JP4619150B2 - Mobile communication system, mobile station apparatus, base station apparatus, and transmission rate control method - Google Patents

Description

  The present invention relates to a mobile communication system, a mobile station apparatus, a base station apparatus, and a transmission rate control method.

  In a mobile communication system such as a cellular phone system that uses a CDMA (Code Division Multiple Access) system, the mobile station device communicates or transmits a new information code, In some cases, a new call or new information code of the mobile station apparatus cannot be decoded in the base station apparatus.

  That is, a communication signal of a certain mobile station apparatus becomes an interference wave for communication signals of other mobile station apparatuses. Since the interference wave is such, as the number of mobile station apparatuses communicating in a certain base station apparatus increases, the amount of interference waves (interference amount) received by the base station apparatus increases. If the amount of interference becomes excessive, the influence of interference waves on new calls and new information codes transmitted by other mobile station devices cannot be ignored. When the influence of the interference wave cannot be ignored in this way, when the new call or new information code is decoded in the base station apparatus, the signal is mixed in with noise and cannot be decoded.

  Therefore, in order to avoid the above situation, for example, in MC (Multi Carrier) -CDMA system used in CDMA2000 and DS (Direct Sequence) -CDMA system used in W-CDMA, a new information code is transmitted. In some cases, the mobile station apparatus starts transmission at the lowest level of antenna power. A communication signal with high antenna power at the time of transmission (that is, a communication signal with a large amplitude) has a greater influence on other communication signals as an interference wave than a communication signal with a small amplitude. That is, a communication signal having a high amplitude increases the amount of interference wave (interference amount). For this reason, first, transmission is started with the lowest level of antenna power, so that the amplitude of the communication signal is lowered, and an increase in the amount of interference is prevented.

  Then, in the system as described above, the antenna power is gradually increased according to the reception level of the pilot signal transmitted from the base station apparatus and the interference amount information notified from the base station apparatus. ing.

  Thus, in the conventional communication system, the amount of interference in the base station apparatus suddenly becomes excessive by preventing the mobile station apparatus trying to communicate with the base station apparatus from suddenly high aerial power. The situation that happens is suppressed.

Patent Document 1 discloses an invention relating to a transmission device, a reception device, and a data transmission method that automatically switches a data transmission rate in accordance with a line condition.
JP 2000-31944 A

  However, in the above conventional method, the base station apparatus does not ensure a margin of interference amount. For example, when a large number of new information codes are transmitted at once, the interference amount is still suddenly excessive. As a result, there is a risk that the base station apparatus may be unable to decode.

  The present invention has been made in view of the above problems, and one of its purposes is a mobile communication system, a mobile station apparatus, a base station apparatus, and a transmission rate that can reduce the situation where decoding becomes impossible in a base station apparatus or the like. It is to provide a control method.

A mobile communication system according to an aspect of the present invention for solving the above-described problem includes a base station apparatus and a mobile station apparatus. In the mobile communication system using a code division multiple access method, the base station apparatus includes the base station apparatus An interference amount acquisition unit that acquires an interference amount of radio waves transmitted from a mobile station device, and a period transmission unit that transmits a period during which the mobile station device transmits at a lower transmission rate than a normal transmission rate, When the amount of interference is in a predetermined range, the mobile station apparatus performs setting to transmit at the low transmission rate during the period transmitted by the period transmission unit, and when the period has elapsed, A rate control unit configured to perform transmission at a normal transmission rate .

  By doing in this way, a transmission rate can be reduced autonomously in a mobile station apparatus. In a mobile communication system using a code division multiple access method, there is generally a correlation between the transmission rate of a mobile station device and the required transmission power (aerial power), and when the transmission rate is reduced autonomously in the mobile station device, The transmission power of the mobile station device can be reduced. For this reason, according to the present invention, it is possible to reduce the transmission power of the mobile station apparatus without interrupting communication and to secure a margin of interference amount in the base station apparatus. As a result, it is possible to reduce the situation in which decoding becomes impossible due to excessive interference in the base station apparatus.

In the mobile communication system, the period transmission unit further transmits a cycle, and the rate control unit performs transmission at a low transmission rate and a normal transmission rate in the cycle transmitted by the period transmission unit. It is also possible to repeat the transmission by .

  In the mobile communication system, the base station apparatus transmits an instruction to increase or decrease the transmission power of the mobile station apparatus to the mobile station apparatus according to a reception error rate of a signal transmitted from the mobile station apparatus. The mobile station apparatus may further include means for transmitting a signal with power according to an instruction transmitted from the base station apparatus. Generally, the higher the transmission rate, the higher the reception error rate (an index indicating the ratio of errors in the received data, such as frame error rate, block error rate, bit error rate). The transmission power of the mobile station apparatus can be raised or lowered by raising or lowering. For this reason, by raising and lowering the transmission rate in the mobile station apparatus, it is possible to ensure a margin of interference amount in the base station apparatus.

  A mobile communication system according to another aspect of the present invention includes a base station apparatus and a mobile station apparatus. In the mobile communication system using a code division multiple access method, the mobile station apparatus includes the base station apparatus. Information code transmitting means for transmitting an information code to the mobile station apparatus, the base station apparatus receiving information code transmitted from the mobile station apparatus, and a low rate for the mobile station apparatus. Low-rate transmission instruction transmission means for transmitting a transmission instruction, wherein the mobile station apparatus transmits a low-rate transmission instruction reception means for receiving the low-rate transmission instruction, and a transmission rate of an information code according to the low-rate transmission instruction. Transmission rate changing means for changing the transmission rate such that the transmission rate decreases.

  According to the present invention, the base station apparatus decreases the transmission rate of the mobile station apparatus, so that the mobile station apparatus can decrease the transmission power. For this reason, it becomes possible to reduce the transmission power of the mobile station apparatus and prevent the amount of interference in the base station apparatus from becoming suddenly excessive.

  In the mobile communication system, the base station device further includes transmission rate determining means for determining that the mobile station device is transmitting the information code at a transmission rate exceeding a predetermined threshold, The low-rate transmission instruction transmission unit may transmit a low-rate transmission instruction to the mobile station apparatus depending on whether transmission is performed at a transmission rate exceeding the predetermined threshold. By so doing, it is possible to transmit a low rate transmission instruction depending on whether or not the mobile station apparatus is transmitting at a transmission rate exceeding a predetermined threshold.

  Further, in the mobile communication system, the base station apparatus further includes interference amount determination means for determining that the interference amount in the base station apparatus exceeds a predetermined threshold, and the low rate transmission instruction transmission means May transmit the low-rate transmission instruction according to whether or not the amount of interference in the base station apparatus exceeds a predetermined threshold. In this way, a low rate transmission instruction can be transmitted according to the amount of interference in the base station apparatus.

  In the mobile communication system, when the transmission rate changing unit changes the transmission rate, the mobile station apparatus includes a transmission rate storage unit that stores a transmission rate before the change, and the transmission rate changing unit. Transmission rate return means for returning the transmission rate of the mobile station apparatus to a transmission rate corresponding to the transmission rate stored in the transmission rate storage means after a predetermined time has elapsed after the change of the transmission rate. Also good. In this way, the throughput of the mobile station device can be increased.

  In the mobile communication system, the mobile station device may further include predetermined time acquisition means for acquiring the predetermined time. In this way, the mobile station apparatus can acquire the time until returning to the transmission rate before the change.

  Further, in the mobile communication system, the base station device includes: a predetermined time determining unit that determines the predetermined time; and a predetermined time transmitting unit that transmits the determined predetermined time to the mobile station device. The mobile station apparatus further includes a predetermined time receiving means for receiving the predetermined time, and the predetermined time acquisition means acquires the predetermined time by receiving the transmitted predetermined time. It is good as well. In this way, the base station apparatus can determine the time until returning to the transmission rate before the change.

  In the mobile communication system, the base station apparatus transmits an instruction to increase or decrease the transmission power of the mobile station apparatus to the mobile station apparatus according to a reception error rate of a signal transmitted from the mobile station apparatus. The mobile station apparatus may further include means for transmitting a signal with power according to an instruction transmitted from the base station apparatus. In general, the higher the transmission rate, the higher the reception error rate. In this way, the transmission power of the mobile station apparatus can be increased or decreased by increasing or decreasing the transmission rate. For this reason, by raising and lowering the transmission rate in the mobile station apparatus, it is possible to ensure a margin of interference amount in the base station apparatus.

A mobile station apparatus according to still another aspect of the present invention is a mobile station apparatus used in a mobile communication system using a code division multiple access method , comprising a rate control unit for setting a transmission rate, and the rate control The unit receives interference amount information, which is information based on the amount of interference in the transmitted radio base station apparatus, and period information indicating a period during which transmission is performed at a lower transmission rate lower than the normal transmission rate, and the interference amount information When the interference amount indicates a predetermined range, during the period indicated by the period information, a setting is made to transmit at the low transmission rate, and when the period elapses, the normal transmission rate It is characterized in that it is set to perform transmission by.

  A mobile station apparatus according to still another aspect of the present invention is a mobile station apparatus used in a mobile communication system based on a code division multiple access method, and transmits an information code to a base station apparatus. A low rate transmission instruction receiving means for receiving a low rate transmission instruction from the base station apparatus, a transmission rate changing means for changing the transmission rate of the information code in accordance with the low rate transmission instruction, and the transmission rate changing means When the rate is changed, the transmission rate storage means for storing the transmission rate before the change, and after the elapse of a predetermined time after the change of the transmission rate, the transmission rate is stored in accordance with the transmission rate stored by the transmission rate storage means. Transmission rate returning means for returning to the transmission rate.

  A base station apparatus according to still another aspect of the present invention is an information code for receiving an information code transmitted from a mobile station apparatus, which is a base station apparatus used in a mobile communication system using a code division multiple access scheme. Receiving means; determining means for determining that the mobile station apparatus is transmitting the information code at a transmission rate exceeding a predetermined threshold; and the mobile transmitting at a transmission rate exceeding the predetermined threshold Low-rate transmission instruction transmission means for transmitting a low-rate transmission instruction to the station apparatus.

A transmission rate control method according to still another aspect of the present invention is a transmission rate control method for a mobile station apparatus used in a mobile communication system using a code division multiple access method, in a base station apparatus for transmitted radio waves. A step of acquiring interference amount information that is information based on the amount of interference; a step of acquiring period information indicating a period during which transmission is performed at a lower transmission rate lower than a normal transmission rate; and A step of performing transmission at the low transmission rate during the period indicated by the period information and a step of performing transmission at the normal transmission rate when the period has elapsed. characterized in that it comprises a and.

  A transmission rate control method according to still another aspect of the present invention is a transmission rate control method for a mobile station apparatus used in a mobile communication system using a code division multiple access method, and includes information transmitted from the mobile station apparatus. Receiving a code, determining that the mobile station apparatus is transmitting the information code at a transmission rate exceeding a predetermined threshold, and transmitting at a transmission rate exceeding the predetermined threshold. Transmitting a low-rate transmission instruction to the mobile station apparatus.

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to the drawings. As shown in FIG. 1, mobile communication system 4 according to the present embodiment includes a plurality of mobile station apparatuses 1, base station apparatus 2, and communication network 3. The base station apparatus 2 normally communicates with a plurality of mobile station apparatuses 1 by the CDMA system.

  As shown in FIG. 2, the mobile station device 1 includes a control unit 11, a communication unit 12, a storage unit 13, an operation unit 14, and a display unit 15. The control unit 11 controls each unit of the mobile station device 1 and executes processing related to a call and data communication. Moreover, the control part 11 is also performing the process for determining the transmission rate, when transmitting the packet for communication used in data communication via the communication part 12. FIG. The communication unit 12 includes an aerial line, and in accordance with an instruction input from the control unit 11, modulates a voice signal, a communication packet, and the like and outputs the modulated signal or the voice signal arriving at the aerial line. A process of receiving and demodulating and outputting to the control unit 11 is performed.

  The storage unit 13 operates as a work memory for the control unit 11. The storage unit 13 holds programs and parameters related to various processes performed by the control unit 11. The operation unit 14 is, for example, a numeric keypad, and receives a telephone number or a character string from a user and outputs it to the control unit 11. The display unit 15 is configured to include, for example, a liquid crystal display device, and displays and outputs information according to a signal input from the control unit 11.

  Next, as shown in FIG. 3, the base station device 2 includes a control unit 21, a network interface unit 22, a wireless communication unit 23, and a storage unit 24. The control unit 21 controls each unit of the base station apparatus 2 and executes processing related to telephone calls and data communication. The network interface unit 22 is connected to the communication network 3 and receives an audio signal, a communication packet, and the like from the communication network 3 and outputs them to the control unit 21, or according to an instruction from the control unit 21. A packet or the like is transmitted to the communication network 3. The wireless communication unit 23 includes an antenna, receives and demodulates a voice signal, a communication packet, and the like from at least one mobile station device 1 and outputs them to the control unit 21 or an instruction input from the control unit 21 Accordingly, processing such as modulating a voice signal or a communication packet input from the control unit 21 and outputting it via an antenna is performed. The storage unit 24 operates as a work memory for the control unit 21. Further, the storage unit 24 holds programs and parameters related to various processes performed by the control unit 21.

  When the base station apparatus 2 communicates with the mobile station apparatus 1 using the radio communication unit 23, a traffic channel and a control channel can be used as logical channels. Traffic channels include uplink and downlink communication channels and power control channels. Voice signals and communication packets are transmitted and received on the upstream and downstream communication channels. Uplink means communication from the mobile station apparatus 1 to the base station apparatus 2, and downlink means communication from the base station apparatus 2 to the mobile station apparatus 1. The power control channel is a channel for the base station device 2 to control the antenna power of the mobile station device 1. The control channel includes an uplink access channel, a downlink pilot channel, a synchronization channel, and a paging channel. The access channel is a channel for transmitting a signal from the mobile station apparatus 1 to the base station apparatus 2, and includes an uplink dedicated control channel. The pilot channel and the synchronization channel are channels for synchronizing the base station device 2 and the mobile station device 1. The paging channel is a channel for the base station apparatus 2 to transmit the control information of the mobile station apparatus 1 to the mobile station apparatus 1, and is a common control that is transmitted to all mobile station apparatuses 1 that can communicate at the same time. A downlink dedicated control channel for performing communication with the channel and the individual mobile station apparatus 1 is included. In the common control channel, specifically, information indicating the amount of interference and information such as transmission restrictions are broadcast to all mobile station apparatuses that can communicate. In the dedicated control channel, various signals used in the communication sequence for controlling each mobile station apparatus are transmitted and received.

  A signal on each logical channel, which is directed from the base station device 2 to the mobile station device 1, is included in a physical downlink channel composed of CDMA radio carriers, and is transmitted from the mobile station device 1 to the base station. A signal directed to the station apparatus 2 is included in a physical uplink channel (hereinafter referred to as an “uplink channel”) composed of CDMA radio carriers.

  A signal (information code) including information such as a packet is primarily modulated into a signal such as ASK (Amplitude Shift Keying), FSK (Frequency Conversion Modulation), or PSK (Phase Shift Keying) at the transmission side device. The In this system, the transmission rate is made variable by changing the frequency of the primary modulation wave and the multilevel (when multilevel modulation is adopted).

  Next, the first-order modulated primary modulated wave is a waveform called a PN (Pseudorandom Noise) sequence, for example, a waveform in which +1 or −1 appear in a random order and is expressed by a function having extremely high autocorrelation , Are converted into a secondary modulated wave obtained by multiplying. Then, after the secondary modulated wave is superimposed on a carrier wave, it is transmitted to the radio section. Here, obtaining the secondary modulation wave from the primary modulation wave is called diffusion. Then, the demodulation side device can obtain the original primary modulation wave by multiplying the received secondary modulation wave by the same PN sequence. Here, obtaining the primary modulation wave from the secondary modulation wave is called despreading. By doing so, even when an interference wave enters during transmission / reception, the interference wave cannot be despread even if multiplied by the PN sequence, and is further diffused. For this reason, even when there is interference, there is an effect that the possibility of demodulation is high.

  Then, by making the PN sequence different for each mobile station apparatus 1, signals to be transmitted / received to / from each mobile station apparatus are identified. For this reason, for example, when there are a large number of mobile station apparatuses 1 and each transmits a signal by the above method, each signal becomes an interference wave with respect to another signal. When there are many interference waves, the influence of the interference waves cannot be ignored when despreading. When the interference waves exceed a certain amount, a primary modulated wave cannot be obtained by despreading. That is, a new call or a new information code cannot be demodulated in the base station apparatus 2 and cannot be accepted. The amount of the interference wave is generally called an interference amount, and is usually represented by a signal-to-noise ratio (S / N ratio) or a carrier power-to-noise power ratio (C / N ratio). The amount of interference can be calculated for each mobile station apparatus 1, and the amount of interference for the base station apparatus 2 as a whole can be a statistical quantity. Specifically, it may be the total amount of interference for each mobile station apparatus 1 or an average value.

  Next, packets used in communication between the mobile station apparatus 1 and the base station apparatus 2 are transmitted at a plurality of stages of transmission rates. For example, packets used in CDMA2000 are usually transmitted and received at a transmission rate of five stages. More specifically, it is determined as any one of 9.6 kbps, 19.2 kbps, 38.4 kbps, 76.8 kbps, and 153.6 kbps, and the base station apparatus 2 and the mobile station apparatus 1 are mutually connected at these transmission rates. To communicate.

  The base station apparatus 2 performs so-called closed loop control. That is, the SIR (reception SIR) of the signal received from the mobile station apparatus 1 is monitored, and if it is equal to or greater than a given target SIR, the mobile station apparatus 1 is instructed to reduce the transmission power. Further, if it is less than the target SIR, the mobile station is instructed to increase the transmission power. At this time, the target SIR is determined by a reception error rate such as FER (Frame Error Rate). For example, the target SIR is increased if the reception error rate is greater than a predetermined value, and the target SIR is decreased if the reception error rate is less than the predetermined value.

  Since the mobile communication system 4 employs such closed loop control in the base station apparatus 2, the transmission rate and transmission power of the mobile station apparatus 1 are correlated. That is, when the mobile station apparatus 1 transmits data at a low rate, the quality of the received signal from the mobile station apparatus 1 is improved in the base station apparatus 2, thereby lowering the target SIR. As a result, the possibility of giving the mobile station apparatus 1 an instruction to decrease the transmission power increases. On the contrary, when the mobile station apparatus 1 transmits data at a high rate, the quality of the received signal from the mobile station apparatus 1 in the base station apparatus 2 decreases, and thereby the target SIR increases. As a result, the possibility of giving the mobile station apparatus 1 an instruction to increase the transmission power is increased.

  As described above, in the mobile communication system 4, the transmission power of the mobile station apparatus 1 is indirectly increased or decreased by increasing or decreasing the transmission rate in the mobile station apparatus 1.

  FIG. 4 is a functional block diagram of the mobile station device 1 and the base station device 2 used in the present embodiment. As shown in the figure, the mobile station apparatus 1 functionally includes a rate control unit 42 and a data transmission unit 44, and the base station apparatus 2 functionally includes a repetition period acquisition unit 41, An interference determination unit 43 and a data reception unit 45 are included. The repetition period acquisition unit 41 notifies the mobile station apparatus 1 of the repetition period for raising and lowering the transmission rate described below using the dedicated control channel. Here, the repetition period may be transmitted every time the mobile station apparatus 1 performs transmission rate control, or may be transmitted in advance to the mobile station apparatus 1 prior to communication. Moreover, you may transmit the same repetition period to all the mobile station apparatuses 1 by transmitting by a common control channel. In this case, when all the mobile devices simultaneously reduce the transmission rate, it is possible to reduce the possibility that the amount of interference becomes excessive and decoding cannot be performed. However, if all the mobile station devices 1 increase the transmission rate at the same time, the amount of interference may be excessive and decoding may not be possible.

  The interference determination unit 43 measures the amount of interference on the uplink channel. Specifically, the amount of interference may be measured from the ratio of the signal received in the uplink channel and noise, or the amount of interference may be measured from the ratio of carrier power and noise power in the uplink channel. Then, a value indicating the range of the interference amount is transmitted to the mobile station apparatus 1 using the common control channel. Note that the interference amount may be a value related to each mobile station apparatus 1 or may be a statistical amount such as an average value of all or a part thereof.

  The rate control unit 42 receives a repetition period transmitted by the repetition period acquisition unit 41 and a value indicating the range of the interference amount transmitted from the interference determination unit 43. Then, the transmission rate determined according to the predetermined range to which the interference amount belongs and the repetition period is determined as the transmission rate for transmitting the packet, and is passed to the data transmission unit 44. Then, the data transmission unit 44 transmits the packet at the transmitted transmission rate using the uplink data channel. The data receiving unit 45 receives the packet transmitted from the data transmitting unit 44 of at least one or more mobile station apparatuses 1 and performs decoding and other processes. Then, the interference determination unit 43 measures the uplink channel interference amount from the ratio of the signal including the packet and the noise, and repeats the above processing.

This embodiment will be described more specifically. The repetition period is transmitted to the mobile station apparatus 1 through the dedicated control channel prior to communication. The contents include a low rate time T ₁ and a return rate time T ₂ , which are associated with a period during which the transmission rate is decreasing and a period during which the transmission rate is increasing (returning to the original transmission rate). It is done. The interference determination unit 43 determines the range to which the current interference amount belongs when the uplink channel interference amount is divided into three levels from LEVEL1 to LEVEL3. Then, a value indicating the range is transmitted using the common control channel. Specifically, as shown in FIG. 8, it can be included in the common control channel 50 as 2-bit information 51. Here, LEVEL1 is the minimum amount of interference, LEVEL2 has an increased amount of interference compared to LEVEL1, and LEVEL3 has the maximum amount of interference. Then, the rate control unit 42 of the mobile station apparatus 1 receives the value indicating the repetition period and the range to which the transmitted interference amount belongs, and changes the process for determining the transmission rate according to them. . That is, when the amount of interference belongs to LEVEL 1, the throughput of each mobile station apparatus 1 is increased by increasing the transmission rate with a predetermined probability according to the random number (and increasing the transmission power). When the amount of interference belongs to LEVEL3, the amount of interference is reduced by decreasing the transmission rate with a predetermined probability according to the random number (and also by reducing the transmission power). On the other hand, when the amount of interference belongs to LEVEL2, closed loop control in the direction of lowering the transmission rate when the amount of interference is LEVEL3 is not sufficient, such as when many new information codes are transmitted at once, and therefore the amount of interference In order to avoid a situation in which the base station apparatus 2 cannot perform decoding, a period for lowering the transmission rate (that is, a period for lowering transmission power) is provided in advance in the spirit of mutual transfer between the mobile station apparatuses 1. If the transmission rate remains low, the throughput only decreases, so that the original transmission rate is restored after a certain period of time (that is, the transmission power is restored). In this way, throughput is also maintained. Further, by periodically lowering or raising the transmission rate, it is possible to reduce the possibility that the base station apparatus 2 cannot perform decoding more effectively. Here, the period is a repetition period transmitted by the repetition period acquisition unit 41.

  Next, a more specific example of processing executed in the rate control unit 42 will be shown.

FIG. 5 is a flowchart of processing in the rate control unit 42 for determining the packet transmission rate according to a predetermined range to which the interference amount belongs. In addition, the code | symbol S in FIG. 5 respond | corresponds to a transmission rate, The detail is shown in FIG. FIG. 6 is a table stored in the storage unit 13. As shown in FIG. 6, the higher the numerical value of the code S that is a numerical value for identifying the transmission rate, the higher the transmission rate is associated. First, through the dedicated control channel, the base station apparatus 2 receives the low-rate time _{T 1} and the return rate time _{T 2} (S201). Further, two values A and B are received from the base station apparatus 2 through the common control channel (S202). As will be described in detail later, A and B are constants used when determining the packet transmission rate, and are threshold values for determining the packet transmission rate according to the value of the random number. Satisfies B. That is, A corresponds to the probability of increasing the transmission rate when the amount of interference is low, and B corresponds to the probability of decreasing the transmission rate when the amount of interference is high. When the mobile station apparatus 1 generates an uplink data transmission request (S203), it transmits a packet at the minimum transmission rate (S204). This is performed in order to reduce the influence on the interference amount in the base station apparatus 2 as much as possible. Then, a storage area for the variable L is secured and 0 is substituted (S205). This L is a variable used to store the level of interference later. Further, a storage area for the variable S ₀ is secured and 1 is substituted (S 206). The S ₀ is a variable used to store the results of the transmission rate after.

When an uplink data transmission request occurs again (S207), a random number X is generated (S208). X is a random number used in order to prevent the influence of the interference amount due to a large number of mobile station apparatuses 1 changing the transmission rate all at once. Then, it is determined which of the LEVEL1 to LEVEL3 the interference amount in the base station apparatus 2 is (S210). If the interference amount is LEVEL1 determines whether or not X> A (S211), if X> A, 1 step higher transmission rate than the transmission rate _{S 0} of packets transmitted immediately before The packet is transmitted by (S213, S214). Of course, if the _{S 0} is already the highest transmission rate, the process of increasing the transmission rate to transmit the packet without (S212, S214). If X> A is not satisfied, the packet is transmitted as S ₀ (S214). Then, 1 is assigned to the variable (S215), and the process proceeds to S223 described later. If the interference amount is LEVEL3 determines whether or not X> B (S216), X > if B, 1 step lower transmission rate than the transmission rate _{S 0} of packets transmitted immediately before The packet is transmitted at (S218, S219). Of course, if _{S 0} is already the lowest transmission rate, the process for lowering the transmission rate for transmitting the packet without (S217, S219). If X> B is not satisfied, the packet is transmitted as S ₀ (S219). Then, 3 is substituted into the variable L (S220), and the process proceeds to S223 described later.

When the amount of interference is LEVEL2, the process shown in FIG. 7 is performed as a rate determination process (S221). In the process in FIG. 7, it is first determined whether or not L = 2 (S301). This is because it is necessary to store the transmission rate when the previous interference amount is not the interference amount for performing the rate determination process. Then, if not L = 2 substitutes _{S 0} to the variable _{S 1} (S302). The S ₁ is the transmission rate of the transmission rate repetition of the reference in the mobile station apparatus. Then, assign the current time to the variable _{t 0} (S303). This t ₀ is a reference of the repetition period.

Next, a specific repetition process is entered, and the transmission rate is repeated as shown in FIG. In FIG. 9, the transmission rate S ₁ is lowered at t ₀ as a reference, maintained for T ₁ , and then restored. Then, after maintaining between S ₁ of T _2, lowering again the transmission rate. This is repeated while the amount of interference is LEVEL2. This specific process is shown in FIG. In S304 of FIG. 7, it is determined whether or not the current time satisfies the following expression (1). And if it meets the equation (1) it is meant to be a period of T ₁ shown in FIG.
n × (T ₁ + T ₂ ) ≦ current time−t ₀ <n × (T ₁ + T ₂ ) + T ₁ (1)

Here, n is an integer of 0 or more. If the above equation (1) is satisfied, that is, it is a period during which the transmission rate is reduced (transmission power is reduced), whether or not S ₀ is equal to S ₁ , that is, whether or not the previous transmission was performed at the reference transmission rate It determines whether (S305), if equal, reduced by α the S from _{S 0,} transmits a packet at a transmission rate corresponding to the S (S306, S308). Here, α is an integer of 0 or more and 4 or less, and S is in the range of 1 or more and 4 or less, and is lower than S ₀ . Α can be selected randomly. If S ₀ is not equal to S ₁ , the process of substituting S ₀ into S is not performed, and the packet is transmitted at a transmission rate corresponding to S (S 308). That is, the reduced transmission rate is maintained. Next, when the above equation (1) is not satisfied, that is, when the transmission rate is a reference transmission rate (transmission power is restored), S ₁ is substituted for S (S307), Packets are transmitted at the corresponding transmission rate (S308). Then, the process returns to FIG. 5, by substituting 2 into L in S222 of FIG. 5, further by substituting S to _{S 0} (S223), the flow returns to S207. Here, S is substituted for S ₀ in order to store the previous transmission rate.

  By doing so, in the present embodiment, in addition to the normal transmission power control by the closed loop control, a period in which the transmission power is lowered by forcibly and temporarily lowering the transmission rate is provided. A margin of interference can be ensured. For this reason, when a lot of new information codes are transmitted at once, the closed loop control is not in time, the amount of interference becomes excessive, and therefore it is possible to avoid a situation in which decoding by the first communication device cannot be performed.

  In addition, since the transmission rate is not only lowered but also raised and lowered repeatedly, a reduction in throughput of each mobile station device can be suppressed. In addition, since the repetition period and the range of interference amount can be freely set by station data, etc., it is possible to determine an appropriate range according to the circumstances of each base station device, such as the location where the base station device is installed and the time zone. Is possible.

Also, if at a different timing for each mobile station apparatus 1 so that the low-rate period T ₁ is imposed, while reducing the burden of the mobile station apparatus 1 side, constant amount of interference margin in the base station apparatus 2 To be able to have. In addition, since the base station apparatus 2 determines which range the interference amount belongs to, the value indicating which range the interference amount transmitted in the common control channel belongs to is at most 2 bits, and is limited. In addition, it is possible to reduce the processing of the mobile station apparatus 1 by effectively using the radio resources and omitting the calculation in each mobile station apparatus 1.

(Embodiment 2.)
A second embodiment of the present invention will be described with reference to the drawings. The configuration of the mobile communication system 4 according to the present embodiment is the same as the configuration shown in the first embodiment and the basic configuration shown in FIGS. 1 to 3, but is different in its function. Specifically, in the first embodiment, the mobile station apparatus 1 autonomously changes the transmission rate by appropriately changing the transmission rate, but in the second embodiment, the transmission rate of the mobile station apparatus 1 is changed. Is changed by an instruction from the base station apparatus 2 to change the transmission power of the mobile station apparatus.

  FIG. 10 is a functional block diagram of the mobile station device 1 and the base station device 2 used in the present embodiment. As shown in the figure, the base station apparatus 2 is functionally configured to include a transmission rate determination unit 60, a data reception unit 62, an interference determination unit 64, an instruction unit 66, and a low rate time determination unit 68. The mobile station apparatus 1 is functionally configured to include a low rate time acquisition unit 70, a transmission rate change unit 72, and a data transmission unit 74.

  The data transmission unit 74 transmits the information code using, for example, an uplink communication channel. Thus, when transmitting the information code, the transmission rate of the information code is selected from a plurality of transmission rates stored in advance. For example, in CDMA2000, when the information code is a packet, any one of 9.6 kbps, 19.2 kbps, 38.4 kbps, 76.8 kbps, and 153.6 kbps is selected as described above, and the selected transmission is performed. The packet is transmitted at a rate. At this time, as in the first embodiment, in the mobile communication system 4, the transmission power of the mobile station apparatus 1 is indirectly increased or decreased by increasing or decreasing the transmission rate in the mobile station apparatus 1.

  The data receiving unit 62 receives the information code transmitted by the data transmitting unit 74. The information code is, for example, a packet included in the uplink communication channel. Then, the data transmission unit 74 outputs the transmission rate of the received packet to the transmission rate determination unit 60.

  The transmission rate determination unit 60 determines whether or not the input transmission rate exceeds a predetermined threshold value. For example, in the case of the CDMA2000, if the predetermined threshold is 150 kbps, it is determined that the predetermined threshold is exceeded when the transmission rate is 153.6 kbps. Then, the result of the determination is output to the instruction unit 66. Note that this determination may be made as to whether or not the input transmission rate has exceeded a predetermined threshold over a predetermined time. In other words, when the transmission rate exceeds a predetermined threshold at a certain point in time, timing is started, and if the transmission rate exceeds the predetermined threshold until a predetermined time comes, the transmission rate is determined to be predetermined. It may be determined that a predetermined threshold is exceeded over time.

  Further, the interference determination unit 64 determines whether or not the uplink channel interference amount exceeds a predetermined threshold. Specifically, the amount of interference is represented by, for example, an S / N ratio as described above, and it is determined whether or not the S / N ratio exceeds a predetermined threshold. Then, the result of the determination is output to the instruction unit 66.

  The instruction unit 66 transmits a low rate transmission instruction to the mobile station apparatus 1 according to the determination result input from the transmission rate determination unit 60 and the determination result input from the interference determination unit 64. Of course, you may transmit according to only one result. Or it is good also as transmitting regardless of these results. When responding to the determination result input from the transmission rate determination unit 60, for example, when the result of the determination exceeds a predetermined threshold, a low rate transmission instruction is transmitted, and the determination result is a predetermined value. If the result does not exceed the threshold, it is preferable to limit transmission. By so doing, it is possible to reduce the transmission rate of the mobile station apparatus 1 that is transmitting at a predetermined threshold value or more. Since the mobile station apparatus 1 with a high transmission rate has high antenna power for transmission as described above and has a large influence on the amount of interference, for example, this reduces the situation in which decoding becomes impossible in the base station apparatus or the like. Can do. Further, when responding to the determination result input from the interference determination unit 64, for example, when the result of the determination exceeds a predetermined threshold, a low-rate transmission instruction is transmitted, and the determination result is predetermined. If it is not the result of exceeding the threshold, it is preferable to limit transmission. In this way, since the transmission rate of the mobile station device 1 can be lowered when the amount of interference is actually large, it is possible to reduce the influence of the uplink channel from the mobile station device 1 on the amount of interference. It is possible to reduce the situation where the station device or the like cannot be decoded. Note that the low rate transmission instruction is preferably transmitted to the mobile station apparatus 1 using the downlink dedicated control channel. The low-rate transmission instruction specifically specifies, for example, 1 bit 0, 1 included in the downlink dedicated control channel, so that the mobile station apparatus 1 does nothing if it is 0, and if it is 1, the current It may be instructed to lower the transmission rate. Alternatively, a specific transmission rate can be designated in the low rate transmission instruction.

  In the mobile station apparatus 1, the transmission rate changing unit 72 receives the low rate transmission instruction. Then, the transmission rate changing unit 72 changes the transmission rate of the information code transmitted by the data transmitting unit 74 in accordance with the low rate transmission instruction. Note that the mobile station apparatus 1 does not necessarily obey the instruction of the low rate transmission instruction, and does not prevent the mobile station apparatus 1 from changing the transmission rate for other reasons. . For example, when a specific transmission rate of 76.8 kbps is specified in the low rate transmission instruction, it is not prevented at all from changing to 38.4 kbps. In such a case, for example, the BER (Bit Error Rate) increases, for example, to 38.4 kbps due to the worsening of the radio wave conditions related to the communication between the mobile station device 1 and the base station device 2. There may be cases where communication cannot be continued without lowering. That is, when the low-rate transmission instruction is received, it is only necessary to reduce the situation where the base station apparatus 2 cannot perform decoding by changing the transmission rate of the information code transmitted by the data transmission unit 74.

  Next, the low rate time determination unit 68 determines the length of time that the mobile station apparatus 1 that has received the low rate transmission instruction reduces the rate to the low rate. That is, the transmission rate changing unit 72 can change the transmission rate of the information code transmitted by the data transmitting unit 74 in accordance with the low rate transmission instruction, but restore it after a predetermined time has elapsed. For this purpose, the low rate time determination unit 68 determines the predetermined time and transmits it to the low rate time acquisition unit 70 of the mobile station apparatus 1. It is preferable that the predetermined time is transmitted to the mobile station apparatus 1 using the downlink dedicated control channel. Further, the determination or transmission may be performed simultaneously with the low-rate transmission instruction, or may be transmitted, for example, at a timing when the mobile station device 1 is located. In addition, when it may be common in each base station apparatus 2, it may be transmitted when the mobile station apparatus 1 is powered on. In addition, when common to each mobile station apparatus 1, the mobile station apparatus 1 may be notified using a common control channel. Further, when there is no need to change, it may be stored in advance in the storage unit 13 at the manufacturing stage of the mobile station apparatus 1. In this case, it is not necessary for the base station apparatus 2 to make a decision and no transmission is required. Of course, it may be determined by the mobile station apparatus 1. In addition, when a plurality of mobile station apparatuses 1 return the transmission rate all at once, for example, it is conceivable that the amount of interference rapidly increases, and therefore the predetermined time may be varied for each mobile station apparatus 1. desirable. Specifically, for example, the predetermined time can be determined based on a random number.

  And the low rate time acquisition part 70 is acquired by receiving the said predetermined time. Then, the predetermined time is output to the transmission rate changing unit 72. Then, when changing the transmission rate of the information code transmitted by the data transmission unit 74 in accordance with the low rate transmission instruction, the transmission rate changing unit 72 stores the transmission rate before the change and the low rate time acquiring unit 70. It is good also as monitoring progress of the said predetermined time input from. When it is determined that the predetermined time has elapsed, the transmission rate may be returned to the transmission rate before the change stored.

  Here, the processing of the transmission rate changing unit 72 will be described again in detail. FIG. 11 is a functional block diagram of internal functions of the transmission rate changing unit 72. First, the receiving unit 80 receives a low-rate transmission instruction from the instruction unit 66 and outputs it to the changing unit 82. The changing unit 82 changes the transmission rate of the information code in the data transmitting unit 74 in accordance with the low rate transmission instruction. The transmission rate before the change is stored in the storage unit 84. The change unit 82 receives time information from the low rate time acquisition unit 70. Then, the time information is passed to the time measuring unit 86. The timing unit 86 starts timing at the timing at which the changing unit 82 changes the transmission rate in the data transmitting unit 74. When the time indicated by the time information being passed has arrived, The change unit 82 reads the transmission rate before the change from the storage unit 84, and returns the transmission rate in the data transmission unit 74 to the read transmission rate.

  The above processing will be described with reference to a more specific processing flowchart.

  FIG. 12 is a flowchart showing processing in the base station apparatus 2. In the process shown in the figure, the base station apparatus 2 first detects that the mobile station apparatus 1 is powered on (S400). Specifically, it is detected by a conventionally known location registration process or the like. Then, the unique Ta is notified to the mobile station device 1 (S402). The Ta is the length of time that the mobile station apparatus 1 that has received the low-rate transmission instruction determined by the low-rate time determination unit 68 lowers to the low rate. The Ta may be a number unique to each mobile station apparatus 1. Then, it is determined that the mobile station apparatus 1 transmits an information code at 153.6 kbps, which is the maximum transmission rate in CDMA2000, for example, and the time during which transmission is continued at the transmission rate is measured (S404). ). Specifically, when it is detected that an information code is transmitted at 153.6 kbps, the time measurement is started from the time of detection, and whether or not the continuing time has reached a predetermined time. Is determined (S406), and when the predetermined time is reached, it is determined whether or not the amount of interference exceeds a predetermined threshold (S408). If the amount of interference exceeds a predetermined threshold, a low rate transmission instruction is transmitted to the mobile station apparatus 1 (S410). When a low rate transmission instruction is transmitted or when the amount of interference does not exceed a predetermined threshold, it is determined that the mobile station apparatus 1 transmits an information code at the maximum transmission rate again. The time during which transmission is continued may be measured (c), or a new Ta may be transmitted again (b), or the process is performed until the mobile station apparatus 1 is powered on again. It is good also as not performing (a).

  FIG. 13 shows processing in the mobile station apparatus 1 corresponding to the processing in the base station apparatus 2 in FIG. In the process shown in the figure, when power is first turned on, Ta transmitted from the base station apparatus 2 using the downlink dedicated control channel is received (S500). Then, for example, an information code such as a packet is transmitted using an uplink communication channel (S502). For example, in CDMA2000, when transmission is started, transmission is started at the minimum transmission rate of 9.6 kbps, and the reception level of a pilot signal transmitted from the base station apparatus or the base station apparatus is notified. The transmission rate is gradually increased according to the information on the interference amount. Therefore, the transmission rate may reach the maximum transmission rate of 153.6 kbps (S504). Then, as described in the processing in the base station apparatus 2, for example, when transmitting at the maximum transmission rate, a low rate transmission instruction may be received from the base station apparatus 2 (S506). When the low-rate transmission instruction is received, the transmission rate is changed, and the transmission rate is lowered, for example, by one level (S508). Then, a timer is started, and when the timer exceeds Ta, the maximum transmission rate is restored (S510, S512, S514). That is, the original transmission rate is restored. In this way, the mobile station apparatus 1 performs processing for increasing or decreasing the transmission rate in accordance with an instruction from the base station apparatus 2, thereby reducing the situation in which the base station apparatus 2 cannot perform decoding. Note that after the maximum transmission rate is increased in S514, it is possible to wait for the low rate transmission instruction to be transmitted again.

  By changing the transmission rate as described above, the transmission power of the mobile station apparatus 1 can be changed indirectly, so that the situation in which the base station apparatus 2 cannot perform decoding can be reduced. In addition, when transmission is performed for a predetermined time at a transmission rate exceeding a predetermined threshold, the base station apparatus can determine the time for performing low rate transmission, and the base station apparatus can determine the time for performing low rate transmission. The transmission rate can be controlled. Further, by giving a low rate transmission instruction when the amount of interference is high, an effect of reducing the amount of interference can be obtained, and the situation where decoding becomes impossible due to the high amount of interference can be reduced. Furthermore, the throughput of the mobile station device 1 can be improved by returning to the transmission rate before the change after a predetermined time.

  For example, although the rate control unit 42 is present in the mobile station device 1 in the first embodiment, it may be present in the base station device 2. In this case, the transmission rate is transmitted from the base station apparatus 2 to the mobile station apparatus 1 using the downlink dedicated control channel. Further, the repetition period may be calculated in the mobile station apparatus 1 or may be stored in the mobile station apparatus 1 in advance. Further, the interference determination unit 43 can also transmit the interference amount itself to the mobile station apparatus 1. When the interference determination unit 43 transmits the interference amount itself, the rate control unit 42 divides the interference amount into predetermined ranges and obtains a value indicating the range. Moreover, it can be divided not by three stages but by other number of stages, and other transmission rate control processing may be inserted. Moreover, although the said embodiment was a mobile communication system, this invention is applicable to the system of what kind of form, if it is a communication system by a code division multiple access system.

  Moreover, although the mobile communication system has been described as an example in the above embodiment, the present invention can be applied to any communication system as long as the communication apparatuses communicate with each other. Specifically, a wireless or wired LAN (Local Area Network) may be used. Taking the case of a wireless LAN as an example, the present invention can be applied not only to an infrastructure mode in which an access point is provided, but also to an ad hoc mode in which communication devices directly communicate with each other without using an access point.

1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. FIG. 2 is a configuration block diagram of a mobile station apparatus according to an embodiment of the present invention. It is a block diagram of the configuration of a base station apparatus according to an embodiment of the present invention. 1 is a functional block diagram of a mobile communication system according to an embodiment of the present invention. It is a flowchart of the transmission rate control process which concerns on embodiment of this invention. It is explanatory drawing of a response | compatibility with the code | symbol S and transmission rate which concern on embodiment of this invention. It is a flowchart of the transmission rate fluctuation process which concerns on embodiment of this invention. It is explanatory drawing of the common control channel which concerns on embodiment of this invention. It is explanatory drawing which shows the relationship between the transmission rate and time which concern on embodiment of this invention. 1 is a functional block diagram of a mobile communication system according to an embodiment of the present invention. 1 is a functional block diagram of a mobile communication system according to an embodiment of the present invention. It is a flowchart of the process which concerns on embodiment of this invention. It is a flowchart of the process which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Mobile station apparatus, 2 Base station apparatus, 3 Communication network, 4 Mobile communication system, 11, 21 Control part, 12 Communication part, 13, 24, 84 Storage part, 14 Operation part, 15 Display part, 22 Network interface part , 23 Wireless communication unit, 41 Repeat period acquisition unit, 42 Rate control unit, 43, 64 Interference determination unit, 44, 74 Data transmission unit, 45, 62 Data reception unit, 50 Common control channel, 60 Transmission rate determination unit, 66 Instructing unit, 68 Low rate time determining unit, 70 Low rate time obtaining unit, 72 Transmission rate changing unit, 80 receiving unit, 82 changing unit, 86 timing unit.

Claims (5)

In a mobile communication system using a code division multiple access system, including a base station device and a mobile station device,
The base station device
An interference amount acquisition unit for acquiring an interference amount of radio waves transmitted from the mobile station device;
A period transmitter that transmits a period during which the mobile station apparatus performs transmission at a low transmission rate lower than a normal transmission rate; and
The mobile station device
When the amount of interference is within a predetermined range, transmission is performed at the low transmission rate during the period transmitted by the period transmission unit, and transmission at the normal transmission rate is performed when the period has elapsed. And a rate control unit configured to perform the setting . The mobile communication system according to claim 1, wherein
The period transmitter further transmits a cycle,
The rate control unit repeats transmission at a low transmission rate and transmission at a normal transmission rate in the period transmitted by the period transmission unit .
A mobile communication system. The mobile communication system according to claim 1 or 2,
The base station device
Means for transmitting to the mobile station apparatus an instruction to increase or decrease the transmission power of the mobile station apparatus in accordance with a reception error rate of a signal transmitted from the mobile station apparatus;
Including
The mobile station device
Means for transmitting a signal with power according to an instruction transmitted from the base station apparatus;
Further including
A mobile communication system. A mobile station apparatus used in a mobile communication system using a code division multiple access system,
It has a rate control unit that sets the transmission rate,
The rate control unit receives interference amount information that is information based on an interference amount of a transmitted radio wave in a base station apparatus, and period information indicating a period in which transmission is performed at a lower transmission rate lower than a normal transmission rate, and the interference When the amount information indicates that the interference amount is within a predetermined range, the transmission is performed at the low transmission rate during the period indicated by the period information. Set to transmit at the transmission rate of
A mobile station apparatus. A transmission rate control method for a mobile station apparatus used in a mobile communication system using a code division multiple access system,
Obtaining interference amount information, which is information based on the amount of interference in the transmitted radio base station device;
Obtaining period information indicating a period during which transmission is performed at a low transmission rate lower than a normal transmission rate;
When the interference amount information indicates that the interference amount is in a predetermined range, performing transmission at the low transmission rate during the period indicated by the period information;
Performing transmission at the normal transmission rate when the period has elapsed;
Including a transmission rate control method.

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