CN102196525B - Coding cooperation soft handoff method - Google Patents

Abstract

The invention relates to a method for coding cooperative soft handover, in particular to a method for coding cooperative handover soft handover, which belongs to the field of wireless mobile communication. Under the mobile channel, each base station encodes the information source, and the encoding code rate is controlled by the large-scale information of the current channel, and the encoded information is distributed. According to the channel characteristics between the transmission information base station and other base stations, the encoding code rate and After power distribution, each base station performs cooperative transmission, so as to realize coded handover and soft handover. The present invention can effectively improve frequency band utilization and reliability, adopt time-division duplex-based coding adaptive technology to make handover fast, convenient and easy to implement, and channel-based reciprocity characteristics enable both sending and receiving to know each other without information transmission channel information.

Description

A Coding Cooperative Soft Handoff Method

technical field

The invention relates to a method for coding cooperative soft handover, in particular to a method for coding cooperative handover soft handover, which belongs to the field of wireless mobile communication.

Background technique

With the advancement of technology, the new generation of mobile communication network has more complete network coverage, higher data service capability and comprehensive real-time multimedia services, and provides users with better network services in a more complex wireless environment. The new-generation mobile communication network also puts forward higher requirements for "intra-network handover", which is a key link in network construction. Handover occurs when the mobile station moves from one cell (referring to the base station or the coverage area of the base station) to another cell, in order to maintain the uninterrupted communication of the mobile user. There are three methods for judging whether a mobile station needs handover: (1) Judging by the carrier level of the received signal, that is, switching when the carrier level of the signal is lower than the threshold level (for example -100dBm); (2) Relying on the carrier level of the received signal Judgment of signal carrier/interference ratio, that is, handover when the carrier/interference ratio is lower than a given value; (3) Judgment based on the distance from the mobile station to the base station, that is, handover when the distance is greater than a given value. The specific handover criteria are as follows:

Criterion 1: Relative Signal Criterion.

The base station with the strongest received signal is selected at any time. The disadvantage of this criterion is that too many unnecessary handovers will be caused when the signal strength of the original base station still meets the requirements.

Criterion 2: Relative signal strength criterion with threshold specification. Only when the signal of the current base station is weak enough (lower than a certain threshold) and the signal of the new base station is stronger than the signal of the current base station can the mobile user be handed over.

Criterion 3: Relative signal strength criterion with hysteresis margin. The mobile user is only allowed to perform handover when the signal strength of the new base station is much stronger than the signal strength of the original base station (that is, greater than the hysteresis margin). This technology can prevent the mobile station from repeatedly switching back and forth between two base stations due to signal fluctuations, that is, the "ping-pong effect".

Criterion 4: Relative signal strength criterion with hysteresis margin and threshold specification. The mobile user is only allowed to perform handover when the signal level of the current base station is below a specified threshold and the signal strength of the new base station is higher than the current base station by a given hysteresis margin.

Handover can be technically divided into hard handover and soft handover. Hard handover means that the old connection is interrupted before the new connection is established. It is suitable for infrequent or medium-frequency switching. When the mobile phone user leaves the signal coverage area of the currently used cell, it will continue to provide continuous uninterrupted communication services for mobile phone users, such as CDMA system. For handover control, only the handover controlled by the mobile station is considered, that is, the mobile station continuously monitors the signal strength and quality of the current base station and several candidate base stations when handing over. When a certain handover criterion is satisfied, the mobile station The best candidate base station with available traffic channels is selected and a handoff request is sent. Small systems such as DECT often adopt a hard handover method, which is likely to cause handover conflicts in large systems. Soft handover refers to channel switching between cells when the carrier frequencies of the pilot channels are the same. During the handover process, the mobile user maintains communication links with both the original base station and the new base station, and only after the mobile station establishes stable communication in the cell of the new target base station, does it disconnect from the original base station, which is unique to the cdma communication information system The switching function can effectively improve switching reliability.

The problem of high-speed mobile handover in microcells. In microcells, high-speed mobile users only need to handover in a short time, which puts too much pressure on the system. An umbrella cell structure combining macrocells and microcells uses macrocells for handover Channels can solve the above problems.

With the development of new mobile communication networks, the cell handover size is continuously reduced, transitioning from macro cells to micro cells and then to pico cells; at the same time, mobile devices are moving faster and faster, resulting in more frequent handovers. Soft handover can reduce user unpleasant experience, balance the load in the current area, and realize resource sharing and other functions. In order to improve frequency reuse efficiency and support high-speed wireless access requirements, a new switching technology must be adopted.

Qualcomm International Patent Application No. PCT/US00/35684 2000.12.28, "Improved Soft Handoff Algorithm and Wireless Communication System for the Third Generation CDMA System", which involves establishing synchronization between MS and multiple base stations communication to perform soft handoff.

Qualcomm's international patent application number PCT/US00/30580 2001.11.6, "Method and device for performing handover in high-speed communication system", the content involves a closed-loop power control system, the mobile station adds verification information, based on The power control parameter judges whether the reverse link signal is received by the target base station with sufficient energy. When the base station providing the best forward link signal does not receive the reverse link signal from the user station with sufficient energy, it will force the overshoot. zone switching.

The above two patents mention soft handover based on power control feedback information and synchronous communication, but do not give specific power detection and specific soft handover methods.

Contents of the invention

The purpose of the present invention is to reduce the user's unpleasant experience in the case of frequent cell switching, and to further improve the efficiency of frequency reuse and support high-speed wireless access, and propose a coded cooperative soft handover method.

The present invention is achieved through the following technical solutions.

Coding technology is used to realize handover soft handover of existing and future mobile communication networks. When a base station and another base station can communicate directly through optical fibers, that is, each base station has a direct connection relationship with another base station without other transfers, the two base stations are defined as neighbor base stations, and each base station in the network Form a neighbor base station relationship with one or more base stations in the network.

The mobile user equipment adaptively adjusts the code rate assigned to each base station according to the user's location and real-time channel estimation information, and uses the coded information to perform soft handover. In the high-speed mobile environment, the sending and receiving parties of the communication mainly transmit data, and the sending and receiving parties only need to know the large-scale information of the channel, which greatly reduces the requirements for channel reciprocity.

Under the mobile channel, each base station encodes the information source, and the encoding code rate is controlled by the large-scale information of the current channel, and the encoded information is distributed. According to the channel characteristics between the transmission information base station and other base stations, the encoding code rate and After power distribution, each base station performs cooperative transmission, so as to realize coded handover and soft handover.

A kind of encoding cooperative soft handoff method of the present invention, its specific steps are as follows:

1) The transmitter obtains the corresponding coding rate between each neighboring base station and the mobile device according to the channel information;

2) The sender detects whether the code rate corresponding to each neighbor base station and the mobile device in step 1) is lower than the preset minimum threshold value, if so, the channel is disconnected by assigning a zero rate, otherwise, each neighbor base station Assign the corresponding rate;

3) The transmitter allocates the distribution power between the base station and the mobile device for each neighboring base station, and the power is adaptively adjusted according to the channel characteristics between the base station and the mobile device, specifically using the water injection theorem for power allocation;

4) The transmitter uses rateless encoding to encode the transmitted data. This encoding method has the characteristics of low encoding and synchronization complexity, and can design encodings of various code lengths, thereby realizing rateless encoding of any ratio;

5) The transmitter encodes and distributes the encoded data in step 4), and sends them to neighboring base stations;

6) Neighboring base stations that receive coded data carry out cooperative transmission of coded and distributed data; during this process, when information of some base stations is lost, the reception effect of users will not be affected under the premise of correct decoding by each base station;

7) The receiver receives the information sent by each base station in step 6) after cooperative transmission, and performs combination and demodulation, and outputs the received symbol soft information;

8) The receiver sends the demodulated soft information of the received symbols to the belief propagation decoder, and outputs the decoded symbols;

9) The receiver sends the decoded symbols output by the belief propagation decoder to the sink. After the sink is correctly decoded, the receiver feeds back to the transmitter to stop sending signals, and the transmitter stops broadcasting and distributing data information to neighboring base stations at this time, and starts the next frame transmission of data;

The above-mentioned transmitter is a base station or a mobile device, and the above-mentioned receiver is also a base station or a mobile device.

A coded cooperative soft handover method of the present invention, when specifically implementing coded soft handover, coded handover based on more than 3 levels does not require air interface support; when the load of the cell covering the current area is unbalanced, the coded soft handover of the present invention can be used to perform Resource sharing; when the service characteristics of the currently used cell do not match, resources are used efficiently according to the speed and service layering.

Beneficial effect

Adopting a coded cooperative soft handover method of the present invention can effectively improve frequency band utilization and reliability, the base station adopts coded cooperative mode to realize handover soft handover, adopts time division duplex-based coding adaptive technology to make handover Fast, convenient, and easy to implement; the channel-based reciprocity feature enables the two transmissions to receive and transmit information without information transmission; the coding switching based on more than 3 levels does not require air interface support, and can be used when the load of the cells covering the current area is unbalanced. Realize resource sharing; when the service characteristics of the currently used cell do not match, use resources efficiently according to the speed layer and service layer.

Description of drawings

FIG. 1 is a schematic diagram of an embodiment of power allocation for coding cooperative soft handover under the condition of two base stations;

Fig. 2 is a schematic diagram of information transmission of the present invention;

FIG. 3 is a specific flow chart of sending in the encoding cooperative soft handover method of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

This embodiment specifically elaborates on the power allocation among different base stations participating in cooperative soft handover during the implementation process of a coding cooperative soft handover method proposed by the present invention. It is assumed that the number of base stations participating in coding cooperative soft handover is 2, respectively BSx and BSy, the number of user equipment participating in code distribution is 1, that is, UE _k , the signal transmitted by base station BSx is a, and the signal transmitted by base station BSy is b, as shown in Figure 1, then a and b can be expressed as

a=k ₀ x, b=k ₁ x

由于总功率是固定的，因此将总功率分为两份，系数分别是k₀和k₁，且

x为复星座点，UE_k接收到的信号为in

Since the total power is fixed, the total power is divided into two parts, the coefficients are k ₀ and k ₁ , and

x is the complex constellation point, the signal received by UE _k is

y=α·a+β·b+ζ

Where α and β are the power distribution coefficients, ζ is the complex Gaussian variable, substituting the expressions of a and b into the expression of y, we get

y=α·k ₀ x+β·k ₁ x+ζ

make

E|ζ| ² ＝N ₀

but

$\mathrm{<span\; class="notranslate">\; SNR</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; E.</span>}{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;\&beta;</span>}<span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

Where E|ζ| ² represents the mathematical expectation of |ζ| ² , and SNR is the signal-to-noise ratio.

set constraints

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}$

Among them, E ₀ and E ₁ are the power allocated by the base stations BSx and BSy respectively, and Es is the average power.

Using the Lagrangian method, maximize the SNR, that is, maximize

$<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;\&beta;</span>}<span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}$

obtained by derivation

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&zeta;</span>}$

Receive signal-to-noise ratio

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; SNR</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

According to the water injection theorem, the optimal power allocation strategy is:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$ ${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

At the same time, the optimal SNR is

$\mathrm{<span\; class="notranslate">\; SNR</span>}{<span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; opt</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\sqrt{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\sqrt{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; .</span>$

Similarly, this embodiment can be extended to coded soft handoff applications where multiple base stations serve one user and multiple base stations serve multiple users.

Example 2

A coding cooperative soft handover method is used in a broadband TDD (time division duplex) mobile communication system. In order to realize fast and efficient coded cooperative soft handover, the distribution process of information rate and power can respectively adopt rateless coding and as in embodiment 1 A method for distributing power based on the principle of water injection in . In the broadband TDD (time division duplex) mobile communication system, the respective base stations adaptively adjust the code rate according to the position of the mobile terminal user equipment, and realize the code distribution and information transmission of information and power, so as to realize code cooperative soft handover. The schematic diagram of information transmission is shown in Figure 2, and the flow chart of the specific sending steps is shown in Figure 3, and the steps of the entire encoding cooperative soft handover method are as follows:

1) The transmitter obtains the corresponding coding rate between each neighboring base station and the mobile device according to the channel information;

2) The sender detects whether the code rate corresponding to each neighbor base station and the mobile device in step 1) is lower than the preset minimum threshold value, if so, the channel is disconnected by assigning a zero rate, otherwise, each neighbor base station Assign the corresponding rate;

3) The transmitter uses the water injection theorem to allocate the distribution power between the base station and the mobile device for each neighboring base station;

4) The sender uses RC-LDPC or RC-LDGM rateless encoding to encode the transmitted data;

5) The transmitter encodes and distributes the encoded data in step 4), and sends them to N ₁ to N _T total T neighbor base stations;

6) A total of T neighboring base stations from N ₁ to N _T perform cooperative transmission of the coded and distributed data;

7) The receiver receives the information sent by each base station in step 6) after cooperative transmission, and performs combination and demodulation, and outputs the received symbol soft information;

8) The receiver sends the demodulated soft information of the received symbols to the belief propagation decoder, and outputs the decoded symbols;

9) The receiver sends the decoded symbols output by the belief propagation decoder to the sink. After the sink is correctly decoded, the receiver feeds back to the transmitter to stop sending signals, and the transmitter stops broadcasting and distributing data information to neighboring base stations at this time, and starts the next frame transmission of data.

The above description is only a preferred embodiment of the present invention, and the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. All equivalents or modifications accomplished without departing from the disclosed spirit of the present invention fall within the protection scope of the present invention.

Claims (3)

1. A coding cooperative soft handover method is characterized in that the specific steps are as follows: 1) The transmitter calculates the corresponding coding rate between each neighboring base station and mobile device according to the channel information; 2) The sender detects whether the code rate corresponding to each neighboring base station and the mobile device in step 1) is lower than the preset minimum threshold value. If so, the channel is disconnected by allocating zero rate, otherwise, each neighboring base station Assign the corresponding rate; 3) The transmitter allocates the distribution power between the base station and the mobile device for each neighboring base station, and the power is adaptively adjusted according to the channel characteristics between the base station and the mobile device; 4) The transmitter uses rateless encoding to encode the transmitted data; 5) The transmitter encodes and distributes the encoded data in step 4) and sends them to neighboring base stations; 6) Neighboring base stations that receive the coded data perform cooperative transmission of the coded data; 7) The receiver receives the information sent by each base station after cooperative transmission in step 6), combines and demodulates, and outputs the soft information of the received symbol; 8) The receiver sends the demodulated soft information of the received symbols to the belief propagation decoder, and outputs the decoded symbols; 9) The receiver sends the decoded symbols output by the belief propagation decoder to the sink. After the sink is correctly decoded, the receiver feeds back to the transmitter to stop sending signals, and the transmitter stops broadcasting and distributing data information to neighboring base stations at this time, and starts the next frame transmission of data; The above-mentioned neighbor base station is a base station that can directly communicate with the base station through optical fiber, that is, the neighbor base station and the base station have a direct connection relationship without other transfers; The above-mentioned transmitter is a base station or a mobile device, and the above-mentioned receiver is also a base station or a mobile device. 2. A coded cooperative soft handover method according to claim 1, characterized in that: in said step 3), the method used by the transmitter to allocate the distribution power between the base station and the mobile device for each neighboring base station is the water injection theorem. 3. A coded cooperative soft handover method according to claim 1, characterized in that: in the step 4), the transmitter uses RC-LDPC or RC-LDGM rateless coding to encode the transmitted data.

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