JP5033364B2 - Wireless terminal apparatus and channel control method - Google Patents

Description

  The present invention relates to a radio terminal device and a channel control method, and more particularly, to a radio terminal device capable of executing MAC channel aggregation that improves throughput by using a plurality of MAC channels collectively, and to be used in the radio terminal device. The present invention relates to a channel control method.

  Conventionally, so-called MAC channel aggregation is known in which throughput is improved by using a plurality of MAC channels, which are communication channels set in a medium access control (MAC) layer, together (see Patent Document 1).

For example, in a wireless communication system compliant with the iBurst (registered trademark) standard, MAC channel aggregation may be performed by using one to three MAC channels together between a wireless base station and a wireless terminal device. it can.
Japanese Patent Laying-Open No. 2005-252897 (page 7, FIG. 2)

  By the way, in recent years, even in the wireless communication system as described above, it is becoming common to relay audio data in which an audio band signal is encoded or video streaming data using RTP, UDP, IP, or the like. .

  In this case, a VoIP packet in which voice data is packetized and an RTP packet including streaming data have a size larger than an IP packet including data transmitted and received by other general applications (for example, file transfer and e-mail). small. For example, a VoIP packet is approximately 60 bytes (uncompressed).

  For this reason, for example, when a throughput of 10 Mbps is secured by MAC channel aggregation, approximately 170,000 packets per second are transmitted via a link layer channel (logical channel) set by using a plurality of MAC channels that are grouped together. Can communicate. However, the wireless terminal device has to process a large amount of small VoIP packets, which may exceed the packet processing capability, specifically, the processing capability of the installed CPU.

  When receiving the IP packet, the wireless terminal device has to execute type interpretation and reconfiguration for each IP packet. Of course, this problem can be solved by increasing the packet processing capability of the wireless terminal device. However, if the packet processing capacity is increased, there is a problem that the cost of the wireless terminal device increases.

  Therefore, the present invention has been made in view of such a situation, and even when processing a large amount of small packets such as VoIP packets while suppressing necessary packet processing capability, the present invention is more reliably performed. An object of the present invention is to provide a wireless terminal device and a channel control method capable of processing a packet.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is that a logical channel setting unit for setting a logical channel using a plurality of MAC channels, which are communication channels at a MAC layer level with a radio base station, is received and received via the logical channel. And a MAC channel control unit that controls the number of the MAC channels used for the logical channel based on the operation status of the processing unit .

According to such a wireless terminal device, the number of MAC channels used for the logical channel is controlled, for example, the number of MAC channels is reduced, according to the operating status of the processing unit . For this reason, when the wireless terminal device processes a large amount of small-sized packets (for example, VoIP packets), there is a margin for the upper limit of the throughput of the logical channel, but due to the limitation of the packet processing capability of the wireless terminal device. Thus, it is possible to avoid that processing such as interpretation and reconfiguration of the packet type cannot be executed.

  That is, according to such a wireless terminal device, when MAC channel aggregation is used, it is more reliable even when processing a large amount of small packets such as VoIP packets while suppressing necessary packet processing capability. The packet can be processed.

A second feature of the present invention relates to the first feature of the present invention, wherein the MAC channel control unit reduces the number of the MAC channels when the free time of the processing unit falls below a predetermined threshold. The gist.

According to a third aspect of the present invention, a step of setting a logical channel using a plurality of MAC channels, which are MAC layer level communication channels in a wireless communication section, and a packet relayed via the logical channel are processed. And a step of controlling the number of MAC channels used for the logical channel based on the operating status of the processing device for the purpose .

A fourth feature of the present invention relates to the third feature of the present invention, wherein, in the step of reducing the number of MAC channels, if the free time of the processing device falls below a predetermined threshold, the number of MAC channels is set. The gist is to reduce.

  According to the feature of the present invention, when MAC channel aggregation is used, even when a large amount of small-sized packets such as VoIP packets are processed while the required packet processing capacity is suppressed, the packet is more reliably processed. A wireless terminal device and a channel control method that can be processed can be provided.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Overall schematic configuration of communication system)
FIG. 1 is an overall schematic configuration diagram of a communication system according to the present embodiment. As illustrated in FIG. 1, the communication system according to the present embodiment includes a radio base station 100 and a radio terminal device 200.

The radio base station 100 and the radio terminal device 200 execute radio communication conforming to the iBurst (registered trademark) standard using TDMA and SDMA / TDD communication schemes. Specifically, the radio base station 100 and the radio terminal apparatus 200 relays telephone terminal 50A~50H belonging to the group _{G A,} and the VoIP packets P transmitted and received between the telephone terminal 60A~60H belonging to the group _{G B} . In the present embodiment, the modulation class (modulation scheme) can be changed (for example, from 8 PSK to QPSK) according to the state of radio communication performed between the radio base station 100 and the radio terminal device 200. Modulation is used.

The radio base station 100 is connected to the Internet 10. VoIP packets P transmitted and received between the groups _{G A} and group _{G B} is via the Internet 10. The radio base station 100 is connected to the PDSN 20. The PDSN 20 executes control of the communication path of the VoIP packet P and the like.

  Further, a SIP server 40 is connected to the Internet 10. The SIP server 40 executes call connection processing according to SIP (session initiation protocol).

  On the other hand, the wireless terminal device 200 is connected to the IP-PBX 30. Similar to the SIP server 40, the IP-PBX 30 also performs call connection processing according to SIP.

(Configuration example of protocol stack and logical channel of communication system)
FIG. 2 shows the protocol stack of the communication system described above. FIG. 3 shows a configuration example of a link layer channel (logical channel) set in the communication system described above.

As shown in FIG. 2, a VoIP packet P (see FIG. 1) using RTP, UDP, and IP is transmitted and received between the telephone terminal 50A and the telephone terminal 60A. Specifically, in the telephone terminal 50A and the telephone terminal 60A, ITU-TG. An audio codec conforming to 729A (8 kbps) is used. When the output (payload) of the two voice codecs is assigned to one using RTP / UDP / IP, the link layer channel C11 relays a VoIP packet P of about 60 bytes every 20 msec. That is, the telephone terminal 50A~50H belonging to the group _{G A} is, when telephone terminal 60A~60H voice data transmitting and receiving at the same time belonging to the group _{G B,} per 400 VoIP packets P are relayed by the link layer channel C11.

  A link layer channel C11 (see FIG. 3) is set between the telephone terminal 50A and the wireless terminal device 200 using PPP (point-to-point protocol) and PPPoE (ppp over Ethernet (registered trademark)).

  The link layer channel C11 is also set between the wireless terminal device 200 and the wireless base station 100 using PPP. In addition, between the wireless terminal device 200 and the wireless base station 100, so-called MAC channel aggregation in which the MAC channels C21 to C23 are collectively used can be executed by control in the link access control (LAC) layer. The MAC channels C21 to C23 are MAC layer level communication channels set between the radio base station 100 and the radio terminal device 200 (radio communication section).

  A link layer channel C11 is set between the radio base station 100 and the PDSN 20 using PPP (point-to-point protocol) and GRE (generic routing encapsulation). Further, a link layer channel C11 is set between the PDSN 20 and the telephone terminal 60A using a predetermined link layer protocol corresponding to the type of communication line connecting the PDSN 20 and the telephone terminal 60A (SIP server 40).

  In the present embodiment, the link layer channel set in each section described above is appropriately displayed as a link layer channel C11.

(Function block configuration)
Next, in this embodiment, a functional block configuration of the wireless terminal device 200 that controls the number of MAC channels used for the link layer channel C11 described above will be described. FIG. 4 is a functional block configuration diagram of the wireless terminal device 200.

  As illustrated in FIG. 4, the wireless terminal device 200 includes a wireless communication unit 201, a link layer channel processing unit 203, a MAC channel control unit 205, a PPP packet counter 207, and a wired LAN interface unit 209.

  The wireless communication unit 201 transmits and receives wireless signals compliant with the iBurst (registered trademark) standard. Specifically, the wireless communication unit 201 is connected to the link layer channel processing unit 203, and a baseband signal including the VoIP packet P output from the link layer channel processing unit 203 is converted into a predetermined modulation scheme (for example, 8PSK). Radio communication section 201 demodulates the received radio signal into a baseband signal and outputs the demodulated baseband signal to link layer channel processing section 203.

  The link layer channel processing unit 203 sets a link layer channel. In the present embodiment, the link layer channel processing unit 203 sets the link layer channel C11 (see FIG. 3).

  The link layer channel processing unit 203 responds to the received communication request, for example, the communication request received from the IP-PBX 30 (or the telephone terminal 50A) via the wired LAN interface unit 209, and the MAC channel (MAC channels C21 to C23). Sets a link layer channel C11 (logical channel) that is used collectively. In this embodiment, the link layer channel processing unit 203 constitutes a logical channel setting unit.

  Specifically, when the link layer channel processing unit 203 receives a communication request, for example, the link layer channel processing unit 203 sets the link layer channel C11 using three MAC channels (MAC channels C21 to C23) collectively (see FIG. 3). ).

  Here, FIG. 6 shows the data rate of the MAC channel in the present embodiment. As shown in FIG. 6, in this embodiment, a data rate (throughput) of 340 kbps can be realized for each MAC channel. That is, when three MAC channels (MAC channels C21 to C23) are used together, a total data rate of 1,020 kbps can be realized according to the link layer channel C11.

  Further, the link layer channel processing unit 203 relays via the link layer channel C11, interprets the type of packet (not shown) at the MAC layer (corresponding to the OSI second layer) level including the VoIP packet P, and the like, and the MAC layer Reconstruction into a packet at a higher layer (e.g., equivalent to OSI layer 3) is executed.

  When setting the link layer channel C11, the link layer channel processing unit 203 requests the MAC channel control unit 205 to set the MAC channel (MAC channels C21 to C23).

  The MAC channel control unit 205 sets the MAC channels C21 to C23 based on a request from the link layer channel processing unit 203. The MAC channel control unit 205 controls the MAC channel used for the link layer channel C11 set by the link layer channel processing unit 203.

  Specifically, the MAC channel control unit 205 is used for the link layer channel C11 according to the packet processing capability of the wireless terminal device 200 including interpretation and reconfiguration of the type of IP packet received via the link layer channel C11. The number of MAC channels being controlled can be controlled, specifically, the number of MAC channels can be reduced.

  More specifically, the MAC channel control unit 205 determines that the number of IP packets (for example, VoIP packet P) received within a predetermined unit time (for example, 1 second) exceeds a predetermined threshold (for example, 300 packets). The number of MAC channels is reduced.

  Here, FIG. 7 shows an example of the threshold. As shown in FIG. 7, in this embodiment, when the number of IP packets (number of received packets d) received via the link layer channel C11 within a unit time (1 second) exceeds 300 packets, one MAC A channel (eg, MAC channel C23) is released. When the number of received packets d exceeds 400 packets, two MAC channels (for example, MAC channels C22 and C23) are released.

  In the present embodiment, the wireless terminal device 200 includes a CPU 200a (see FIG. 1) that executes processing of the VoIP packet P received via the link layer channel C11.

  In the present embodiment, when MAC channel aggregation using three MAC channels is executed due to the limit of hardware performance including the CPU 200a, the wireless terminal device 200 uses 300 IP packets such as the VoIP packet P per second. Can only handle. That is, when the data rate of the link layer channel C11 is 1,020 kbps, about 1,900 VoIP packets P per second can be relayed by the link layer channel C11 in consideration of the overhead due to the LAC and the MAC layer.

  However, since the wireless terminal device 200 can process only 300 IP packets per second, it is necessary to limit the data rate of the link layer channel C11, specifically, the number of MAC channels.

  Note that the MAC channel control unit 205 can also determine whether to reduce the number of MAC channels based on the operating status of the CPU 200a. Specifically, the MAC channel control unit 205 can reduce the number of MAC channels when the percentage of free time of the CPU 200a within a unit time is less than a predetermined threshold (for example, 20%). Note that the MAC channel control unit 205 may reduce the number of MAC channels when the remaining time of the CPU 200a is not the ratio of the idle time of the CPU 200a, for example, when the operating rate of the CPU 200a exceeds a predetermined threshold.

  The PPP packet counter 207 monitors the number of IP packets (specifically, IP packets included in the PPP frame) received via the link layer channel C11. In the present embodiment, the PPP packet counter 207 constitutes a packet number monitoring unit. The PPP packet counter 207 counts the number of IP packets received via the link layer channel C11, and sends information indicating the counted number of IP packets via the link layer channel processing unit 203 for each unit time (1 second). To the MAC channel control unit 205.

  The wired LAN interface unit 209 provides an interface compliant with a predetermined wired LAN system (for example, Ethernet (registered trademark)). In the present embodiment, the wireless terminal device 200 performs communication with the IP-PBX 30 and the telephone terminals 50A to 50H via the wired LAN interface unit 209.

(Operation of wireless terminal device)
Next, the operation of the wireless terminal device 200 will be described. Specifically, an operation in which the wireless terminal device 200 reduces the number of MAC channels used as the link layer channel C11 will be described.

  As shown in FIG. 5, in step S10, the wireless terminal device 200 receives the number of IP packets (specifically, IP packets included in the PPP frame) received via the link layer channel C11 (number of received packets d). Count. Specifically, the wireless terminal device 200 counts the number of IP packets received per unit time (1 second).

  In step S20, the wireless terminal device 200 determines whether or not the counted number of IP packets (the number of received packets d) exceeds a predetermined threshold (see FIG. 7).

  If the counted number of IP packets exceeds a predetermined threshold (YES in step S20), in step S30, the wireless terminal device 200 reduces the number of MAC channels used as the link layer channel C11. Here, it is assumed that the MAC channels C21 to C23 are used as the link layer channel C11.

  For example, when the number of IP packets counted (the number of received packets d) exceeds 300 and is 400 or less (see FIG. 7), one MAC channel used as the link layer channel C11 (for example, the MAC channel C23) Opened.

  If the counted number of IP packets does not exceed the predetermined threshold (NO in step S20), the wireless terminal device 200 repeats the processing from step S10.

(Action / Effect)
According to the wireless terminal device 200, the number of MAC channels used for the link layer channel C11 is reduced according to the packet processing capability of the wireless terminal device 200 (CPU 200a). For this reason, when the wireless terminal device 200 processes a large amount of a small-sized VoIP packet P of about 60 bytes, there is room for the upper limit (for example, 1,020 kbps) of the throughput of the link layer channel C11. It can be avoided that the processing of interpreting and reconfiguring the type of the IP packet cannot be executed due to the limit of the packet processing capability of the CPU 200a.

  That is, according to the wireless terminal device 200, when MAC channel aggregation is used, it is more reliable even when processing a large amount of small IP packets such as the VoIP packet P while suppressing necessary packet processing capability. The IP packet can be processed.

  When a general wireless terminal device receives an IP packet that exceeds the packet processing capability, the wireless terminal device takes measures by discarding the IP packet. However, when a large amount of small-sized IP packets are received, the MAC terminal level packet in the wireless section is reconfigured into an IP packet and the processing load increases until it can be discarded in units of IP packets. In some cases, packet processing capacity was exceeded. According to the wireless terminal device 200, the data rate (throughput) of the link layer channel C11 is reduced by reducing the number of MAC channels, and the number of received IP packets is suppressed. For this reason, occurrence of such a problem can be avoided.

  In the present embodiment, the wireless terminal device 200 reduces the processing load by reducing the number of MAC channels to suppress the throughput. Therefore, as shown in FIG. 7, normally, only up to 300 IP packets can be processed per second, but up to 400 IP packets per second can be obtained by reducing the processing load. Can be processed.

(Example of change)
In the wireless terminal device 200 described above, the number of MAC channels used for the link layer channel C11 is reduced according to the packet processing capability of the wireless terminal device 200 (CPU 200a), but instead of the number of MAC channels. The radio communication modulation class (modulation method) executed between the radio base station 100 and the radio terminal device 200 may be changed.

  FIG. 8 is a functional block configuration diagram of a wireless terminal device 200V according to such a modification. In the following, portions different from the above-described wireless terminal device 200 will be mainly described, and description of portions similar to the wireless terminal device 200 will be omitted as appropriate.

  Compared to the wireless terminal device 200, the wireless terminal device 200V includes a modulation class control unit 211 instead of the MAC channel control unit 205.

  Similarly to the wireless terminal device 200, the wireless communication unit 201 can transmit and receive IP packets using adaptive modulation that can change the modulation class according to the state of wireless communication with the wireless base station 100.

  Here, FIG. 9 shows an example of a modulation class used in the wireless terminal device 200V. As shown in FIG. 9, in the radio terminal device 200V, one to four modulation classes can be set.

  The modulation class is defined by a combination of the number of bits (bit / symbol) allocated to one symbol and the modulation scheme, and 408, 612, 816 or 1,020 kbps is set as the data rate. In radio terminal apparatus 200V, QPSK and 8PSK are used as modulation schemes. The modulation method is not limited to PSK, and QAM may be used.

  FIG. 10 shows modulation class selection conditions used for selecting each modulation class shown in FIG. As shown in FIG. 10, the modulation class selection condition is defined by the RSSI of the radio signal received by the radio communication unit 201.

  The wireless communication unit 201 selects a modulation class corresponding to the state of wireless communication, specifically, received RSSI, and modulates a baseband signal including an IP packet or the like by a predetermined modulation method (for example, 8PSK). In addition, the wireless communication unit 201 demodulates the received wireless signal into a baseband signal.

  The modulation class control unit 211 controls the modulation class used in the wireless communication unit 201. Specifically, the modulation class control unit 211 can control the modulation class used in the wireless communication unit 201 based on the packet processing capability of the wireless terminal device 200V.

  In this embodiment, as shown in FIG. 11, when the number of IP packets (received packet number d) received via the link layer channel C11 within a unit time (1 second) exceeds 300 packets, modulation class control is performed. Unit 211 instructs radio communication unit 201 to select modulation class 1. That is, the modulation class control unit 211 can change to a modulation class 1 (low rate modulation method) having a lower data rate than the modulation class (for example, modulation class 4) used in the wireless communication unit 201. In the present modification example, the modulation class control unit 211 constitutes a modulation method change unit.

  If the received packet count d does not exceed 300 packets, the modulation class control unit 211 does not instruct the wireless communication unit 201 at all. For this reason, the radio communication unit 201 selects a modulation class according to the modulation class selection condition shown in FIG.

  Also, the modulation class control unit 211 can change to the low-rate modulation method based on the operating status of the CPU, similarly to the wireless terminal device 200. Specifically, the modulation class control unit 211 can change to modulation class 1 when the CPU idle time falls below a predetermined threshold.

  According to the wireless terminal device 200V, since the data rate is changed to the modulation class 1 based on the packet processing capability of the wireless terminal device 200V, the necessary packet processing capability is increased as in the wireless terminal device 200 described above. Even when a large amount of small-sized IP packets such as the VoIP packet P is processed, the IP packet can be processed more reliably.

(Other embodiments)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the communication system including the wireless base station 100 and the wireless terminal device 200 compliant with iBurst has been described as an example. However, the present invention can be applied to a digital wireless communication method other than iBurst. it can.

  In the above-described embodiment, the number of MAC channels (modulation class) is controlled in the wireless terminal device 200 (and the wireless terminal device 200V). However, the wireless base station 100, that is, the wireless terminal device 200 receives the MAC channel. The number of MAC channels (modulation class) may be controlled on the IP packet transmission side.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a communication system according to an embodiment of the present invention. It is a figure which shows the protocol stack of the apparatus which comprises the communication system which concerns on embodiment of this invention. It is a figure which shows the structural example of the link layer channel (logical channel) set in the communication system which concerns on embodiment of this invention. It is a functional block block diagram of the radio | wireless terminal apparatus which concerns on embodiment of this invention. It is an operation | movement flowchart of the radio | wireless terminal apparatus which concerns on embodiment of this invention. It is a figure which shows the data rate of the MAC channel which concerns on embodiment of this invention. It is a figure which shows an example of the open threshold value of the MAC channel which concerns on embodiment of this invention. It is a functional block block diagram of the radio | wireless terminal apparatus which concerns on the example of a change of this invention. It is a figure which shows an example of the modulation class used in the radio | wireless terminal apparatus which concerns on the example of a change of this invention. It is a figure which shows an example of the modulation class selection conditions used in the radio | wireless terminal apparatus which concerns on the example of a change of this invention. It is a figure which shows an example of the open threshold value of the MAC channel which concerns on the example of a change of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Internet, 20 ... PDSN, 30 ... IP-PBX, 40 ... SIP server, 50A-50H, 60A-60H ... Telephone terminal, 100 ... Wireless base station, 200, 200V ... Wireless terminal device, 200a ... CPU, 201 ... Wireless communication unit, 203 ... Link layer channel processing unit, 205 ... MAC channel control unit, 207 ... PPP packet counter, 211 ... Modulation class control unit, 209 ... Wired LAN interface unit, C11 ... Link layer channel, C21 to C23 ... MAC channel, _{G A, G} B _... group, P ... VoIP packet

Claims (4)

A logical channel setting unit that sets a logical channel using a plurality of MAC channels that are communication channels at a MAC layer level with a radio base station, and
A processing unit for processing a packet received via the logical channel ;
A wireless terminal device comprising: a MAC channel control unit that controls the number of the MAC channels used for the logical channel based on an operation status of the processing unit . The wireless terminal device according to claim 1 , wherein the MAC channel control unit reduces the number of the MAC channels when the free time of the processing unit falls below a predetermined threshold. Setting a logical channel using a plurality of MAC channels that are MAC layer level communication channels in a wireless communication section;
A channel control method comprising: controlling the number of the MAC channels used for the logical channel based on an operating status of a processing device for processing a packet relayed via the logical channel. The channel control method according to claim 3 , wherein, in the step of controlling the number of MAC channels, the number of MAC channels is reduced when an idle time of the processing device falls below a predetermined threshold.

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