WO2006046741A1

WO2006046741A1 - Method for allocating timeslots in a packet-switched circuit concurrent with a circuit-switsched connection in a mobile communication system, mobile station, base station and computer program

Info

Publication number: WO2006046741A1
Application number: PCT/JP2005/020045
Authority: WO
Inventors: David Edward Cooper; Timothy Giles Beard; Mungal Singh Dhanda; Wen Tao Kuang
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-10-25
Filing date: 2005-10-25
Publication date: 2006-05-04
Also published as: GB2419498B; GB2419498A; GB0423654D0

Abstract

A method for allocating timeslots for a packet-switched connection to a mobile station in a time-division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the method comprising: constructing an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; transmitting an identification value in a given timeslot to signal the allocation of assigned slots to said mobile station; wherein when said mobile station detects an identification value assigned to it in a timeslot at position i in said ordered list, said mobile station may cease to monitor all timeslots in the downlink ordered list at positions before i in the downlink ordered list for data transmissions and begins to transmit on all timeslots in the uplink ordered list at positions up to and including i. The method can be applied to mobile stations of DTM multislot classes 6, 7, 10 to 12, 32 to 34 and 37 to 39, as defined in 3GPP TS 45.002 Release 6.

Description

DESCRIPTION

METHOD FOR ALLOCATING TIMESLOTS IN A PACKET-SWITCHED CIRCUIT CONCURRENT WITH A CIRCUIT-SWITSCHED CONNECTION IN A MOBILE COMMUNICATION SYSTEM, MOBILE STATION, BASE STATION AND COMPUTER PROGRAM

Method of Allocating Timeslots in a Packet-Switched Circuit in a Mobile Communication System, Mobile Station, 5 Base Station and Computer Program

Technical Field

The present invention relates to methods of controlling slot assignment and allocation for packet- 10 switched circuits in a time division multiple access (TDMA) communication system, to base stations and mobile stations using the method and to computer programs for implementing the invention.

5 Background Art

GSM is a mobile communications system employing frequency and time division multiple access (FDMA & TDMA) techniques as well as a cellular structure that can carry both voice signals and data, using a system known as GPRS. 0 To operate the TDMA scheme, time in the GSM system is divided into a repeating structure of frames with each frame comprising 8 timeslots. For convenience, the beginning of each frame in the uplink, that is the channel for communication from a mobile station to a base station 5 begins 3 timeslots after the beginning of the corresponding frame on the downlink, that is the base to mobile station channel. This arrangement is shown in Figure 1 of the accompanying drawings. (It should be noted that the actual time at which a give mobile station transmits may be advanced from the time defined by the frame structure by an amount known as the timing advance, TA, which is determined according to the distance between the mobile station and the base station from time-to-time. For simplicity, this aspect of the GSM system is disregarded below.) As is well known, four TDMA frames are grouped in a radio block. Voice communications in GSM are carried on a "circuit- switched" basis whereby one timeslot per frame on a given radio channel is allocated to the downlink to a given mobile station and the correspondingly numbered timeslot on a corresponding radio channel is allocated to the uplink from that same mobile station for the entire duration of a call, irrespective of whether there is data to be transmitted at a given time. (Comfort noise may be transmitted in the event that one half of the conversation is silent) . The combination of one downlink slot and one uplink slot per frame is referred to as a full-rate traffic channel or TCH/F; a half-rate traffic channel or TCH/H comprising one uplink and one downlink slot every alternate frame may also be defined and used for voice communication. The constant time relationship between packets of data aids reconstruction of the voice signal.

GPRS is an extension of GSM that enables data communication carried out on a "packet-switched" basis whereby one or more slots in the uplink and downlink are assigned to a mobile when a GPRS connection is established for potential use for data transmission but assigned slots are allocated for actual use on a frame by frame basis according to the level of traffic on the network and whether or not data is waiting to be transmitted to or by the mobile station. It allows an increased data rate during packet data transfer by using more than one timeslot either for transmission or reception. For example, Figure 2 of the accompanying drawings illustrates a GPRS system where two slots are used for transmission and one for reception. The allocation of slots is controlled by the network (base station) and various schemes (referred to as MAC modes) are defined: fixed allocation, exclusive allocation, dynamic allocation and extended dynamic allocation. The later mode (described in GB-2, 398, 708-A) aims to assign multiple timeslots per frame in a flexible manner to make maximum usage of the capability of the mobile station, which is determined, among other things, by the rapidity with which the mobile station can

"turnaround" from receiving to transmitting and vice versa. The turnaround time is determined, among other things, by the ability of the mobile station to retune and stabilise its internal oscillator to match the different frequencies for transmission and reception and also by the need to perform adjacent cell signal level measurement. The 3GPP standards define various multislot classes for mobile stations according to their turnaround times and ability to use multiple slots per frame. For each multislot class, certain performance characteristics are defined: Rx - the maximum number of slots per frame in which the mobile can receive;

Tx - the maximum number of slots per frame in which the mobile can transmit;

Sum - the total number of slots per frame in which the mobile can transmit or receive

T_ta - the number of slots required by the mobile to perform adjacent cell signal level measurement and get ready to transmit;

T_tb - the number of slots required by the mobile to get ready to transmit without performing adjacent cell signal level measurement;

T_ra - the number of slots required by the mobile to perform adjacent cell signal level measurement and get ready to receive; T_rb - the number of slots required by the mobile to get ready to receive without performing adjacent cell signal level measurement.

Where a mobile station is capable of transmitting and receiving on more than one timeslot per frame, it would be desirable for a mobile station to be able to perform data transmissions at the same time as a voice transmission - known as a class A service. Figure 3 of the accompanying drawings shows an example of simultaneous use of circuit- switched and packet-switched connections. A so-called dual transfer mode (DTM) is defined for GSM/GPRS which makes use of the MAC modes known for GPRS. Unfortunately, DTM does not allow the mobile's full capability to be used in conjunction with dynamic channel allocation (which is an important case since dynamic allocation allows sharing of resources between different mobiles) . In particular the 3GPP standards do not permit any configuration of timeslots that allows mobiles of certain multislot classes (for example class 12 mobiles) to be dynamically allocated the maximum number of uplink slots "Tx" which they are capable of transmitting (although by using a static, exclusive allocation this is permitted) . Therefore the standards unnecessarily restrict the maximum amount of uplink bandwidth that can be dynamically allocated to the mobile, to less than the mobile's actual capability.

It should be noted that the above description of GSM and GPRS is a considerable simplification and additional information as to the operation of these systems is to be found in the various 3GPP standards available from the 3^rd Generation Partnership Project (www.3gpp.org) . Particularly relevant specifications are: 3GPP TS 45.002, 3GPP TS 44.060, 3GPP TS 44.018 and 3GPP TS 43.055. A useful primer and history of the early developments of GSM is "The GSM System for Mobile Communications" by M Mouly & M-B Pautet (ISBN 2-9507190-0-7) . It is an aim of the present invention to provide a method of allocating timeslots in a time-division multiple access communication system when providing circuit-switched and packet-switched connections to the same mobile station concurrently.

According to there is provided a method for allocating timeslots for a packet-switched connection to a mobile station in a time-division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the method comprising: constructing an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; transmitting an identification value in a given timeslot to signal the allocation of assigned slots to said mobile station; wherein when said mobile station detects an identification value assigned to it in a timeslot at position i in said ordered list, said mobile station need not monitor all timeslots in the downlink ordered list at positions before i in the downlink ordered list for data transmissions and begins to transmit on all timeslots in the uplink ordered list at positions up to and including i. With the allocation system of the present invention, the full capabilities of certain multi-slot classes of mobiles can be exploited for packet-switched data transmissions, that is a connection occupying dynamically allocated timeslots, concurrently with a circuit-switched connection, that is one occupying a fixed timeslot per frame. The invention thereby overcomes the special problem of the fixed position of the CS slot timing. The allocation scheme of the present invention may be referred to as "Special Extended Dynamic Allocation " (SEDA) , which is similar in some respects to Extended Dynamic Allocation (EDA) as defined for GPRS, but has a novel slot allocation rule.

The present invention may advantageously be applied to mobiles of multi-slot classes 3, 6, 7, 10 to 12, 31 to 34 and 36 to 39.

Brief Description of Drawings

The present invention will be described further below with reference to the following description of exemplary embodiments and the accompanying schematic drawings, in which:

Figure 1 illustrates the time slot structure used in

GSM; Figure 2 illustrates transmission on multiple time

slots in GPRS (packet-switched communication) ;

Figure 3 illustrates simultaneous circuit-switched

and packet-switched communication (Dual Transfer

Mode) in GSM/GPRS;

Figure 4 is a key for Figures 5 to 7;

Figures 5 to 7 illustrate possible multislot

configurations according to an embodiment of the

invention of dual transfer mode for various multislot

mobile stations;

Figure 8 illustrates a mobile communication system

according to an embodiment of the invention;

Figure 9 is a flow chart of the construction of an

uplink ordered list used in an embodiment of the

invention;

Figure 10 is a flow chart of the construction of a

downlink ordered list used in an embodiment of the

invention; Figure 11 is a flow chart of the construction of an

uplink ordered list used in another embodiment of the

invention; and

Figure 12 is a flow chart of the construction of a

downlink ordered list used in another embodiment of

the invention.

In the drawings, like elements are designated by like references.

Best Mode for Carrying Out the Invention

In an embodiment of the invention, rules are defined for the dynamic allocation of uplink and downlink slots in a packet-switched connection with a mobile station having multi-slot capabilities concurrently with a circuit- switched connection. For the sake of economy, only relevant details of a communication system embodying the invention will be described below, further information can be obtained from the references given above.

As shown in Figure 8, a GSM/GPRS mobile communication system comprises a base transceiver station BTS which communicates via radio with a plurality of mobile stations MSl, MS2. The base transceiver station is connected to a base station controller BSC, which in turn is connected to a wider communications network, such as a PSTN, ISDN or the Internet. The division of functions between BTS and BSC is not relevant to the present invention and the two are together referred to as a base station below. The mobile stations may receive and initiate voice calls from and to other mobile stations in the same or other communications systems as well as fixed terminals in the PSTN or ISDN networks. Data connections may also be made to connect the mobile station to the Internet or another communications network, e.g. to allow collection and transmission of e- mail or browse WAP or WWW sites via the Internet. A voice call is carried over a circuit-switched connection CSl or CS2 between the mobile station and the base station whilst a data connection is made over a packet-switched connection PS. In a so-called Class-A or Dual Transfer Mode, a circuit-switched connection CSl and a packet-switched connection PS are made concurrently with a single mobile station MSl.

The mobile communication system operates on a repeating frame structure, shown in Figure 1, in which radio channels are divided into frames, each frame comprising 8 timeslots of equal length numbered 0 to 7. This shows the frame from the point of view of the mobile stations, in that uplink slots are designated tx for transmit and downlink slots rx for receive. The frames of radio channels designated for uplink, that is from mobile station to base station, communication begin three timeslots later than those designated for downlink communication. It should be noted that the timing relationship between up and downlink frame structures is defined at the base station BTS; a mobile station will transmit ahead of its slot by an amount known as the timing advance TA which is determined dynamically in order to ensure that the burst transmitted by the mobile station arrives at the base station in its correct slot. This aspect of the system is well known and will not be discussed further below. When a voice connection is established to a mobile, the mobile station is allocated a full- or half-rate traffic channel TCH/F or TCH/H. A full-rate traffic channel TCH/F comprises one timeslot per frame in the downlink radio channel and the correspondingly numbered timeslot in the corresponding uplink radio channel. These slots are allocated to, and used by, the mobile station throughout the duration of the call, so that the mobile always receives and decodes data in the allocated downlink slot and always transmits data in the allocated uplink slot Comfort noise may be transmitted in the event that either half of the conversation is silent. A half-rate traffic channel comprises one downlink timeslot and the correspondingly numbered uplink timeslot in every alternate frame. In both cases there is a fixed timing relationship at the base station between signal bursts in the up and downlinks. If the mobile station has multislot capabilities - that is its ability to turnaround from transmission to reception and vice versa, the speed with which it can perform adjacent cell signal level measurement, its power supply and its processing speed are such that it is capable of transmitting and or receiving in more than one timeslot per frame - then a packet-switched connection may be made concurrently with the circuit-switched connection, as shown in Figure 3. A packet-switched connection differs from a circuit- switched connection in that although one or more downlink and/or uplink slots are assigned to the mobile station for potential use, they are not actually allocated for use unless there is actually data to be transmitted. The allocation of slots is controlled by the base station and takes account of network traffic and in particular the demands of other mobiles that may also have been assigned the same slots in the same channels. Methods for the mobile station to signal that it requires uplink bandwidth and for dividing the available slots between mobile stations are known and will not be described further herein,

In the prior art, when a packet-switched connection is being established, the base station sends to the mobile station a timeslot assignment message. This message identifies the timeslots in the up and downlinks that are allocated to the mobile station and provides and identification code for each timeslot. The identification code is known as a USF and may take one of eight values, allowing up to eight mobile stations to be assigned each slot. Different USF values may be assigned for each assigned timeslot. Timeslots may be assigned as full-rate packet data channels, referred to as a PDCH/F, in which the assignment is of the timeslot of that number in every frame. They may also be assigned as half-rate packet data channels, a PDCH/H, in which the assignments is of a given numbered timeslot in every alternate timeslot. Thus, the significance of a specific value taken by the USF depends on the timeslot in which it resides. In general, the value of the USF indicates two things:

(1) it identifies a mobile, if any, to which certain uplink resources will be allocated during the next radio block

(2) It identifies which uplink resources will be allocated to the identified mobile (if any is identified) .

Note that way in which the identified mobile determines the uplink resource is dependant on factors specific to the identified mobile, including the allocation mode of the mobile, the multislot class of the mobile and the currently assigned PDCHs. Existing allocation modes defined in the GSM standards include fixed allocation, dynamic allocation, exclusive allocation and extended dynamic allocation. The mobile station then monitors the assigned downlink timeslots to detect, in a signalling part- of the burst, a matching USF. For example, if mobile station MSl has been assigned slot 0 and given a USF value for that slot of 5, then if mobile station MSl detects the USF value 5 broadcast in downlink slot 0, it determines that a matching USF is detected. The detection of the matching USF and the timeslot in which it is detected signals to the mobile station which timeslots in the uplink it should use to transmit data.

To increase the number of packet channels that can be used by a mobile operating in DTM, the present invention decouples the USF from the corresponding downlink slot number. In other words, the downlink timeslot number on which USF_TNx appears is no longer restricted to timeslot x, The multislot class, the slot number allocated for the circuit switched call, and a set of ordering rules, and example of which is defined below, allow both the network and the mobile to construct the same slot ordering seguences (one seguence for the order of activating uplink slots, and one for the downlink slots on which the corresponding USFs will appear) . These orderings are dependant on multislot class and the CS timeslot number. The rules of the invention apply to the following multislot classes: 6, 7, 10, 11, 12, 32-34, 37-39. The mobile station may indicate its capability of operating according to the method of the invention to the network. SEDA will have to be explicitly enabled when uplink slots are assigned if it is to be applied to assignments that are currently possible without SEDA. Alternatively, SEDA can be implicit if a given assignment is not possible with existing allocation methods.

The present invention provides rules to define DL/UL mapping implicitly in both NW and MS, based on information available to both. This allows for a dynamic yet unambiguous allocation of maximum possible resources in Dual Transfer Mode.

In the following text, the Circuit Switched (CS) timeslot number is called N_Cs-

Firstly, an ordered set of numbers called the ^λuplink PDCH ordered list' is specified. This corresponds to the set of uplink PDCH numbers that the mobile can potentially be assigned in SEDA.

The uplink PDCH ordered list shall be contained within a contiguous range of integers i such that lo<= i<= hi , where: 0<= lo<=hi<=7, (1)

and

hi-lo <= Tx. (2) where Tx is the maximum number of transmit slots allowed by the MS multislot class. Tx_max is related to the maximum number of uplink PDCHs that can be assigned for a given multislot class in DTM and is given by the following equation:

Tx_max = max (0,min (Sum-3, Tx-I) ) (3)

The creation of the uplink PDCH ordered list is shown in Figure 9 and involves the following steps:

1) Initialise the uplink PDCH ordered list to the empty- set, i.e. containing no elements.

2) Construct the right hand set of list j uplink timeslots for potential allocation (see below) . 3) Modify the uplink PDCH ordered list if half rate CS is used (see below) .

The right hand set contains timeslots with the ordered list given below

[Ncs + 1 / Ncs +2 , N_cs +3 , ..., N_cs + j ] (4 ) This set is constructed by adhering to the following rules:

1. The slot number N_Cs +j is less than or equal to 7.

2. The Tra must be respected by slot number N_Cs +j and

the CS receive slot N_Cs in the next TDMA frame.

3. With this set appended to the uplink PDCH ordered

list, the total number of slots in the set are no

more than Tx_max

The right hand set is appended to the uplink PDCH ordered list. ^ If the half rate CS is used then the uplink PDCH

ordered list is modified by adding N_cs -1 to the end of the

list, hence the final list will contain:

[Ncs + 1 , Ncs +2 , ... . , N_cs + j , Ncs - 1 ] (5) Next, an ordered set of numbers called the ^downlink PDCH ordered list' is specified. This corresponds to the set of downlink PDCHs that the mobile can potentially monitor for USF in SEDA.

The downlink PDCH ordered list shall be contained within a contiguous range of integers (lo, hi) where 0<= lo<=hi<=7, and hi-lo <= Rx.

The maximum number of timeslots monitored on the downlink for USF is Tx_max as defined before.

The creation of the downlink PDCH ordered list is shown in Figure 10 and involves the following steps:

1. Initialise the downlink PDCH ordered list to the

empty set, i.e. containing no elements;

2. Add the slot N_cs +1 to the downlink PDCH ordered list;

3. Construct the left hand set of q timeslots for

potential USF monitoring (see below) ;

4. Reverse the downlink PDCH ordered list (see below) ; 5. Modify the downlink PDCH ordered list if half rate CS

is used (see below) ;

If the downlink PDCH ordered list contains fewer than Tx_max numbers, then numbers from the beginning of the following sequence (the ""receive left hand set') are appended to the downlink PDCH ordered list until either it contains Tx_max numbers or all numbers in the left hand set have been used:

The receive left hand set contains timeslots with the

ordered list given a below:

[Ncs -1, Ncs -2 , Ncs "3, ..., N_cs-q] (6)

This set is constructed by adhering to the following

rules :

1. The slot number N_Cs-q is greater than or equal to 0.

2. The Ttb must be respected by slot number N_Cs~q and the

CS transmit slot N_Cs in the previous TDMA.

3. With this set appended to the downlink PDCH ordered

list, the total number of slots in the set is no more

than Tx_max.

The final ordered set is reversed and called the downlink PDCH ordered list [Ncs-q, .../ Ncs-1/ N_cs+1] ⁽7⁾

If half rate CS is used then slot N_Cs is appended at the end of the downlink PDCH ordered list, hence the final list will contain: [Ncs-q, ..., Ncs-1, N_cs+1, N_cs] (8)

In the method of the present invention, the USF of an assigned uplink PDCH that occurs at position i in the uplink ordering can be monitored on the ith PDCH in the downlink PDCH ordering. Uplink PDCH ordered list:

[Ncs+1, ...., Ncs+j] (9) Downlink PDCH ordered list: [Ncs-q, -, Ncs-1, N_cs+1] (10)

The elements in the uplink PDCH ordered list and downlink PDCH ordered list are numbered consecutively starting from 1. The first element in the list has index 1 and the next element has index 2 and so on.

In operation, the mobile station shall monitor for a USF in downlink PDCHs contained in the downlink PDCH ordered list.

The mobile station shall search for a matching USF on all the PDCHs in the downlink PDCH ordered list whose index in that list corresponds to the index of an assigned PDCH in the uplink PDCH ordered list. If it finds a matching USF at position i in the downlink PDCH ordered list, then in the subsequent radio block (or group of 4 radio blocks) it need not monitor downlink PDCHs that have a position lower than i in the downlink PDCH ordered list, but shall attempt to monitor downlink PDCHs at position i or higher in the downlink PDCH ordered list.

If the CS channel is full rate, in the subsequent radio block (or group of 4 radio blocks) it shall transmit on all assigned PDCHs that have a position lower than or equal to i in the uplink PDCH ordered list.

If the CS channel is half rate, in the subsequent 2 radio blocks (or group of 4 radio blocks) it shall transmit on all assigned PDCHs that have a position lower than or equal to i in the uplink PDCH ordered list. If the mobile station is polled on the half rate channel, then the mobile station may send a poll response on one of the uplink assigned timeslots. Table 1 below shows the result of applying the rules defined in this document to a MS that is capable of transmitting on 5 slots, for example class 34. The uplink CS timeslot N_Cs is never used for packet data. The bottom row and rightmost column are only applicable if a half rate CS is resource is assigned. The table shows the of the uplink ordered list (contained in top row) and the downlink ordered list, (contained in left hand column) . The ticks in a horizontal row show the uplink PDCHs on which the mobile station can transmit if a USF is found on the downlink PDCH at the left of that row.

Table 1

Transmit Slot

Figures 5, 6 and 7 show example allocations using the

method of an embodiment of the invention, Figure 4 gives a

key to these figures .

An alternative embodiment of the invention utilises a

modification of the above rules, as described below.

The creation of the uplink PDCH ordered list is shown in Figure 11 and involves the following steps: 1. Initialize the uplink PDCH ordered list to the empty set, i.e. containing no elements.

2. Add the slot N_cs -1 to the uplink PDCH ordered list.

3. Construct the right hand set of list j uplink timeslots for potential allocation (see below) .

The right hand set contains timeslots with the ordered list given below

[Ncs +1, Ncs +2 , ..., Ncs +j ] (11) This set is constructed by adhering to the following rules:

1. The slot number N_Cs +j is less than or equal to 7.

2. Tra must be respected by slot number N_Cs +j and the CS receive slot N_Cs in the next TDMA frame. 3. With this set appended to the uplink PDCH ordered list, the total number of slots in the set are no more than Tx_max

The right hand set is appended to the uplink PDCH ordered list and hence the final list will contain:

[Ncs -1/ Ncs +1, Ncs +2, .... , N_cs +j ] (12) The creation of the downlink PDCH ordered list is shown in Figure 12 and involves the following steps:

1. Initialise the downlink PDCH ordered list to the

empty set, i.e. containing no elements

2. Construct the left hand set of q timeslots for

potential USF monitoring (see below)

3. Reverse the downlink PDCH ordered list (see below)

4. Modify of the downlink PDCH ordered list if half rate

CS is used (see below)

If the downlink PDCH ordered list contains fewer than Tx_max numbers, then numbers from the beginning of the following sequence (the ^receive left hand set') are appended to the downlink PDCH ordered list until either it contains Tx_max numbers or all numbers in the left hand set have been used.

The receive left hand set contains timeslots with the ordered list given below: [Ncs -1, Ncs -2 , N_cs -3, ..., N_cs -q] (13) This set is constructed by adhering to the following rules :

1. The slot number N_Cs -q is greater than or equal to 0. 2. Ttb must be respected by slot number N_Cs -q and the CS transmit slot N_Cs in the previous TDMA.

3. The total number of slots in the set is no more than Tx_max.

The final ordered set is reversed and called the downlink PDCH ordered list

[N_cs -q, ..., Ncs -1] (14)

If half rate CS is used then slot N_Cs is appended at the end of the downlink PDCH ordered list, hence the final list will contain: [Ncs -q, ..., N_cs -1, N_cs] (15)

In this embodiment, the rules about USF monitoring

and the relationship to the uplink timeslots is exactly

same as in the first embodiment.

Table 2 below shows the result of applying the alternative rules defined in this document to a MS that is capable of transmitting on 5 slots, for example class 34.

The uplink CS timeslot N_Cs is never used for packet data.

The bottom row is only applicable if a half rate CS resource is assigned. The table shows the uplink ordered list (contained in top row) and the downlink ordered list (contained in left hand column) . The ticks in a horizontal row show the uplink PDCH on which the MS can transmit if a USF is found on the downlink PDCH at the left of that row.

Table 2

The method of the invention can be applied to mobile stations of DTM multislot classes 6, 7, 10 to 12, 32 to 34 and 37 to 39, as defined in 3GPP TS 45.002 Release 6. The capabilities of these classes are set out in Table 3 below:

Table 3

Rx :

Rx describes the maximum number of receive timeslots that the MS can use per TDMA frame. The MS must be able to support all integer values of receive TS from 0 to Rx (depending on the services supported by the MS) . The receive TS need not be contiguous. For type 1 MS, the receive TS shall be allocated within window of size Rx, and no transmit TS shall occur between receive TS within a TDMA frame. Tx:

Tx describes the maximum number of transmit timeslots that the MS can use per TDMA frame. The MS must be able to support all integer values of transmit TS from 0 to Tx (depending on the services supported by the MS) . The transmit TS need not be contiguous. For type 1 MS, the transmit TS shall be allocated within window of size Tx, and no receive TS shall occur between transmit TS within a TDMA frame. Sum: Sum is the total number of uplink and downlink TS that can actually be used by the MS per TDMA frame. The MS must be able to support all combinations of integer values of Rx and Tx TS where 1 <= Rx + Tx <= Sum (depending on the services supported by the MS) . Sum is not applicable to all classes. T_ta :

T_ta relates to the time needed for the MS to perform adjacent cell signal level measurement and get ready to transmit. For type 1 MS it is the minimum number of timeslots that will be allowed between the end of the previous transmit or receive TS and the next transmit TS when measurement is to be performed between. It should be noted that, in practice, the minimum time allowed may be reduced by amount of timing advance.

For type 1 MS that supports extended TA, the parameter T_ta is increased by 1 if TA > 63 and there is a change from RX to TX.

For type 2 MS it is not applicable.

T_tb relates to the time needed for the MS to get ready to transmit. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected. For type 1 MS it is the minimum number of timeslots that will be allowed between the end of the last previous receive TS and the first next transmit TS or between the previous transmit TS and the next transmit TS when the frequency is changed in between. It should be noted that, in practice, the minimum time allowed may be reduced by the amount of the timing advance. For type 1 MS that supports extended TA, the parameter T_tb = 2 if TA > 63 and there is a change from RX to TX.

For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last transmit burst in a TDMA frame and the first transmit burst in the next TDMA frame.

Tra.•

T_ra relates to the time needed for the MS to perform adjacent cell signal level measurement and get ready to receive.

For type 1 MS it is the minimum number of timeslots that will be allowed between the previous transmit or receive TS and the next receive TS when measurement is to be performed between. For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.

An MS, except for multislot class 30 - 45, shall be able to decode SCH from a neighbour cell, independent of its relative timing, using an idle frame in combination with T_ra from the preceding frame.

Trb^:

^rb relates to the time needed for the MS to get ready to receive. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected. For type 1 MS it is the minimum number of timeslots that will be allowed between the previous transmit TS and the next receive TS or between the previous receive TS and the next receive TS when the frequency is changed in between.

For type 2 MS it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.

It will be appreciated that the above description of exemplary embodiments is intended to be illustrative not limitative. The invention may be embodied in other forms and is defined in the appended claims. Computer programs to implement the method of the invention in a mobile station or base station can be written in any suitable language, given the teachings set out above.

Claims

1. A method for allocating timeslots for a packet- switched connection to a mobile station in a time-division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the method comprising: constructing an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; transmitting an identification value in a given timeslot to signal the allocation of assigned slots to said mobile station; wherein when said mobile station detects an identification value assigned to it in a timeslot at position i in said ordered list, said mobile station may cease to monitor all timeslots in the downlink ordered list at positions before i in the downlink ordered list for data transmissions and begins to transmit on all timeslots in the uplink ordered list at positions up to and including i.

2. A method according to claim 1 wherein data of a plurality of frames is combined to form a radio block and changes in allocation of timeslots are applied in the radio block after the radio block in which said identification value is transmitted.

3. A method according to claim 2 wherein the mobile station transmits in timeslots determined by the position of the detected identification value for the next radio block if the circuit-switched connection occupies one time slot in the uplink and downlink in each frame.

4. A method according to claim 2 wherein the mobile station transmits in timeslots determined by the position of the detected identification value for the next two radio blocks if the circuit-switched connection occupies one time slot in the uplink and downlink only in every alternate frame.

5. A method according to claim 2 wherein the mobile station transmits in timeslots determined by the position of the detected identification value for the next four radio blocks.

6. A method according to any one of the preceding claims wherein the uplink ordered list consists of timeslot numbers [N_Cs+l/ ...• / N_Cs+j ] / where N_Cs is the number of the timeslot containing the circuit-switched connection, and j is determined such that N_Cs+j is less than or equal to 7, the interval between N_Cs+j and N_Cs is sufficient to allow the mobile station to perform turnaround to receive with adjacent cell power measurement, and the total number of slots in the uplink ordered list is less than or equal to Tx_max, where Tx_max is the largest of 0 and the smallest of Sum-3 and Tx-I, where Sum is the maximum number of slots the mobile can transmit or receive on in a frame and Tx is the maximum number of slots the mobile station can transmit on in a frame.

7. A method according to claim 6 wherein if the circuit- switched communication link occupies one time slot in the uplink and downlink only in every alternate frame, said uplink ordered list further comprises the slot N_Cs~l in the final position.

8. A method according to any one of claims 1 to 5 wherein the uplink ordered list consists of timeslot numbers [N_Cs-l_/ Ncs+1, Ncs+2,...., Ncs+j ] , where N_cs is the number of the timeslot containing the circuit-switched connection, and j is determined such that N_Cs+j is less than or equal to 7, the interval between N_Cs+j and N_Cs is sufficient to allow the mobile station to perform turnaround to receive with adjacent cell power measurement, and the total number of slots in the uplink ordered list is less than or equal to Tx_max, where Tx_max is the largest of 0 and the smallest of Sum-3 and Tx-I, where Sum is the maximum number of slots the mobile can transmit or receive on in a frame and Tx is the maximum number of slots the mobile station can transmit on in a frame.

9. A method according to anyone of claims 1 to 7 wherein the downlink ordered list comprises Tx_max timeslots from the beginning of the list [N_Cs-l_/ N_Cs-2, ...., N_Cs~q] , where Tx_max is the largest of 0 and the smallest of Sum-3 and Tx-I, where Sum is the maximum number of slots the mobile can transmit or receive on in a frame and Tx is the maximum number of slots the mobile station can transmit on in a frame, N_Cs is the number of the timeslot containing the circuit-switched connection, and q is determined such that Ncs~q is greater than or equal to 0 and the interval between Ncs-q and N_Cs is sufficient to allow the mobile station to perform turnaround to transmit without adjacent cell power measurement, the timeslots taken from the list [N_Cs-l_/ N_Cs-2, ...•_/ Ncs-q] being positioned in ascending order in the downlink ordered list and the downlink ordered list further comprising timeslot N_cs+1.

10. A method according to claim 9 wherein if the circuit- switched communication link occupies one time slot in the uplink and downlink only in every alternate frame, said uplink ordered list further comprises the slot N_Cs in the final position.

11. A method according to any one of claims 1 to 5 or 8 wherein the downlink ordered list comprises Tx_max timeslots from the beginning of the list [N_Cs~l, N_Cs-2, .... , Ncs-q] / where Tx_max is the largest of 0 and the smallest of Sum-3 and Tx-I, where Sum is the maximum number of slots the mobile can transmit or receive on in a frame and Tx is the maximum number of slots the mobile station can transmit on in a frame, N_Cs is the number of the timeslot containing the circuit-switched connection, and q is determined such that Ncs~q is greater than or equal to 0 and the interval between N_Cs-q and N_cs is sufficient to allow the mobile station to perform turnaround to transmit without adjacent cell power measurement, the timeslots taken from the list [Ncs~l/ Ncs~2, ...., Ncs-q] being positioned in ascending order in the downlink ordered list.

12. A method according to claim 11 wherein if the circuit- switched communication link occupies one time slot in the uplink and downlink only in every alternate frame, said downlink ordered list further comprises the slot N_Cs in the final position.

13. A method according to any one of the preceding claims wherein said mobile station satisfies the requirements of one of multi-slot classes 6, 7, 10 to 12, 32 to 34 and 37 to 39.

14. A method in a mobile station of transmitting data to a base station over a packet-switched connection in a time- division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the method comprising: constructing an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; monitoring timeslots in the downlink for an identification value assigned to the mobile station to signal the allocation of assigned slots; and when an identification value assigned to the mobile station is detected in a timeslot at position i in said ordered list, transmitting on all timeslots in the uplink ordered list at positions up to and including i.

15. A method according to claim 14 wherein when the identification value is detected, the mobile station ceases to monitor all timeslots in the downlink ordered list at positions before i in the downlink ordered list.

16. A method in a base station for receiving data from a mobile station over a packet-switched connection in a time- division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the method comprising: constructing an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; transmitting an identification value in a given timeslot to signal the allocation of assigned slots to said mobile station; and receiving data from the mobile station on all timeslots in the uplink ordered list at positions up to and including i.

17. A mobile station for transmitting data to a base station over a packet-switched connection in a time- division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the mobile station comprising: a processor arranged to construct an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; a receiver arranged to monitor timeslots in the downlink for an identification value assigned to the mobile station to signal the allocation of assigned slots; and a transmitter arrange, when an identification value assigned to the mobile station is detected in a timeslot at position i in said ordered list, to transmit on all timeslots in the uplink ordered list at positions up to and including i .

18. A mobile station according to claim 17 wherein said receiver is further adapted, when the identification value is detected, to cease to monitor all timeslots in the downlink ordered list at positions before i in the downlink ordered list.

19. A base station for receiving data from a mobile station over a packet-switched connection in a time- division multiple access communication system, having a repeating cycle of frames each divided into timeslots, concurrently with a circuit-switched connection occupying fixed timeslots in uplink and downlink channels, the base station comprising: a processor arranged to construct an uplink ordered list of timeslots and a downlink ordered list of timeslots according to a predetermined rule; a transmitter arranged to transmit an identification value in a given timeslot to signal the allocation of assigned slots to said mobile station; and a receiver arranged to receive data from the mobile station on all timeslots in the uplink ordered list at positions up to and including i.

20. A communication system comprising a base station according to claims 16 and a mobile station according to claim 17 or 18.

21. A computer program comprising program code means that, when executed by a processor in a mobile station, instructs the mobile station to effect the method of claim 14 or 15.

22. A computer program comprising program code means that, when executed by a processor in a base station, instructs the base station to effect the method of claim 16.