RU2364025C2 - Method and device for virtual unidirectional channel - Google Patents

Abstract

FIELD: communication facilities. ^ SUBSTANCE: invention claims mobile communication device and method of mobile communication device operation. It involves storage of at least one frame of data transfer signal received from network, and application of stream management to lower levels for network re-selection maintenance. According to one aspect of invention, a message is sent to notify that operation mode of virtual unidirectional channel is supported by a mobile communication device. Mobile communication device operates selectively in virtual unidirectional channel mode depending on the response obtained by the next transmission of that kind. Additionally, stream management can depend mainly on detection of inevitable cell change. ^ EFFECT: improved transmission of services with packet switch to maintain multiple bandwidth modes and high versatility without significant modification of the systems used. ^ 14 cl, 17 dwg

Description

Technical field

The present invention relates to wireless data exchange, and more particularly to a method and apparatus for improving the quality of wireless communications.

State of the art

The General Packet Radio Service (GPRS) and the development of the GSM standard with an increased data rate (EDGE) for the global mobile communications system (GSM) have provided the opportunity for users to exchange data in mobile wireless products. GPRS and its extended suite, EDGE, allow efficient use of radio and network resources when the data transfer characteristics are: i) packet based, ii) periodic and non-periodic, iii) probably frequent, with small data transfers, for example less than 500 octets, or iv) probably rare, with large data transfers, such as more than a few hundred kilobytes. Custom applications were originally intended to include Internet browsers, email, file transfer, and other applications that are suitable for the “best effort” data transfer.

The original GPRS and EDGE specifications, which first appeared in versions R97 and R99, respectively (hereinafter collectively referred to as R97 / R99), have added the most effortless user packet data service to the previously used GSM voice service. Since GSM did not initially provide notification of a user packet data service, the initial GPRS and EDGE offerings in R97 / R99 were designed to operate in an architectural environment optimized for preparing a voice service, which greatly limits the capabilities and extensibility of these services. These restrictions were considered an acceptable compromise, which allowed the introduction of a new service while reducing the impact on the existing architecture and / or outdated GSM services.

FIG. 1 illustrates the fundamental flat architecture of the GPRS / EDGE data system in version R97 / R99. In general, the mobile device 101 communicates with a base station controller (BSC) 106 through one of the base stations 103-105.

The base station controller communicates with a circuit switched domain (CS) via interface A and a packet switched domain (PS) via a Gb interface.

The original GSM domain was a circuit switched domain whereby voice traffic is routed between the radio subsystem represented by the base station controller 106 (FIG. 1) and the transceiver stations (BTS) 103-105 and the public switched telephone network 108 (PSTN) via the A interface , to the center 110 switching mobile communications (MSC). The packet-switched domain is routed by a Protocol Control Unit (PCU) 112, which is a convergence component and contains a layer of a radio link controller (RLC) and a medium access control protocol (MAC) (not shown) through which packet data is routed by the second generation GPRS support gateway node 114 (SGSN) and the edge node 118 connected to the packet data network 120. A packet-switched network may, for example, be the Internet or a closed data network.

With few exceptions, coordination between circuit switched and packet switched domains is virtually non-existent. In addition, the original R97 / R99 specifications do not support multiple packet data streams, Quality of Service (QoS) control, real-time data transfer, or “real handover” in a packet-switched domain between cells and / or network domains.

There is no defined procedure for GPRS that is equivalent to the handover procedure used in GSM dial-up voice and data calls. Instead, a “flip-flop” reselection is used to maintain the mobility of the mobile station in a mode where a time block flow (TBF) is established. As a result, the input data stream is interrupted each time a cell reselection is performed.

More specifically, a mobile station in GPRS Standby and Ready states can perform cell reselection. Cells to be monitored for cell reselection are specified in the broadcast allocation list (BA), which is transmitted on the PBCCH or BCCH if the PBCCH does not exist. In burst mode, the mobile station constantly monitors the carrier frequency of the served cell and all BCCH carrier frequencies indicated in the BA list (neighboring cells). In each TDMA frame, a sample for measuring the level of a received signal is sampled at least on one of the BCCH carrier frequencies following one after another.

To decide whether to reselect, the average level of the received signal (labeled RLA_P) is calculated as the moving average of the samples collected over a period of 5 seconds and stored for each BCCH carrier frequency. The samples allocated for each carrier frequency are distributed as evenly as possible over the evaluation period. At least 5 samples to measure the level of the received signal is necessary for a valid RLA_P value.

According to the GSM standard, the following cell reselection conditions (measured in dBm) are used for GPRS.

A. The C1 loss criterion parameter (3GPP TS 05.08, 6.4) is used as the minimum signal level criterion for cell reselection for GPRS in the same way as for the GSM Idle mode. The calculation of C1 for each cell (served and neighboring) is based on the corresponding RLA_P value.

B. Cell32 ranking criterion parameter C32 (3GPP TS 05.08, 6.4) is used to select cells from cells with the same priority. For the served cell, C32 is equal to the corresponding C1. For each neighboring cell, C32 is equal to the corresponding C1 modified with the cell transmission parameters.

C. The signal level threshold criterion parameter C31 (3GPP TS 05.08, 6.4) for the hierarchical cell structure (HCS) is used to evaluate the priority hierarchical GPRS.

At least for each new sample or every second (more), the mobile station updates RLA_P and calculates the values C1, C31, and C32 for the served cell and the non-served (neighboring) cells. The mobile station reselects the cell if:

i) the parameter of the loss criterion on the path C1 for the served cell becomes less than zero;

ii) an unattended suitable cell (see 3GPP TS 03.22) is rated to be better than a served cell.

The best cell is the one with the highest C32 value.

When evaluating the best cell, the hysteresis values are extracted from the C32 value for neighboring cells. Hysteresis values are transmitted on the PBCCH of the served cell. In the case when the cell is reselected within the previous 15 seconds, the hysteresis value becomes 5 dB. If no suitable cell is found within 10 seconds, the 3GPP TS 03.22 cell selection algorithm is executed.

As a consequence of this flip operation, GPRS / EDGE is limited to interrupt-tolerant data modes. However, it would be desirable to implement an improved handover of packet-switched services in order to support more bandwidth modes and greater versatility without significant modifications to the systems used.

Brief Description of the Drawings

The present invention and related advantages and features provided in connection with it will be better understood and taken into account after reviewing the following detailed description of the invention, taken in conjunction with the following drawings, in which like numbers represent like elements, in which:

FIG. 1 is a schematic representation of a wireless cellular communication system;

FIG. 2 is a schematic diagram in the form of a block diagram of a mobile communication device connected to a BTS;

FIG. 3 is a block diagram illustrating a software architecture of a mobile communication device;

FIG. 4 is a block diagram illustrating a portion of the mobile communication device of FIG. 3;

FIG. 5 is a state diagram illustrating operating states of a mobile communication device;

FIG. 6 is a state diagram illustrating transitions between the ON (on) and OFF (off) states of TBF;

FIG. 7 is a state diagram illustrating transitions between states of receipt of a virtual unidirectional channel in a queue;

FIG. 8 is a state diagram illustrating transitions between exit states of a virtual unidirectional channel;

FIG. 9 is a block diagram illustrating control of a virtual unidirectional channel;

FIG. 10A and 10B are flowcharts illustrating the operation of a mobile device and network;

FIG. 11 is a block diagram illustrating an alternative embodiment of part of the software architecture of FIG. 3;

FIG. 12 is a schematic diagram illustrating a mobile device moving through cells of a cellular communication system;

FIG. 13 is a schematic representation of the management of change (change) of cells in a mobile communication device;

FIG. 14 is a block diagram further illustrating cell change control for a mobile communication device;

FIG. 15 is a representation of measurements for reselection in a prediction device;

FIG. 16 is a representation of re-selection conditions in a prediction device.

Detailed Description of Drawings

A mobile communication device and a method of operating a mobile communication device includes storing at least one frame of a communication signal received from a network, and applying flow control for lower layers to support network reselection. The lower levels are the levels below the virtual unidirectional channel. According to one aspect of the invention, a message is transmitted to the network indicating that the mobile communication device supports the virtual bearer operation mode. The mobile communication device selectively operates in a virtual unidirectional channel mode depending on the response received after this transmission. In addition, flow control through a virtual network may advantageously be dependent on the discovery that a cell change is inevitable. Thus, interruption-tolerant data modes can be easily implemented with a slight modification to the system used.

The wireless communication device 101 (FIG. 2), also called subscriber equipment, a mobile device or a mobile station, may be a stationary or portable cellular radio communication device, personal digital assistant (PDA), a personal computer modem, or any other device, operating in a wireless communication system, for example the typical GSM system of FIG. 1. The communication device includes an antenna 202, a radio frequency (RF) transceiver 204, a controller 206, and a user interface 208. The antenna 202 can be implemented using any suitable antenna. The transceiver 204 can be integrated or separated from the controller 206 and can be implemented using any global communication scheme with a wireless interface, such as hardware or software that implements a radio frequency cellular transceiver. The controller 206 may include logic, memory, and software, and provides functionality for a communication device. It can be implemented using one or more of the following: microprocessor; digital signal processor; microcontroller; programmable logic, etc. User interface 208 facilitates the transfer of information or directives to and from the controller or transceiver. User interface 208 may include the interface of any device, for example, one or more of the following: a keyboard; converter; display; local connection, such as infrared or radio frequency connection, etc .; as well as a connector such as a universal serial bus, an RS-232 connector, and the like.

The software architecture of the mobile station in the controller 206 of the communication device is shown in FIG. 3. The controller 206 of the mobile device 101 includes a physical layer 302 that communicates with a radio frequency transceiver 204. The physical layer 302 schedules the reception and transmission of physical data, adjusts the gain of the receiver, controls the power of the transmitter, measures signal strength and other functions, not described in more detail in this document. A media access controller (MAC) 304 organizes the transmission and reception of packet-based information to and from the physical layer interface 302. The medium access controller 304 mainly includes logic by which the mobile device 101 is informed of the right of the mobile device 101 to transmit at a predetermined time on the uplink (communication line from the mobile device to the base station) and to recognize messages addressed to the mobile device 101 on the downlink (communication lines from the base station to the mobile device).

A radio link controller 306 controls the mobile station 101 with respect to a network oriented transmission of signals related to radio communications, i.e. the appointment of time slots (time intervals), the configuration / dismantling of packet data channels, the assignment of radio frequency channels and other functions not described in more detail in this document, in addition to transmitting messages originating from the network and transmitted via the physical layer interface 302. The radio link controller 306 is mainly involved in the error correction process at the radio level, i.e. to absorb periodic errors resulting from channel attenuation, and also processes certain aspects of setting up and dismounting data transmission in GPRS / EDGE. Thus, the radio link controller 306 maintains the operability of the radio link by acknowledging and retransmitting.

For packet data, a logical communication controller (LLC) 308 packetizes or divides network protocol packet data into radio packets for broadcast over the radio frequency channel 102 and provides compression and encryption services. The subnet convergence / divergence protocol block 310 (SNDCP) de-packages / splits the radio packets received by the mobile device 101 into network protocol packet data for transmission to the application interface 311 of the mobile device 101. The application interface exchanges network protocol data between the convergence / divergence subnet protocols with the corresponding application in mobile station 101. Thus, user packet data or traffic packet data is transferred between the application interface and the physical layer 302 after 310 stvom protocol convergence / divergence subnet, the controller 308 logic operation, the radio controller 306 and controller 304 access to the transmission medium.

The controller 206 further includes a radio resource manager (RRM) 316 and a GPRS radio resource manager (GRR) 316 for controlling intra-cell mobility and radio resource assignment. Mobility Management (MM) and GPRS Mobility Management (GMM) layer 318 controls intra-cell mobility.

The digitized speech speech channel passes through the physical layer 302 and CODEC 322. CODEC receives incoming speech from the user interface for uplink transmission and outputs speech received from the downlink to user interface 208 for playback through a speaker (not shown). You may notice that voice and packet data are processed through separate channels in the mobile device 101, reflecting various channels for voice and packet data traffic in the network, as shown in FIG. 1. Such a system structure allows the addition of GPRS / EDGE to the telephone networks used, without prejudice to the reliable outdated GSM voice systems used.

The limitation of the system used is that it does not support data exchange, which requires uninterrupted connections, which is called in this document intolerant to interrupt data exchange. Examples of such data exchange are streaming video or music. This is due to the fact that GPRS / EDGE uses "flip" reselection to support reselection of the mobile station by establishing a temporary blocking stream (TBF), as is known to those skilled in the art. As a result, the input data stream is interrupted each time a cell reselection is performed.

In order to effect interruption-free data transmission to mobile device 101 with minimal impact on the used GPRS / EDGE system, virtual unidirectional channel 312 is integrated into mobile device 101. Those skilled in the art will recognize that a downlink that is a path from the network to the mobile device , is the main communication line under the condition of such data exchange, and thus the virtual unidirectional channel is described with respect to the downlink. However, it should be recognized that the virtual unidirectional channel may also find application in the uplink. A typical virtual unidirectional channel 312 is inserted between the logical communication controller 306 and the logical radio channel 308. The virtual unidirectional channel 312 stores uplink data from the radio communication controller for further transmission to the logical communication controller 308 and then for use by the mobile device applications 101. By logically inserting the virtual component a downlink unidirectional channel above the level of the radio link controller 306 and below the level of the controller 308 For virtual communication, the virtual unidirectional channel operates on the frames of the logical communication controller from the receiving side. The function of the virtual downstream unidirectional channel 312 is to store downlink data when the downlink is not interrupted, and then provide the stored data to the logical communication controller when the downlink stream is interrupted. Thus, the virtual unidirectional channel continues to provide data to the logical communication controller until the connection is restored.

The virtual unidirectional channel 312 is described in more detail below, starting with reference to FIG. 4. In the first embodiment, which is an extension of the common GPRS / EDGE architecture used, one new virtual unidirectional channel 312, for example a virtual streaming unidirectional channel, is inserted into the mobile device 101 between the logical communication controller (LLC) 308 and the radio link controller 306 ( RLC) via interfaces 313, 315. The illustrated virtual unidirectional channel 312 receives downlink data and loads it into queue 402. The output of the queue is fed to the controller 308 communication via interface 315. In general, for a unidirectional streaming channel, the queue input controls the insertion of data into the queue to i) ensure that the downlink data queue is sufficiently filled before sending any data to the logical communication controller; and ii) Maintain queue data at a sufficient level whenever data is received.

Queue 402 virtual unidirectional channel can be controlled by processing (separately or jointly) two of the following parameters:

- coefficient of the input / output data rate; and

- queue size of the virtual unidirectional channel (lower limit and / or upper limit). Those skilled in the art will recognize that by controlling these parameters, cell reselection can be made without loss of streaming data, even when the downlink is interrupted.

More specifically, the following variables will be used to describe the operation of a virtual unidirectional channel:

Ton - temporary blocking stream is ON: in this state, packet data is transmitted;

Toff - the temporary blocking stream is DISABLED: data is not being streamed or the temporary blocking stream occurs in this state, but the “ready timer” works, allowing a quick return to the transfer operation before its time expires;

I - WAIT: idle burst mode. There is no temporary lock flow and the ready timer has expired. To get a temporary blocking stream, full configuration is required;

A - temporary blocking stream is running: There is no transfer of active packet data;

Rs - the ready timer is running;

Rx - the ready timer expired;

Rc - the ready timer is cleared;

F - downlink data stream from the RLC is turned on;

QLL - data in the downlink data queue is less than the lower limit of the QL queue;

QHH - data in the downlink data queue is greater than the upper limit of the QH queue; and

S - sending a frame to LLC.

In the course of operation, it is assumed that the virtual unidirectional channel is activated or deactivated each time the radio link controller has a fully assembled logical communication controller frame for delivery. Each time the VSB process wakes up from the standby state, it follows the following set of rules to control its execution:

determine the state of the RR / GRR: if it is not in the Ton packet transmission state, then no automatic operation is required. In addition, the last GRR state follows, so that (I <-> Ton) can be tested every time Ton EQ TRUE;

IF state GRR Ton EQ TRUE IF (I <-> Ton) EQ TRUE;

set the variable VSB_Reset = TRUE;

Fl;

<Execute automatic machine of the input queue>;

<Execute automatic machine of the output queue> Fl.

Virtual Unidirectional Channel (VSB) logic contains three state machines.

1. In the transition between the radio resource states of the GSM specification, a substate is added, which is based on whether or not the “ready timer” is started when it is in packet transmission or double transmission mode. This may be called a basic control unit.

2. The input queue automaton controls the data entry into the downlink data queue by controlling the flow of the transmitting radio medium.

3. An output queue automaton that controls the output of the downlink data from the queue to the LLC level.

The operation is controlled to maintain a downlink data queue so that i) minimizes the effect on jitter caused by short-term changes in data rate due to a schedule, retransmission, etc., and ii) reduce the effect of cell reselection on data continuity downlink.

In addition, placing the virtual unidirectional channel component above the radio link controller further reduces its effect on the components used by allowing the reuse of temporary blocking logic in the radio link controller. Those. even if the radio link controller is transparently controlled, it is still responsible for initiating the signaling necessary to start and control the temporary blocking flow.

The following are basic conditions with respect to GSM GPRS / EDGE terminology with reference to FIG. 5 and 6. These states are controlled as follows. The phone operates in batch mode 502 "idle / idle" when data is not transmitted. Special mode 504 is activated when a radio resource is allocated, and ends when a radio resource is turned off. Packet mode 506 is activated when packet access is initiated, and ends when the temporary blocking stream ends. Dual transmission mode 508 is activated when voice and packet data are simultaneously transmitted.

With reference to FIG. 6, state 602 TBF ON is a distinct condition where the radio resource state of the mobile device is either i) a dual transmission mode (DTM) and a temporary blocking stream is executed, or ii) only a packet transmission mode. In the 604 TBF OFF state, the start of the standby timer is a condition under which the standby timer is started and the TBF is off, it should be understood that the standby timer starts every time the temporary lock flow completes normally. In the event that there is no active temporary blocking stream and the ready timer is running, a sequence of complete signal transmission settings is not required to start a new temporary blocking stream. State 606 represents an idle packet.

The input queue automaton is shown in FIG. 7. Before initiating the temporary blocking stream 702, the downlink data is loaded into the queue 402, and this continues until the queue 402 is full. The queue is loaded at 704 until it reaches the marked upper limit of the queue (upper storage threshold, which is the limit on the capacity of the queue). When it reaches this threshold, data storage is completed at step 706. The queue loading is stopped until the queue reaches the lower limit (storage threshold, which is the minimum capacity of the queue). In this way, the queue can be controlled to remain between the upper and lower thresholds. This queuing process is effective for data transfer types such as audio and video streaming that are delay sensitive (the user may allow a certain delay before the data reaches the application), but are not tolerant of interruption (after the interrupt is triggered, it causes failures).

It is contemplated that a virtual bearer can advantageously be controlled more intelligently. The virtual unidirectional channel queue state variable S is set to be a variable representing the filling of the virtual unidirectional channel queue (%). The value of S can be recursively specified at any given time (i + 1) as follows:

where Q _L is the lower limit of the VSB queue, Q _H is the upper limit of the VSB queue, R _IO is the input / output data rate coefficient, and F _CR is the frequency of random cell reselection operations. The period of adjustment (control) of the output speed of the queue is given in this document as T _adj . The output data rate at the end of each interval, for example, sets it for the next interval.

For any reasonable control period I, trivial control rules will be defined to set the output data rate r _out (i + 1) for the next interval, which ensures that the same amount of data that came from the radio link controller in the previous period r is transmitted to the LLC level _ln (i). Thus, the output data rate for the period (I + 1) can be defined as:

r _out (i + 1) = r _ln (i)

When the transmission rate of the input data stream from the radio link controller increases, the virtual unidirectional channel queue can become full and requires activation of the flow control. When the transmission rate of the input data stream decreases, the level of the logical communication controller does not receive enough data, and the application is frozen. As a result, the perceived quality of service to the user may be reduced.

According to an alternative embodiment, the above formula is modified to take into account the state of the queue 402. In this case, the output speed for the next time period should be equal to the current contents of the queue plus the same amount of data that was received in the previous period. It means that:

where T _adj is the duration of the adjustment period of the queue.

Regardless of which of the above embodiments is used, it should be appreciated that there is a possibility that the queue 402 is periodically cleared during cell reselection. There are three main reasons for this: (i) the length of the data flow interruption caused by reselection, (ii) the speed at which the application consumes data from the queue (more precisely, the ratio of the input and output data rates of the queue), and (iii) the size queues (for example, upper and lower limits).

An alternative embodiment is illustrated in FIG. 9. For the queue of a virtual unidirectional channel, the quality of control (control conditions) can be specified as an integer number of occurrences of “freezing” during a session. The purpose of the control mechanism is to reduce (minimize) the control conditions in comparison with an "open loop system" without control. The proposed system is an integrated system that uses closed loop control along with cell change prediction. It is further contemplated that a device for predicting randomly occurring cell reselection operations can also significantly improve control quality.

More specifically, the queue management loop for queue 402 is illustrated in FIG. 9. The virtual bearer queue 402 is controlled to maintain the desired state of the queue. Another input to the control loop is the reselection command generated by the cell change controller (described with reference to FIGS. 15, 16) and the reselection parameters generated by the reselection prediction device 904 (also described with reference to FIGS. 15, 16). In addition, the ratio of the input / output data rates is calculated at step 906 and is the ratio of the speed at which the queue is filled to the speed at which the queue is cleared. The virtual unidirectional channel queue state prediction device 908 predicts the queue state, and transfers this forecast to the input of the queue state controller.

The controller can dynamically change the capacity of the queue depending on the forecasted demand. Thus, when cell reselection occurs frequently, the upper threshold (upper limit) of QH may be large. When cell reselection is rare, the upper threshold of QH can be lowered, saving memory for other applications in the mobile device and reducing the delay caused by the queue. It should be borne in mind that in working environments, for example in central London, even if the mobile station is physically stationary, the channel may not be such. Quite often you can find mobile devices that re-select cells every 10 seconds or so and oscillate within the same group of two or three cells, depending on the settings of the system parameters (hysteresis and reselection timer). In such an environment, a very reliable unidirectional channel will be required. Alternatively, in other environments, such as rural environments, cell reselection will be rare except for permanent cells. The present invention can adapt to both environments by providing the proper amount of memory using excessive resources and creating significant latency.

In addition, the queue controller 910 can adjust the output data rate to keep the queue at a constant level when conditions change. Finally, the reselection component 912 controls the queue to operate in an interrupt mode when the stored data is output smoothly during cell reselection. The control loop manages the queue to support it for the most part unchanged. In addition, the size of the queue may vary depending on whether or not cell reselection is expected.

It also sets the queue fill target S _tar , which is the queue fill that must be reached and maintained by the management system during the session. In order to improve the quality of control, the system selects within each control period, measures the input data rate and supports its moving average:

For each queue adjustment (control) period, the control algorithm works as follows.

равным нулю в начале периода i.Stage 1. Set

equal to zero at the beginning of period i .

в ходе текущего периода регулировки i.Stage 2. Measure the input data rate and maintain a moving average

during the current adjustment period i .

Step 3. Determine the filling of the queue of the virtual unidirectional channel S (i) at the end of the adjustment period i .

Step 4. Set the output data rate for the next control period (I + 1) according to the following formula:

вычисляется на основе выборок, взятых в рамках каждого периода управления. Скользящее среднее

сбрасывается в начале каждого периода регулировки очереди. Это означает, что состояние очереди в конце интервала регулировки зависит от состояния очереди, отмеченного в конце предыдущего периода управления, и не зависит от предыдущих интервалов.Moving average

calculated on the basis of samples taken within each management period. Moving average

reset at the beginning of each queue adjustment period. This means that the state of the queue at the end of the adjustment interval depends on the state of the queue marked at the end of the previous control period, and does not depend on previous intervals.

During the simulation, it was determined that by setting the transmission rate of the input data to the queue more than 20% higher than the transmission speed of the output data of the queue, cell reselection can be performed. Download speeds of less than 10% greater than the transmission speed of the output of the queue in an otherwise reselected simulation made it possible to keep the streaming signals at the output of the mobile device intact.

According to an alternative embodiment, when virtual bearer services are not used, it is contemplated that the radio link controller may be transparently managed. This is represented by a pass 314 in FIG. 3. For transmissions that require a virtual unidirectional channel, a virtual unidirectional channel can be used. On the other hand, in traditional GPRS / EDGE transmissions by the best effort method, the virtual unidirectional channel is omitted. It is contemplated that it can be implemented by exchanging data between a network and a mobile device.

More specifically, the radio link controller 306 sends a notification to the GPRS Radio Resource Control (GRR) level 316 that an establishment is required. According to one embodiment, the GRR may notify the network that the operation of the virtual bearer is supported by the mobile device 101, as represented by step 1002 in FIG. 10A. The mobile device then waits for a response, as shown in step 1004. The network can respond to the notification recognized in step 1012 of FIG. 10B, by indicating that the operation of the virtual bearer will be started, as indicated in step 1014, which illustrates the notification of the mobile device and the initiation of over-transmission.

This notification may include a virtual unidirectional channel type when multiple virtual unidirectional channels can be used. For example, the network may indicate that the operation of the streaming virtual unidirectional channel will be initiated, and may initiate data transmission at a higher rate (excessive speed) to support queue filling in preparation for cell reselection. GPRS radio resource management can then notify the radio link controller when it can start sending radio blocks to the medium access control (MAC) layer. In addition, this architecture supports transparent mode, which is a mode that omits a virtual unidirectional channel, where traditional GPRS / EDGE packet data transfer is sufficient. In transparent mode, the mobile device and network operate as if there was no virtual unidirectional channel when a virtual unidirectional channel was not needed. This mode may be the standard mode of operation until receiving acknowledgment from the network, as shown in step 1008. When the virtual bearer is not active, the network transmits data at its usual data rate, as shown in step 1016. Those skilled in the art will recognize that GRR can work to initiate virtual mode independent of the network (for example, without notifying the network), as an alternative to the negotiation between the network and the mobile device described in this document.

Another embodiment is illustrated in FIG. 11, a component 1100 of a composite virtual unidirectional channel is illustrated. A composite virtual unidirectional channel includes several virtual unidirectional channels 312, 1102, 1104, consistent via common interface layers 1106, 1108. Thus, any serialization and / or prioritization of data can be performed in addition to matching several unidirectional radio channels. More specifically, the first virtual unidirectional channel 312, the streaming virtual unidirectional channel, can be delay tolerant, non-tolerant of interruption, as described above by the virtual unidirectional channel. Other unidirectional channels for other types of data exchange may be included, for example, a background unidirectional channel for transmitting large background blocks or a real-time unidirectional channel for delay-tolerant data transmission. The common interface layers can be controlled to prioritize the flow of data and traffic data for the logical communication controller according to their relative priority and the needs of the data related application. This component of the composite unidirectional channel can be used with or without a pass 314.

Thus, it can be seen that the present invention can be applied to the current GPRS / EDGE architecture and i) provides the operator with a commercially useful feature, and ii) provides the network and mobile station industry with a quick way to implement this feature with minimal risk. An additional option to embed a “spoken” unidirectional channel (or real-time unidirectional channel) is also offered. In the case of adding a real-time unidirectional channel to the protocol, the functionality of both RLC and MAC will be completely omitted, since the requirements for the services of transmitting user data using the best effort method and real-time data transmission are very different. RLC / MAC functionality customized to the needs of real-time conversation services is then replaced by the addition of a “real-time unidirectional channel”, then “tunneled” to the physical layer, probably into a component of the flexible first layer principle (FLOC).

It is contemplated that if any virtual unidirectional channel runs on LLC frames transmitted in transparent mode, then the existing transparent RLC mode may be used. If a virtual unidirectional channel runs on radio blocks, it may be architecturally easier to create a separate unidirectional channel component that will be placed in an existing RLC component. In addition, the addition of any virtual unidirectional channel will likely have a significant impact on data buffering between components in both the mobile device and the network. In the case of a network, the reverse transmission capacity must also be taken into account. Additionally, isolating the effect of a trait on one component is usually a non-trivial task and may even be impossible for certain types of traits. Part of the decision to use this type of architectural direction must be based on relevance.

It is also contemplated that a virtual bearer can be inserted into a network. If plugged into a network, this component is likely to be bound to a protocol control unit (PCU).

According to yet another aspect of the invention, the method and device i) allows the network to set and adjust thresholds that control when and how the mobile device re-selects a cell, ii) allow the mobile device to predict the likelihood of cell reselection, and iii) allow the mobile device to notify the network, when re-selection is very likely during the transmission of packet data, which in turn forces the network to take appropriate action to designate a new cell, on which packet exchange will continue E data. Such reselection can be instructed in a network having one radio interface, or between dissimilar radio interfaces, for example GSM and UMTS.

FIG. 12 illustrates a general mobile environment in which prediction of cell reselection can be advantageously used. Mobile device 101 moves between cells A, B, and C. In the illustration, the following events occur. Packet data transmission is initiated in cell A. The mobile device re-selects cell B, interrupting packet transmission in cell A (flip operation). The mobile device is trying to access cell B, but access is denied. After that, the mobile device 101 re-selects the cell C. The mobile device successfully accesses the cell C, updates the routing area and continues to transmit packet data.

The ability to predict cell changes will be useful for the following reasons. First, if the virtual unidirectional channel described above is used in a mobile device, the operation of the virtual unidirectional channel can be adjusted to allow for the upcoming cell change. Secondly, regardless of whether a virtual unidirectional channel is used, the network can determine in advance whether cell B has the capacity to serve the mobile device, and whether there will be a cell C supporting radio frequency parameters for communicating with and responding to the mobile device to communicate with the mobile device directly to direct the mobile device 101 to the cell C before interruption, thereby minimizing interruptions in data transmission.

FIG. 13 illustrates part of a mobile device 101. A reselection prediction device 1302 is at the radio resource level of the mobile device 101. A reselection prediction device is connected to receive measurements of a received signal strength (level) indicator (RSSI) from a measurement collection unit 1304 at a physical layer 302. Measurements RSSIs are also provided to a cell change controller (CCC) that implements used cell changes for a mobile device known in the art, for example cell change for mobiles Nogo device as set out in GSM 3GPP TS 05.08 specification. The cell change controller outputs the value C1 to the reselect prediction device module 1302. The reselection prediction device generates an indication of a predicted cell reselection to the measurement result message controller 1304, which reports the network change results by setting the sign of the inevitability of reselection to True (T) in step 1306. Although the above has been described with reference to mobile device 101, those skilled in the art The technical fields recognize that the logical arrangement of the proposed device may be within the radio resource control (RR) level of the mobile device and / or network.

Those skilled in the art will also recognize that the manner in which the mobile device 101 is to measure for the purpose of controlling a network controlled cell reselection, as well as the way the mobile device is to measure for the conventional cell reselection, are known. The method and rules for a mobile device to follow in order to select, reselect a cell in idle mode, as well as packet transmission mode, are known. These rules are implemented at the radio resource level, along with support at the physical layer called the cell change controller (CCC). This usable set of logic that performs measurements is also called a measurement acquisition unit (MAU) 1304, and a logic set that reports measurement results from a mobile device to the network can be called a measurement result message controller (MRC) 1304.

One improvement to the existing components of the cell reselection logic for a mobile device residently adds an additional component to the radio resource, referred to herein as a reselection prediction (RP) unit. This new component receives its input mainly from the cell change controller module and sends its output mainly to the change result message controller. The purpose of the reselection prediction device is to i) analyze the pre-processed measurement results sent to the CCC from the MAU, and ii) notify the network via MRC.

The cell reselection structure is illustrated in FIG. 14. The reselect prediction device 1402 has one logical input 1408 and a first probable output 1404 containing a “warning” to the network that re-selection is predicted by setting the “re-selection inevitability” bit in the uplink measurement report, and a second likely output 1406 as an indication to the virtual unidirectional channel (VB), which may be, for example, a virtual streaming unidirectional channel (VSB), that re-prediction is predicted. Output 1404 or 1406 may be provided in the alternative, or both may be provided. The reselection prediction device has its own logical input 1408 and the output of the measurement acquisition module 1410. The reselection prediction device receives C1 measurements (RSSI) as an input from the measurement module 1410 of the cell change controller. Re-selection 1412 occurs when the cell change controller determines that re-selection is to occur, which can be determined by the network or mobile device.

In one embodiment, the architecture of the mobile station includes a reselection prediction device that predicts when reselection is likely to occur. In a typical implementation (FIG. 14), reselect prediction device 1302 receives parameter C1 values, which are calculated based on RSSI measurements, at input 1406 from measurement module 1410. The value of parameter C1 is shown in this document, but other conditions may alternatively be used.

The reselection prediction device includes an output 1404 for indicating when a reselection is likely to occur. In one embodiment, for example, the mobile station sets a “reselect” bit in the uplink measurement report sent to the network to notify the network of an imminent reselection based on the output of the reselection prediction device. A typical reselection prediction device also includes a second output 1406 for indicating a virtual unidirectional channel (VB), such as a virtual streaming unidirectional channel (VSB), or some other module in a mobile station that re-selection is unavoidable. Output 1404 or 1406 may be provided in the alternative, or both may be provided.

In FIG. 14, the reselection is performed by the reselection module 1412 in the mobile station in response to the reselection command when reselection is necessary. The reselection command may be the result of a determination made in the network or mobile station, as described in more detail below.

In one embodiment, in general, reselection is predicted based on the reselection criterion RC calculated using a set of several curves corresponding to approximate the values of parameter C1 of the respective sets and based on the coefficients of the curve. In a typical embodiment, the parabolic curves approximate a set of several parameter values _{i i} = C1, which are based on the corresponding RSSI changes collected during t _j . The coefficients of the curve a ₀ , a ₁ and a ₂ are calculated as a function of y and t using the least squares method based on the corresponding set of values of parameter C1. In FIG. 15, each parabolic curve is calculated to approximate 5 values of parameter C1. For each new value of the parameter C1, a new set of coefficients of the parabolic curve is generated to approximate the last 5 values of the parameter C1. In FIG. 15, the first parabolic curve is based on C1 values at time instants t _j ... t _{j + 4} , the next parabolic curve is based on C1 values at time instants t _{j + 1} ... t _{j + 5} , and the next parabolic curve is based on values C1 at times t _{j + 2} ... t _{j + 6} , etc. For each parabolic curve, the reselection criterion is calculated at the time corresponding to the last value C1 using the dependence RC = a ₀ + a ₁ t _n + a ₂ t _n ² . Several points of the reselection criterion, RC, are illustrated in FIG. fifteen.

A typical algorithm for a re-prediction prediction device starts calculating an n- point shift parabola by finding the necessary initial sums based on the first y _j , where y _j is the value of parameter C1 from the GSM 3GPP standards described above, and the values of the re-selection criterion at the corresponding times t _j :

. Calculation of reselection criteria based on raw RSSI measurements separated by time interval

.

The following calculations are performed, starting with the initialization i = 1 .

BEGIN

RSSli = get_RSSI_measurement_results (ti);

yi = compute reselection_criteria (RSSH);

// Current amounts are based on previous

//Extra options

Q = D / n;

E = E-QB;

F = F-QC;

R = R-QP;

Q = K / n;

L = L-QB;

M = M-QC;

S = S-QP;

Q = L / E;

// Coefficients shift parameters end at time t _n

a ₂ = (S-RQ) / (M-FQ);

a _one = (R-Fa ₂ ) / E;

a ₀ = (P-Ba _one -Ca ₂ ) / n;

// Criterion for re-selection at time t _n , calculated on the basis of approximation

RC (t _n ) = a ₀ + a ₁ t _n + a ₂ t _n ²

i = i + 1;

End

FIG. 16 is a graphical illustration of RC reselection criteria and coefficients a ₀ , a ₁ and a ₂ . Re-selection is determined to be inevitable when the RC values estimated at the endpoints of several consecutive curves decrease, and when the coefficients a ₀ , a ₁ and a ₂ for at least some of the several consecutive curves satisfy conditions indicative of an inevitable re-selection as described in more detail below. In one embodiment, when reselection is unavoidable, the approximate time that cell reselection occurs is determined by the relationship T _r = −a ₀ (T _d ) / a ₁ (T _d ). The time point T _d is the moment when a potential reselection has been recognized, and T _c = T _d + mΔT is the current time. In one embodiment, when m = 3, reselection is predicted as follows:

IF

0 <RC (T _c ) <RC (T _c -ΔT) <RC (T _c -2ΔT) <RC (T _d = T _c -3ΔT)

AND

a ₀ (T _d )> 0 ANDa ₁ (T _d ) <0 AND sign [a ₂ (T _d -ΔT)] <0 AND sign [a ₂ (T _d + Δ T)]> 0

AND

sign [a _o (T _c )]> 0 AND sign [a ₁ T _c )] < 0

THEN,

the predicted cell reselection time is

T _r = -a ₀ (T _d ) / a _one (T _d )

The reselection prediction device may operate continuously during a connection. Each time the prediction conditions for reselection are satisfied, T _{r is} updated. When the reselection conditions are no longer satisfied, cell reselection is not predicted.

Alternatively, the reselection prediction algorithm according to another embodiment uses the following steps:

Stage 1. The first collection of n RSSI measurements, where n > 2

Step 2. Collection of RSSI measurement at time t _i

Step 3. Calculation of the reselection criterion yi = C1 according to 3GPP TS 05.08, clause 6.4, for a complete set of n RSSI measurements.

Step 4. Calculation of a ₀ , a ₁ , and a ₂ as a function of y _i and t _i using the least squares method based on the previous n measurements, where n > 3.

Step 5. The calculation of the predicted RC based on a ₀ , a ₁ and a ₂ at the last moment of time n ,

those. RC = a ₀ + a ₁ t _n + a ₂ t _n t _n

Step 6. Determining whether a ₀ , a ₁ and a ₂ have a predetermined ratio and whether RC is tilted down for 3 consecutive samples AND

Step 6. IF a ₀ for the current period T _{d is} greater than zero, AND

Step 7. a ₁ for the current period T _{d is} less than zero, AND

Step 8. IF a ₁ changes sign from negative, as in the previous period, to positive in the current period T _d , AND

Step 9. IF the slope of the predicted RC parabola, starting in the current period T _d , decreases for a minimum of 3 periods, AND

Step 10. IF the a ₀ sign at the last point at which RC was predicted is positive,

AND

Step 11. IF the a ₁ sign at the last point at which RC was predicted is negative,

TO

Step 12. Re-selection of the cell is considered inevitable, and its time in the future is calculated to be equal to T _r = -a _o (T _d ) / a ₁ (T _d )

Step 13. The increment of the time interval I

Step 14. Go to Step 2.

Each predetermined time period of the AT RP receives RSSI measurements for the served cell from the measurement module. As mentioned above, the mobile station performs RSSI measurements every time a TDMA frame (4.615 ms) is in TBF mode. The time period Δ T can be estimated as approximately 100 TDMA frames.

After receiving a new measurement, the RP module calculates one of the RC reselection criteria. C1 is shown in this document, but the invention will find application with a different reselection criterion and in standards other than GSM and its subsequent generations.

Based on the previous n re-selection criteria (for example, n can be assigned a value of 5), RP approximates the RC values using a parabolic curve according to the formula:

RC (t) = a ₀ + a ₁ t + a ₂ t ² .

The parameters a ₀ , a ₁ and a ₂ are set by the least square method (MLS). The concept of “sliding parabola” approximation is graphically represented in FIG. fifteen.

The foregoing detailed description of the invention and the examples described herein are presented for purposes of illustration and description. Although the principles of the invention have been described above in connection with a particular device, it should be clearly understood that this description is provided only as an example, and not as a limitation on the scope of the invention.

Claims (14)

1. The method of operation of a mobile communication device, configured to communicate over a communication line through the air, which consists in transmitting over the air, which supports the operation mode of a virtual unidirectional channel; receive a response associated with the operation mode of the virtual unidirectional channel for the communication line; and operate in a virtual unidirectional channel mode depending on the response, moreover, in a virtual unidirectional channel mode, the virtual unidirectional channel operates to provide flow control in said communication device, while the flow control of the virtual unidirectional channel is designed to save data when the communication line is not interrupted, and to provide stored data when the link is interrupted. 2. The method according to claim 1, in which the mobile communication device includes a first controller that maintains the operability of the radio link, and a second controller, and in which said operation step includes the steps of communicating between the first controller and the second controller through virtual unidirectional channel in virtual unidirectional channel mode and communicate between the first controller and the second controller without controlling the flow of the virtual unidirectional channel in transparent mode when the virtual bearer mode is not selected. 3. The method of claim 1, wherein the virtual unidirectional channel mode is initiated in response to a response indicating that a streaming unidirectional channel will be established. 4. A mobile communication device comprising: a radio link controller; a virtual unidirectional channel associated with the radio link controller and including a buffer that stores at least one frame of the communication signal of the logical connection controller; and a logical connection controller connected to the virtual unidirectional channel for receiving frames of the logical connection controller from the virtual unidirectional channel; wherein the virtual unidirectional channel is operable to apply flow control and is responsive to determining that a cell change is unavoidable, whereby the virtual unidirectional channel operates to store data when it is determined that a cell change is inevitable, and to provide stored data, when the data stream is interrupted to change the cell. 5. The mobile communication device according to claim 4, in which the determination that a cell change is inevitable is received from the network. 6. The mobile communication device according to claim 4, wherein the determination that a cell change is inevitable is made by the mobile communication device. 7. The mobile communication device according to claim 6, in which the determination that a cell change is inevitable is made by the controller using a predicative algorithm. 8. The method of operation of a communication system including a network element, which consists in determining in the network element that the receiving device requires flow control of a virtual unidirectional channel; transmitting the type of virtual unidirectional channel for reception by the receiving device; and transmitting a signal providing flow control of the virtual unidirectional channel by the receiving device, and this signal is re-launched to support flow control of the virtual unidirectional channel in the receiving device, while the virtual unidirectional channel is configured to save data when the communication line is not interrupted, and output stored data when the communication line is interrupted. 9. The method of claim 8, wherein the transmitting type of the virtual unidirectional channel includes transmitting a type indicator of the streaming unidirectional channel for streaming data. 10. The method of claim 8, wherein the transmitting type of the virtual unidirectional channel includes transmitting a type indicator of the background unidirectional channel for transmitting background data. 11. The method of claim 8, wherein the transmitting type of the virtual unidirectional channel includes transmitting a non-virtual unidirectional channel flow control pointer for data. 12. The method according to claim 9, in which the step of transmitting the signal includes the step of restarting the transmitted signal to provide control of the flow of the virtual unidirectional channel in the receiver. 13. The method of operation of a communication system including a network element, which consists in determining that a mobile communication device requires a virtual unidirectional channel for transmission on a downlink; and the downlink signal for the mobile communication device is reset to provide flow control in said communication device during a cell change by the mobile communication device during the virtual unidirectional channel operating mode, the signal being reset depending on the type of virtual unidirectional channel to support the flow control of the virtual unidirectional channel , while the virtual unidirectional channel is configured to save data when the communication line is not interrupted, and Water stored data when the communication link is interrupted. 14. The method according to item 13, in which the downlink signal is not additionally reset to ensure that the cell is changed by the mobile communication device during the operation of the background type of unidirectional channel in the virtual unidirectional channel operation mode.

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