CN1364391A - Multiplexing of real time users and non-priority users EGPRS channels - Google Patents

Abstract

In real-time communication, once a quiet period is detected, real-time services (such as voice communication) are multiplexed with non-priority services (such as SMS and/or email). When real-time communication resumes after the quiet period, non-priority services are discontinued.

Description

Multiplexing of real-time users and non-priority users on EGPRS channels

Background of the invention

The present invention relates to radio communication systems, and more particularly, to techniques and structures for effectively utilizing silent time in voice communication.

The development of commercial communication systems, especially the explosive growth of cellular radiotelephone systems worldwide, has forced system designers to find ways to increase system capacity and flexibility without degrading communication quality to unacceptable levels for users . Mobile calls can be routed using, for example, circuit switching, packet switching, or some combination thereof. There is an increasing need to connect and integrate mobile cellular telephone networks, such as the Global Network for Mobile Communications, with Internet Protocol (IP) networks to route calls. Routing voice calls over an Internet Protocol network is often referred to as "Voice over IP," or more succinctly VoIP.

Packet switching technology can be connection-oriented (such as X.25), or it can be "connectionless" like IP. It does not need to establish and withdraw physical connections, which is completely different from circuit switching technology. This reduces data latency and improves the channel's efficiency in processing relatively short, bursty, or interactive transactions. A connectionless packet-switched network distributes the routing function over multiple routing points, thereby avoiding the communication bottlenecks that would occur when using a central switching hub. Data is "packaged" with appropriate end-system addressing techniques and then sent in individual units over the data path. Intermediate systems between communicating end systems, sometimes called "routers," determine the most appropriate route for each data packet. Routing selection is based on a number of characteristics, including: least-cost routing or selection according to cost; link capacity; the number of packets waiting to be transmitted; link security requirements and the working status of intermediate systems (nodes).

Figure 1 depicts a representative architecture for communication over the air link, using packet data protocols, between mobile end systems (e.g., mobile stations), mobile data base stations (MDBS), and mobile data intermediate systems (MD-IS ) to provide connections. The following describes the elements in Figure 1 and the path to each element when considering alternative RF technologies.

Internet Protocol/Connectionless Network Protocol (IP/CLNP) is a connectionless network protocol widely supported throughout traditional data networks. These protocols have nothing to do with the physical layer, and it is best not to change when the radio frequency technology changes.

Security Management Protocol (SMP) provides security services in the air link interface. Services provided include data link security, M-ES authentication, key management, access control and algorithm updatable/replacement. The SMP should remain the same when using different RF technologies.

Radio Resource Management Protocol (RRMP) manages and controls the use of radio frequency resources by mobile units. Radio resource management protocols and related procedures are specific to the AMPS RF infrastructure and are subject to change depending on the radio frequency technology employed.

The Mobile Network Registration Protocol (MNRP) is used together with the Mobile Network Location Protocol (MNLP) to enable registration and authentication of mobile end systems. The mobile network registration protocol should not change when different radio frequency technologies are used.

The mobile data link protocol provides efficient data transmission between MD-IS and M-ES. MDLP supports mobile system mobility, mobile system power saving, radio frequency channel resource sharing and error recovery. The MDLP should not change when different RF technologies are used.

The medium access control (MAC) protocol and related procedures control the management of the radio frequency channel shared access M-ES method. This protocol and its functions are provided by different radio frequency technologies.

When a new service or application is introduced into a packet data system, such as a real-time (RT) service such as VoIP, there will be a large number of Quality of Service (QoS) requirements on the network. Certain users, such as those using real-time voice applications, will have very high requirements for the availability of transmission resources, while users sending short messages or e-mails will be satisfied with lower availability of transmission resources.

For example, in the well-known Universal Mobile Telecommunications System (UMTS), there are four types of quality of service: dialog type; stream type; interactive type and background type. The main difference between these classes is the sensitivity to communication delays. The traditional class of communication is the communication that is very sensitive to delay, while the background class of communication is the communication class that is least sensitive to delay. Dialogue class and stream class are used to transfer real-time communication data flow, interactive class and background class are used to transfer Internet application information (such as WWW, email, remote login, FTP, etc.).

Real-time services include time constraints on reserved access channels. That is, delays in the transmission and/or reception of successive data packets can have an undesirably significant impact on quality of service (eg, voice quality). For quality-critical communications, these time constraints can be resolved by always reserving access time at predetermined intervals. In this way, real-time communication can take place without interruption, since it is allocated communication resources whether or not there are data packets to be sent. That is to say, in real-time voice communication, there may be silent time, for example, and in order to save battery resources, no signal needs to be sent during the silent time.

Silent periods can be detected with a Voice Activity Detector (VAD). During the silent time, a silence descriptor (SID) is sent to the receiver. This silence descriptor tells the receiver that the silence period has started. Additionally, the silence descriptor specifies the type of "comfort noise" to be generated at the receiver. The receiver generates comfort noise in order to mimic well the naturally occurring background noise so that the user on the receiver side understands that the channel between the transmitter and receiver is still functioning. In addition to the silence descriptor, the transmitter can be told that no voice activity has been detected, and the transmitter can reduce its transmitter output power, or set it to zero. This technology is called Discontinuous Transmission Technology (DTX). Interference in the system is reduced when discontinuous transmission is used because the transmitter only transmits output power when there is information to send (such as when voice activity is detected).

However, since resources are allocated to real-time traffic users regardless of whether packets are sent from the transmitter, it would be desirable if these dead times could be utilized in a more efficient manner by allowing other applications to use the allocated resources during the dead time. resources without degrading the service quality of real-time business.

Brief description of the invention

The present invention separates real-time traffic (such as voice communications) from non-priority or time-insensitive traffic (such as short message and/or email traffic) when a dead time is detected in real-time communications by providing a method and system Multiplexing is performed to overcome the above-mentioned shortcomings in the prior art. Furthermore, the solution in the present invention exits these other services when the real-time communication starts again after the quiet time.

In one aspect, the invention provides a method of allocating communication resources. The method includes the steps of dedicating communication resources to real-time applications; monitoring resource usage by real-time applications; allocating resources to non-priority applications when resources are not used by real-time applications.

In another aspect, the present invention provides a system for allocating communication resources. The system includes a device capable of monitoring the activity status of the first application and transmitting a status signal, and a switch coupled to the transmitter in response to the status signal. If the status signal indicates that the first application is active, the switch connects the first application to the transmitter, and if the status signal indicates that the first application is not active, the switch connects the second application to the transmitter stand up.

In yet another aspect, the present invention provides a system for allocating communication resources. This system includes a first module that dedicates communication resources to real-time communication; a second module that monitors resource usage by real-time applications; and a third module that dedicates resources when real-time applications are not using resources. Resources are allocated for use by non-priority applications.

Brief description of the drawings

The above-mentioned features of the present invention will be more apparent by describing in detail preferred embodiments of the present invention while referring to the accompanying drawings. In these drawings:

Figure 1 illustrates a protocol architecture for communication over the air link;

Figure 2 illustrates an exemplary embodiment of the invention;

FIG. 3A is a flowchart illustrating an exemplary technique for the downlink of the present invention;

FIG. 3B is a flowchart illustrating an exemplary technique for the uplink of the present invention; and

Figure 4 illustrates the allocation of blocks in an exemplary embodiment of the invention.

Detailed description of the invention

In the following description, for purposes of illustration and not limitation, specific details are given, such as particular circuit boards, circuit elements, techniques, etc., in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, and circuits are omitted so as not to obscure the topic.

The exemplary radio communication system discussed herein employs a Time Division Multiple Access (TDMA) protocol in which communications between base stations and mobile terminals occur in multiple time slots. However, those skilled in the art will appreciate that the concepts disclosed herein can also be applied to other protocols, including but not limited to Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Time Division Duplex (TDD), or any of the above protocols. some combination.

Figure 2 illustrates an exemplary embodiment of the present invention. The communication system includes a base station 202 and a plurality of communication devices 204,206. The communication device 206 includes a transceiver 211, a speech codec 213, and a module 207 for performing VAD, SID and DTX functions. The communication device 204 includes a transceiver 205 and a non-priority (NP) application 215 (eg short message service or e-mail service). Thus, in this example, device 206 is a RT device and device 204 is an NP device.

The base station 202 includes a transceiver 214 connected to a multiplexing device 212 . Multiplexing means 212 selectively couples speech codec 208 or other real-time (RT) applications and non-priority applications 210 to transceiver 214 . Although only one non-priority application is shown in FIG. 2, a plurality of non-priority applications may be provided, selectively connected to the multiplexing device 212, and selectively accessing transmission or reception resources in the base station.

As shown, speech codec 208 includes a module 209 that implements VAD, SID and DTX functions. In the normal case (ie, uplink or downlink), the multiplexing means 212 couples the speech codec to the transceiver 214 when the voice activity detector detects a speech signal. However, the multiplexing device 212 connects the non-priority application 210 with the transceiver 214 when the voice activity detector detects a period of silence.

In this way, the multiplexing means 212 enables non-priority applications to access transmission resources (eg, blocks) used by real-time (RT) applications. Since at least some resources are occupied by real-time applications when they are working, the present invention can increase the total capacity of the system by non-priority applications "stealing" the occupied real-time resources when there is no active voice.

The scheduling of different applications in the downlink is done at the radio link control (RLC) or MAC layer of the network. FIG. 3A is a flowchart illustrating an exemplary downlink scheduling technique of the present invention. During the silent time, since the silent speech block is not sent to the real-time device 206, when the allocated transmission resources are used by non-priority applications, comfort noise may be generated by the real-time device 206 . In addition, during the silent time, the uplink block including the silence descriptor can also be transmitted periodically (for example, every 480 milliseconds), so that the parameters for generating the comfort noise can be updated.

A voice activity detector in the speech codec 208 examines each block of real-time speech generated by the real-time application. If in step 320 the voice activity detector detects speech in the speech block, then in step 322 the downlink block is scheduled for real-time applications and the multiplexing means 212 connects the speech codec 208 to the transceiver. If the voice activity detector detects a block of silent speech, the first downlink block including the silence descriptor is transmitted to the real-time device 206 . In step 323, the silence descriptor is used to generate (or update) parameters for generating comfort noise. In step 324 , the next downlink block is scheduled for the non-priority application, and the multiplexing means 212 connects the non-priority application 210 with the transceiver 214 .

While the communication device transmits real-time uplink blocks including speech information to base station 202, the communication system arranges for real-time device 206 to continuously transmit its uplink blocks. When the real-time device 206 detects a dead time, the real-time device sends a first uplink block including a silence descriptor, telling the communication system that the real-time device 206 is entering a dead time. During the quiet time, further uplink blocks including the silence descriptor may be transmitted periodically (eg, every 480 ms), enabling updating of the parameters used to generate the comfort noise. However, during the quiet time, uplink resources can be allocated for non-priority applications (such as non-priority device 204), and real-time applications of real-time devices 206 will still be allocated resources periodically, so that the communication system can determine when real-time The application wishes to resume sending uplink blocks. By having non-priority applications on non-priority devices 204 use uplink resources allocated to real-time applications on real-time devices 206 during inactive periods, real-time applications may lose data or fail to regain uplink resources at the end of the inactive period. There is a delay when linking resources. To guarantee quality of service, the frequency at which uplink blocks are allocated to non-priority applications should be set in such a way that a trade-off (loss and/or or delay).

One example of the above technique will be described below with reference to FIG. 3B. In the uplink, the communication system receives an uplink block from the real-time device 206 . In step 332, the communication system determines whether the uplink block from the communication device 206 includes a silence descriptor. If speech is detected instead of the silence descriptor, then in step 336 the next downlink block is scheduled for the real-time user. But if a descriptor is detected, the next three uplink blocks are arranged in step 334 in the following manner: (1) the first uplink block is arranged for non-priority applications; (2) the second is arranged for real-time applications two uplink blocks; and (3) arrange a third uplink block for non-priority users. By alternating non-priority and real-time uplink blocks, real-time applications can be quickly resumed when there are speech blocks to transmit. Those skilled in the art will recognize that the particular alternation pattern may vary depending on the quality of service requirements placed on the system. For example, for a cycle with N blocks, arrange one block for real-time applications and N-1 blocks for non-priority. If the uplink real-time blocks are scheduled with a small interval (for example, within 2 blocks or within 20 milliseconds), real-time applications will not lose speech information significantly. But other real-time applications may be more tolerant of the loss of data blocks before resuming communication, which allows a larger interval (eg, 3 blocks or more) between scheduled uplink real-time blocks.

During an uplink real-time block scheduled in step 338, the communication system checks whether an uplink real-time block has already been sent. If an uplink real-time block has been sent, the communication system checks whether this block contains speech or a silence descriptor. If it includes speech signals, then in step 336 the next uplink block is scheduled for real-time applications. If in step 340 the uplink real-time block includes a silence descriptor, the comfort noise parameters are updated in the communication system, and the following three uplink blocks are scheduled according to step 334 . If no uplink real-time blocks are sent to the communication system, the next three uplink blocks are scheduled according to step 334 .

Figure 4 illustrates how blocks are allocated in the exemplary embodiment of the invention shown in Figure 3B. A downlink frame from a communication system, an uplink frame from a communication device using a real-time application, and an uplink frame from a communication device using a non-priority application are shown. Each block in the downlink frame includes an uplink state flag field (USF) 352 , 360 and a temporary flow identifier field (TFI) 354 . The uplink status flag field tells the communication device to allocate the next uplink block. For example, if a downlink block 350 includes an uplink status flag (see USF 352) with a real-time value, the communication device running the real-time application is notified that it is scheduled to send a real-time block in the next uplink block 362. But if the value of the uplink status flag is non-priority (see downlink block 358, uplink status flag 360), the communication device using the non-priority application is notified that it has been scheduled to transmit in the next uplink block A non-priority block 374. The temporary stream identifier 354 is used to indicate that the payload 356 (eg, voice data) of the downlink block 350, 358 needs to be received. The uplink block also includes a temporary flow identifier field, which specifies the identity of the sender (eg, temporary flow identifier 364 for real-time applications and temporary flow identifier 376 for non-priority applications).

The uplink real-time block includes a silence descriptor 368 indicating the start of the silence period. Blocks 372 and 380 represent blocks that are not used by the real-time communication device during the quiet time. The communication system is informed by the receive block 382 during the scheduled time slot that the real-time communication device is back in real-time communication. Normal real-time communication is resumed with an uplink real-time block 384 after the last uplink non-priority block 375 scheduled.

In another embodiment of the present invention, if it is desired to resume real-time communication during a scheduled non-priority application, the unsent chunks can be stored in the communication device and transmitted in a later scheduled chunk. This technique introduces a delay proportional to the number of unsent blocks stored in the communication device.

The foregoing has described the principles, preferred embodiment and mode of operation of the invention. However, the invention is not limited to the specific embodiments discussed above. Although the above embodiments have been described with respect to time division multiple access technology, those skilled in the art will appreciate that the present invention can be used with any number of different protocols, such as code division multiple access, time division multiple access, time division duplex, etc. . Accordingly, the above-described embodiments should be considered as illustrative rather than restrictive, and it should be recognized that modifications may be made to the above-described embodiments by persons skilled in the art without departing from the present invention as set forth in the following claims. the scope of the invention.

Claims (32)

1. A method for allocating communication resources, comprising the steps of: Dedicate communication resources to real-time applications; monitoring resource usage by the real-time application; and When the resource is not used by the real-time application, the resource is allocated to a non-priority application for use. 2. The method of claim 1, wherein the monitoring step includes checking the first block for real-time applications, and wherein the assigning step includes specifying the presence of dead time. 3. The method of claim 2, wherein the method further comprises the steps of: send a block for a non-priority application if the checking step does not detect a real-time application; and Said first block is sent if the checking step finds a real-time application. 4. The method of claim 1, wherein the real-time application is a speech application. 5. The method of claim 1, wherein the non-priority application is a Short Message Service application. 6. The method of claim 1, wherein the non-priority application is an email application. 7. The method of claim 2, wherein the step of indicating that a period of silence exists comprises the step of sending a silence descriptor. 8. The method of claim 1, wherein the monitoring step further comprises receiving an activity status signal of said real-time application. 9. The method of claim 8, wherein the signal is sent from the codec and indicates the presence of a dead time. 10. The method of claim 8, wherein the signal includes a silence descriptor. 11. The method of claim 1, wherein the allocating step allocates resources for a predetermined number of blocks. 12. The method of claim 11, wherein the predetermined number of blocks is less than or equal to the number of blocks representing the loss that the real-time application can tolerate. 13. A system for allocating communication resources, comprising: means for monitoring the first application activity status and sending a status signal; and a switch connected to the transmitter responsive to said status signal, a switch connecting the first application to the transmitter if the status signal indicates that the first application is active, and A switch therein connects a second application to the transmitter if the status signal indicates that the first application is not active. 14. The system of claim 13, wherein the means is a codec, wherein the status signal indicates the presence of dead time. 15. The system of claim 13, wherein the signal includes a silence descriptor. 16. The system of claim 13, wherein the first application is a real-time application. 17. The system of claim 13, wherein the second application is a non-priority application. 18. The system of claim 16, wherein the first application is a speech application. 19. The system of claim 16, wherein the second application is a short message service application. 20. The system of claim 17, wherein the second application is an email application. 21. A system for allocating communication resources, comprising: The first module that dedicates communication resources to real-time applications; a second module that monitors whether the real-time application uses the resource; and When the resource is not used by the real-time application, the resource is allocated to the third module used by the non-priority application. 22. The system of claim 21, wherein the second module includes a fourth module for checking the first block for real-time applications, and wherein the third module includes a module for indicating whether dead time exists. 23. The system of claim 22, further comprising: If the fourth module does not detect the presence of a real-time application, send a block of the fifth module for non-priority applications; and If the fourth module determines that the real-time application exists, the sixth module of the first block is sent. 24. The system of claim 21, wherein the real-time application is a speech application. 25. The system of claim 21, wherein the non-priority application is a Short Message Service application. 26. The system of claim 21, wherein the non-priority application is an email application. 27. The system of claim 22, wherein the means for indicating the presence or absence of periods of silence comprises means for transmitting a silence descriptor. 28. The system of claim 21, wherein the second module further comprises a module for receiving signals indicative of real-time application activity status. 29. The system of claim 28, wherein the means for receiving a signal receives said signal from a codec indicating the presence of a dead time. 30. The system of claim 28, wherein the signal includes a silence descriptor. 31. The system of claim 21, wherein the third module allocates said resources for a predetermined number of blocks. 32. The system of claim 31, wherein the predetermined number of blocks is less than or equal to a number representing a number of block losses that the real-time application can tolerate.

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