HK1090202A - Method and system for managing radio resources in a time-slotted communication system - Google Patents

Description

Method and system for managing wireless resources of time-slotted communication system

[ technical field ] A method for producing a semiconductor device

The present invention relates to a wireless communication system, and more particularly, to a method and system for managing radio resources in a time-slotted wireless communication system based on quality of user service (QoS) information.

[ background of the invention ]

In conventional wireless communication systems, the demand for radio resources often exceeds what is available. Among many users, many schemes have been developed to share the available radio resources. The efficiency of Radio Resource Management (RRM) algorithms makes such systems possible.

Various Time Division Duplex (TDD) communication schemes exist today, and the benefits of TDD systems include efficiency and flexibility in bandwidth usage. For example, at any given time, a channel is either configured as an uplink or downlink based on the needs of the transmission. However, resource management in TDD systems is a challenge. When transmission types change rapidly over time, it is difficult to make the most appropriate resource management decisions. Some resource management issues in TDD systems include the amount of bandwidth assigned to a user and the number of timeslots configured for uplink and downlink communications. Although various QoS schemes are well known, most schemes rely on assigning a static QoS class to a user, and the system then operates accordingly.

There is therefore a need for a method and system for more efficiently managing radio resources in a time-slotted communication system.

[ summary of the invention ]

The present invention relates to radio resource management in time slotted systems, such as TDD or Time Division Multiple Access (TDMA) systems. The system of the present invention designs a particular level of QoS and capacity for each timeslot. In accordance with a preferred embodiment of the present invention, timeslots (as well as users, geographical areas, coverage) are assigned to three types, with system capacity being the second consideration and QoS being the most important of the issues in the first type of assignment. In the second type of assignment, system capacity is more important than QoS. In a third type of specified relationship, QoS is treated the same in importance as system capacity.

A Radio Resource Management (RRM) function assigns appropriate assignments to time slots based on statistics of transmission types. The RRM function may use admission control, congestion control, call handover, user link maintenance, and Real Time (RT) or non-real time (NRT) packet switching algorithms as references to allocate timeslots to a particular user.

In one embodiment, a system receives a radio resource request from a user and, in response to the request, the system allocates a particular timeslot to the user based on user QoS information obtained from the core network.

The QoS criteria may include the status of user registration, the nature of the user application, geographic area information regarding the user requesting radio resources, or the like. The system controls the initial allocation of radio resources to particular users based on the type specific relationships associated with the users.

After the initial allocation is established, the system continues to monitor the transmission. If the system detects transmission congestion in timeslots having a higher level of QoS, the system may increase the number of timeslots having a higher level of QoS and decrease the number of timeslots having a lower QoS level.

[ description of the drawings ]

A more detailed understanding of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a block diagram of a time slotted communication system in accordance with the present invention;

FIG. 2 is a process flow diagram of method steps for managing radio resources and monitoring various conditions in accordance with the present invention;

FIG. 3 is a process flow diagram including method steps for classifying slot types and associating a user with a particular slot type in accordance with the present invention.

[ detailed description ] embodiments

The present invention is described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. The following base stations include, but are not limited to, node bs, site controllers, access points, or any other type of interfacing device in a wireless environment.

Figure 1 is a block diagram of a wireless communication system 100 in which a plurality of WTRUs 105 communicate with a base station 110. The base station 110 is controlled by a Radio Network Controller (RNC) 115. The RNC 115 is connected to a core network 120. The RNC 115 or the base station 110 includes a means for classifying timeslots of a plurality of radio resources into a plurality of different types and a means for mapping user assignments to a particular timeslot based on the user's QoS information received from a core network 120, as described in more detail below.

In a slotted communication system in which communications are transmitted over time slots, one or more time slots being assigned to a particular user for uplink or downlink communications, the system 100 assigns one of a plurality of assignments to time slots based on the QoS of a user, in a preferred embodiment, the system 100 uses three assignments: high QoS timeslots, high capacity timeslots, and balanced timeslots. It should be understood that any number of designated relationships may be used and that the names of the designated relationships are merely illustrative of the preferred embodiments of the present invention. Thus, although three assignments are described herein, more or fewer assignments may be used, and the primary icon may be used for channels of an uplink or downlink.

Communication parameters such as maximum delay, signal-to-interference ratio, packet error rate, and bit error rate are defined differently for each designated relationship of time slots. Thus, a different level of QoS may be provided for timeslots having a different assigned relationship.

The high QoS timeslot provides the highest QoS, and thus system capacity is a secondary consideration for RRM and is considered after QoS.

The high capacity timeslots provide only a minimum QoS, and system capacity is a major consideration for RRM because the high capacity timeslots are considered ahead of QoS.

The QoS of the balanced timeslots falls between the high QoS timeslots and the high capacity timeslots, and for RRM, the system capacity and QoS are considered to be of relative equal importance for the balanced timeslots.

The RRM dynamically adjusts the parameters for each designated relationship of timeslots based on the transmission status, for example, to avoid transmission congestion or radio resource starvation, the communication parameters of the balanced timeslots are preferentially adjusted to provide a minimum QoS. If congestion persists, calls from high capacity timeslots are reduced. Thus, high QoS timeslots are generally not adversely affected by transmission congestion.

The system also assigns timeslots as either RT timeslots, which are more suitable for voice applications, or NRT timeslots, which are more suitable for packet data applications, with different ways of controlling RRM, and different levels of QoS provided for the RT and NRT timeslots.

The system initially maps a user to a particular timeslot assignment based on QoS criteria, and then controls radio resources based on the same criteria. The QoS classification of a user depends on the overall QoS policy applied to the network, and the QoS classification may include the registration status of the user, geographic information, the nature of the user's application, QoS requirements, or the like. For example, in a commercial network, users with a high traffic volume are assigned to a high QoS timeslot regardless of the QoS requirements for their communications, while users with a low traffic volume requiring a high QoS service are assigned to a balanced timeslot.

In a preferred embodiment of the present invention, users are classified into three categories: a high QoS service user, a high capacity service user, and a balanced service user, and it should be understood that these categories are merely illustrative of the preferred embodiment and that any other number or name may be used. In some specific examples, where high QoS timeslots are assigned to users of high QoS services, balanced timeslots are assigned to users of balanced services, and high capacity timeslots are assigned to users of high capacity services, the system 100 controls the allocation of radio resources for a particular user based on the usage status of that user.

The system 100 also uses operation and maintenance (OAM) information to generate initial timeslot assignment decisions, for example, an operator can specify that a certain radio access bearer should be sent into a certain timeslot, such as: all voice calls as well as high-rate data calls (i.e., those greater than 384 kbps) should be sent to the high QoS timeslot, all medium-rate data calls (i.e., those between 124kbps and 384 kbps) should be sent to the balanced timeslot, and all low-rate data calls (i.e., those less than 124 kbps) should be sent to the high capacity timeslot.

The system 100 may also incorporate one of a specific geographic area and designated relationships of timeslots, for example, the system 100 may incorporate an airport or a train station into the high QoS timeslots only which are suitable for communication between traffic to and from these areas. Thus, only a high QoS service subscriber can access the radio resources in these areas, and if a balance service subscriber or a high capacity service subscriber intends to make a call in an area designated as a high QoS area, a special authorization must be obtained before it makes a call to be temporarily promoted to a high QoS service subscriber.

The system 100 can also assign timeslots based on the application used by the user, for example, a 911 call is common in a high QoS application, so that any user requiring a 911 service can access a radio resource with the identity of a high QoS service subscriber even if the user is not a high QoS service subscriber.

Different RRM algorithms are applied in different timeslots, which assign an appropriate number of timeslots to each assigned relationship based on statistics of transmission types, and which can use admission control, congestion control, call handover, user link maintenance, and RT or NRT packet switching algorithms.

Figure 2 is a flow diagram of a process 200 including method steps for managing radio resources and monitoring different transmission conditions in accordance with the present invention. In step 205, the system 100 of fig. 1 receives a radio resource request from a user of a WTRU 105 accompanied by QoS information relating to the request, the status of user registration, the location where the request originated, and the applications used by the user. In step 210, the core network 120 generates QoS information associated with the user. In step 215, the QoS information is obtained by the core network 120. Based on the user's QoS information, the system 100 maps the user to an appropriate designated time slot (e.g., a high QoS time slot, a balanced time slot, a high capacity time slot, etc.) in step 220. As mentioned above, with some exceptions, high QoS slots are assigned to high QoS service subscribers, balance slots are assigned to balance service subscribers, and high capacity slots are assigned to high capacity service subscribers, the system 100 controls the initial allocation of the radio resources to a particular subscriber based on the registration status of that subscriber.

After the initial allocation is complete, the system 100 constantly monitors the transmission status and controls the radio resources according to a prioritization mechanism of the present invention, and once the system 100 detects the occurrence of congestion, i.e., the lack of radio resources (step 225), the system 100 dynamically adjusts the number of timeslots assigned to each timeslot in the assigned relationship (step 230), for example, if congestion occurs in a high QoS timeslot, the system 100 increases the effective number of high QoS timeslots and decreases the effective number of high capacity timeslots and, if necessary, decreases the effective number of balancing timeslots after the exhaustion of the available high capacity timeslots, which may be call termination or avoidance of new access to the high capacity timeslots, and call or packet dropping is considered the last resort. If congestion occurs in the balanced timeslots, the system 100 increases the effective number of balanced timeslots and decreases the effective number of high capacity timeslots, however, high QoS timeslots are not adversely affected in this case.

The system 100 may control the call handover (step 235) according to the prioritization scheme of the present invention, where mobile units are allowed to wrap around a plurality of cells, when a mobile unit crosses the boundary between two cells, a call handover procedure is initiated and not accompanied by a call handover if there are insufficient resources in the target cell, and a cell may be dropped. In that case, the system 100 releases the high capacity timeslots to accept the entry of high QoS users, and balancing requests are also accepted by adjusting the QoS requirements so that the system 100 is not congested, but rather high capacity requests are rejected (step 240).

The system 100 may set the priority of NRT packet scheduling according to the prioritization mechanism of the present invention (step 245). For example, users assigned to high QoS timeslots are provided with minimum delay and jitter for scheduling their data packets, users assigned to balanced timeslots are provided with medium delay and jitter for delivering their data packets, and users assigned to high capacity timeslots are provided with maximum delay and jitter for transmitting their data packets (step 250).

The system 100 maintains the connection at different data rates for each timeslot at the assigned relationship (step 255). For example, high QoS timeslots are given a guaranteed bit rate plus a predetermined limit, balanced timeslots are given a guaranteed bit rate, high capacity timeslots are not guaranteed a bit rate, but the actual connection may be below the provided rate (step 260). If the system 100 detects a decrease in the data rate of a given relationship for a particular timeslot, the system 100 can change the number of timeslots in the given relationship in accordance with the prioritization mechanism of the present invention.

Figure 3 is a flow chart of a process 300 according to the present invention that includes method steps for classifying slot types and associating a user with a particular slot type. Radio resources are managed in a slotted wireless communication system 100 by classifying a plurality of time slots of the radio resources into a plurality of types, each type being associated with a different level of quality of service (QoS) (step 305), obtaining QoS information about a user in response to a radio resource request received by the user (step 310), the user then being associated with a particular type of time slot based on the QoS information of the user (step 315).

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention described above.

Claims (20)

1. A method for managing radio resources in a time-slotted wireless communication system, the method comprising:

(a) classifying a plurality of time slots of a radio resource into a plurality of different types, each type associated with a different level of quality of service (QoS)

(b) Obtaining quality of service (QoS) information for a user in response to a radio resource request received from the user; and

(c) associating the user with a particular timeslot type based on quality of service (QoS) information for the user.

2. The method of claim 1 wherein each timeslot is further designated as either a real time timeslot or a non-real time timeslot.

3. The method of claim 1 wherein the quality of service (QoS) information indicates a priority of the user's radio resource request.

4. The method of claim 3 wherein a radio resource request for the emergency call is assigned as a highest level of quality of service (QoS).

5. The method of claim 1 wherein the quality of service (QoS) information includes information regarding a particular one of a plurality of user classes, each class having a different level of QoS.

6. The method of claim 5 wherein a user designated as belonging to a higher subscriber category has a higher priority during handoff than a user of a lower subscriber category.

7. The method of claim 5 wherein a user designated as belonging to a higher subscriber category is guaranteed a higher data service rate than a user designated as belonging to a lower subscriber category.

8. The method of claim 5 wherein a user designated as belonging to a higher user class has a packet schedule with less delay and jitter than a user designated as belonging to a lower user class.

9. The method of claim 1 wherein the quality of service (QoS) information has information about a particular one of a plurality of different geographic regions, each region having a different level of quality of service (QoS), whereby only users with an appropriate level of priority are allowed access to radio resources in the particular geographic region.

10. The method of claim 1, further comprising:

(d) increasing the number of timeslots having a higher level of quality of service (QoS); and

(e) if congestion occurs in timeslots having a higher level of quality of service (QoS), the number of timeslots having a lower level of quality of service (QoS) is reduced.

11. A time-slotted wireless communication system for managing radio resources, the system comprising:

(a) means for classifying time slots of a plurality of radio resources into a plurality of different types, each type associated with a different level of quality of service (QoS);

(b) means for obtaining quality of service (QoS) information for a user in response to a radio resource request received by the user; and

(c) means for associating the user with a particular timeslot type based on quality of service (QoS) information for the user.

12. The system of claim 11 wherein each time slot is further designated as either a real time slot or a non-real time slot.

13. The system of claim 11 wherein the quality of service (QoS) information indicates the priority of the user's radio resource request.

14. The system of claim 13 wherein a radio resource request for the emergency call is assigned as a highest level of quality of service (QoS).

15. The system of claim 11 wherein the quality of service (QoS) information includes information about a particular one of a plurality of user classes, each class having a different level of quality of service (QoS).

16. The system of claim 15 wherein a user designated as belonging to a higher subscriber category has a higher priority during handoff than a user of a lower subscriber category.

17. The system of claim 15 wherein a user designated as belonging to a higher subscriber category is guaranteed a higher data service rate than a user designated as belonging to a lower subscriber category.

18. The system of claim 15 wherein a user designated as belonging to a higher subscriber category has less delay and jitter packet scheduling than a user designated as belonging to a lower subscriber category.

19. The system of claim 11 wherein the quality of service (QoS) information has information about a particular one of a plurality of different geographic areas, each area having a different level of quality of service (QoS), whereby only users with an appropriate level of priority are allowed access to radio resources in the particular geographic area.

20. The system of claim 11, further comprising:

(d) means for increasing the number of timeslots having a higher level of quality of service (QoS); and

(e) means for reducing the number of slots having a lower level of quality of service (QoS) if congestion occurs in slots having a higher level of quality of service (QoS).