Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0446—Resources in time domain, e.g. slots or frames
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
  • H04W28/18—Negotiating wireless communication parameters
  • H04W28/22—Negotiating communication rate

Definitions

• the invention relates to a method for traffic management in a radio system and a network element.
• NRT non-real-time
• Multisystem radio traffic management is required to balance RT (real time) load and, naturally in pursuance also interference, evenly between cells, thus maximizing the trunking efficiency.
• the purpose of multiradio traffic management is to balance the NRT load (and/or interference) evenly between cells and thus to maximize the throughput i.e. to minimize the delay experienced by a user.
• trunking gain can be achieved, for example, by directing an RT user and/or NRT user to another system, or to another layer or frequency when the load is heavy thus reducing blocking.
• a NRT user can also be directed to an adjacent cell of the same layer or system.
• directing is typically called handover (HO) but it can also be called network controlled cell reselection (NCCRS).
• the cell load of the radio cells in a radio system has typically been measured by monitoring occupation of physical resources, interference or throughput or buffer delays.
• the calculation/mapping of delay/throughput values to actual nRT load is problematic mainly because it depends a lot on the system (GPRS/EGPRS, for instance).
• a problem is also that calculating and mapping depends a lot on the radio conditions (network scenario, frequency reuse, etc.).
• the delay caused by network elements such as SGSN (serving GPRS support node) cannot necessarily be taken into account.
• the invention provides an improved traffic management method in a telecommunication system.
• a traffic management method in a telecommunication system includes dividing a time slot into a predetermined number of sub-blocks, defining the amount of available capacity for non-real time use in a time slot, defining the number of sub-blocks reserved by real time use in a time slot, defining the number of sub-blocks reserved by non-real time use in a time slot, defining the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non-real time use, calculating a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, averaging a sub-block reservation rate for a time slot to get down link sub-block reservation rate.
• a traffic management method in a telecommunication system includes dividing a time slot into a predetermined number of sub-blocks, defining the amount of available capacity for non-real time use in a time slot, defining the number of sub-blocks reserved by real time use in a time slot, defining the number of sub-blocks reserved by non-real time use in a time slot, defining the number of free sub-blocks in a time slot on the basis of sub- blocks reserved by real time use and sub-blocks reserved by non-real time use, calculating a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, averaging a sub-block reservation rate for a time slot to get down link sub-block reservation rate, directing transmission in the telecommunication system to less loaded cells or timeslots
• a network element including means for dividing a time slot into a predetermined number of sub-blocks, defining the amount of available capacity for non-real time use in a time slot, defining the number of sub- blocks reserved by real time use in a time slot, defining the number of sub- blocks reserved by non-real time use in a time slot, defining the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non-real time use, calculating a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, averaging a sub-block reservation rate for a time slot to get down link sub-block reservation rate.
• a network element including means for dividing a time slot into a predetermined number of sub-blocks, defining the amount of available capacity for non-real time use in a time slot, defining the number of sub- blocks reserved by real time use in a time slot, defining the number of sub- blocks reserved by non-real time use in a time slot, defining the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non-real time use, calculating a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, averaging a sub-block reservation rate for a time slot to get down link sub-block reservation rate, directing transmission in the telecommunication system to less loaded cells or timeslots.
• a network element configured to divide a time slot into a predetermined number of sub-blocks, define the amount of available capacity for non-real time use in a time slot, define the number of sub-blocks reserved by real time use in a time slot, define the number of sub-blocks reserved by non-real time use in a time slot, define the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non- real time use, calculate a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, average a sub-block reservation rate for a time slot to get down link sub-block reservation rate.
• a network element configured to divide a time slot into a predetermined number of sub-blocks, define the amount of available capacity for non-real time use in a time slot, define the number of sub-blocks reserved by real time use in a time slot, define the number of sub-blocks reserved by non-real time use in a time slot, define the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non- real time use, calculate a sub-block reservation rate for a time slot on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use, average a sub-block reservation rate for a time slot to get down link sub-block reservation rate, direct transmission in the telecommunication system to less loaded cells or timeslots.
• the invention is capable of providing information on how many RT and NRT users are sharing per timeslot, i.e., cell load information including also NRT users.
• Figure 1 shows an example of a telecommunication system
• Figure 2 is a flow chart of a method for traffic management according to one embodiment of the invention.
• Figures 3A-B show examples of an embodiment of the invention.
• Figure 4 illustrates an example of a base station controller according to an embodiment of the invention.
• FIG. 1 illustrates a simplified radio system, which includes the main parts of a radio system: a core network (CN) 100, radio access networks 106 and user equipment (UE) 150.
• CN core network
• UE user equipment
• the radio system of the 2.5 generation radio system is represented by a radio system which is based on the GSM (Global System for Mobile Communications), and which uses the EDGE technique (Enhanced Data Rates for Global Evolution) for increasing the data transmission rate, and which can also be used for implementing packet transmission in the GPRS system (General Packet Radio System).
• GSM Global System for Mobile Communications
• EDGE Enhanced Data Rates for Global Evolution
• GPRS General Packet Radio System
• the Base Station Subsystem (BSS) 106 based on the GSM includes a base station controller (BSC) 108 and base transceiver stations (BTS) 110, 112.
• BSC base station controller
• BTS base transceiver stations
• the base station controller 108 controls the base transceiver stations 110, 112.
• the interface 114 between the core network 100 and the BSS 106 is called A.
• the interfaces between the BSC 108 and BTS 110, 112 are called A- bis.
• the devices implementing the radio path and their functions should be located in the base transceiver station 110, 112 and the management devices in the base station controller 108. Different implementations may however naturally exist.
• Figure 1 also illustrates the coverage areas, i.e. cells, of the base stations of the different radio access networks.
• Cells 146 and 148 represent the coverage areas of the base stations 110 and 112.
• Base station 110, 112 may either serve one cell, as illustrated in Figure 1, or several cells which in the case of base stations, can be sectored cells.
• User equipment 150 illustrated in Figure 1 includes at least one transceiver for establishing a radio connection to the radio access network 106.
• user equipment 150 is a mobile station, further including an antenna, a user interface and a battery.
• Various kinds of user equipment 150 are available, e.g. equipment installed in a car and portable equipment, and user equipment 150 can also have properties similar to those of a personal computer or a portable computer.
• User equipment 150 is connected to the radio system via the base station and the base station controller, for providing the user with access to the core network of the telecommunications system.
• Trunking efficiency of a network can be improved by introducing a method to balance the load between different systems or carriers.
• Trunking gain in a multi-radio environment can be achieved by, for example, directing a real-time (RT) user to other system, layer or frequency when the load is high or directing a non-real time (NRT) user to other system, layer or frequency when the cell throughput is below predetermined threshold, in other words, when delay is too long.
• RT real-time
• NRT non-real time
• the purpose of multi-radio traffic management is to balance NRT load (and/or interference) evenly between cells and therefore maximize throughput i.e. minimize delay.
• NRT load estimation is used in CRRM (common radio resource management or centralized radio resource management) prioritization algorithms to evaluate target cells for NRT services.
• RT load has to be included in target cell evaluation since the probability to acceptable throughput for NRT users is lower when RT load is high.
• the main purpose of the traffic management method is to define a sub-block reservation rate for down link. By the aid of the defined sub-block reservation rate it is possible to control cell load and direct users to a suitable (not overloaded) system, layer or frequency. The method starts from block 200.
• a time slot is divided into a predetermined number of sub-blocks.
• TBF means temporary block flow or temporary GPRS connection block flow. It is used principally in GPRS or EGPRS networks.
• GPRS means general packet radio service. GPRS is a mobile service which gives packet-switched access over GSM to external data networks. EGPRS in turn means enhanced general packet radio service. It differs from a general packet radio service such that its data rate is increased up to threefold with EDGE (enhanced data rates for GSM evolution) modulation.
• EDGE enhanced data rates for GSM evolution
• TBF typically means a physical connection where multiple mobile stations (MS) share one traffic channel which is dedicated to one MS at a time, meaning that one MS is transmitting or receiving at a time. TBF is maintained only for the duration of the data transfer. Seven uplink and nine downlink TBFs can share the resources of a time slot.
• the amount of available capacity for non-real time use in a time slot is defined. This can be done by using the equation NRT _ share _ per _ TSL
• M the number of real time users per timeslot having a guaranteed bit rate
• GBR means a guaranteed bit rate
• R rb _ est average bit rate per radio block in a time slot, i means a time slot of interest.
• R r e st is the average bit rate per radio block in a time slot, accordingly, it is the number of bits transmitted (kbps) in a radio block as estimated by a scheduler divided by block period duration (for instance 20 ms), and averaged over several radio blocks.
• Tp est instead of R r b est .
• Throughput estimation parameter Tp es t indicates the minimum throughput that a time slot can provide to guaranteed bit rate (GBR) connections.
• the parameters are typically set by an operator or they are adapfively estimated.
• a real time user can be a guaranteed bit rate user. If the bit rate is guaranteed, the radio management has to take care that the guaranteed resources are allocated to a user even if there is rush (shortage of resources) in a network.
• the number of sub-blocks reserved by real time use in a time slot is defined.
• network elements taking care of radio resource management such as base station controllers, have the knowledge of real time communication in its area.
• the number of sub-blocks reserved by non-real time use in a time slot is defined.
• network elements taking care of radio resource management such as base station controllers, have the knowledge of non-real time communication located in their area.
• the number of free sub-blocks in a time slot on the basis of sub-blocks reserved by real time use and sub-blocks reserved by non- real time use is defined.
• the number of free sub-blocks are preferably calculated by using the equation
• FreeTBFs 1 9 - TBF R l T - TBF m l ⁇ (2)
• TBF R ' T is the number of sub-blocks reserved for real time use
• TBF m ' ⁇ is, the number of sub-blocks reserved for non-real time use, i means a time slot of interest.
• the sub-block division is not TBF sub-block division, the number of sub-blocks per time slot naturally changes.
• a sub-block reservation rate for a time slot is calculated on the basis of the number of free sub-blocks, the amount of available capacity for non-real time use in a time slot and the number of sub-blocks in a time slot not reserved by real time use. This is preferably done by using the equation
• TBF RT is the number of sub-blocks reserved for real time use
• TBF N ' RT is the number of sub-blocks reserved for non-real time use
• NRT_share_per_TSL 1 is the amount of available capacity for non-real time use in a time slot calculated in block 204, i means a time slot of interest.
• the sub-block division is not TBF sub-block division, the number of sub-blocks pre time slot naturally changes.
• a sub-block reservation rate for a time slot is averaged to determine the down link sub-block reservation rate.
• the averaging is done within a group, the group including time slots reserved for non-real time use in a cell.
• the averaging can be done by using the equation
• TBFreservationrate ' TBFreservationrateDL — (4)
• TBFreservationrate is calculated according to the equation (3), i means a time slot of interest,
• TSL means a predetermined number of time slots reserved for packet data in a cell.
• Packet data is typically relayed as non-real time transmission. In GPRS systems this is called a dedicated PS (Packet Switched) territory or GPRS territory. All the packet switched data is directed to this territory.
• PS Packet Switched
• the size of the PS territory can vary according to the load in PS territory in relation to the load elsewhere in a cell.
• TBFreservationrate is calculated according to the equation (3), i means a time slot of interest,
• NRT_share_per_TSL 1 is the amount of available capacity for non-real time use in a time slot calculated in block 204,
• TSL means a predetermined number of time slots reserved for packet data in a cell.
• the invention takes into account the guaranteed bit rate (real-time) users while determining the TBF reservation rate by estimating how many NRT TBFs are needed for replacing the RT TBFs in order to generate equal bit rate per NRT TBF in the scheduler, while certain number of TBFs are still available for NRT users.
• NRT users are directed to less loaded cells or time slots on the basis of this information.
• the arrow 220 depicts the possibility to continue the method from beginning and thus define reservation rates for more time slots or cells before directing transmission, for instance.
• the method ends in block 218.
• the arrow 222 depicts one example of repeating the method.
• a carrier is divided into 8 time-slots one of which (the slot 0) is used as BCCH (broadcast control channel).
• BCCH is a channel from a base transceiver station to a mobile station used for transmission of messages to all mobile stations located in the base transceiver station area. It is not used as a traffic channel and therefore there are 7 time-slots reserved for traffic.
• Time slots of one carrier are marked with number 306.
• RT and NRT traffic per a time-slot a solid line filling indicates real time, RT, users and a broken line filling indicates non-real time, NRT, users.
• All the 7 traffic time-slots are in turn divided into 9 sub-blocks that is shown by the aid of the square 300. Each box indicates one TBF sub-block.
• the boxes marked with a solid line filling are real time RT users as shown with the reference number 302.
• the boxes marked with a broken line filling are non-real time NRT users, which is shown with the number 304. There are 24 sub-blocks reserved by NRT users and eight sub-blocks reserved by RT users.
• throughput estimation parameter Tp es t indicates the minimum throughput that a time slot can provide to guaranteed bit rate (GBR) connections
• GRR guaranteed bit rate
• TBF reservation rate is in reality higher than the result calculated by the prior art method, where TBF reservation rate is calculated by dividing the maximum number of available TBFs by currently reserved TBFs. The prior art method would give 0.49 as TBF reservation rate in this example.
• a carrier is divided into 8 time-slots one of which (the slot 0) is used as BCCH.
• BCCH is a channel from a base transceiver station to a mobile station used for transmission of messages to all mobile stations located in the base transceiver station area. It is not used as a traffic channel and therefore there are 7 time-slots reserved for traffic.
• Time slots of one carrier are marked with number 314.
• a solid line filling indicates real time, RT, users and a broken line filling indicates non-real time, NRT, users.
• All the 7 traffic time-slots are in turn divided into 9 sub-blocks that is shown by the aid of the square 308. Each box indicates one TBF sub-block.
• the boxes marked with a solid line filling are real time RT users as shown with the reference number 310.
• the boxes marked with a broken line filling are non-real time NRT users, which is shown with the number 312. There are 12 sub-blocks reserved by NRT users and 26 sub-blocks reserved by RT users.
• throughput estimation parameter Tp es indicates the minimum throughput that a time slot can provide to guaranteed bit rate (GBR) connections
• GRR guaranteed bit rate
• TBF reservation rate is calculated by dividing the maximum number of available TBFs by currently reserved TBFs
• GBR low bit rate
• a Push-to-talk means establishing a half-duplex voice connection (similarly to a walkie- talkie-system) by selecting a contact or group of contacts.
• Figure 4 illustrates an example of a base station controller which is one example of a network element according to an embodiment of the invention.
• the base station controller of Figure 4 is depicted as a block diagram which illustrates the logical structure of a base station controller.
• a base station controller is a switching and controlling element of a cellular radio network.
• a base station controller can be implemented in many ways: it can be a separate device belonging to a telecommunication system or it can be a computer program run in an Internet server, for instance, just to mention but a few examples.
• the base station controller is the switching and controlling element of the network.
• the switching unit 400 takes care of the connection between the core network and the user equipment.
• the base station controller is connected to these interfaces via interface units 404, 412.
• the precise implementation of the radio network controller is vendor-dependent.
• the functionality of a base station controller can be classified into two classes: radio resource management 408 and control functions 406.
• An operation and management interface function 410 serves as a medium for information transfer to and from the network management functions.
• the radio resource management is a group of algorithms used to share and manage the radio path connection so that the quality and capacity of the connection are adequate. The most important radio resource management algorithms are handover control, power control, admission control, frequency hopping and packet scheduling.
• a base station controller has information on free and reserved radio channels and the quality of them. It also processes measurement results made by user equipment or base stations.
• the radio resource management block therefore typically includes also memory 418.
• the control functions take care of functions related to the set-up, maintenance and release of a radio connection between the base stations and user equipment.
• the disclosed functionalities of the described embodiments of the traffic management method can be advantageously implemented by means of software which is typically situated in the radio resource management block of a base station controller or of a corresponding device.
• the implementation solution can also be for instance an ASIC (Application Specific Integrated Circuit) component.
• a hybrid of these different implementations is also feasible.

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• 2004
  • 2004-05-12 WO PCT/FI2004/000285 patent/WO2004102899A1/en active Application Filing
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