largest FFR is selected as the candidate user.
  • a k,m is equivalent to a. k,q , that is, there is no need to distinguish the difference between the user m and the cell q in the parameter corner.
  • the average FFR is defined as:
  • FFR FFR 1 ⁇ P 1 +FFR 2 ⁇ P 2 +FFR 3 ⁇ P 3 +...+FFR Q ⁇ P Q formula (5)
  • the above method will turn off the transmission of the carrier when the user selects the off criterion, and the selection criterion 1 is: the signal to noise ratio of the user on the carrier is located in the cooperative scheduling user on the carrier in the system. The lowest, while the most affected;
  • the selection criterion 2 is: the signal-to-noise ratio of the user on the carrier is located on the carrier in the system, and the lowest among the cooperative scheduling users. At the same time, the interference is greater than the noise value;
  • the average soft frequency reuse factor FFR weight the number of users not closed on the carrier / the total number of cooperative scheduling users on the carrier.
  • the judgment when performing cell reselection, the judgment may be performed according to criteria such as a weighted average rate.
  • the cell reselection criterion based on the weighted average rate includes the following two steps:
  • Step 1 Calculate R m* (q)/R m* (j) of the user, where j is the original serving cell and q is another cell;
  • Step 2 If the user m* selects q*, its R m* (q*)/R m* (j) is greater than the threshold R_th, ie:
  • the third step the cell and q* respectively update their respective service user sets.
  • the heterogeneous network is composed of one macro cell and two pico cells, wherein the macro cell has a radius of 500 meters and a power of 43 dBm.
  • the two pico cells are located under the coverage of the macro cell.
  • the macro cell is set to cell 1
  • the pico cell is set to cell 2 and cell 3.
  • the bandwidth of all base stations is aggregated by two carriers. Assume that there are a total of 40 users in three communities.
  • FIG. 2 is a block diagram of an implementation based on the embodiment, which is mainly divided into two layers:
  • a cooperative base station such as base station i (Fig. 2b) and base station j (Fig. 2c);
  • the central node base station (as shown in FIG. 2a) may be any one of the base stations, such as a macro cell base station.
  • PF scheduler An independent fair scheduler (PF scheduler) and carrier selection are run on the coordinated base station, wherein the fair scheduler calculates the user scheduling priority according to the average instantaneous rate and the historical average rate of the serving user of the base station, and then determines the scheduling user according to the priority order. Finally, the PF scheduler schedules the user according to the jointly designed beam vector on the selected carrier according to the output result of the central node.
  • the central node base station runs joint cell carrier selection, beam selection, and cell selection algorithms:
  • the central node base station may receive measurement results of the respective base stations, such as a channel matrix of each user to each cell, and the like;
  • the central node base station runs a joint cell carrier selection and a beam selection algorithm, jointly determines a carrier selection vector of each user, and jointly designs a beam vector of each user;
  • the central node base station selects an alternate user in the entire network according to the output result of the joint cell carrier selection, the beam selection algorithm in a certain period of time, or the parameter statistics according to the candidate user selection criterion;
  • the central node base station determines whether the candidate user performs a reselection operation according to the reselection criterion. And initiate a cell re-selection process.
  • FIG. 3 is a flowchart of implementing heterogeneous network serving cell selection based on inter-cell cooperation according to an embodiment of the present invention.
  • Figure 3 shows the implementation flow of the above method.
  • system messages are carried over the SIB information of the broadcast channel SBCH.
  • cell 1 is the base station where the central node is located.
  • the central node base station determines that the cells 1 to 3 are the coordinated cells, and therefore also the measurement cell set.
  • the cells 1, 2, and 3 are extended by the SIB message (that is, the newly defined cell measurement set in the SIB message of the LTE), and are broadcast in the local cell.
  • the user UE1 can obtain the measurement cell set, that is, the cells 1 to 3 by reading the SIB message.
  • the measurement configuration of the UEs 1 to 3 is implemented by the Measurement Configuration IE in the RRCConnnectionReconfiguration message.
  • the measurement configuration message IE is an extension of the original message IE of the LTE system.
  • the user UE1 completes the parameter measurement required by the cell set ⁇ cell 1, 2, 3 ⁇ algorithm according to the measurement configuration, such as RSRP and RSRQ (Reference Signal Received Quality), channel matrix, etc., and adopts the respective cells of the cells 1 to 3 The pilot symbols are measured.
  • the measurement configuration such as RSRP and RSRQ (Reference Signal Received Quality), channel matrix, etc.
  • the cell 2 and the cell 3 report the measurement result of the respective cell user to the cell 1.
  • Cell 1 collects measurements of all users for the cell set ⁇ cell 1, 2, 3 ⁇ .
  • the cell 1 calculates a carrier selection vector and a beam selection vector of the user, and notifies each cell, and the PF scheduler of each cell sequentially schedules the user;
  • the cell 1 counts the parameters according to the calculation result of the carrier and the beam selection vector, and selects the candidate users among all the users of the three cells according to the candidate user selection criterion. If the user UE1 is an alternative user, the cell reselection module Determining whether UE1 meets the reselection criteria,
  • the cell 1 calculates the cell reselection result of the UE1 according to the reselection criterion according to the reselection criterion, and if the target cell is the cell 3, notifies the selection result to each cell ⁇ cell 1, 2, 3 ⁇ ;
  • Each cell ⁇ cell 1, 2, 3 ⁇ notifies each user of the cell to select a result
  • User UE1 enters the cell reselection process.
  • FIG. 4 is a flowchart of implementing a cell selection algorithm based on inter-cell cooperation according to another embodiment of the present invention.
  • FIG. 4 is a flow chart showing a cell selection algorithm in the above method.
  • the algorithm mainly includes three parts, namely pre-allocation, user cell selection and re-selection.
  • the pre-allocation includes steps 1 and 2 in FIG.
  • Pre-allocation primarily provides initial values for subsequent cell selection algorithms.
  • cell 1 first collects channel measurements for all users, and second, finds the equivalent rate for each user. The largest cell is pre-assigned to the user as the serving cell; cell 1 counts the pre-assigned number of users and statistical parameters of each cell based on the pre-assigned serving cell; finally, cell 1 selects the initial value of the cell, and other cell user channels And the number of users in each cell notifies each cell, such as the cell value of the cell 2 user to the cell 1 and the cell 3;
  • the initial selection value of the cell is [20 12 8], that is, cell 1 has 20 users, cell 2 has 12 users, and cell 3 has 8 users, and in the user cell selection part of the algorithm, each cell user is calculated separately. He goes to the equivalent rate of 3 cells, and reports the ratio of the maximum equivalent rate of other cells to the equivalent rate of the cell to the serving cell.
  • the serving cell 1 firstly will be 20x1 (20 users, one for each user)
  • the equivalent rates of the selected cells are queued in order from large to small.
  • the user cell selection process selects the user at the beginning of the queue and reports the user and its rate ratio to the central node.
  • the central node first queues the candidate user rate ratios of the three cells, and secondly selects the first user in the queue, and then performs cell reselection criteria verification on the user: assuming the first largest in the queue
  • the user and the base station corresponding to the value are respectively m, q'.
  • the last process is a post-processing process, the purpose of which is to notify the serving base station base station of the user who has determined the serving cell through the above selection algorithm, and the user then initiates a cell reselection procedure.
  • FIG. 5 is a block diagram of a heterogeneous network serving cell selection apparatus based on inter-cell cooperation according to an embodiment of the present invention.
  • the embodiment provides a heterogeneous network serving cell selection device based on inter-cell cooperation, which is a base station device, where the base station includes a processor, a program storage device, and a data storage device, and the method of Embodiment 1 above can be implemented. It mainly includes the following modules:
  • An alternative user selection module is configured to acquire an alternate user in each cell in the heterogeneous network when the device is a central node base station in the heterogeneous network, and then in the heterogeneous network according to a preset alternative user selection criterion. Selecting an alternate user in the entire network among the candidate users in the cell;
  • the cell reselection module initiates a cell reselection process when an alternate user in the entire network is to perform a reselection operation.
  • the foregoing apparatus may also serve as a coordinated cell base station in a heterogeneous network. Therefore, the apparatus may further include a reporting module.
  • the apparatus is a coordinated cell base station in the heterogeneous network, according to a preset alternative user selection criterion, An alternative user in a cell is selected in the cell, and the candidate user in the selected cell is reported to the central node base station.
  • the maximizing system rate criterion refers to: in the rate ratio R m (q)/R m (j) of the cell reselection of all users, the user whose rate ratio R m (q)/R m (j) is the largest is selected as the preparation. The user is selected, where R m (q) is the rate obtained by the user m in the reselected cell q, and R m (j) is the rate obtained by the user m in the current serving cell j.
  • the rate ratio R m (q)/R m (j) may be determined according to the cell reselection of the user:
  • the rate obtained by each user in each cell is determined according to the following formula:
  • R m (q*) is the rate at which the user m is obtained in the cell q*, and M is the total number of users supported under the cell q*;
  • Time indicates that the cell q* is the serving cell of the user m. Indicates that the cell q* is not the serving cell of the user m;
  • the degree of freedom recovery criterion refers to: in the airspace beam joint selection algorithm in the set time, the user with the largest number of beam closures in the beam closure times of all users is selected as the candidate user.
  • the parameters A and b k,q when the system combining rate is maximum are calculated in an iterative manner, and when the system combining rate is maximum
  • the parameters A and b k, q the number of beam closures of each user is counted
  • K is the number of download waves in the cell q
  • SINR k, m, q is the signal to interference and noise ratio of the user m in the block fading scene on the cell q download wave k
  • a k,m 1 indicates that carrier k is allocated to user m
  • a k, and m 0 indicates that carrier k is not allocated.
  • the frequency reuse criterion refers to: among the average soft frequency reuse factor FFR of all users in the set time, the user with the largest FFR is selected as the candidate user.
  • the FFR of the user can be calculated according to the following formula:
  • FFR FFR 1 ⁇ P 1 +FFR 2 ⁇ P 2 +FFR 3 ⁇ P 3 +...+FFR Q ⁇ P Q
  • P 1 , P 2 , ... P Q are weighting coefficients.
  • the technical solution provided by the embodiment of the present invention combines cell selection and interference management to reduce the complexity of the interference management algorithm and improve the effectiveness of the interference management, thereby improving the system capacity of the low power node.

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Abstract

基于小区间协作的异构网服务小区选择方法及装置，涉及数字通信领域。本发明实施例公开的方法包括：异构网中的中心节点基站获取异构网中各小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；若所述全网内的备选用户要进行重选操作，则发起小区重选流程。本发明实施例还公开与上述方法相对应的基于小区间协作的异构网服务小区选择装置。本发明实施例的技术方案将小区选择与干扰管理联合考虑，降低了干扰管理算法的复杂度，提高了干扰管理的有效性，从而提高低功率节点的系统容量。

Description

基于小区间协作的异构网服务小区选择方法及装置 技术领域
本文涉及数字通信领域，特别是涉及一种基于小区间协作的载波聚合(Carrier Aggregation)系统的异构网服务小区选择方案。
背景技术
由于异构网可以通过改进网络的拓扑结构实现系统性能的优化而成为移动通信的研究热点之一。异构网由网络规划的高功率宏基站和位于其覆盖之下具有自主摆放特点的低功率节点组成，低功率节点包括家庭基站、微微蜂窝、和Relay站等，能够实现热点区域覆盖、小区业务分流，从而获得小区分裂增益。异构网由于不同类型基站的功率、覆盖不同，低功率节点的自主摆放特点，使得不同基站的控制信道、业务信道的干扰问题非常突出，异构网面临巨大的技术挑战。
在下一代演进系统如3GPP-LTE-A标准中，采用了小区间干扰协调技术来解决由此造成的干扰问题，即eICIC(enhanced inter-cell interference coordination schemes)。eICIC是LTE-A中标志性的关键技术之一，用于改善小区边缘覆盖，实现小区业务分流为目的的覆盖距离扩展(range extension，简称RE)。eICIC主要分为两类：第一类为基于载波聚合技术的eICIC方案，第二类为基于时域ABS(almost blank subframes)的方案。ABS通过在干扰小区中配置ABS子帧实现业务静默，而被干扰小区则使用这些ABS子帧为原来在小区中受较强干扰的用户提供业务，从而实现了小区间干扰的协调。
载波聚合作为LTE-A的关键技术之一，除了在聚合形成的大带宽上提供高速业务以外，还能在成员载波(component carrier,简称CC)分辨率级别实现异构网络的频域干扰避免。假设异构网络的带宽由两个成员载波组成：f1和f2。为了实现宏基站和微微基站的干扰协调，可以将f1和f2分别分配给宏基站和微微基站的用户，从而实现用户业务信道和控制信道的干扰避免。或者微微基站的小区中心用户可以分配和宏小区相同的成员载波，而边缘用户则分配与宏基站不同的成员载波。这种方案的缺点是只能被LTE-A用户采用， 不能兼容LTE用户。所有上述技术的应用有一个重要的前提，即首先解决小区中的用户服务小区选择问题。在蜂窝移动通讯网中，所有用户有一个归属的服务小区，为用户提供广播、业务传输等服务。在传统的同构网中，用户的服务小区选择基于接收信号强度的测量。在异构网中，由于新增节点的发射功率远低于宏基站，基于接收信号强度的服务小区选择方法，将造成这些节点的覆盖范围很小，没有实现小区分裂增益最大化。围绕提高低功率节点的优先级、扩大低功率节点覆盖范围这个目标，3GPP会议展开了研究与讨论，提出了一些增强型的LTE一A异构网络小区选择与重选算法，主要是高通公司提出的RE(Range Extension)算法以及路损算法。RE算法的核心思想是在传统的服务小区选择算法中，给低功率节点的接收功率RSRP(Reference Signal Receiving Power)增加一个大于0的bias值(偏移值)，而对宏小区的RSRP补偿值bias为0，从而降低低功率节点的门槛，增大UE选择低功率节点作为服务小区的几率。在基于路径损耗的小区选择算法中，每个UE选择路径损耗最低(Minimum Path Loss)的小区作为服务小区。
上述方法使得低功率节点的覆盖范围显著增大，甚至可以与宏小区相仿。但是对于处在低功率节点覆盖边缘的用户，即使采取干扰消除措施去除强干扰源的影响，由于其服务小区(低功率节点)的发射功率过低而导致下行SINR(信干噪比)很低，从而引起小区频谱利用率降低。
当采用多天线技术时，小区间干扰协调可进一步在空域进行，如协作多点传输技术(CoMP,Coordinated Multi-Point)，通过相邻小区间移动用户信道信息的交互，相邻小区对边缘用户采取一定的干扰避免策略或者多个小区对移动用户进行联合传输，从而提高边缘用户的吞吐量和高数据传输率的覆盖，减小边缘用户的干扰，提高小区吞吐量。在异构网情形，COMP可以作为对上述eICIC技术的增强技术，在eICIC获得的增益之上，进一步获得系统容量增加。
目前小区选择与干扰管理是两个独立过程，小区选择通过负载均衡实现低功率节点用户数量的增加，而干扰管理用于解决小区间干扰增加问题。随着低功率节点密度增大，如果继续按照上述方法处理，将会带来干扰管理算法的复杂度急剧地增加，降低干扰管理算法的有效性，进而影响低功率节点 用户数量的增加。
发明内容
本发明实施例提供一种基于小区间协作的异构网服务小区选择方法及装置，以提高低功率节点的系统容量。
为了解决上述技术问题，本发明实施例公开了一种基于小区间协作的异构网服务小区选择方法，该方法包括：
异构网中的中心节点基站获取异构网中每个小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；
若所述全网内的备选用户要进行重选操作，则发起小区重选流程。
可选地，上述方法还包括：
所述异构网中每个小区基站按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，将所选择的小区内的备选用户上报给所述中心节点基站。
可选地，上述方法中，所述备选用户选择准则包括如下一种或几种的组合：
最大化系统速率准则、自由度恢复准则、频率复用准则。
可选地，上述方法中，所述最大化系统速率准则指：
将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。
可选地，上述方法中，按照如下过程确定用户的小区改选的速率比值Rm(q)/Rm(j)：
分别计算Rm(q)和Rm(j)，得到用户的小区改选的速率比值Rm(q)/Rm(j)；
其中，按照如下公式确定每个用户在每个小区下取得的速率：
Figure PCTCN2015074516-appb-000001
式中，Rm(q*)是用户m在小区q*取得的速率；
Figure PCTCN2015074516-appb-000002
是
Figure PCTCN2015074516-appb-000003
的数学期望，
Figure PCTCN2015074516-appb-000004
是用户m从小区q*的载波k上可实现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
Figure PCTCN2015074516-appb-000005
为连接到小区q*上的用户数量，
Figure PCTCN2015074516-appb-000006
时表示小区q*是用户m的服务小区，
Figure PCTCN2015074516-appb-000007
时表示小区q*不是用户m的服务小区，M为小区q*下支持的用户总数；
Figure PCTCN2015074516-appb-000008
为多用户的分集增益。
可选地，上述方法中，所述自由度恢复准则指：
将设定时间内空域波束联合选择算法中，所有用户的波束关闭次数中波束关闭次数最大的用户选择为备选用户。
可选地，上述方法中，在设定时间内空域波束联合选择算法中，确定用户的波束关闭次数的过程如下：
采用迭代方式计算系统合速率最大时的参数A和bk,q，并在计算系统合速率最大时的参数A和bk,q时，统计每个用户的波束关闭次数；
其中，按照如下公式计算Q个小区组成的系统合速率R：
Figure PCTCN2015074516-appb-000009
式中，K为小区q下载波数量；
SINRk,m,q为用户m在小区q下载波k上块衰落场景下信干噪比；
ak,q＝1表示小区q下载波k分配给用户m，ak,q＝0表示小区q下载波k未分配给用户m。
可选地，上述方法中，所述频率复用准则指：
将设定时间内所有用户的平均软频率复用因子FFR中，FFR最大的用户选择为备选用户。
可选地，上述方法中，按照如下公式计算所述用户的FFR：
FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ
其中，FFR1＝1/3，FFR2＝2/3，FFR3＝1，FFRQ＝1/Q；
P1,P2,…PQ是加权系数。
本发明实施例还公开了一种基于小区间协作的异构网服务小区选择装置，包括：
备选用户选择模块，设置为获取异构网中每个小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；
小区重选模块，设置为在所述全网内的备选用户要进行重选操作时，则发起小区重选流程。
可选地，上述装置中，所述备选用户选择准则包括如下一种或几种的组合：
最大化系统速率准则、自由度恢复准则、频率复用准则。
可选地，上述装置中，所述最大化系统速率准则指：
将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。
可选地，上述装置中，所述备选用户选择模块是设置为：
分别计算Rm(q)和Rm(j)，得到用户的小区改选的速率比值Rm(q)/Rm(j)；
其中，按照如下公式确定每个用户在每个小区下取得的速率：
Figure PCTCN2015074516-appb-000010
式中，Rm(q*)是用户m在小区q*取得的速率；
Figure PCTCN2015074516-appb-000011
是
Figure PCTCN2015074516-appb-000012
的数学期望，
Figure PCTCN2015074516-appb-000013
是用户m从小区q*的载波k上可实现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
Figure PCTCN2015074516-appb-000014
为连接到小区q*上的用户数量，
Figure PCTCN2015074516-appb-000015
时表示小区q*是用户m的服务小区，
Figure PCTCN2015074516-appb-000016
时小区q*不是用户m的服务小区，M为小区q*下支持的用户总数；
Figure PCTCN2015074516-appb-000017
为多用户的分集增益。
可选地，上述装置中，所述自由度恢复准则指：
将设定时间内空域波束联合选择算法中，所有用户的波束关闭次数中波束关闭次数最大的用户选择为备选用户。
可选地，上述装置中，所述备选用户选择模块设置为在设定时间内空域波束联合选择算法中，确定用户的波束关闭次数，包括：
采用迭代方式计算系统合速率最大时的参数A和bk,q，并在计算系统合速率最大时的参数A和bk,q时，统计每个用户的波束关闭次数；
其中，按照如下公式计算Q个小区组成的系统合速率R：
Figure PCTCN2015074516-appb-000018
式中，K为小区q下载波数量；
SINRk,m,q为用户m在小区q下载波k上块衰落场景下信干噪比；
ak,q＝1表示小区下载波k分配给用户m，ak,q＝0表示小区q下载波k未分配给用户m。
可选地，上述装置中，所述频率复用准则指：
将设定时间内所有用户的平均软频率复用因子FFR中，FFR最大的用户选择为备选用户。
可选地，上述装置中，所述备选用户选择模块是设置为按照如下公式计算所述用户的FFR：
FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ
其中，FFR1＝1/3，FFR2＝2/3，FFR3＝1，FFRQ＝1/Q；
P1,P2,…PQ是加权系数。
可选地，上述装置还包括：
上报模块，设置为在本装置为异构网中协作小区基站时，按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，将所选择的小区内的备选用户上报给中心节点基站。
本发明实施例还提供一种计算机可读存储介质，所述存储介质存储有计算机程序，该计算机程序包括程序指令，当该程序指令被基站设备执行时，使得该设备可执行上述基于小区间协作的异构网服务小区选择的方法。
本发明实施例的技术方案将小区选择与干扰管理联合考虑，降低了干扰管理算法的复杂度，提高了干扰管理的有效性，从而提高低功率节点的系统容量。
附图概述
图1为异构网示意图；
图2(a)为本发明一实施例的基于小区间协作的异构网服务小区选择的中心节点基站的实现框图；
图2(b)为本发明一实施例的基于小区间协作的异构网服务小区选择的协作基站i的实现框图；
图2(c)为本发明一实施例的基于小区间协作的异构网服务小区选择的协作基站j的实现框图；
图3为本发明一实施例的基于小区间协作的异构网服务小区选择的实现流程图；
图4为本发明另一实施例的基于小区间协作的进行小区选择算法的实现流程图；
图5为本发明一实施例的基于小区间协作的异构网服务小区选择装置的框图。
本发明的较佳实施方式
下文将结合附图对本发明技术方案作进一步详细说明。需要说明的是，在不冲突的情况下，本申请的实施例和实施例中的特征可以任意相互组合。
实施例1
本申请发明人发现现有技术中主要存在如下缺陷：
一方面，由于低功率节点的引入，产生了大量的边缘用户，目前已有的小区选择方法都是基于信号强度(RE算法)或干扰(路损方法)提出的。但是在小区边缘，信干比对用户的选择影响较大。
另一方面，异构网中引入的低功率节点采用多天线技术，如果在服务小区选择时同时考虑相邻小区的干扰和空域信息，则可以获得更好的小区分裂增益，但是现有方法都没有考虑这些因素。
因此，针对上述缺陷，本申请发明人提出，可以通过动态小区选择(Dynamic Cell Selection,COMP中简称DCS)技术，动态地选择边缘用户的服务小区，通过小区分集增益提高用户数量；同时将小区选择与干扰管理联合考虑，降低干扰管理算法的复杂度，提高干扰管理的有效性，从而提高低功率节点的系统容量。
基于上述思想，本实施例提供一种基于小区间协作的异构网服务小区选择方法，其中，异构网由宏小区及其覆盖之下的数个低功率基站如家庭基站、 微微基站等组成，基站聚合的载波包括多个成员载波CC1,CC2,…CCK。该方法主要包括：
异构网中的中心节点基站获取异构网中各小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；
若所述全网内的备选用户要进行重选操作，则发起小区重选流程。
其中，中心节点基站获取异构网中各小区内的备选用户的过程是，异构网中各小区基站按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，再将所选择的小区内的备选用户上报给中心节点基站。
而中心节点基站和各小区基站所依据的备选用户选择准则至少包括如下一种或几种准则：
最大化系统速率准则、自由度恢复准则、频率复用准则等。
在本实施例中，最大化系统速率准则指，将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。还要说明的是，本实施例中所涉及的用户在各小区中取得的速率均指一定时间内的平均速率值。
具体地，确定各用户的小区改选的速率比值Rm(q)/Rm(j)的过程如下：
假设系统共有M个用户，其中用户m在q*小区取得的速率Rm(q*)为：
Figure PCTCN2015074516-appb-000019
  公式(1)
式中，M为小区q*下支持的用户总数；
Figure PCTCN2015074516-appb-000020
是
Figure PCTCN2015074516-appb-000021
的数学期望，
Figure PCTCN2015074516-appb-000022
是用户m从小区q*的载波k上可实现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
Figure PCTCN2015074516-appb-000023
为连接到小区q*上的用户数量，
Figure PCTCN2015074516-appb-000024
时表示小区q*是 用户m的服务小区，
Figure PCTCN2015074516-appb-000025
时小区q*不是用户m的服务小区；
Figure PCTCN2015074516-appb-000026
为多用户的分集增益，它取决于对同一资源竞争的用户数量。
其中，上述公式计算用户m在q*小区取得的速率Rm(q*)时，采用的是加权速率的计算方式。
在本实施例中，自由度恢复准则指：统计设定时间内空域波束联合选择算法中，所有用户的波束关闭次数，将波束关闭次数最大的用户选择为备选用户。
假设系统为M个用户和K载波的下行链路。假定基站和用户分别具有N个发射天线和一个接收天线。每个小区的每个载波上发送功率保持不变。用二进制矩阵
Figure PCTCN2015074516-appb-000027
描述用户之间的载波选择。ak,m＝1表示载波k分配给用户m，否则ak,m＝0。
用Sk,m,i＝hk,m,ibk,i表示在某个时隙的信道增益，hk,m,i＝[h1 k,m,ih2 k,m,i,…,hN k,m,i]表示信道，bk,i∈CN×1表示波束形成矩阵，假设是块衰落场景，则信干噪比为：
Figure PCTCN2015074516-appb-000028
 公式(2)
第m用户的速率定义为：
Figure PCTCN2015074516-appb-000029
 公式(3)
则由Q个小区做成的系统合速率为：
Figure PCTCN2015074516-appb-000030
Figure PCTCN2015074516-appb-000031
  公式(4)
其中，i是除了小区q以外的相邻小区，i＝1,2,…,Q,但i≠q；
为了找出合适的A和bk,q,采用交替迭代的方式：假设bk,q已知,在A中尝试关闭某个载波，即令ak,m＝0，使得系统和速率最大，得到新的A，再基于新的A值，求解新的bk,q，其中bk,q表示小区q用户在载波k上的波束预编码向量。本实施例中频率复用准则指：统计设定时间内载波波束联合选择算法中，所有用户的平均软频率复用因子FFR，将FFR最大的用户选择为备选用户。
需要说明的是，针对每个小区，其下可能有多个用户，但在任何时刻，小区内只有一个用户在进行数据传输，此时，对于任意用户m而言，ak,m等同于ak,q，即此时不用区分参数角标中用户m与小区q的差别。
具体地，平均FFR定义为：
FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ  公式(5)
其中，FFR1＝1/3；FFR2＝2/3；FFR3＝1，FFRQ＝1/Q,P1,P2,…PQ是加权系数。
另外，上述方法在联合小区载波波束选择选择时，用户满足关闭准则时，将关闭载波的发射，选择准则1为：该用户在该载波上信噪比是系统中位于该载波上协作调度用户中最低，同时所受干扰最大；
上述方法在联合小区载波波束选择选择时，用户满足关闭准则时，将关闭载波的发射，选择准则2为：该用户在该载波上信噪比是系统中位于该载波上，协作调度用户中最低，同时所受干扰大于噪声值；
上述方法在联合小区载波波束选择选择时，平均软频率复用因子FFR权值＝该载波上未关闭用户数/该载波上协作调度用户总数。
而上述方法中，进行小区重选时，可依据加权平均速率等准则进行判断。
具体地，基于加权平均速率的小区重选准则包括下面两个步骤：
第一步：计算该用户的Rm*(q)/Rm*(j),其中j是原服务小区，而q是其他小区；
第二步：如果用户m*选择q*，其Rm*(q*)/Rm*(j)大于门限R_th，即：
Rm*(q*)/Rm*(j)＞R_th，公式(6)
且小区用户数小于Um，则用户m*将服务小区从j改为q*；
第三步：小区和q*分别更新各自的服务用户集合。
下面以LTE-A系统为例说明上述方法的具体实现。
如图1所示，异构网由一个宏小区和两个微微小区组成，其中宏小区半径为500米，功率为43dBm。两个微微小区位于宏小区的覆盖之下。宏小区设为小区1，而微微小区设为小区2和小区3。所有基站的带宽由两个载波聚合而成。假设共有三个小区共有40个用户。
图2所示是基于本实施例的一种实现框图，主要分解为两层：
协作基站，如基站i(如图2b)和基站j(如图2c)；
中心节点基站(如图2a)，可以是任意一个基站，例如宏小区基站。
协作基站上运行独立的公平调度器(PF调度器)和载波选择，其中公平调度器根据所属基站服务用户的平均瞬时速率和历史平均速率计算用户调度优先级，其次根据优先级次序决定调度用户，最后PF调度器根据中心节点的输出结果，在选择的载波上，按照联合设计的波束矢量调度用户。
首先，中心节点基站运行联合小区载波选择、波束选择、以及小区选择算法：
其中，为了进行上述各算法操作，中心节点基站可以接收各个基站的测量结果，如各个用户到各个小区的信道矩阵等；
其次，中心节点基站运行联合小区载波选择、波束选择算法，联合决定各个用户的载波选择矢量，联合设计各个用户的波束矢量；
然后，中心节点基站根据联合小区载波选择、波束选择算法在一定时间段的输出结果，或者参量统计，依据备选用户选择准则，在全网选择一个备选用户；
最后，中心节点基站根据重选准则，决定该备选用户是否进行重选操作， 并发起小区重选流程。
图3为本发明一实施例的基于小区间协作的异构网服务小区选择的的实现流程图。图3所示是上述方法的实现流程。
在LTE中，系统消息通过广播信道SBCH的SIB信息携带。假设小区1是中心节点所在基站。中心节点基站确定小区1～3是协作小区，故也是测量小区集合，小区1、2、3通过SIB消息扩展(即LTE的SIB消息中，新定义小区测量集合)，在本小区广播。用户UE1通过读取SIB消息，即可获得测量小区集合，即小区1～3。
UE1对小区1～3的测量配置是通过RRCConnnectionReconfiguration消息中的Measurement Configuration IE来实现的，测量配置消息Measurement Configuration IE是对LTE系统的原消息IE扩展而成。
用户UE1根据测量配置，完成小区集合{小区1，2，3}算法所需要的参数测量，如RSRP和RSRQ(Reference Signal Received Quality)，信道矩阵等的测量，采用小区1～3的各自小区公有导频符号进行测量。
小区2和小区3将各自小区用户的测量结果上报小区1。
小区1收集所有用户针对小区集合{小区1，2，3}的测量值。
小区1计算用户的载波选择矢量和波束选择矢量，并通知各个小区，各个小区的PF调度器依次调度用户；
小区1依照载波、波束选择矢量的计算过程结果统计参数，且依照备选用户选择准则，在3个小区的所有用户中，挑选备选用户，假如用户UE1是备选用户，则小区重选模块判决UE1是否满足重选准则，
小区1依据重选准则，依据重选算法计算UE1的小区重选结果，假如目标小区是小区3，则将选择结果通知到各个小区{小区1，2，3}；
各个小区{小区1，2，3}各自通知本小区的各个用户选择结果；
用户UE1进入小区重选流程。
图4为本发明另一实施例的基于小区间协作的进行小区选择算法的实现流程图。图4所示为上述方法中进行小区选择算法的流程图。
算法主要包括三个部分，即预分配，用户小区选择和重选。其中预分配包括图4中的步骤1和2。预分配主要为后续的小区选择算法提供初始值。为此，小区1首先收集所有用户的信道测量值，其次，为每个用户寻找等效速率
Figure PCTCN2015074516-appb-000032
最大的小区，并将其预分配给该用户作为服务小区；小区1基于预分配的服务小区统计各小区预分配的用户数和统计参数；最后，小区1将小区选择初值，其他小区用户信道，以及各小区用户数通知每个小区，如通知小区2关于小区选择初值，小区2用户到小区1和小区3的信道值；
假如小区初始选择值为[20 12 8]，即小区1有20个用户，小区2有12个用户，小区3有8个用户，在算法的用户小区选择部分，每个小区的用户，分别计算他到3个小区的等效速率，并将其他小区最大等效速率和本小区的等效速率之比上报服务小区，服务小区1首先是将20x1(20个用户，每个用户对1个备选小区)个等效速率根据由大到小依次排队。用户小区选择过程选择队列开始位置的用户，并将该用户及其速率比值上报中心节点。
在重选环节中，中心节点首先将三个小区的备选用户速率比进行排队，其次选取队列中第一个用户，接着，对该用户进行小区重选准则验证：假设队列中第一个最大值对应的用户和基站分别为m，q’，首先验证公式(1-6)是否满足，如果满足，则将用户m分配给基站q’，同时更新基站q’的Qhm，并置用户m已重选，否则，算法结束。
最后一个过程是后处理过程，其目的是将经过上述选择算法确定服务小区的用户，通知给服务基站基站，该用户随后发起小区重选流程。
经过上述三个过程，所有用户完成一次小区、协作选择更新过程。
实施例2
图5为本发明一实施例的基于小区间协作的异构网服务小区选择装置的框图。本实施例提供一种基于小区间协作的异构网服务小区选择装置，为基站设备，所述基站包括处理器、程序存储设备和数据存储设备，可实现上述实施例1的方法。其主要包括如下模块：
备选用户选择模块，在本装置为异构网中的中心节点基站时，获取异构网中各小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所 有小区内的备选用户中选择一个全网内的备选用户；
小区重选模块，在所述全网内的备选用户要进行重选操作时，则发起小区重选流程。
另外，上述装置，也可能作为异构网中协作小区基站，因此，该装置还可以包括上报模块，在本装置为异构网中协作小区基站时，按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，将所选择的小区内的备选用户上报给中心节点基站。
而本实施例中所涉及的备选用户选择准则包括如下一种或几种的组合：
最大化系统速率准则、自由度恢复准则、频率复用准则。
其中，最大化系统速率准则指：将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。
具体地，可以按照确定用户的小区改选的速率比值Rm(q)/Rm(j)指：
分别计算Rm(q)和Rm(j)，得到用户的小区改选的速率比值Rm(q)/Rm(j)；
其中，按照如下公式确定各用户在各小区下取得的速率：
Figure PCTCN2015074516-appb-000033
式中，Rm(q*)是用户m在小区q*取得的速率，M为小区q*下支持的用户总数；
Figure PCTCN2015074516-appb-000034
是
Figure PCTCN2015074516-appb-000035
的数学期望，
Figure PCTCN2015074516-appb-000036
是用户m从小区q*的载波k上可实现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
Figure PCTCN2015074516-appb-000037
为连接到小区q*上的用户数量，
Figure PCTCN2015074516-appb-000038
时表示小区q*是用户m的服务小区，
Figure PCTCN2015074516-appb-000039
时表示小区q*不是用户m的服务小区；
Figure PCTCN2015074516-appb-000040
为多用户的分集增益。
自由度恢复准则指：将设定时间内空域波束联合选择算法中，所有用户的波束关闭次数中波束关闭次数最大的用户选择为备选用户。
具体地，在设定时间内空域波束联合选择算法中，确定用户的波束关闭次数时：采用迭代方式计算系统合速率最大时的参数A和bk,q，并在计算系统合速率最大时的参数A和bk,q时，统计各用户的波束关闭次数；
其中，按照如下公式计算Q个小区组成的系统合速率R：
Figure PCTCN2015074516-appb-000041
式中，K为小区q下载波数量，SINRk,m,q为用户m在小区q下载波k上块衰落场景下信干噪比，此
Figure PCTCN2015074516-appb-000042
得到ak,m，其中，ak,m＝1表示载波k分配给用户m，ak,m＝0表示载波k未分配。需要说明的是，针对每个小区，其下可能有多个用户，但在任何时刻，小区内只有一个用户在进行数据传输。此时，对于任意用户m而言，ak,m等同于ak,q，即此时不用区分参数角标中用户m与小区q的差别。
频率复用准则指：将设定时间内所有用户的平均软频率复用因子FFR中，FFR最大的用户选择为备选用户。
具体地，可以按照如下公式计算所述用户的FFR：
FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ
其中，FFR1＝1/3，FFR2＝2/3，FFR3＝1，FFRQ＝1/Q；
P1,P2,…PQ是加权系数。
由于上述装置可实现上述实施例1的方法，故上述装置的详细实施方式可参见上述实施例1的相应内容，在此不再赘述。
本领域普通技术人员可以理解上述方法中的全部或部分步骤可通过程序来指令相关硬件完成，所述程序可以存储于计算机可读存储介质中，如只读存储器、磁盘或光盘等。可选地，上述实施例的全部或部分步骤也可以使用一个或多个集成电路来实现。相应地，上述实施例中的各模块/单元可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。本申请不限制于任何特定形式的硬件和软件的结合。
以上所述，仅为本发明的较佳实例而已，并非用于限定本发明的保护范围。凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
工业实用性
本发明实施例提供的技术方案，将小区选择与干扰管理联合考虑，可以降低干扰管理算法的复杂度，提高干扰管理的有效性，从而提高低功率节点的系统容量。

Claims (19)

  1. 一种基于小区间协作的异构网服务小区选择方法，包括：
    异构网中的中心节点基站获取异构网中每个小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；
    若所述全网内的备选用户要进行重选操作，则发起小区重选流程。
  2. 如权利要求1所述的方法，还包括：
    所述异构网中每个小区基站按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，将所选择的小区内的备选用户上报给所述中心节点基站。
  3. 如权利要求1或2所述的方法，其中，所述备选用户选择准则包括如下一种或几种的组合：
    最大化系统速率准则、自由度恢复准则、频率复用准则。
  4. 如权利要求3所述的方法，其中，所述最大化系统速率准则指：
    将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。
  5. 如权利要求4所述的方法，其中，按照如下过程确定用户的小区改选的速率比值Rm(q)/Rm(j)：
    分别计算Rm(q)和Rm(j)，得到用户的小区改选的速率比值Rm(q)/Rm(j)；
    其中，按照如下公式确定每个用户在每个小区下取得的速率：
    Figure PCTCN2015074516-appb-100001
    式中，Rm(q*)是用户m在小区q*取得的速率；
    Figure PCTCN2015074516-appb-100002
    是
    Figure PCTCN2015074516-appb-100003
    的数学期望，
    Figure PCTCN2015074516-appb-100004
    是用户m从小区q*的载波k上可实 现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
    Figure PCTCN2015074516-appb-100005
    为连接到小区q*上的用户数量，
    Figure PCTCN2015074516-appb-100006
    时表示小区q*是用户m的服务小区，
    Figure PCTCN2015074516-appb-100007
    时表示小区q*不是用户m的服务小区，M为小区q*下支持的用户总数；
    Figure PCTCN2015074516-appb-100008
    为多用户的分集增益。
  6. 如权利要求3所述的方法，其中，所述自由度恢复准则指：
    将设定时间内空域波束联合选择算法中，所有用户的波束关闭次数中波束关闭次数最大的用户选择为备选用户。
  7. 如权利要求6所述的方法，其中，在设定时间内空域波束联合选择算法中，确定用户的波束关闭次数的过程如下：
    采用迭代方式计算系统合速率最大时的参数A和bk,q，并在计算系统合速率最大时的参数A和bk,q时，统计每个用户的波束关闭次数；
    其中，按照如下公式计算Q个小区组成的系统合速率R：
    Figure PCTCN2015074516-appb-100009
    式中，K为小区q下载波数量；
    SINRk,m,q为用户m在小区q下载波k上块衰落场景下信干噪比；
    ak,q＝1表示小区q下载波k分配给用户m，ak,q＝0表示小区q下载波k未分配给用户m。
  8. 如权利要求3所述的方法，其中，所述频率复用准则指：
    将设定时间内所有用户的平均软频率复用因子FFR中，FFR最大的用户选择为备选用户。
  9. 如权利要求8所述的方法，其中，按照如下公式计算所述用户的FFR：
    FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ；
    其中，FFR1＝1/3，FFR2＝2/3，FFR3＝1，FFRQ＝1/Q；
    P1,P2,…PQ是加权系数。
  10. 一种基于小区间协作的异构网服务小区选择装置，包括：
    备选用户选择模块，设置为获取异构网中每个小区内的备选用户，再依据预设的备选用户选择准则，在异构网中所有小区内的备选用户中选择一个全网内的备选用户；
    小区重选模块，设置为在所述全网内的备选用户要进行重选操作时，发起小区重选流程。
  11. 如权利要求10所述的装置，其中，所述备选用户选择准则包括如下一种或几种的组合：
    最大化系统速率准则、自由度恢复准则、频率复用准则。
  12. 如权利要求11所述的装置，其中，所述最大化系统速率准则指：
    将所有用户的小区改选的速率比值Rm(q)/Rm(j)中，速率比值Rm(q)/Rm(j)最大的用户选择为备选用户，其中，Rm(q)是用户m在改选后的小区q中取得的速率，Rm(j)是用户m在当前服务小区j中取得的速率。
  13. 如权利要求12所述的装置，其中，所述备选用户选择模块是设置为：
    分别计算Rm(q)和Rm(j)，得到用户的小区改选的速率比值Rm(q)/Rm(j)；
    其中，按照如下公式确定每个用户在每个小区下取得的速率：
    Figure PCTCN2015074516-appb-100010
    式中，Rm(q*)是用户m在小区q*取得的速率；
    Figure PCTCN2015074516-appb-100011
    是
    Figure PCTCN2015074516-appb-100012
    的数学期望，
    Figure PCTCN2015074516-appb-100013
    是用户m从小区q*的载波k上可实现的瞬时的平均最大数据速率，K为小区q*中的载波总数；
    Figure PCTCN2015074516-appb-100014
    为连接到小区q*上的用户数量，
    Figure PCTCN2015074516-appb-100015
    时表示小区q*是用户m的服务小区，
    Figure PCTCN2015074516-appb-100016
    时小区q*不是用户m的服务小区，M为小区q*下支持的用户总数；
    Figure PCTCN2015074516-appb-100017
    为多用户的分集增益。
  14. 如权利要求11所述的装置，其中，所述自由度恢复准则指：
    将设定时间内空域波束联合选择算法中，所有用户的波束关闭次数中波束关闭次数最大的用户选择为备选用户。
  15. 如权利要求14所述的装置，其中，所述备选用户选择模块设置为在设定时间内空域波束联合选择算法中，确定用户的波束关闭次数，包括：
    采用迭代方式计算系统合速率最大时的参数A和bk,q，并在计算系统合速率最大时的参数A和bk,q时，统计每个用户的波束关闭次数；
    其中，按照如下公式计算Q个小区组成的系统合速率R：
    Figure PCTCN2015074516-appb-100018
    式中，K为小区q下载波数量；
    SINRk,m,q为用户m在小区q下载波k上块衰落场景下信干噪比；
    ak,q＝1表示小区下载波k分配给用户m，ak,q＝0表示小区q下载波k未分配给用户m。
  16. 如权利要求11所述的装置，其中，所述频率复用准则指：
    将设定时间内所有用户的平均软频率复用因子FFR中，FFR最大的用户选择为备选用户。
  17. 如权利要求16所述的装置，其中，所述备选用户选择模块是设置为按照如下公式计算所述用户的FFR：
    FFR＝FFR1·P1+FFR2·P2+FFR3·P3+…+FFRQ·PQ
    其中，FFR1＝1/3，FFR2＝2/3，FFR3＝1，FFRQ＝1/Q；
    P1,P2,…PQ是加权系数。
  18. 如权利要求10至17任一项所述的装置，其中，还包括：
    上报模块，设置为在本装置为异构网中协作小区基站时，按照依据预设的备选用户选择准则，在本小区内选择一个小区内的备选用户，将所选择的小区内的备选用户上报给中心节点基站。
  19. 一种计算机可读存储介质，所述存储介质存储有计算机程序，该计算机程序包括程序指令，当该程序指令被基站设备执行时，使得该设备可执行权利要求1-9任一项的方法。
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