WO2007109939A1

WO2007109939A1 - Method and device for band allocation

Info

Publication number: WO2007109939A1
Application number: PCT/CN2006/003523
Authority: WO
Inventors: Hongjie Hu; Junwei Wang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-03-28
Filing date: 2006-12-21
Publication date: 2007-10-04
Also published as: CN101047938A; CN100568996C

Abstract

A method and a device for band allocation are used for more efficient usage of finite band resource. In the present invention, a part of band will only be assigned as subband for broadcast-multicast in the same frequency at the time when the broadcast-multicast is needed, the residual band is used for unicast in the manner of interference coordination among the cells. The residual band can be reassigned among the cells in the interference coordination model or keep the same assigning manner unchanged as the manner when the broadcast-multicast is not needed. Band can also be assigned in time division multiplex, only assign some time slots belonging to the subband for broadcast-multicast in the same frequency, and the other time slots belonging to the subband and all of the time slots belonging to the residual band are used for unicast in frequency soft multiplex. The frequency-hopping means can also be combined, so the broadcast-multicast can use different band in different time slot.

Description

Frequency band allocation method and device thereof

The present application claims priority to Chinese Patent Application No. 200610070952.6, entitled "Wireless Cellular Network and Its Medium Band Assignment Method", filed on March 28, 2006, the entire contents of which is incorporated herein by reference. in.

Technical equipment

The present invention relates to the field of wireless communications, and in particular, to a frequency band allocation method and apparatus therefor.

Background technique

Mobile communication has greatly changed people's lives. With the development of mobile communication and the increasing demand for communication, users' requirements for mobile network quality are also increasing. The most widely used mobile communication application is personal mobile communication, and its cellular mobile system dominates.

The wireless cellular network divides the entire service area into a number of cellular sub-coverage areas, called cells or cells. The cell is covered by one transceiver for each cell. This transceiver is called a base station. Referred to as "BS,,", users in the entire cell complete communication by this base station. Since the wireless cellular network can use the same frequency resource in different cells, different 7 cells in Figure 1 use the same frequency resource. By using only a narrow frequency band, mobile communication services can be provided for the entire service area, which greatly saves frequency resources.

However, the problem also arises. For networks with different frequency resources in different cells, users at the edge of the cell will be interfered by other neighboring cells, so that the cell-to-edge ratio of the cell edge users will be lower. The easiest way to improve the cell edge to interference ratio is to use frequency reuse. The frequency reuse technique refers to a radio channel of the same carrier frequency covering different cells, and cells using the same carrier frequency are separated by a certain distance to suppress the co-channel interference within an acceptable range.

In the early wireless cellular networks, due to the low level of resistance and adjacent frequency interference, a more relaxed frequency reuse method was generally adopted. For example, in the UK's Total Access Communications System (TACS) and the Advanced Mobile Phone System (AMPS) in the United States, the analog modulation is used because the signal is used. Anti-fading and signal demodulation capabilities are poor, so it has higher requirements for the same-frequency protection threshold, generally greater than 18dB. The more popular frequency reuse method in TACS system is 7/21 multiplexing. 7/21 multiplexing is to divide all frequency points into 21 cells of 7 base stations (in the cellular system, each base station is generally used). Divided into 3 cells), the frequency points in these 21 cells are not reused, and the 21 cells are used as one extension. The Park structure is reused throughout the network. From this relationship, we can see that the highest carrier frequency configuration of each cell depends on two factors, one is the frequency resource owned by the operator, and the other is the frequency reuse mode adopted in the network design. Taking 7/21 multiplexing as an example, the highest carrier frequency configuration per cell is equal to all frequency points /21. We also call 21 the frequency reuse factor, which is a major parameter to measure the degree of easing of a network frequency reuse.

In the early days of the Global System of Mobility (GSM), the 4/12 frequency reuse method was more popular. Compared with the 7/21 multiplexing of the TACS system, it has been used in the utilization of frequency resources. There has been a big improvement. The 4/12 structure has a multiplexing factor of 12, which can allocate more carrier frequencies in each cell than 21, providing more capacity per unit area. However, it uses the frequency of the four base stations as a group, and the 7/21 multiplex with 7 base stations is smaller than the same frequency separation distance. The GSM system is able to use a more compact frequency reuse technique because it uses digital modulation technology, and the signal is much stronger than analog signals in terms of anti-fading and anti-interference.

With the further development of mobile communication technology, it can be seen that for a certain degree of anti-fading and anti-interference ability of the signal, for a regular wireless cellular network, the frequency reuse coefficient only needs to reach 3 to guarantee any two. The frequencies used by neighboring cells are different, as shown in Figure 2, so that the limited frequency resources can be better utilized, and each cell can be configured more when the frequency resources owned by the operators are unchanged. Carrier frequency.

Even so, each cell can still only use the original 1/3 frequency, and since the cell spacing using the same frequency becomes smaller, the small-area interference increases, thereby further introducing the concept of inter-cell interference coordination. A basic scheme for inter-cell interference coordination is for downlink resource management, that is, adding constraints (such as the construction of common channels and the scheduling of non-ordinary channels) in a coordinated manner between cells, which are usually restrictions on resource managers. The available time/frequency domain resources, or the transmission power limit on a timed frequency domain resource.

The small-interval interference coordination technology mainly has frequency soft multiplexing technology. Frequency soft multiplexing, also known as partial frequency multiplexing, means that users in the center of each cell in the same mobile communication network can use the same frequency, but must transmit and receive at a lower power, while users at the edge of each cell use the frequency. The multiplexing method ensures that two adjacent cells use different frequencies.

That is to say, the mobile communication network uses a frequency reuse coefficient greater than 1 for a cell edge region where interference is severe, and a frequency reuse coefficient of 1 for a cell interior. Specific edge zone The frequency reuse coefficient is 3, as shown in FIG. 3, the frequency is first divided according to the multiplexing coefficient of 3, and each cell obtains its own primary frequency. For each cell, the frequency other than its dominant frequency is called the secondary frequency. . That is to say, the primary frequency of the cell 1 becomes the secondary frequency in the cell 2. In general, the available power on the secondary frequency needs to be limited, to ^: to be lower than the primary frequency. The user inside the cell can use the primary frequency or the secondary frequency to transmit or receive signals arbitrarily, and the user at the edge of the cell can only use the primary frequency to transmit or receive signals, thereby preventing the signals of the cell edge users from being interfered by other cells.

However, in practical applications, the above solution still has the following problems: The unicast service using the frequency reuse technology cannot be well compatible with the same-frequency broadcast multicast service.

The main reason for this situation is that since the unicast frequency soft multiplexing needs to divide the specified frequency resources, all the frequency resources are divided into the primary frequency and the secondary frequency of each cell, so that no frequency band is reserved for the network side. Broadcast multicasting is performed, and since broadcast multicasting does not occur frequently on the network side, if part of the frequency band is divided from the designated frequency resources dedicated to broadcast multicast, the resources cannot be fully utilized.

Summary of the invention

The technical problem to be solved by the embodiments of the present invention is to provide a frequency band allocation method and a device thereof, to solve the problem that the unicast service using the frequency division multiplexing technology in the prior art cannot be compatible with the same frequency broadcast multicast service.

To solve the above technical problem, an embodiment of the present invention provides a frequency band allocation method, including the following steps:

Allocating the primary frequency and the secondary frequency of the unicast frequency soft multiplexing of each cell in the preset area in the specified frequency range; when the broadcast multicast is required in the preset area, the specified frequency band used from the preset area A part of the frequency band is divided into the same frequency broadcast multicast, and in the remaining frequency band, each cell in the preset area performs unicast in an interference coordination manner.

In addition, an embodiment of the present invention further provides a frequency band allocating apparatus, including:

a unicast frequency allocation unit, configured to allocate a primary frequency and a secondary frequency of unicast frequency soft multiplexing of each cell in the preset area within a specified frequency range;

a decision unit, connected to the unicast frequency allocation unit, configured to determine whether broadcast multicast is required in the preset area, and send the determination result;

a frequency band allocation unit, connected to the decision unit, for broadcasting multicast needs according to the judgment result When a certain frequency band is allocated for the same frequency broadcast multicast, the remaining frequency bands are uniformly allocated by using the specified frequency band used by the preset area in the inter-cell interference coordination mode; or the designated frequency band is all allocated to the preset area. Each cell performs unicast in an interference coordination manner.

It can be seen from the above technical solution that the main difference between the embodiment of the present invention and the prior art is that only part of the frequency band is allocated for the same frequency broadcast multicast when the broadcast multicast is required, and the remaining frequency band is unicasted by the inter-cell interference coordination mode. . This approach enables a dynamic combination of broadcast multicast and unicast in the same frequency band, allowing for more efficient use of limited spectrum resources.

DRAWINGS

1 is a schematic diagram of the same frequency used by each cell in a wireless cellular network in the prior art; FIG. 2 is a schematic diagram of frequency reuse of each cell in a wireless cellular network in the prior art;

3 is a schematic diagram of frequency soft multiplexing of each cell in a wireless cellular network in the prior art; FIG. 4 is a flowchart of a method for allocating frequency bands in a wireless cellular network according to the first embodiment of the present invention; FIG. 5 is a first embodiment of the present invention; A schematic diagram of frequency band allocation when broadcast multicast is not performed in the wireless cellular network;

6 is a schematic diagram of frequency band allocation when performing broadcast multicast in a wireless cellular network according to the first embodiment of the present invention;

FIG. 8 is a flowchart of a frequency band allocation method in a wireless cellular network according to a second embodiment of the present invention; FIG. 8 is a schematic diagram of frequency band allocation when performing broadcast multicast in a wireless cellular network according to a second embodiment of the present invention;

Fig. 9 is a diagram showing the frequency band allocation when broadcasting multicast is performed in the wireless cellular network according to the fourth embodiment of the present invention.

FIG. 10 is a schematic structural diagram of a frequency end allocation apparatus according to an embodiment of the present invention.

detailed description

The invention will be further described in detail below with reference to the drawings and specific embodiments. In the following embodiments, the frequency band allocation in the wireless cellular network is taken as an example, but is not limited thereto, and may be other network communication networks.

The core of the present invention is that, in a preset area composed of at least two neighboring cells, when the network side needs to perform broadcast multicast, some frequency bands are divided from the specified frequency band used by the preset area to perform the same frequency. Broadcast multicast, in the remaining frequency band, each cell in the preset area performs the interference coordination mode. When the broadcast multicast is not required, all the specified frequency bands are allocated to the cells in the preset area to perform unicast in the interference coordination mode. The interference coordination mode may be unicast frequency soft multiplexing.

Referring to FIG. 4, it is a flowchart of a method for allocating frequency bands in a wireless cellular network according to a first embodiment of the present invention. As shown in FIG. 4, the method includes:

In step 410, the network side allocates the primary frequency and the secondary frequency of the unicast frequency soft multiplexing of each cell in the preset area within a specified frequency range. For example, in the specified frequency range, the network side allocates the primary frequency to the adjacent three cells in the same preset area, which are the primary frequency 1, the primary frequency 2, and the primary frequency 3, respectively, except for the primary frequency in the designated frequency band. The frequency is the secondary frequency of the cell, as shown in FIG.

Then, proceeding to step 420, the network side determines whether broadcast multicast is currently required. If necessary, the process proceeds to step 440. If not, the process proceeds to step 430, that is, the user equipment of each cell in the preset area performs unicast according to the allocated primary and secondary frequencies. The frequency is soft multiplexed, after which it returns to step 420 to continue to determine whether broadcast multicast is currently required.

In step 440, the network side needs to perform broadcast multicast, and part of the frequency band is divided into the same frequency band for the same frequency broadcast multicast.

Then, proceeding to step 450, the network side re-allocates the primary frequency and the secondary frequency of the unicast frequency soft multiplexing of each small area in the preset area within the remaining frequency range. For the example shown in FIG. 5 above, in the same frequency range, the network side divides part of the frequency band as a broadcast multicast frequency segment, and re-divides the remaining frequency bands into three frequency bands, respectively, and assigns them to the original three cells as their The primary frequency (ie, primary frequency 1, primary frequency 2, and primary frequency 3), likewise, the frequency other than the primary frequency in the remaining frequency band is the secondary frequency of the cell, as shown in FIG.

In the actual network, some content may only need to be broadcast multicast in some cells. At this time, the pure unicast cell adjacent to the cell that needs to perform broadcast multicast may not consider the existence of broadcast multicast, if it is normal. Unicast soft multiplexing is configured, but this approach may cause mutual interference on the cell edges.

Then, proceeding to step 460, the user equipment of each cell in the preset area performs unicast frequency soft multiplexing according to the re-allocated main sub-frequency.

When broadcast multicast is required, part of the original frequency band is divided into broadcast multicast, and in the remaining frequency band, each cell in the preset area is unicasted by frequency soft multiplexing, so that the unicast frequency is soft. Multiplexing and broadcast multicast can be dynamically combined in the same frequency band, without adding additional resources, without affecting unicast frequency soft multiplexing, and network-side broadcast multicasting, effectively utilizing limited frequency. 'rate resources.

Referring to FIG. 7, a frequency band allocation method in a wireless cellular network according to a second embodiment of the present invention is shown in FIG. 7. Steps 710 to 730 are similar to steps 410 to 430, and details are not described herein again.

In step 740, the network side needs to perform broadcast multicast, and the network side directly occupies part of the frequency band in the specified frequency band for intra-frequency broadcast multicast, and the unicast frequency of each cell in the preset area is soft-multiplexed with the primary and secondary frequencies. The division is the same as when broadcast multicast is not required. For example, the network side previously allocates different primary frequencies for three adjacent cells in the same preset area, which are primary frequency 1, primary frequency 2, and primary frequency 3, respectively, when broadcast multicast is required, as shown in FIG. The network side directly occupies all the frequency bands of the main frequency 3 and the partial frequency bands of the main frequency 2 for the same frequency broadcast multicast, and the division manner of the primary and secondary frequencies of the unicast frequency soft multiplexing of each cell in the remaining frequency bands is unchanged. This avoids the overhead caused by frequent re-division of the primary and secondary frequencies.

Then, proceeding to step 750, the network side changes the primary and secondary frequencies of the corresponding cell. Specifically, since the frequency occupied by the broadcast multicast can no longer be used for unicast, the network side no longer allows the cell to use the part of the frequency as the primary frequency or the secondary frequency, and the cell that originally used the frequency as the primary frequency is also It can no longer be used as the primary frequency, and the network side will make corresponding changes to the primary and secondary frequencies of each cell in the preset area.

Then, proceeding to step 760, the user equipment of each cell in the preset area performs soft multiplexing of the unicast frequency according to the changed primary and secondary frequencies. Thereafter, returning to step 720, it continues to determine whether broadcast multicast is currently required.

The method for allocating a frequency band in a wireless cellular network according to the third embodiment of the present invention is substantially the same as that of the first embodiment. The difference is only that, in this embodiment, the designated frequency band is divided into time slices by time division multiplexing, and the network side needs to perform In broadcast multicast, the same-frequency broadcast multicast is only performed in part of the time slots of the partial frequency bands divided from the specified frequency band, and the remaining time slots in the partial frequency bands are still in accordance with the originally allocated primary and secondary frequencies, and the frequency is softly recovered. Use for unicast.

For example, when the network side needs to perform broadcast multicast, part of the frequency band is divided into a broadcast multicast frequency band within a specified frequency band, and within the remaining frequency band, the unicast frequency soft multiplexing of each cell in the preset area is re-allocated. Main frequency and secondary frequency. After that, in the singular time slice, the network side performs the same-frequency broadcast multicasting at the broadcast multicast frequency, and at the same time, the users of the cells in the preset area perform unicast frequency soft multiplexing according to the re-assigned primary and secondary frequencies; In the double-numbered time slice, the network side does not perform the same-frequency broadcast multicast, and the users of the cells in the preset area still perform unicast frequency soft multiplexing according to the originally allocated primary and secondary frequencies.

A method for allocating a frequency band in a wireless cellular network according to a fourth embodiment of the present invention is substantially the same as the second embodiment The same, the difference is that the specified frequency band is divided by time slice according to the time division multiplexing mode. When the network side needs to perform broadcast multicast, in the different time slices, part of the frequency band directly used by the same frequency broadcast multicast is specified. The different parts of the frequency band, that is, the mega-frequency processing of some frequency bands used for the same-frequency broadcast multicast.

For example, the network side allocates different primary frequencies for three adjacent cells in the same preset area, which are primary frequency 1, primary frequency 2, and primary frequency 3. When broadcast multicast is required, as shown in FIG. In time slice 1, the network side directly occupies all the frequency bands of the primary frequency 1 and the partial frequency bands of the primary frequency 2 for the same frequency broadcast multicast, and in the time slice 2, the network side directly occupies all the frequency bands and the primary frequency 2 In the frequency band 3, the same frequency band is broadcasted in the same frequency band. Then, in the time slice 3, the network side directly occupies all the frequency bands of the main frequency 3 and the partial frequency bands of the main frequency 2 to perform the same frequency broadcast multicast. By performing the same-frequency broadcast multicasting in different frequency bands at different time slots, it is possible to prevent the situation that some cells do not have a dominant frequency on the broadcast multicast time slice due to the wide bandwidth occupied by the broadcast multicast, so that the throughput of each cell edge is The volume is generally more balanced.

The method for allocating a frequency band in a wireless cellular network according to the fifth embodiment of the present invention is substantially the same as that of the second to fourth embodiments. The difference is that, in the present embodiment, the network side needs to further determine that the cell that performs the same-frequency broadcast multicast is occupied. Whether the broadcast multicast band has a partial overlap with the dominant frequency of the adjacent pure unicast cell, and if there is partial overlap, the primary frequency of the overlapping portion of the pure unicast cell is changed to the secondary frequency. For example, the network side broadcasts multicast in three cells in the preset area, and occupies part of the frequency band in the specified frequency band as the broadcast multicast band. At this time, the network side needs to further determine the master of the pure unicast cell in the adjacent area. Whether the frequency partially overlaps with the broadcast multicast band, if any, changes the overlapping frequency of the pure unicast cell to the secondary frequency. Thereby avoiding mutual interference between broadcast multicast and unicast frequency.

In addition, the present invention further provides a frequency band allocating device, which is shown in FIG. 10, and the wireless cellular network includes: a unicast frequency allocating unit 101, a decision unit 101, and a frequency band allocating unit 102. The unicast frequency allocating unit 101 is configured to allocate, in a specified frequency range, a primary frequency and a secondary frequency of unicast frequency soft multiplexing of each cell in the preset area; the determining unit 101, and the unicast frequency allocation unit The connection 101 is configured to determine whether broadcast multicast is required in the preset area, and send the determination result to the frequency band allocating unit 102. The frequency band allocating unit 102 is connected to the decision unit 101, and is configured to use the Partial frequency bands are allocated in the specified frequency band for multicast broadcasting in the same frequency band. In the remaining frequency bands, each cell in the preset area performs unicast in interference coordination mode, or the designated frequency is specified. The segments are all allocated to each cell in the preset area to perform unicast in an interference coordination manner.

Specifically, the network firstly allocates the primary frequency and the secondary frequency of the unicast frequency soft multiplexing of each cell in the preset area by using the unicast frequency allocation unit 101; and then determines whether the broadcast is currently required by the decision unit 101. Multicast, if the decision unit 101 determines that broadcast multicast is required, the judgment result is sent to the frequency band allocating unit 102, and the partial frequency band is divided from the specified frequency band for the same frequency broadcast multicast, and the preset is in the remaining frequency band. Each cell in the area performs unicast in an interference coordination manner. If the decision unit 101 determines that broadcast multicast is not required, the decision result is sent to the frequency band allocating unit 102, and all the designated frequency bands are allocated to the cells in the preset area. Unicast in interference coordination mode.

For the specific functions and functions of the various units in the frequency band allocating device, refer to the implementation process of each step in the foregoing method, and details are not described herein again.

It can be seen that the embodiment of the present invention only performs partial frequency band multicasting when the broadcast multicast is required, and the remaining frequency bands are unicasted by the inter-cell interference coordination mode. This approach enables a dynamic combination of broadcast multicast and unicast in the same frequency band, allowing for more efficient use of limited spectrum resources.

For the remaining frequency bands, it can be allocated again in the interference coordination mode between the cells, and the allocation mode when the broadcast multicast is not required can be maintained. Taking the unicast frequency soft multiplexing as an example, the redistribution scheme can make the primary and secondary frequency resource allocation of each cell relatively balanced, and the scheme of maintaining the original allocation mode can avoid the overhead caused by frequently re-dividing the primary and secondary frequency.

It is also possible to time-multiplex the above frequency bands, and only allocate part of the time slots of the partial frequency bands to be used by the same frequency broadcast multicast, and all the time slices in the other frequency bands and all the time slices in the remaining frequency bands are used for soft multiplexing of the unicast frequency. . With this time division multiplexing, the frequency resources occupied by the broadcast multicast can be more flexibly controlled.

If the remaining frequency bands remain unchanged when the broadcast multicast mode is not required, and time division multiplexing is used, frequency hopping technology can be used, that is, each time-frequency broadcast multicast station in the time slice of the same-frequency broadcast multicast The occupied frequency bands are different. By frequency hopping, it is possible to prevent certain cells from having a dominant frequency on the broadcast multicast time slice due to the relatively wide bandwidth occupied by the broadcast multicast, so that the throughput of each cell edge is generally balanced.

If the multicast multicast band occupied by the cell broadcasting in the same frequency broadcast is small and the adjacent pure unicast is small If the primary frequencies of the regions overlap at least partially, the primary frequency of the overlapping portion of the pure unicast cells is changed to the secondary frequency, thereby avoiding mutual interference between the broadcast multicast and the unicast primary frequencies.

Although the invention has been illustrated and described with reference to the preferred embodiments of the present invention, it will be understood The spirit and scope of the invention.

Claims

Rights request

A frequency band allocation method, comprising:

The frequency band allocation method according to claim 1, wherein when the broadcast multicast is not required in the preset area, all the designated frequency bands are allocated to each cell in the preset area to interfere with the coordination mode. Do unicast.

The frequency band allocation method according to claim 1 or 2, wherein the preset area includes at least two neighboring cells.

The frequency band allocation method according to claim 1 or 2, wherein the interference coordination mode comprises unicast frequency soft multiplexing.

The frequency band allocation method according to claim 4, wherein, when the broadcast multicast is required, the unicast frequency soft complex of each cell in the preset area is reallocated in the remaining frequency band range. The primary and secondary frequencies used.

The frequency band allocation method according to claim 4, wherein, when the broadcast multicast is required, part of the frequency bands in the specified frequency band are directly occupied for the same frequency broadcast multicast, and the preset is in the remaining frequency band. The division mode of the unicast frequency soft multiplexed primary and secondary frequencies of each cell in the area is consistent with the case where broadcast multicast is not required.

The frequency band allocation method according to claim 6, wherein the specified frequency band is divided into time slices by using a time division multiplexing mode, and when broadcast multicasting is required, the direct occupation is provided in different time slices. Some of the frequency bands used by the frequency broadcast multicast are different parts of the specified frequency band.

The frequency band allocation method according to claim 1 or 2, wherein the specified frequency band is divided into time slices by using a time division multiplexing mode, and when broadcast multicast is required, only the frequency band is allocated from the specified frequency band. The intra-frequency broadcast multicast is performed in part of the time slots of the partial frequency bands, and the unicast is performed in the interference coordination mode in the remaining time slices of the partial frequency bands.

The frequency band allocation method according to claim 4, wherein the broadcast multicast frequency band occupied by the cell performing the same frequency broadcast multicast and the primary frequency of the adjacent pure unicast cell are at least partially weighted. In the case of a stack, the dominant frequency of the overlapping portion of the pure unicast cell is changed to the secondary frequency.

10. A frequency band allocating device, comprising:

The frequency band allocation unit is connected to the decision unit, and is configured to perform the same frequency band broadcast multicasting when part of the frequency band is selected according to the judgment result, and the remaining frequency band is unicasted by the inter-cell interference coordination mode. The specified frequency band is uniformly allocated; or the designated frequency band is all allocated to each cell in the preset area to perform unicast in an interference coordination manner.