CN101882946A - Frequency Hopping Method in GERAN/VAMOS System - Google Patents

Abstract

A frequency hopping method in a GERAN/VAMOS system, comprising steps: for users on VAMOS subchannel 1, calculate the frequency used in each frame according to the frequency hopping scheme in the GSM standard; for users on VAMOS subchannel 2, in each Change its own MAIO value every frame or at intervals of several frames, and then combine the frequency hopping sequence number HSN and the current frame number to calculate the frequency used by the current frame. By adopting the method of the present invention, only the frequency hopping scheme is changed for the users on the sub-channel 2, and the frequency hopping scheme for the users on the sub-channel 1 is not changed. While achieving frequency diversity and user diversity, it does not bring additional computational complexity.

Description

Frequency Hopping Method in GERAN/VAMOS System

technical field

The present invention relates to a wireless communication system, more specifically, to a frequency hopping method in a GERAN/VAMOS system, which is used in a wireless communication system to improve user diversity gain by using an improved frequency hopping scheme in order to improve transmission reliability.

Background technique

In recent years, due to the sharp increase in the demand for mobile voice services, the GSM network has ushered in a huge development. However, limited frequency resources are increasingly difficult to meet people's call needs, especially in densely populated cities. With the increase of the aging degree of the existing GSM network equipment, it is more urgent to expand the capacity of the existing GSM network. On the other hand, since the tariff of the voice service is reduced year by year, operators need to reuse existing hardware resources and frequency resources more effectively. Therefore, how to increase the system capacity without increasing the frequency resources of the existing system has become a very important research direction.

The technology of Multiple User Reuse One Slot (MUROS) is mainly applied in 3GPP GSM/EDGE Radio Access Network (GSM/EDGE RadioAccess Network, GERAN). The discussion began at the 36th meeting, aiming to increase the user capacity of the GSM system and help operators relieve network pressure. The Work Item phase began at the GERAN#40 meeting in November 2008, and was officially named VAMOS (Voice services over Adaptive Multi-user channels One Slot).

The VAMOS system needs to further improve voice capacity on the basis of reusing existing network equipment and wireless resources. In the feasibility study stage, the candidate VAMOS solution is mainly to multiplex two or more users in the same time slot (Slot) without degrading the call quality. The main consideration at present is to increase the voice capacity of the system by 2 times, that is, to reuse two users per time slot. On the one hand, affected by this are the full-rate and half-rate voice channels, TCH/FS, TCH/HS, TCH/EFS, TCH/AFS, TCH/AHS and TCH/WFS, and the associated control channels such as slow Fast Associated Control Channel (SACCH) and Fast Associated Control Channel (FACCH). On the other hand, after the use of VAMOS technology, as the number of users in the cell increases, it will inevitably lead to an increase in co-channel interference and adjacent channel interference, resulting in a decrease in carrier-to-interference ratio (C/I) and frequency reuse. How to achieve a compromise between reducing frequency reuse and increasing time slot reuse requires further research.

There are three main types of existing VAMOS candidate solutions:

1) Co-voice frame (Co-TCH) scheme

Downlink: linearly combine two channels of Gaussian minimum frequency shift keying (GMSK) baseband modulation signals (the two channels have a phase difference of Pi/2), perform radio frequency modulation and power amplification, and then transmit.

Uplink: Each mobile station adopts GMSK modulation and uses different training sequences (TSC), and uses methods such as joint detection at the base station to separate two multiplexed user signals.

2) Orthogonal sub-channel (OSC) scheme

Downlink: Quadrature Phase Shift Keying (QPSK) is used to transmit the signals of two users. At the user receiving end, the signals of each user can be received by GMSK modulation.

Uplink: Each mobile station adopts GMSK modulation and uses different training sequences, and uses methods such as interference cancellation at the base station to separate the two multiplexed signals.

3) Adaptive Symbol Constellation Mapping (ASC) scheme

Downlink: The alpha-QPSK scheme is adopted, and the transmission power of the I channel and the Q channel can be controlled by adaptively adjusting the constellation mapping.

Uplink: Each mobile station adopts GMSK modulation and uses different training sequences, and uses a multi-user-multiple-input multiple-output (MU-MIMO) receiver at the base station to demodulate two multiplexed signals.

At present, in the VAMOS Work Item stage, the above three solutions are mainly considered, so that two users can share the same time-frequency resources to achieve the goal of doubling the system capacity. However, which solution is adopted by 3GPP GERAN is still under discussion.

Either way, it can be regarded as two sub-channels sharing the same time-frequency resource, sub-channel 1 and sub-channel 2 . Usually, sub-channel 1 is compatible with older phones and only VAMOS phones can be used on sub-channel 2.

Fig. 1 is a frame structure diagram of the GSM system. The GSM system adopts time division multiple access (TDMA), and each TDMA frame is divided into 8 time slots, numbered from 0, 1, ..., 7. Neither frames nor time slots overlap each other. A time slot (Slot) is a basic radio resource unit of the GSM system. According to a certain time slot allocation principle, each mobile station can only send signals to the base station in the designated time slot in each frame. Under the condition of timing and synchronization, the base station can receive each mobile station in each time slot respectively. signals without interfering with each other. At the same time, the signals sent by the base station to multiple mobile stations are arranged in sequence and transmitted in predetermined time slots. As long as each mobile station receives in the designated time slot, it can distinguish the signal sent to it from the combined signal.

Figure 2 is a VAMOS frame structure diagram. In circuit switching mode, VAMOS allows multiplexing of two users on the same time-frequency resource, and these two users form a VAMOS pair. The uplink and downlink share the same time slot number, absolute radio frequency channel number (ARFCN) and TDMA frame number.

Figure 3 is a schematic diagram of the downlink modulation of the VAMOS user group. The bits from the TCH channel of each user in the VAMOS pair and the corresponding channel-associated control channel are mapped to an adaptive QPSK (AQPSK) modulation symbol. At the receiving end, the user demodulates its own TCH channel and the bits of the corresponding channel-associated control channel, and performs radio link measurement at the same time.

In the uplink, in the same cell, two user signals modulated by GMSK are sent on the same time-frequency resource, that is, the two users have the same time slot label, ARFCN and TDMA frame number. The distinction between users depends on the training sequence (TSC) in the data sent by the user. In the same cell, the user on subchannel 1 uses the training sequence in TSC set 1, and the user on subchannel 2 uses the training sequence in TSC set 2. sequence. At the receiving end of the base station, multi-user detection or interference cancellation technology is used to demodulate and decode the received signals of the two users, and at the same time perform corresponding radio link control for the two users.

In the GSM system, Discontinuous Transmission (DTX) technology is used. When the speech codec detects a speech gap, it does not transmit during the gap period.

The role of DTX is to:

1. The use of DTX can reduce the interference level in the system and improve the system effectiveness.

2. Due to the use of the DTX transmitter, the total transmission time is reduced, and the power loss is reduced while extending the battery life of the MS.

To implement DTX, Voice Activity Detection (VAD) is used to indicate when there is a pause in speech.

In the downlink, when the TCH channel adopts DTX technology, for a VAMOS pair, if both users have data to send, that is, when they are both in the non-DTX state, the base station adopts AQPSK modulation, as shown in Figure 3; If the TCH channel of one of the users is in the DTX state, and the other user is in the non-DTX state, then at this time, the base station will send the GMSK modulation signal to the user in the non-DTX state; when the TCH channels of the two users are in the DTX state , the base station only sends DTX information. Therefore, if it can be matched with DTX users, the user's channel quality will be greatly improved.

Although the three existing VAMOS candidate schemes (Co-TCH, OSC, and alpha-QPSK) guarantee the orthogonality between the two multiplexed users at the sending end, the multi-path propagation characteristics of the wireless channel cause inter-symbol Interference, as well as the non-linear characteristics of the transmit and receive filters, can cause signal leakage between the two subchannels at the receive end. In the downlink, this means that the two multiplexed users interfere with each other; in the uplink, the random phase difference between the users makes the orthogonality of the receiving end not guaranteed, even if the channel does not experience time-dispersive fading . It is precisely because the orthogonality between the two sub-channels cannot be guaranteed at the receiving end that intra-cell interference (intra-cell interference) occurs, and the two multiplexed sub-channels interfere with each other, causing system performance degradation.

In GSM network, whether to support frequency hopping is optional. The main advantage of frequency hopping is that it can provide frequency diversity gain (especially for slow mobile users) and interference diversity gain (ie, achieve interference averaging in each communication link).

According to the suggestion of GSM, the frequency hopping of the wireless channel of the base station is based on each physical channel, so for the mobile station, it only needs to hop once in the corresponding time slot of each frame, and its frequency hopping rate is 217 hops/ seconds, that is, every TDMA frame with a duration of 4.615ms jumps once. The mobile station uses a fixed frequency to send and receive in a time slot, and then needs to jump to the next TDMA frame after the time slot.

In the definition of cell parameters, two frequency groups are defined, one is called cell allocation table (Cell Allocation) to define all frequency points used in the cell, and the other is called mobile allocation table (Mobile Allocation) to define All frequency points participating in frequency hopping. The carrier frequency carrying BCCH cannot be used for frequency hopping, because it carries FCCH, SCH and BCCH channels, and needs to continuously broadcast synchronization messages and system messages to all mobile phones in the cell.

The frequency hopping sequence is orthogonal in a cell, that is, different users in the same cell will not hop to the same frequency at the same time, and they are independent in the same cell group. In the GSM specification, there are two parameters used to define the Hopping Sequence (Hopping Sequence), which are MAIO (Mobile Allocation Pointer Offset) and HSN (Hopping Sequence Number).

Since MAIO needs to describe the starting point of the frequency hopping repetition function, the possible values of the offset are as many as the number of frequencies participating in the frequency hopping. The number of frequency points of MA should be between 1 and 64. When generating the frequency hopping sequence, it needs to go through a very complex algorithm process. The parameters involved in the calculation are FN (the current frame number and the T1 and T2 describing the frame number obtained from the SCH channel. , T3 value), MAIO, HSN.

The HSN value has 64 different values. Generally, the channels of a cell should have the same HSN value and different MAIO values, because this is to avoid interference between channels in the same cell. When the same MAIO occurs in the same cell, it will cause serious problems. assignment failure rate. Two channels with the same HSN and different MAIO will not use the same frequency in the same burst (Burst), avoiding frequency collision in a cell.

The mobile station can obtain MA, HSN and MAIO from the cell parameters provided in the system broadcast message, and then derive the frequency hopping sequence according to the algorithm, and the mobile station will know which frequency should be sent/received in each frame.

When VAMOS technology is introduced, according to the existing GSM frequency hopping scheme, the two users forming VAMOSpair will use the same frequency in each TDMA frame, that is to say, each user will continuously interfere with its own pairing in each frame In this way, although the user has obtained the frequency diversity gain, there is no user diversity gain. Especially when the system adopts DTX technology, if users can be matched with DTX users, their channel quality will be greatly improved. On the other hand, when the system is a fractional load, that is, there is only one user on some frequencies, so if according to the existing standard, those users who exclusively use a frequency will always be in an unpaired state and will not be affected by the cell. Internal co-channel interference. From a system point of view, the gain of interference diversity is not reflected.

Therefore, it is necessary to improve the existing frequency hopping scheme in the VAMOS system, and the basic principles of improvement are:

1) At each moment, at most two users can hop on the same frequency;

2) Make the paired two users hop on different frequencies every frame or after several frames, change the pairing situation between users, ensure that one user is not continuously interfered by another user, and obtain user diversity gain and Interference diversity gain.

Contents of the invention

The object of the present invention is to provide a frequency hopping method in GERAN/VAMOS system.

In order to achieve the above object, according to one aspect of the present invention, a frequency hopping method in a GERAN/VAMOS system is provided, comprising steps:

a) For users on VAMOS sub-channel 1, calculate the frequency used in each frame according to the frequency hopping scheme in the GSM standard;

b) For the users on the VAMOS sub-channel 2, change their own MAIO value every frame or several frames apart, and then combine the frequency hopping sequence number HSN and the current frame number to calculate the frequency used by the current frame.

According to another aspect of the present invention, a kind of frequency hopping method in GERAN/VAMOS system is proposed, comprising steps:

a) For users on VAMOS sub-channel 1, calculate the frequency used in each frame according to the frequency hopping scheme in the GSM standard, and frequency hop in each frame once;

b) For users on the VAMOS sub-channel 2, the users on the VAMOS sub-channel 2 have a fixed MAIO value, calculate the frequency used by the current frame according to the frequency hopping scheme in the GSM standard, and every other frame or several frames The frequency hops once.

Adopting the method of the present invention in the GERAN/VAMOS system not only does not need to pre-store the frequency hopping sequence at the mobile terminal, but also requires little additional signaling overhead. It can be guaranteed that only two users occupy the same frequency at most at any one time, and one user will not be continuously interfered by another user. By adopting the method of the present invention, only the frequency hopping scheme is changed for the users on the sub-channel 2, and the users on the sub-channel 1 are not changed. While achieving frequency diversity and user diversity, it does not bring additional computational complexity.

Description of drawings

Fig. 1 is a frame structure diagram of the GSM system;

Fig. 2 is a schematic diagram of two users reusing the same time-frequency resource in the GERAN/VAMOS system according to the present invention;

Fig. 3 is a schematic diagram of paired user downlink modulation in the GERAN/VAMOS system according to the present invention;

Fig. 4 is a flowchart of an improved frequency hopping scheme according to the present invention.

Detailed ways

When the GSM system introduces VAMOS technology, the basic principles for improving the frequency hopping scheme are:

1) At each moment, at most two users can hop on the same frequency;

2) Obtain the interference diversity gain while obtaining the frequency diversity gain.

The first method uses fast frequency hopping based on cyclic MAIO-fast pairing method can be used in GERAN/VAMOS system, including steps:

All users in the same cell have the same frequency hopping sequence number (HSN) and mobile allocation list (MA). The user on sub-channel 1 calculates the frequency used by himself in each TDMA frame according to the scheme in the existing GSM standard (TS45.002); number and available MAIO (MAIOA, MAIO Allocation) to calculate the MAIO value of the current frame, and then combine the HSN of the cell and the current frame number, according to the frequency hopping scheme in the existing GSM standard to calculate the current The frequency used by the frame. By adopting the frequency hopping method, the frequency used by the user and the pairing situation may change every frame, and the frequency diversity gain and the user diversity gain can be obtained.

The second method, using slow frequency hopping-fast pairing method can be used in GERAN/VAMOS system, including steps:

All users in the same cell have the same frequency hopping sequence number (HSN) and available frequency hopping frequency set (MA). In this cell, the set formed by all users on sub-channel 1 is called set 1, and the set formed by all users on sub-channel 2 is called set 2. Each user has a fixed MAIO value that is unique within the set it belongs to. All users in the cell calculate their frequency according to the frequency hopping scheme in the existing GSM standard (TS45.002). Frequency hopping is performed every two frames or several frames, and the frequency of frequency hopping is fixed.

The third method adopts fast frequency hopping based on cyclic MAIO-slow pairing method can be used in GERAN/VAMOS system, including steps:

All users in the same cell have the same frequency hopping sequence number (HSN) and available frequency hopping frequency set (MA). The user on sub-channel 1 calculates the frequency used by himself in each TDMA frame according to the scheme in the existing GSM standard (TS45.002); the user on sub-channel 2 changes the MAIO value every other frame or several frames, which depends on Based on the set user pairing step. When the current frame needs to change the MAIO value, the user calculates his own MAIO value in the current frame according to the initial MAIO value assigned by the base station, the current TDMA frame number, the MAIOA value and the MAIO change step size; if the current frame does not need to change the MAIO value value remains unchanged. After obtaining the MAIO value, combined with the HSN of the cell and the current frame number, the frequency used by the current frame can be calculated according to the frequency hopping scheme in the existing GSM standard.

Users on sub-channel 2 can be selectively allowed to perform frequency hopping according to the present invention. For example, one remaining bit in the broadcast channel or the downlink SACCH channel is used to indicate whether to use the frequency hopping method of the present invention or to calculate the frequency used by the current frame according to the frequency hopping scheme in the GSM standard. Also use bit 8 of the first octet in the downlink SACCH channel or use bit 8 of Octet 1 in one or more messages of Cell Description, Cell Options, Channel Description, ChannelDescription 2, and Channel Description 3 in the broadcast channel to indicate Whether to use the frequency hopping method of the present invention or to calculate the frequency used by the current frame according to the frequency hopping scheme in the existing GSM standard.

At the same time, the user's MAIO change step size (applied to the first method and the third method) and frequency hopping step size (applied to the second method) can be adaptively adjusted through the downlink broadcast channel or control channel .

In an actual system, the speed of frequency hopping and the moving speed of users will affect the frequency diversity gain. When the user is moving at a slow speed, the faster the frequency hopping and the greater the frequency diversity gain, the smaller the step size should be; when the user is moving at a high speed, the fading of the wireless channel changes very sharply, and the frequency The smaller the gain of diversity, the larger the frequency hopping step should be. Therefore, in the GSM system, the frequency hopping step size can be adaptively configured according to different scenarios.

In the first and third methods, the MAIOA can be obtained by receiving the MAIOA broadcast on the broadcast channel. The MAIOA can also be notified to the user during channel allocation through a downlink control channel (eg, SDCCH).

Example

This section presents the embodiments of the invention. In order to avoid making the description of this patent too lengthy, in the following description, detailed descriptions of functions or devices that are well known to the public are omitted.

Embodiment one

The fast frequency hopping-fast pairing method based on cyclic MAIO can be used in GERAN/VAMOS system.

As shown in Figure 4, all users in the same cell have the same frequency hopping sequence number (HSN) and available frequency hopping frequency set (MA). Users on sub-channel 1 have a fixed MAIO value, which is allocated by the base station during the channel establishment phase. Therefore, the user on sub-channel 1 can calculate the frequency used by himself in each TDMA frame according to the frequency hopping scheme in the existing GSM standard (TS45.002), as shown in the following formula:

MAI=f(FN, HSN, MAIO) (1)

ARFCN(FN)＝MA(MAI) (2)

Among them, MAI represents the index of the mobile allocation table MA, and f(.) represents the calculation function of the frequency hopping sequence given in TS45.002. Therefore, the frequency used by the user in the FNth frame can be known according to (1) and (2).

At this time, the user's MAIO value on sub-channel 2 changes cyclically in each frame, that is, the user's initial MAIO value plus the current TDMA frame number FN, and then modulo the number of elements in MAIOA to ensure the user's MAIO value It is in the set MAIOA, as shown in the following formula:

MAIO(FN)＝(MAIO ₀ +FN) mod M (3)

MAI=f(FN, HSN, MAIO(FN)) (4)

ARFCN(FN)＝MA(MAI) (5)

Among them, MAIO ₀ is the user's initial value of MAIO, and M represents the number of elements in MAIOA.

Since the initial MAIO value of the user on sub-channel 2 is sent to the user by the base station during the channel establishment phase, and is unique among all user sets using sub-channel 2. In this way, it is guaranteed that at most two users occupy the same frequency at the same time, and the MAIO value of the user on sub-channel 2 changes cyclically every frame, so the pairing situation of the users may change every frame, thereby realizing fast frequency hopping- Fast user pairing, while obtaining frequency diversity gain, user diversity gain is also obtained.

The basic idea of this example method is that: the MAIO value of the user on sub-channel 1 is fixed, and its frequency hops once every frame, while the MAIO value of the user on sub-channel 2 is cyclically selecting possible MAIO values in the MAIOA set every frame . In addition to using the MAIO initial value plus the current frame number and then taking the modulus with the MAIOA value, you can also use the difference between the MAIO initial value and the current frame number to remove the MAIOA value to generate the MAIO value for each frame of the user on sub-channel 2, or let MAIO Incremental or decremental changes in fixed or variable steps. The faster the change, the better the randomness you get. In addition, it is also possible to define many calculation methods of MAIO initial value and the calculation result of the current frame number and then modulo MAIOA. In order to avoid the present invention being too lengthy, no further details are given here, but they are all within the scope of protection of the present invention. Inside.

Embodiment two

The slow frequency hopping-fast pairing method can be used in GERAN/VAMOS systems.

All users in the same cell have the same frequency hopping sequence number (HSN) and available frequency hopping frequency set (MA). In this cell, the set formed by all users on sub-channel 1 is called set 1, and the set formed by all users on sub-channel 2 is called set 2. Each user has a fixed MAIO value that is unique within the set it belongs to.

The user on sub-channel 1 calculates the frequency used by himself in each frame according to the frequency hopping scheme in the existing GSM standard (TS45.002), that is, the frequency hops once in each frame.

At this time, the user on sub-channel 2 hops every two frames or several frames. The frequency hopping step size can be a preset fixed value, or the frequency hopping step can be changed through the downlink broadcast channel or control channel. long. The MAI of each frame of the user on sub-channel 2 can be calculated by the following formula:

MAI＝f((FN div η), HSN, MAIO) (6)

Wherein, n is the step size of frequency hopping, that is, the frequency hops once every n frames. div means divisibility.

In addition, the following formula can also be used to calculate the MAI of each frame of the user on sub-channel 2,

if(FN mod η==0)

MAI=f(FN, HSN, MAIO);

(7)

else

MAI=f((FN-FN modη), HSN, MAIO);

Among them, mod represents a modulo operation.

The basic idea of the method in this example is to keep the MAIO values of all users in the cell constant, the frequency of users on sub-channel 1 hops every frame, and the frequency of users on sub-channel 2 hops every other frame or several frames. That is to say, the frequency hopping frequency of the user on sub-channel 2 is lower than that of the user on sub-channel 1. In addition, other frequency hopping methods that allow users on sub-channel 1 and sub-channel 2 to have different frequency hopping frequencies are within the protection scope of the present invention.

Embodiment three

The fast frequency hopping-slow pairing method based on cyclic MAIO can be used in GERAN/VAMOS system.

All users in the same cell have the same frequency hopping sequence number (HSN) and available frequency hopping frequency set (MA). Users on sub-channel 1 have a fixed MAIO value, and can calculate the frequency they use in each TDMA frame according to the frequency hopping scheme in the existing GSM standard (TS45.002).

At this time, the user on sub-channel 2 changes the MAIO value every one frame or several frames, and the specific number of frames to change the MAIO value depends on the set user pairing step.

In the GSM system, the uplink SACCH channel is used to send the user's measurement report, and then the base station uses the downlink SACCH to tell the user how to adjust the power. Therefore, the pairing step length of users may be one or more SACCH periods, which is beneficial to realize the stability between two paired users. Here, the larger the pairing step size, the lower the diversity gain, but the higher the stability of the power control; otherwise, the greater the diversity gain, but the lower the stability of the power control. Therefore, in practical applications, the pairing step can be adjusted according to the actual situation of the system.

In fact, the pairing step size corresponds to the pairing period of two users. The pairing period refers to the number of frames in which two users continuously occupy the same time slot and the same frequency in the same cell. The pairing period of two users can be changed by frequency hopping.

Let λ be the user pairing step size. When the current frame needs to change the MAIO value, that is, when the frame number of the current frame is an integer multiple of λ, the user on sub-channel 2 assigns the initial MAIO value MAIO ₀ and the current TDMA frame number assigned to him by the base station. FN, MAIOA value, and MAIO change the step size to calculate the MAIO value of the current frame; if the current frame does not need to change the MAIO value, the MAIO value remains unchanged, thereby continuing to maintain the current user pairing situation. After obtaining the MAIO value, combined with the HSN of the cell and the current frame number, the frequency used by the current frame can be calculated according to the frequency hopping scheme in the existing GSM standard.

The specific MAIO calculation process is as follows:

if(FN modλ==0)

MAIO(FN) = (MAIO ₀ +η×FN) mod M;

(8)

else

MAIO(FN)=(MAIO ₀ +η×(FN-FN modλ)) mod M;

MAI=f(FN, HSN, MAIO(FN)) (9)

The basic idea of the method in this example is to keep the MAIO value of the user on sub-channel 1 fixed, and the frequency hops once every frame, while the user on sub-channel 2 changes the MAIO value every other frame or several frames, the specific interval How many frames to change the MAIO value depends on the set user pairing step. MAIO is worth changing. You can use the initial value of MAIO plus a certain incremental step to modulo MAIOA. In addition, it is also possible to define many calculation methods of MAIO initial value and the calculation result of the current frame number and then modulo MAIOA. In order to avoid the present invention being too lengthy, details are not repeated here, but all are within the protection scope of the present invention.

Claims (18)

1. A frequency hopping method in a GERAN/VAMOS system, comprising steps: a) For users on VAMOS sub-channel 1, calculate the frequency used in each frame according to the frequency hopping scheme in the GSM standard; b) For the users on the VAMOS sub-channel 2, change their own MAIO value every frame or several frames apart, and then combine the frequency hopping sequence number HSN and the current frame number to calculate the frequency used by the current frame. 2. The method according to claim 1, characterized in that the frequency hopping scheme in the GSM standard is the TS45.002 standard. 3. The method according to claim 1, wherein the user on the sub-channel 2 changes its own MAIO value every frame. 4. The method according to claim 1, wherein the user on sub-channel 2 changes the MAIO value every other frame or several frames, and the frequency hops every frame. 5. The method according to claim 3 or 4, wherein the MAIO value of the user on sub-channel 2 is calculated by using the available MAIO value set MAIOA. 6. The method according to claim 3 or 4, characterized in that, the MAIO value of the user on the sub-channel 2 is incremented or decremented by a preset fixed step size, and then taken modulo with the number of elements in the MAIOA to ensure The user's MAIO value is in the MAIOA. 7. The method according to claim 5, wherein the MAIOA is obtained by receiving the MAIOA broadcast on a broadcast channel. 8. The method according to claim 1, characterized in that the pairing steps of users on sub-channel 1 and sub-channel 2 are adaptively changed according to the downlink broadcast channel or control channel. 9. The method according to claim 1, characterized in that the change step of the user's MAIO value on the sub-channel 2 is adaptively changed according to the downlink broadcast channel or control channel. 10. The method according to claim 8 or 9, characterized in that, based on user diversity gain and power control stability, the change step size and user pairing step size of the user's MAIO value on subchannel 2 are adaptively changed. 11. A frequency hopping method in a GERAN/VAMOS system, comprising steps: a) For users on VAMOS sub-channel 1, calculate the frequency used in each frame according to the frequency hopping scheme in the GSM standard, and frequency hop in each frame once; b) For users on the VAMOS sub-channel 2, the users on the VAMOS sub-channel 2 have a fixed MAIO value, calculate the frequency used by the current frame according to the frequency hopping scheme in the GSM standard, and every other frame or several frames The frequency hops once. 12. The method according to claim 11, characterized in that the frequency hopping scheme in the GSM standard is the TS45.002 standard. 13. The method according to claim 11, characterized in that the frequency hopping frequencies of users on sub-channel 1 and sub-channel 2 are not equal, thereby changing the pairing situation of users. 14. The method according to claim 11, wherein said step b) includes changing the frame number of the current frame according to the frequency of frequency hopping, and using the changed frame number, HSN and MAIO values to calculate the current frame Frequency of. 15. The method according to claim 11, characterized in that the frequency hopping step size of the user on the sub-channel 2 is adaptively changed according to the downlink broadcast channel or control channel. 16. The method according to claim 1 or 11, further comprising the step of: before performing the step b), using 1 remaining bit in the broadcast channel or the downlink SACCH channel to indicate whether to use step b) or according to the GSM standard The frequency hopping scheme calculates the frequency used by the current frame. 17. The method according to claim 1 or 11, wherein, before performing the step b), utilize the bit 8 of the first octet in the downlink SACCH channel to indicate whether to utilize the step b) or according to the GSM standard The frequency hopping scheme calculates the frequency used by the current frame. 18. The method according to claim 1 or 11, characterized in that, before performing step b), one or more of Cell Description, Cell Options, ChannelDescription, Channel Description 2 and Channel Description 3 in the broadcast channel is used Bit 8 of Octet 1 in this message indicates whether to utilize step b) or to calculate the frequency used by the current frame according to the frequency hopping scheme in the GSM standard.

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