SE518262C2 - Channel jumping in a radio communication system - Google Patents

Abstract

The invention relates to a method and apparatus for channel hopping between mobile stations (MS1-MS3) and a base station (BS1) in a radio communications system. A channel allocation means (211) within the base station (BS1) generates channel hopping sequences that are transmitted via a control channel (SACCH) to hopping sequence lists (204-206) in the mobile stations (MS1-MS3). The hopping sequences are also transmitted to corresponding hopping sequence lists (201-203) in the base station (BS1). A channel hopping sequence is divided into a number of sequence intervals (Ti) corresponding to the time between two adjacent channel hops within a channel hopping sequence. In the channel allocation means (211) the attenuation ( delta ) of the connections (F1-F3) and the interference (I(channel,t)) of the channels are continuously being observed within each sequence interval (Ti). The channel allocation means (211) generates channel hopping sequences according to the principle that a connection that has poor connection quality will be allocated a channel hopping sequence with channels of high channel quality and connections with successively better connection quality are allocated channel hopping sequence having successively poorer channels.

Description

\, 2 ... M opposite direction from the mobile station to the base station. Transmission and reception of radio traffic for different connections takes place on channels, which can be defined by a certain frequency in an FDMA system ("Frequency Division Multiple Access") or by a combination of a certain frequency and a certain time slot in a Time Division Multiple Access (TDMA) systems In a Code Division Multiple Access (CDMA) system, a channel can be defined by a code.In general, the channels available in a radio communication system 10 in be disturbed to a different degree by other radio traffic, also by radio signals on the same channels used for other connections, each channel in the system having a certain level of interference. If each connection only uses one channel, this will thus lead to the connections having different Some connections may then be so interfered with that an acceptable call quality is not obtained.

To even out these differences in the call quality of the connections, they can jump between different channels, the connections using channels with different interference levels. In this way, the use of the channels is spread between the different connections and with the help of interleaving and error-correcting coding, more connections can obtain an acceptable call quality if the system is considered as a whole.

Each connection can be assigned a plurality of channels, the system controlling the connections during the communication thread so that they jump between the channels according to a given rule for the jumps. The said rule may, for example, be a predetermined pseudo-random series, in which case the connections in that case seem to jump randomly between all available channels, see for example the European patent application EP 93905701-4. 518 262 j§_ m ||| However, the level of interference can become unnecessarily high when this type of channel hopping is used, since the channels are not always assigned to the connections in an optimal way when using a pseudo-random series.

Another type of canal jumping is cyclic canal jumping. This means that a connection jumps between a number of channels according to a channel jump sequence which is repeated cyclically.

As is well known, channel jumping can be applied in a GSM system.

The GSM system is a TDMA system, which means that each frequency is divided into a number of time slots which form a TDMA frame. In the GSM system, a TDMA frame consists of eight time slots. When connecting a connection between base station and mobile station in a GSM system, the connection is assigned one of the time slots per TDMA frame. The channel jump is then achieved by the connection jumping between different channels having the same time slot, whereby the connection in practice only jumps between different frequencies. According to the GSM specification, a frequency can only occur once within a channel jump sequence and the frequencies in a channel jump sequence always occur in ascending order. However, the length of the channel jump sequences may vary between different base stations.

In a radio communication system, there are normally a number of channels that can be used for connections between a certain base station and mobile stations. It is then important that the same channel is not used simultaneously for two or more connections between the base station and mobile stations. If two transmitters in the base station transmit different signals simultaneously on the same channel to their respective receivers, it is very likely that at least one receiver will be disturbed due to interference from the transmission to the other receiver. If the above-mentioned situation can not occur, ie when only one of the base station's connections can transmit on one channel at a time, what is called "base station orthogonality" or "base tononality" is obtained.

If a connection in a radio communication system is too poor, whereby unacceptable call quality is obtained, this may be due, among other things, to the ratio between the signal strength and the interference being too low. The signal strength referred to is the signal strength of the received desired signal. By interference is meant the sum of the signal strength of all received unwanted signals on the channel used. These unwanted signals come mainly from other connections that use the same channel in nearby cells in the radio communication system. The received unwanted signals may also come from connections within the own cell, which connections use an adjacent frequency or time slot.

The desired received signal strength depends on the transmitter power and how much the desired signal is attenuated on its way from the transmitter to the receiver. The attenuation is determined, among other things, by the distance, direction and topology between the transmitter and the receiver. Other concepts that occur in parallel with attenuation are channel gain or "path gain" and "path loss" as is well known to those skilled in the art.

© Pèvsta s / oas International patent application WO96 / 02979 describes channel hopping 5. a radio communication system Channel hopping 25 takes place between a number of channels, which are assigned to each connection. xx; A signal attenuation parameter, for example "path gain", is measured; "¿§ for the connections which are then arranged with respect to the signal attenuation parameter. Furthermore, an average value of a channel quality parameter, such as for example the interference, is measured on individual channels. The channels are then arranged" ~ 518 262 4 ~ i 518 262: II = gg, 5 with respect to the measured channel quality parameter_ Only the best channels with respect to channel quality are used for the connections.

When assigning channel hop sequences to connections, the connection quality of each connection and the channel quality of the channels in each channel jump sequence are taken into account. A low quality connection is assigned a channel skip sequence where the input channels have high channel quality and a high quality connection is assigned a channel jump sequence where the input channels have low (poorer) channel quality. When assigning channel jump sequences to connections, the orthogonality in each base station is ensured. The number of included channels in a channel skip sequence may be different in different base stations. Within a base station, the number of included channels in a channel jump sequence is fixed.

Oßæz Swedish patent application SE 940fl @ 492-4 describes a method and a device for channel hopping in a radio communication system. An average value of the interference of the channels in the radio communication system is measured for each connection. The values are stored in an interference list for each of the connections. The values in the interference lists are then weighted and the weight lists thus obtained are analyzed. For each connection, a hop sequence list is then generated depending on the analysis of the weight lists. A channel with a high weight value for a certain connection occurs more often in the corresponding hop sequence list, compared with a channel with a low weight value. ma> n According to the methods described above, an average value of the interference is obtained. However, the interference may vary with time, so that the interference of the channels at different time intervals within a channel jump sequence may differ. It would therefore be a u. U. u u. . . . . . . ,.,,: ::: z n - .u n u. n H '. _. n I - »nn - I." - u I o ».fl- v .. v o... _ iv - .-. -. 1» n. Ü Û I! lI II II; .g | ¿ It is desirable to be able to obtain values of the interference within the different time intervals within a channel jump sequence in which a channel can be used.

U.S. Patent No. 4,998,290 discloses a radio communication system utilizing frequency hopping.

The system includes a central control station that allocates frequencies for communication with several participating local radio stations. The control station maintains an interference matrix that reflects the capacity needs of the various radio stations 10 as well as interference for all connections.

A disadvantage of this method is that a central control station must be introduced into the system, which makes the system more complex.

German patent application DE 4403483A describes a method for rearrangement of frequency hopping groups for an FDM / TDM radio transmission. A number of predefined frequency hopping tables are stored in the BSC. A table is currently used (TAB). If any connection that uses any of the frequency hopping sequences in the table shows poor quality, the current table (TAB) is replaced with a new table (TAB1). The change from 20 current tables to new tables takes place step by step. According to one example, the frequency hopping sequences are changed for two time slots at a time. Change only takes place when no information is transmitted on these time slots.

A disadvantage of this method is that the frequency hopping tables are predefined. When the interference situation is not observed continuously, optimal utilization of the best HH 'channels with respect to the interference cannot be obtained. A further disadvantage is that no attenuation of the connections is taken into account when assigning jump sequences to connections. 518,262 fi; International patent application WO 91/13502 describes a method for carrier-shared frequency hopping. All frequencies available in the radio communication system that can be used for frequency hopping are in a frequency pool from which channel hopping sequences are determined. Each base station is allowed to select frequencies from the frequency pool when frequency hopping. When allocating a time slot to a mobile station that wants to establish a connection, the distance of the mobile station to the base station is taken into account. Nearby mobile stations get the middle time slots in a TDMA frame and remote mobile stations get time slots located at the beginning and end of a TDMA frame. This is done to prevent the problem of time alignment.

International Patent Specification WO 93/17507 discloses a method of communication in a TDMA cellular mobile radio communication system using frequency hopping.

A mobile station in a cell selects radio channels and time slot independently of a mobile station in a neighboring cell. The jump sequences within a cell are selected so that no co-channel interference occurs.

Co-channel interference between cells may occur, but is considered to occur on a small scale. The output power of the mobile stations is regulated so that mobile stations which are close to the base station transmit with lower power than mobile stations which are far from the base station.

A disadvantage of the latter two patents is that no account is taken of the interference situation when generating jump sequences. A further disadvantage is that no attenuation of the connections is taken into account when assigning jump sequences to connections. 10 15 20 25 5 1 8 2 6 2 fï 8 RECOGNITION OF THE INVENTION The invention addresses a problem of how channels are to be assigned to different connections between a base station and mobile stations, which are within the coverage area of the base station.

The base station is part of a radio communication system which uses channel hopping, whereby a problem is that the channels must be assigned so that the connections do not interfere with each other unnecessarily, preferably to the least possible degree, and so that good connection quality is obtained. Included in the mentioned problem is how orthogonality within the base station is ensured.

Another problem is how the radio communication system is to be observed at different time intervals within a channel skip sequence with respect to channel quality of the channels used for channel skip, so that reliable quality values are obtained continuously.

An object of the present invention is thus to, by means of a channel hopping method, optimize the use of available channels in a base station with respect to the connection quality of connections between the base station and mobile stations which are in the coverage area of the base station.

Another object is to observe the radio communication system with respect to channel quality at different time intervals within a channel jump sequence.

Another object is to, in connection with the above-mentioned optimization of the channel use, ensure orthogonality in the base station or base tonality, ie that only one at a time of the base station's connections uses a channel which is available in the base station. . 1. vv. -up- .vv- 10 15 20 25 n. and n q n. . ,,. _. _ I. I 30 .: v n n - n: _: u nn n n o u 'nu u .nu. u ~ - ø ø u one now. o .., .., I I a Ü .n 0 n,,: a o n v n n n u u. 9 The above problems are solved by a method and a radio communication system according to the invention. The method may include observing the system for connection quality and channel quality, thereby generating signal attenuation and channel quality parameters.

The signal attenuation parameter indicates how much the connection is affected by attenuation. A low value of the signal attenuation parameter means that the connection has low attenuation and a high value of the signal attenuation parameter consequently means that the connection has high attenuation.

The channel quality parameter indicates how much a channel or frequency is disturbed due to interference. A low value of the channel quality parameter means that the channel and the frequency have low interference and a high value consequently means that the channel and the frequency have high interference.

In the method, it is assumed that the number of channels included in a channel jump sequence is constant in the radio communication system, which can be expressed as all connections in the system using the same jump sequence length.

In the generation of the channel quality parameters, the hop sequence length and thus the channel hop sequences are divided into a number of sequence intervals. The sequence intervals can then in turn be divided into one or more generation intervals within which the channel quality parameter is generated.

According to the method, a channel quality parameter is generated for each frequency and for each generation interval. 10 15 20 25 518 262 -...- n 1 lo. . .

Generation of channel jump sequences can take place depending on the measured channel quality parameters. Assignment of the generated channel jump sequences to different connections can then take place depending on the connection and channel quality parameters.

More specifically, a procedure may involve observing the connections in the system with respect to connection quality. on The connection quality can refer to how much the connection is affected by attenuation. A signal attenuation parameter, such as path gain, is measured for the connections. The connections are then arranged depending on the measured signal attenuation parameter.

Furthermore, the method comprises that the channels, or the frequencies where applicable, in the system are observed with respect to channel quality. Channel quality can refer to how much a channel or frequency is disturbed due to interference. A channel quality parameter, such as interference, is measured for each frequency and for each generation interval.

Depending on the length of the generation interval and depending on the type of radio communication system, a channel quality parameter is obtained for each frequency or for each channel. If the generation interval is a time slot in a TDMA system, this means that a channel quality parameter is measured on each channel. The channels or frequencies are then arranged depending on the measured channel quality parameter. The channels / frequencies are arranged in a channel list for each sequence interval depending on the measured channel quality parameter. -u ~ .n- u 10 15 20 .. --25. The channel quality parameter can also be obtained by measuring, for example, the C / I value or the bit error rate BER and then calculating an interference value with the C / I value or the bit error rate as input.

Channel jump sequences are then generated. Each channel jump sequence utilizes a channel from the respective channel list, i.e. for each sequence interval. Only the best channels with respect to the channel quality parameter are used.

Jump sequences are then assigned to the connections according to the principle that a connection that has poor connection quality is assigned a channel jump sequence with channels of high channel quality.

Connections with successively better connection quality are assigned channel jump sequences with successively worse channels. Another way of expressing the same thing in a simplified way is that the worse a connection is with respect to the attenuation, or some other measure of the connection quality, the better channels with respect to the interference, or some other channel quality measure, will be assigned to the connection. By only allowing a given channel to occur once per sequence interval, orthogonality in the base station is ensured.

Note that the terms high and low channel quality refer to the quality of the channels that are actually used in the channel jump sequences. Channels that will not be used in a channel jump sequence at all will have poorer channel quality than the worst channel used in a channel jump sequence.

The connections then jump between their assigned channels. Within each sequence interval, a channel in the channel jump sequence is used.

When the last channel in a channel jump sequence has been used, the first channel in the channel jump sequence is used again, and so on.

The process according to the invention can be repeated continuously or intermittently, whereby the channel assignment to old connections can be updated. By repeating the procedure, any new connections can also be assigned channels to jump between. The invention also comprises a device for carrying out the method.

The advantages of the invention are that an adaptive channel allocation is obtained and that orthogonality in the base station is ensured at the same time.

A further advantage is that the channel quality of the channels included in a channel jump sequence is measured at the different time intervals within a channel jump sequence in which they can be used.

This means a better accuracy in the observation of channel quality. In this way, the advantages of channel jumping, i.e. a division of the interference on different connections, can be combined with the advantages of a radio communication system which does not use channel jumping. In such a systenx, the interference situation may. observed for 'each channel.

Another advantage is that the method leads to a better channel utilization by assigning a high attenuation connection to low interference channels, and a low attenuation connection is assigned to higher interference channels, i.e. higher interference relative to the best channels used. The advantages thus provide better call quality on more connections, increased capacity and a lower total level of interference in the radio communication system_ 10 15 20 '; '25 518 262 13 n ou | o o | The invention will now be described in more detail by means of preferred embodiments and with reference to the accompanying drawing.

DESCRIPTION OF THE FIGURES Figure 1a schematically shows a view of a part of a radio communication system.

Figure 1b shows with a block diagram the principle of channel jumping according to the invention.

Figure 2 shows a schematic block diagram of three mobile stations and a base station, which are located in a cell in the radio communication system, and illustrates the channel skipping principle according to the invention.

Figure 3a shows a first embodiment of the invention in the form of a block diagram.

Figure 3b shows in more detail a first embodiment of a means for generating a channel quality parameter according to the invention.

Figure 3c shows in more detail a second embodiment of a means for generating a channel quality parameter according to the invention.

Figure 4 shows a second embodiment of the invention in the form of a block diagram.

Figure 5 shows a third embodiment of the invention in the form of a block diagram.

Figure 6 shows a fourth embodiment of the invention in the form of a block diagram. 10 15 20 wm; 518 262 w: ''. . . . . . . . Figure 7 illustrates a schematic flow diagram of the channel jumping method according to the invention.

PREFERRED EMBODIMENTS In Figure 1a, a part of a radio communication system is schematically shown. Said system is illustrated in the figure as a cellular mobile radio network PLMN, which comprises base stations BS1-BS8. Each base station has a certain range within which radio communication can be obtained with mobile radio stations or mobile stations MS1-MS6 which are within the coverage range defined by the range of the base station. The cells C1 + C8 represent these geographical coverage areas for the base stations BS1-BS8.

The base stations are connected to the other nodes of the mobile radio network, such as, for example, base station switching centers BSC, mobile switching centers MSC and gateway mobile switching centers GMSC, according to known technology.

These nodes are not shown in the figure and are not described in more detail in this context, as they are not of particular importance to the invention.

Figure 1b schematically shows the principle of channel jumping according to the present invention. The base stations in the radio communication system include hop sequence lists. The hop sequence lists contain information about which channels the base station should use when communicating with the mobile stations that are within the base station's coverage area. Accordingly, if a base station provides a number of connections to different mobile stations, there is a hop sequence list in the base station for each connection.

Thus, the base station BS1 in the cell C1 includes a hop sequence list 101 for the connection to the mobile station MS1. 10 15 20 .... »30 518 262 '15 The corresponding hop sequence lists for the connections to the mobile stations MS2 and MS3 are not shown in the figure.

The jump sequence list 101 in the base station BS1 comprises three channels ch1-ch3 for transmission, denoted TX, and three channels ch4-ch6 for reception, denoted Rx. The time to go through a channel jump sequence is divided into a number of sequence intervals Ti.

The transmitter in the base station thus transmits on channel ch1 during all or parts of a first sequence interval Th on channel ch2 during all or parts of a second sequence interval T2 and on channel ch3 during all or parts of a third sequence interval T3. The index i that indicates the number of the sequence interval Ti is its sequence index. These three channels are said to form a channel hop sequence for transmission from the base station BS1 to the mobile station MS1. The transmission from the base station to a particular mobile station and vice versa may be time-shifted within the sequence intervals. When the last channel in a channel jump sequence is used, the first channel in the channel jump sequence is used again, and so on.

The jump sequence ch1-ch3 is then repeated cyclically during the time the radio connection to the mobile station MS1 is connected or until a new assignment of channels to the jump sequence list 101 is performed in accordance with what will be explained in more detail below. The receiver in the base station BS1 receives on the channels ch4-ch6 in the sequence intervals T1-Tg, after which this channel skip sequence is then repeated in the same way as described above for the transmitter. In this example, three channels are used in each channel jump sequence. The number of channels used in the channel jump sequences, i.e. the sequence length L, is a system parameter, which can be selected arbitrarily. However, the sequence length L must be the same in all base stations in the system, for reasons explained in more detail below. 10 15 20 §2s u .. ~ 1 ... - ~ ...- - oo nu 518 262 I 16 In the mobile station MS1 there is a hop sequence list 102.

The jump sequences in the jump sequence lists 101 and 102 are identical, but the channel jump sequence used in the base station for transmission is of course used for reception in the mobile station and the channel jump sequence used in the base station for reception is used for transmission in the mobile station. Thus, the channels ch1-ch3 form the channel jump sequence upon reception and the channels ch4-ch6 the jump sequence upon transmission for the sequence intervals T1-T3 in the mobile station MS1.

The channels stored in the hop sequence lists and used by the base stations and the mobile stations are selected according to a method according to the invention which will be explained in more detail below.

However, some main principles can already be mentioned. Preferably, a channel jump sequence is generated in the base station, for example the channel jump sequence for transmission from the base station. By utilizing the so-called duplex distance, which is the frequency distance between uplink and downlink as is generally known to the person skilled in the art, channel jump sequences for reception in the base station can then be obtained. The hop sequence list thus obtained for reception in the base station is then transmitted to the mobile station from the base station via a control channel, where it is used as the hop sequence list for the mobile station in the manner explained above. The above-mentioned transmission of the hop sequence list 101 in the base station to the jump sequence list 102 in the mobile station MS1 is symbolized by the dashed line in the figure.

It is also possible to generate a channel jump sequence in the mobile station and then use the duplex distance to provide the second channel jump sequence, thereby obtaining a jump sequence list for the base station. This is then transmitted to the base station on the control channel as described above. w ... 10 15 20 25 518 262 šïï * * Äššïïš-Ãfï j; A further possibility is to generate the channel jump sequences for transmission and reception for each connection, either in the base station or in the mobile station, without using the duplex distance. This option can be used in systems that do not use a duplex distance. This is described in an exemplary embodiment with reference to Figure 6.

Figure 2 shows a schematic block diagram of parts of the three mobile stations MS1-MS3 and the base station BSI in the cell 1 in figure 1a. The base station comprises means such as circuits for storing 201-203 for each of the hop sequence lists the three connections between the subscribers a1-a3, which may be fixed or mobile subscribers, and the mobile stations MS1-MS3.

The mobile stations comprise circuits for each jump sequence list 204-206, which constitute the equivalents of the jump sequence lists in the base station as explained above. It is assumed in this example that the jump sequence lists 201-206 comprise three channels for transmission and three channels for reception.

The base station comprises a transmitter / receiver unit 207, which transmits / receives radio signals to / from the mobile stations on the assigned channels.

The receiver portion of the unit 207 can also be used to perform channel quality measurements, for example by measuring the interference of the channels used in the system. This interference is generally dependent on channel and time and can thus be written I (channel, t). Instead of the 207 embodiment assigned to use the receiver part in the unit for the channel quality measurements, a special broadband receiver can be arranged in the base station for this purpose. In the following example, however, it is assumed that the receiver part of the unit 207 is used for said channel quality measurements. 10 15 20 | | 518 262 18 The mobile stations MS1-MS3 each comprise a transmitter / receiver unit 208-210 for radio signals to / from the base station. An interference I (channel, t) is also received in the receivers of the mobile stations. channel assignment means 211 in the base station BS1, the assignment of channels which form the channel jump sequences in the jump sequence lists is effected, which will be explained in more detail below. The jump sequences are then transmitted from the channel assignment means 211 to the jump sequence lists 201-203, 204-206 of the base station and the mobile stations. For example, the transmission channel SACCH ("Slow Associated Control Channel"), to be used for the transmission of the mobile stations as mentioned above, the transmission of the channel jump sequences to the jump sequence lists 204-206 is shown in the figure separately with the dashed line for clarity, but is performed in a known manner. by means of the transmitters / receivers 207-210 under the control of a control means CPU (Fig. 3) . By means of the channel jump sequences, and then the base station, the mobile stations know on which channel transmission and reception are to take place within each sequence interval Tr. In Figure 3a, the channel assignment means 211 and the base station BS1 are shown in block diagram in more detail. The channel assignment means 211 comprises a means 212 for generating a signal attenuation parameter, which indicates how much a radio signal is attenuated between the transmitter and the receiver for a certain connection. The generation of the signal attenuation parameter for a certain connection between a base station and a mobile station can in principle take place in such a way that a measurement signal with known signal strength is transmitted from the base station to the mobile station.

The mobile station registers the received signal strength and reports the value back to the base station, whereby the signal attenuation parameter can be calculated. It is likely that the mm; 10 15 20 '2130 518 262 19 n n n a nu nu u nu an: the signal strength received in addition to the signal strength contribution from the transmitted measurement signal also contains signal strength contributions from other base stations. However, it can be assumed that the majority of the received signal strength derives from the transmitted measurement signal. In a mobile radio network, for example, such measurements of the signal attenuation are repeatedly performed on connections which are about to be connected and which are already connected. This is done by means of control channels on one for the person skilled in the art. known manner, why the function of the member 212 is not described in detail in this context.

The measurement of the signal attenuation parameter has been described here in the downlink, ie when the measurement signal is transmitted from the base station. It is understood that the measurement signal can just as easily be transmitted from the mobile station, whereby the signal attenuation parameter is then measured in the uplink. However, as a good approximation, the signal attenuation on a connection can be considered to be the same in both the uplink and downlink, so it is normally irrelevant for the application of the invention if the signal attenuation parameter is measured in the uplink or downlink.

The means 212 generates a connection list 213, in which a signal attenuation parameter above 52, .. is stored for the respective connection F1, F2, .. The signal attenuation parameters stored in the connection list 213 constitute input data to the algorithm used for assigning channels to the hop sequence lists as described below. A sorting means 214 compares the signal attenuation parameters with each other and stores the connections depending on the parameters in a sorted connection list 215, the connection having the lowest signal attenuation parameter being stored first in the connection list.

The connection that has the lowest signal attenuation parameter is denoted mo in the sorted connection list 215, the one that has the second lowest a of ... _ .. vv. suv- 10 15 20 25 518 262 §II = 20 signal attenuation parameters are denoted ml and so on, whereby the connections are thus arranged in order after increasing signal attenuation. If a connection has a low signal attenuation parameter, this means that the signal is attenuated slightly on that connection, the connection being of good quality with respect to the signal attenuation.

The channel assignment means 211 also comprises a means 216 for generating a channel quality parameter for each channel or for each frequency which can be used in channel skipping and for each sequence interval Ti as will be described in more detail in the following embodiments. The means also generates, depending on the generated values of the channel quality parameter, a sorted channel list KL for each sequence interval Ti in the channel jump sequence as described in more detail in connection with Figures 3b and 3c (units 307a-307c, 407a-407c).

The sorted link list 215 and the sorted channel lists (307a-307c in Figure 3b, 407a-4070 in Figure 3c) are supplied to a means 220 for generating channel jump sequences. The means 220 generates and assigns channels to the channel jump sequences, which channels are then transmitted to the jump sequence lists 201-203 in the base station and to the jump sequence lists 208-210 in the mobile stations MS1-MS3 via the control channel SACCH (Fig. 2).

The means 220 for generating channel jump sequences assigns these sequences to connections according to the principle that a certain connection with poor quality should have a channel jump sequence with channels of good quality. Connections with successively better quality are assigned channel jump sequences with channels of successively lower quality. In the ideal case, all connections would have - »~ _ .. .nan 10 15 20 uno- 25 51 8 262 21 the same C / I value. The assignment of channels to the channel hop sequences for the connections can take place by means of the method according to the invention as will be described in more detail below.

Slightly simplified, the principle of assigning channel jump sequences to the connections works in such a way that a connection having low connection quality, for example expressed as high attenuation, is assigned a number of channels with high channel quality, for example expressed as low interference, and a connection having higher connection quality is assigned a number of channels that have lower channel quality, for example expressed as higher interference. Another way of expressing the same thing in a somewhat simplified way is that the worse a connection is with respect to the attenuation, the better channels with respect to the interference, assigned or some other channel quality measure, will be the connection. The assignment of channels to connections takes place so that the orthogonality is ensured, ie so that several connections with the base station do not use the same channels at the same time.

In order to illustrate in a simple and clear manner the control of the means included in the invention, Figure 3a shows a control means CPU. This control means CPU in the channel assignment means 211 can communicate with the means described above and control the described channel assignment process. The communication can take place via control signals transmitted between the control means CPU and said means, a bus line 222 between at 213p, ..., the control signals being transmitted to the control means and ports 212p, 220p of said means as schematically shown in Figures 3a-3c. For reasons of space, not all ports have been numbered in the figure. . | a. Q n a ~ n -v-o mm; 10 15 20 25 | a o - n; 518 262 22 n u.

The control of the various means included in the invention does not, of course, need to take place from a central control means CPU in the channel assignment means 211. Each means. may include its own software for controlling its functions, the control being distributed in the system.

The channel lists (307a-307c in Figure 3b, 407a-407c in Figure 3c) contain channels or frequencies, depending on the system in question, sorted with respect to the one measured on the channel quality parameter. The background to this is that a channel is defined by a frequency in an FDMA system and by frequency and time slot in a TDMA system. In addition, in a TDMA system, channel skipping for a connection can mean skipping only between channels in the same time slot, which means skipping only between frequencies. In a TDMA system, jumps between channels that have different time slots can also be applied, ie jumps between both frequencies and time slots can be applied.

The respective channel lists may contain the channels, or frequencies where applicable, that can be used for channel jumping sorted with respect to the measured channel quality parameter. A channel quality parameter is measured for each frequency in each generation interval ATk, which generation interval constitutes all or part of a sequence interval Ti, as described in more detail below with reference to Figure 3b. Thus, if the generation interval in a TDMA system is the time of a time slot, this means that the channel quality parameter is measured for each channel.

An exemplary embodiment of the means 216 for generating a channel quality parameter will now be described in more detail with reference to Figure 3b. 518 262 23 An average value of the channel quality parameter for each of the frequencies fl-fn is measured by the receiver part of the unit 207. x = 1,2, .., n. The channel quality parameter is generally time dependent and indicates the quality of a channel with respect to, for example, the interference I (t) on the channel. Index x denotes frequency numbers.

It is also possible to measure other parameters, such as the bit error rate or the C / I value, on the frequency and calculate an interference value from these values. In, for example, a mobile radio network, such measurements of the interference of the frequencies are repeatedly performed in a manner known to those skilled in the art.

If a particular receiver, for example a broadband receiver, were to be used to measure the average values of the channel quality parameter, a channel filtering means can be used to filter the received broadband signal so that a value is obtained for each frequency. The filters separate the received broadband signal into all the frequencies fl-fn that can be used within the system.

The signal values obtained from the measurement of the channel quality parameter can be squared, after which the result obtained reflects 'the incoming signal strength for' each frequency fl-fn.

The means 216 for generating a channel quality parameter - v-a. further comprises a sequence counter 303. The sequence counter 303 ... u 25 indicates which sequence interval Ti the channel jump sequence »- -... -.« is in, where the index i denotes the sequence index.

Each time interval within which the connection transmits on a channel occurs during a sequence interval Ti. The first channel included .n 1; | nu »n v» sr. Thus, in a channel jump sequence, all or parts of a first sequence interval T1 denoted by a first sequence index i = 1 are used. The second channel in the channel jump sequence is used during all or part of a second time interval T2 denoted by a second sequence index i = 2, and so on. In the present example, it is assumed that the generation interval ATK consists of the entire sequence interval, which means that a channel quality parameter is generated for each frequency within each sequence interval. The sequence length L in example three is why the jump sequence index assumes the values i = 1, 2 and 3, respectively.

To exemplify what generation interval ATk means in the present case, the system can be assumed to be a GSM system where each frequency is divided into eight time slots which are said to form a TDMA frame. The generation interval ATk then becomes the time for a TDMA-Iam.

The receiver portion of the unit 207 and the sequence counter 303 are connected to a multiplexer 302. The multiplexer 302 may select one of several connections, in the present example three different connections, between the receiver portion of the unit 207 and a plurality of averaging means 304a-304c. When the sequence counter 303 indicates the sequence index i = 1, the connection from the receiver part of the unit 207 to the first averaging means 304a is selected, and when the sequence counter 303 changes the index to the sequence index i = 2, the second connection is selected, and so on.

In the following description, it is assumed that the sequence counter 303 indicates the sequence index i = 1, the receiver part of the unit 207 being connected to the first averaging means 304a via the multiplexer means 302, as shown in Fig. Bb. This means 304a comprises a number of averaging filters. For each frequency 15, for example, the means 304a may average the signal strength of the interference. The means on the averaging value means can in the averaging form use some type of unambiguous, monotonically growing and non-linear imaging (for example a logarithmic function), in order to be able to weight different measured values. The averaging may take place throughout the first generation interval AT1 when the sequence counter 303 indicates i = 1, i.e. during the time that the means 301 is connected to the first averaging means 304a. The obtained values of the channel quality parameter In, ImJ where the first index denotes frequency number x and the second sequence index i, for the respective frequencies f1-fn and for sequence index i = 1 are stored in a first channel quality list 305a.

The averaging means have been described in the present example as one means for each sequence interval.

The averaging for the different sequencing intervals can be performed by only one averaging means which then has the same function as the three averaging means.

The first channel quality list 305a is then sorted by a first sorting means 306a with respect to the obtained values of the channel quality parameter. The sorting results in a first sorted channel list 307a, whereby the frequency which is least disturbed due to interference, i.e. the frequency which has the lowest channel quality parameter, is denoted clloch the one which has the second lowest channel quality parameter is denoted cm and so on, whereby the first index denotes the sequence number of the frequency and the second index denote the sequence index i.

The procedure is repeated in the same way when the sequence counter 303 indicates the sequence index i = 2 and i = 3, respectively. A second 10 15 20 518 262 a. N; 26 averaging means 304b and a third averaging means 304c then averaging during the second and third generation intervals AT2 and AT3, respectively, when the sequence counter 303 shows the sequence indices i = 2 and i = 3, respectively, the values of the channel quality parameter In-Im and In-IH3 for the respective frequencies fl-fn is obtained. The values are stored in a second channel quality list 305b and a third channel quality list 3050, respectively, after which these are sorted by a second sorting means 306b and a third sorting means 306c, respectively.

Thereby a second sorted list 307b is obtained where the frequency having the best channel quality is denoted c12 and a third sorted channel list 307c where the corresponding frequency is denoted on, with indexing as before.

The time constant of the averaging filters in the averaging means 304a-304c is preferably in the order of hours to days, i.e. during this time the collection of values and averaging of them takes place. The result from the means 216 for generating a channel quality parameter is thus a sorted channel list 307a-307c for each sequence interval T1-T3. The respective list contains the frequencies fl-fn sorted with respect to the value of the channel quality parameter for the respective frequencies within the respective sequence intervals T1-T3.

A frequency with a high channel quality parameter is slightly disturbed due to interference, the frequency being of good quality with respect to the interference.

In order to be able to measure the interference in a generation interval within each sequence interval, it is desirable that the interference situation does not change within the respective 10 sequence intervals in which the system is observed. This wish places demands on the radio communication system. The sequence count on must run coherently at both the transmitting and receiving ends of a particular connection. In order to be able to measure the channel quality for frequencies within different sequence intervals Ti, it is required that the sequence length L in different base stations within the radio communication system is the same. The sequence intervals for a base station are not obtained in the base stations. slide relative to the sequence intervals of another base station. The sequence counters 303 in different base stations, on the other hand, may be in different phases within the channel jump sequence, i.e. they do not have to change the sequence index at the same time, but their counting frequency must be the same.

In connection with Figure 3c, a variant of the above exemplary embodiment of the means 216 for generating a channel quality parameter will be described below. The sequence length is the same as in the previous example, i.e. L = 3 and the radio communication system is assumed to be a slightly modified GSM system. In the present case, the generation interval ATk 'is assumed to be the time of a time slot in a TDMA frame. The index k indicates the time slot number, k = 1, 2, .., 8¿ The means 216 for generating a channel quality parameter comprises a sequence counter 403 which, like in the previous example, indicates the sequence index in that 'i.e.' which sequence interval Ti the channel jump sequence is within, but in the present case as a function of time slots i = i (k).

A multiplexer means 402 selects connections from the receiver portion of the unit 207 to three averaging means 404a-4040 depending on which sequence index the sequence counter below indicates, in the same manner as previously described. thus, the first sequence interval T1 when the sequence counter 403 indicates 518 262 get '28 sequence index i = 1, the connection from the receiver portion of the unit 207 to the first averaging means 404a is selected and the connections to the second 404b and the third 404c averaging means are not connected.

While the first averaging means 404a is connected to the receiver part of the unit 207, i.e. when the sequence counter 403 indicates i = 1, the sequence counter 403 has time to count through 8 time slots, k = 1,2, .., 8. The sequence counter 403 controls the first averaging means 404a so that averaging takes place for the respective generation interval ATk, i.e. the time for a time slot k. A value of the channel quality parameter is hereby obtained for each frequency fl-fn and for each time slot k = 1,2, .. , 8 for each sequence interval TI-T3. In other words, a value of the channel quality parameter is obtained for each channel chl-chn and for each sequence interval 13-T3. The obtained values of the channel quality parameter Infïnl for the channels chl-chn during the first sequence interval T1 when the sequence index is i = 1 are stored in a first channel quality list 405a. Similarly, values of the channel quality parameter for the second and third sequence intervals T2 and T3 are obtained when the sequence index is i = 2 and i = 3, respectively. These values In-Inz and IB-In3, respectively, are stored in a. second and a third channel quality list 405b and 405c, respectively. The respective channel quality lists 405a-405c are sorted by separate sorting means 406a-406c, with respect to the measured values of the channel quality parameter. This generates a sorted channel list 407a-407c for each sequence interval Ti. The best channel, i.e. the least disturbed channel, within each sequence interval Ti is denoted cli. The second best channel in each list is called cn and so on. . «-.- 10 15 20 518 262 šïïiïïïïvš š = ~~ = -ÃI ;. vn vv; 29 In the present case, the radio communication system must not only be sequence synchronous but also time slot synchronous, ie the duration of the time slots must not change over time. Otherwise, the interference situation within a time slot may vary with time.

Hereinafter, the means 220 for generating channel hop sequences and assigning the channel jump sequences to connections will be described in more detail. Different cases will be described depending on the type of radio communication system in question. Channel hopping includes hopping only between can, as previously mentioned, frequencies, hopping between both frequencies and time slots and hopping only between time slots.

The term channel jump sequence hereinafter includes a jump sequence containing channels which in an FDMA system is defined by frequency and in a TDMA system is defined by frequency and time slot. The term frequency jump sequence refers to jump sequences containing only frequencies. Thus, in an FDMA system, a frequency hopping sequence and a channel hopping sequence are the same.

Below, the generation of channel jump sequences will be described for the case where the radio communication system is an FDMA system.

The generation interval ATk constitutes the entire sequence interval Ti as described in connection with Figure 3b. This means that the 307a-307c contain frequencies. A sorted channel lists channel is in this case defined only by frequency. To obtain orthogonality in the base stations, only one frequency from each sorted channel list may be included in a channel skip sequence. The respective frequencies must maintain their respective sequence index in the channel jump sequence. Thus, a frequency from the channel list 307a for the sequence index i = 1 must be used during the first sequence interval T1 for the sequence index i = 1.

One. possible jump sequence algorithm1 is to select the highest ranked frequencies from the respective sorted channel list 307a-307c, clu Cu, C13 and let these constitute the best channel jump sequence.

Then the second highest ranked frequencies cn, C22: C23 are selected and these constitute the second best channel jump sequence and so on.

The best channel jump sequence then consists of the three best frequencies with respect to the interference and the worst channel jump sequence consists of the three worst frequencies.

In order to obtain a smaller quality difference between the different channel jump sequences, another jump sequence algorithm according to the invention can be used. According to this hop sequence algorithm, the best channel jump sequence is assigned the best frequency cn of the first and second channel lists 307a and 307b, and the second best frequency cn of the third third channel list 307c. The second best channel jump sequence is assigned to the second and second channel lists 307a and 307b the second best frequency cn, cn and the third 307c channel list best frequency cn. This process can be repeated in pairs for the remaining successively inferior frequencies in the channel lists 307a-307c. The third best channel hop sequence is thus assigned the third best frequency cn from the first and second channel lists 307a and 307b C31: and the fourth best frequency ca from the third channel list 307c. In this way, the difference in quality between the different channel jump sequences becomes smaller than in the first described case OVaIl.

It will be appreciated that there are additional ways to allocate the frequencies included in the channel lists to channel jump sequences and that the longer the sequence length L, the greater the choice. nu nu »u p o: o. u ~ I | n o o c on c w co ø n | c and n n u a 1. nu o n | o an: u n nu o q nu un: u; nu »an: n lo 0 n n n o -p n o o u n o n n n n n. n »au n. 1 .: o. n. 31 However, in order to maintain orthogonality in the base station, never more than one frequency from the respective channel list, that is, from the same sequence interval Ti, may be included in a channel jump sequence.

The frequencies included in the channel jump sequence must also retain their sequence index i, i.e. a frequency from the first channel list 307a for sequence index i = 1 must be used in the channel jump sequence during the first sequence interval T1 when the sequence index is i = 1.

Allocation of frequencies to the channel jump sequence for a connection can in the present case take place according to. the principle. as previously described where the worst connection in terms of connection quality is assigned the best channel jump sequence down in terms of interference. The second worst connection is assigned to the next best channel jump sequence, after which successively better connections are assigned successively worse channel jump sequences.

Below, the generation of channel jump sequences will be described for the case where the radio communication system is a TDMA system where jumping between time slots is not allowed. The generation interval ATk constitutes the entire sequence interval Ti as described in connection with Figure 3b. Channel skipping in such a system then means that only the frequency is changed for each connection, ie skipping takes place only between channels that have the same time slot. In such a system, frequency jump sequences are first generated, which can be done according to the jump sequence algorithms described above. Thereafter, each connection is assigned a respective time slot, after which each connection is assigned a frequency hopping sequence.

»Hi The frequency jump sequence in combination with the time slot assigned to the connection forms a channel jump sequence where each channel in the jump sequence is defined by the same time slot. As previously mentioned, the GSM system 30 has eight time slots per TDMA frame. This u ou ~ a 10 15 20 518 262 32 o a. U; means that up to eight connections can use UP channel jump sequences that contain the same frequency jump sequence provided that the connections are not assigned the same time slot.

One strategy is then to let as many of the worst connections as possible, ie the connections with the largest signal attenuation parameter, use the best frequency within each sequence interval. The channel jump sequences for these connections contain different channels within each sequence interval, all of which are defined by the same frequency. A channel skip sequence for a connection consists of channels that are all defined by the same time slot. A number of successively better connections may utilize the second best frequency within each sequence interval and so on. However, it may be appropriate to save some time slots that can utilize the same frequency hopping sequence, which channel hopping sequences can be utilized by later added connections.

Below, the generation of channel jump sequences will be described for the case where the radio communication system is a TDMA system where jumps between time slots are allowed and where the generation interval ATk is the time for a sequence interval Ti, as described in connection with Figure 3b. First, frequency jump sequences are generated by some jump sequence algorithm as previously described, and then time slot jump sequences are generated. The time slot jump sequences can be generated by a random number generator. Each frequency jump sequence is then combined with a time slot jump sequence from which channel jump sequences are formed.

Allocation of frequencies to the channel jump sequence of a connection can in the present case take place according to the same principle as n u v v | I: Q v: n n I fl »1 10 15 20 25 51 s 262. "33 has been described previously, where the worst link in terms of link quality is assigned the best channel jump sequence in terms of interference. The second worst link is awarded in the second best channel jump sequence, after which successively better links are assigned successively worse channel jump sequences.

Below comes the 'generation. of 'channel jump sequences' to be described for the case where the radio communication system is a TDMA system and where the generation interval ATk is the time for a time slot.

As described in connection with Figure 3c, the sorted channel lists 407a-407c in this case contain all frequency / time slot combinations, i.e. channels which can be used for channel jumping, sorted with respect to the channel quality parameter. Channel jump sequences can therefore be generated directly from these channel lists according to any jump sequence algorithm described in the first example above.

In this case, one can choose to generate channel jump sequences where all channels in a sequence are defined by the same time slot, if jumping between time slots is not allowed.

Selection of frequencies to the channel jump sequence for a connection can in the present case take place according to the principle described earlier where the worst connection with respect to connection quality is assigned the best channel jump sequence with respect to interference. The second worst connection is assigned to the second best channel jump sequence, after which successively better connections are assigned successively worse channel jump sequences.

In all of the cases described above, the means 220 then generates an additional channel jump sequence for each connection nn-ms by utilizing the duplex distance as mentioned above. One channel skip sequence is then used by the base station transmitter and 518 262 .Q now. 34 the second channel skip sequence is used by the base station receiver part for the respective connections. The two channel jump sequences per connection are then stored in the respective jump sequence list in the base station, such as the jump sequence lists 201-203 in Figure 3. The two channel jump sequences per connection are also transmitted to the mobile stations via a control channel SACCH and stored there in the respective jump sequence list in the mobile stations. in Figure 2.

The controller CPU with the bus line 222 and the ports 212p, 213p, 10 ..., 220p are not shown in the following figures for the sake of simplicity and clarity.

Figure 4 shows a second embodiment of the invention and the channel assignment means 211 in block schematic form. In comparison with the exemplary embodiment in Figures 3a-3c, the sorted channel lists 307a-307c, 407a-4070 are provided in a different way.

In the present example, the interference I (t) in the downlink of each mobile station MS1-MS3 is measured. Each mobile station MS1-MS3 thus measures an average value for the interference of the respective frequencies. These values are then sent to a respective means 408a-4080 for generating channel quality lists in the base station. The transmission takes place via a control channel, as schematically shown in the figure with the dashed line designated SACCH. The transmission of the measured interference values, from the mobile stations to the means 408a-408c f .25 for generating channel quality lists in the base station, is shown in the figure separately with the dashed line for clarity, ¿.; sake, but is performed in a known manner by means of the transmitters / receivers 207-210.

In the current example, the number of mobile stations is three. For each mobile station MS1-MS3 there are in the base station a respective 518 262 §Iï = n: n. 35 means 408a-408c for generating channel quality lists. Such means 408a-408c include means 302,303,304a-304c and 305a-305c in Figure 3b or means 402,403,404a-404c and 405a-405c in Figure 3c. For reasons of space, these means are illustrated as a means 408a-408c in Figure 4. Respective means 408a-408c for generating channel quality lists thus generate three channel quality lists, one for each sequence interval T, The channel quality lists obtained by means of the respective means 408a-408c for generation of channel quality lists for the respective sequence intervals TH-T3 is averaged and sorted by a first, second and third sorting means 409a-409c. The three channel quality lists obtained for the first sequence interval T1, when the sequence index i = 1, are averaged and sorted by the first sorting means 409a. The lists obtained for the second sequence interval T2 when the sequence index is i = 2 are averaged and sorted by the second sorting means 409b, and so on. This is indicated in the figure by three input signal paths to the respective sorting means 409a-409c, one from the respective means 407a-407c for generating channel quality lists. These respective sorting means 409a-409c will calculate an average of the values of the channel quality parameter for each frequency / channel and for each sequence interval and sort the frequencies / channels depending on the calculated averages. The means 409a-409c can use some type of unambiguous, monotonically growing and non-linear imaging (for example a logarithmic function) in the average value formation, in order to weight different measured values. Thereafter, a linear averaging is suitably performed, after which the sorting of the frequencies / channels for each sequence interval Ti is performed: zavu 10 15 20 30 518 262 36 1. ... depending on the averaging, i.e. after increasing interference.

In the current example, all processing of measurement data such as averaging and sorting takes place in the base station. It is also possible to have the mobile station perform part or all of the data processing until the generation of channel jump sequences.

For example, each mobile station could be provided with its own means 408a-408c for generating channel quality lists, its own sorting means 409a-409c and its own sorted channel lists 307a-307c or 407a-407c. In such a case, the sorted channel lists are transmitted to the base station via SACCH. Other means 212-215 and 220-221 operate in the same manner as in Figure 3a and are therefore not described in connection with Figure 4.

Figure 5 shows a third embodiment of the invention and the channel assignment means 211 in block schematic form. Unlike the two previous embodiments in Figures 3a-3c and Figure 4, the sorted channel lists 307a-307c and 407a-407c, respectively, are provided by measuring values of the interference from both the uplink and the downlink. In the present example, the downlink interference of each mobile station MSI-MS3 is measured in the same manner as described with reference to Figure 4. In addition, the interference values measured in the uplink and stored in the channel quality lists 305a-305c in Figure 3b and 405a-405c in Figure 3c are also used. . This is accomplished by using the means 302,303, 304a-304c in Figure 3b and 402,403,404a-404c in Figure 3c to generate the channel quality parameter. For space reasons, the means 302,303,304a-304c and 305a-305c in 3b, figure or 402,403,404a-404c and 405a-405c in figure 3c, are drawn as a means 501.

However, the first channel quality list 305a or 405a is connected in this. exemplary embodiment of the first sorting means 409a | n ø - fnn - .u 518 262 3 7 for averaging and sorting, which first sorting means 409a operates according to the principle described with reference to the exemplary embodiment in Figure 4. The second and third channel quality lists 305b, 405b and 305c, 405c are connected to the same to the second and third sorting means 409b and 409c, respectively.

In this way, interference values soul measured in the uplink can also be used in the calculation of the interference averages. In Figure 5, the means 212-215 in Figure 3a are shown as a single member 502 for space saving reasons. The means 502 thus performs corresponding functions as the means 212-215 in Figure 3a.

Figure 6 shows a fourth embodiment of the invention and the channel assignment means 211 in block schematic form. Unlike the embodiments described above, the duplex spacing is not used to create channel jump sequences. The means 220a thus generates only one channel jump sequence per connection, which channel jump sequence can be used in, for example, transmission from the base station. The channel jump sequence generating means 220b operates according to the same principle as the means 220a and generates one channel jump sequence per connection, which channel jump sequences are used in reception at the base station if the channel jump sequences generated in the means 220a are used for transmission in the base station. The means 220a receives input data concerning the channels. from the body 601. This body. correspond to the means: - 25 408a-4080, 409a-409c and 307a-307c in Figure 4. These inputs have been obtained by measuring the interference in the downlink as described with reference to Figure 4. r11> | The means 220b receives input data concerning the channels from the means 216 previously described in connection with Figures 3b and 3c. These inputs have been obtained by measuring the interference in - u - ~ o ø n. nu 518 262 38 n. nu. the uplink as described with reference to Figures 3b and 3c.

By not mixing the interference values measured in the uplink and downlink, as described with reference to Figure 5, completely independent channel hop sequences can be created in means 220a-220b, one channel hop sequence being used for transmission and the other channel hop sequence being used for reception in the base station. .

The jump sequences are stored in the base station in the jump sequence lists 201-203 and transmitted on the control channel SACCH to the jump sequence lists 204-206 in the mobile stations in the same manner as described above. In Figure 6, the means 212-215 in Figure 3a are shown as a single member 502 for space saving reasons. The means 502 thus performs corresponding functions as the means 212-215 in Figure 3a.

Figure 7 illustrates a flow chart of a channel jumping method according to the invention. In step 700, the channel jump sequences are divided into sequence intervals T. The duration of a sequence interval corresponds to the time between two channel jumps within a channel jump sequence Ti.

In step 701, the signal attenuation parameter Ö is generated for each connected connection F1-F3. The signal attenuation parameter can be generated by measuring the attenuation in the uplink and / or downlink for each connection.

In step 702, the channel quality parameter is then generated for each u .vo frequency fl-fn and for each generation interval ATk within .fi and the sequence interval Ti, respectively. The term "each frequency" may, for example, refer to all frequencies in a base station or in the whole telecommunication system, or a predetermined subset of these frequencies. The channel quality parameter can be generated by measuring the interference in the uplink and / or the downlink for each frequency fl-fn and for each e ø o u ø n n ø nu 518 262 šïï = šïïë 'é 39 generation interval ATk, within each sequence interval Ti. It is also possible to measure other quantities, such as the C / I value or the bit error rate BER, and with these quantities as input data within each sequence interval Ti calculate an interference value for each frequency íffn and generation interval ATk.

The generation interval etATk may be the time for all or part of the sequence interval Tr. The generation interval ATk can, for example, be the time for a time slot in a TDMA reindeer in a TDMA system. In the latter case, this means that an interference value is obtained for each channel chl-chn and for each sequence interval Ty. In step 703, the obtained values of the signal attenuation parameter are stored in a connection list 213 and the obtained values of the channel quality parameter in a respective channel quality list 307a-30c 407a-407c for the respective sequence intervals T1-T3.

In step 704, the connections are sorted according to the measured signal attenuation parameter (attenuation) and the connections are then stored in the sorted connection list 215. If measured values from the uplink or from both the uplink and downlink are used, an average value of the attenuation is calculated for each connection and the connections are then sorted into depending on the calculated 23; the mean.

In step 705, are the frequencies / channels for each ff sorted? Sequence interval T1-T3 depending on the measured T "É channel quality parameter (interference) and then stored in the sorted channel lists 307a-307c or 407a-407c. If measured values from the uplink or from both the uplink and downlink are used, an average value of the interference is calculated for each man: 10 15 20 518 262: ff * 40 frequency / channel within the respective sequence range T1-T, and the frequencies / channels are then sorted within the respective sequence range T1-T3 depending on the calculated average value.

In step 706, a method of generating channel jump sequences described above is applied in conjunction with the channel jump sequence generating means 216. The respective channel / frequency to be used during a respective sequence interval in the channel jump sequence. selected in. depending on its position in the channel list for the respective sequence interval. As described in connection with Figures 3a-3c, a best channel jump sequence is generated with respect to the channel quality parameter for the channels / frequencies within the respective sequence range. Thereafter, additional channel jump sequences are generated which, in comparison with the best channel jump sequence, have successively poorer channel quality.

The channel skip sequences can be used for transmission from either the base or mobile station. The corresponding channel jump sequence used for reception can be achieved by utilizing the duplex distance as mentioned above. As a further possibility, channel jump sequences can be provided for both transmission and reception for each connection by the method of generating channel jump sequences, i.e. without using the duplex spacing. It will be appreciated that a channel jump sequence used for transmission in the base station shall be used for reception in the mobile station and a channel jump sequence used for transmission in the mobile station shall be used for reception in the base station.

In step 707, it is checked whether the assignment of channel jump sequences to the connections (F1-F3) is to be updated. If the answer is negative according to an alternative N, the procedure from step 701 is repeated without performing the update. If the answer is in the affirmative according to an alternative J, in step 708 each connection is assigned a channel jump sequence according to the principle that a connection with poor connection quality with respect to the signal attenuation parameter is assigned a channel jump sequence with good quality with respect to . the channel quality parameter. The worst connection with respect to the signal attenuation parameter is assigned the best channel jump sequence with respect to the channel quality parameter. Gradually better connections are gradually assigned worse channel jump sequences. As previously described in connection with Figure 3c, several channel jump sequences may have the same channel quality. Several connections can then be assigned to a channel jump sequence that contains channels with the same channel quality.

In step 709, the channel jump sequences are stored in jump sequence lists 201-203,204-206. in the base station and the mobile stations. The base station 15 includes a hop sequence list for each connection and the hop sequence lists each include channel hop sequences for transmission and reception, respectively. The channel jump sequences for transmission and. reception to be used by the mobile stations is transmitted to them via a control channel SACCH and is then stored in 20 respective hop sequence lists in the mobile stations. The procedure is repeated after step 708, skipping to step 701.

Whether or not the channel jump sequences are to be updated is thus determined by a monitoring in step 707, for example by means of the ÄT controller CPU. The channel assignment means 211 can continuously create "new" channel jump sequences, one. new 'channel jump sequence can replace an "old" channel jump sequence for example if H1; the difference in call quality for the two channel jump sequences exceeds a predetermined limit value or if the interference level exceeds a predetermined value. The update does not have to be complete, ie the channel jump sequences are updated only at n ø | I u u o u nu .n n 518 262 42 those connections where the difference j. Call quality exceeds the limit value. Updates may be required, for example, when new connections are established or when reception conditions have changed due to the movement of the mobile stations. The invention. can also be implemented without the generation of the channel jump sequences taking place continuously. In such a case, a set of channel jump sequences can be generated according to the method according to the invention, for example when starting up the radio communication system. In a later update of the radio communication system, a new set of channel jump sequences can be generated and used for the next update and so on.

As an alternative, steps 704 and 705 may be skipped, with the information stored in the connection and channel lists 213, 217 being input to the hop sequence algorithm used in step 706. It should be noted that the jump sequence algorithm in this case does not work in accordance with the previously described. Since no sorted connection and channel lists have been provided, the hop sequence algorithm 20 must be able to find the channels to be used and assign them to the correct connection. The implementation of the jump sequence algorithm itself can thus be accomplished in several ways, but all jump sequence algorithms work according to the principle: the worse a connection is ß with respect to a signal attenuation parameter, the better channels with respect to a channel quality parameter will be assigned to it; the connection.

As an alternative, the hop sequence lists in the base and mobile stations may include only one channel jump sequence. Means 30 are in this case arranged to generate an additional channel hop sequence for each connection, for example by utilizing the duplex distance. One of the channel jump sequences is then assigned to the transmitter and the other channel jump sequence is assigned to the receiver by said means.

The radio communication system has in the preferred embodiments been described as comprising base stations, within which channels of the respective coverage areas of base stations are used in base-to-channel channel jump sequences in the radio communication with the mobile stations located within a certain base station's coverage area. The base station can generally be considered as a first radio station and the mobile stations as a number of second radio stations. The available channels within a coverage area may be a number of channels specifically assigned to the base station, a subset of the total number of channels or all channels in the radio communication system, signal attenuation parameters being generated for these channels.

It is too. It is possible to implement parts of the described embodiments in a mobile switching center MSC or in a base station switching center BSC, which in that case contains means which provide the functionality of the means described above.

The generation of the channel quality parameter and / or the signal attenuation parameter need not necessarily involve a continuous physical measurement of a quantity. The generation of said parameters can also take place by theoretically generated values of said parameters when, for example, starting up on the radio communication system. This can be achieved in the planning of the system by means of theoretical calculation models. 44 Channel jump sequences are then generated depending on the generated values as previously described. These channel jump sequences can then be used until a possible radio communication system takes place, whereby new updates of theoretical values are generated. Even if the figures illustrate vehicle-borne car stations, the invention can of course be applied in systems with portable, hand-held mobile stations.

Claims (33)

518 262 ........ .. 45 PATENT REQUIREMENTS A method of channel hopping according to a channel hopping sequence in a radio communication system (PLMN), which radio communication system comprises at least a first radio station (BS1) and at least a second radio station (MS1-MS3) between which information is transmitted on connections (F1-F3), the connections are subjected to signal attenuation and interference, which method comprises: dividing the channel jump sequences into sequence intervals (TQ, which sequence intervals (TQ together constitute the time to go through a channel jump sequence; generating a signal attenuation parameter (5) "rmyar ogh x-l5 _en # ay de resp generating a channel quality parameter (I, BER, C / I) within each sequence interval (Ti) for frequencies (f1-f6) used in the radio communication system and for different generation intervals (ATk), wherein a generation interval ( ATK) comprises the time for all or part of a sequence interval (Ti); generating at least one channel jump sequence, whereby a nun: fï channel hop sequence comprises one channel per sequence interval (TQ, between which channels a connection skips, which generation takes place depending on the generated values of the channel quality parameter (I, C / I, BER); vf assignment of the channel jump sequences to a respective Zë 30 connection, which assignment takes place in dependence on the generated v 15 'veva' f: 25 n n u | No. 518 262 46 «-. - nu n; n. the values of the channel quality parameter (I, C / I, BER) for the channels included in the hop sequences and depending on the signal attenuation parameter (ö); channel skipping between the channels included in the channel skipping sequences, during radio communication on the connections between the first radio station (BS1) and said second radio stations (MSI-MS3). The method of claim 1, comprising storing the channel jump sequences in a respective jump sequence list (201-203, 204-206) of the first radio station (BS1) and said second radio stations (MS1-MS1). The method of claim 1, wherein the number of channels included in a channel jump sequence and the duration of a sequence interval (TQ are constant within the radio communication system, and wherein the duration of one corresponds to the time sequence interval (TQ between two channel jumps). A method according to any one of claims 1-3, wherein the generation interval (ATk) comprises the entire sequence interval (Ti) - A method according to any one of claims 1-3, wherein the generation interval (ATk) comprises the time of a time slot in a TDMA frame when the radio communication system is a TDMA system, wherein the generation of a channel quality parameter takes place for the respective sequence interval (T1-T3) and for respective channel (ch1 ~ chy). A method according to any one of claims 4 and 5, wherein the generation of a channel skip sequence comprises: a selection of a channel depending on generated values of the channel quality parameter within the first sequence interval (T1), which channel constitutes that channel in the channel jump sequence to be used during the first sequence interval; selection of additional channels depending on generated values of the channel quality parameter within the remaining sequence intervals (IQ-TJ, which additional channels constitute the channels in the channel jump sequence to be used during the remaining sequence intervals; The method of any of claims 4-6, wherein the generating the channel jump sequences further comprises: selecting the best channel quality parameter on (I, C / I, BER) within each sequence interval (TI-T3), these best channels forming a best channel jump sequence; selecting the best channel of the remaining channels with respect to the channel quality parameter within the respective sequence range (T1-T3), these channels successively forming at best inferior channel jump sequences with respect to the channel quality parameter in comparison with that channel jump sequence; The method of any of claims 4-6, wherein the generation of the channel jump sequences further comprises selecting the best channel with respect to the channel quality parameter (I, C / I, BER) within a number of the sequence intervals, and 518 262 48 and selecting the second best channel within the remaining sequence interval, these channels forming a best channel jump sequence; selection of the second best channel within the sequence intervals where the best channels are included in the best channel jump sequence with respect to the channel quality parameter (I, C / I, BER), and selection of the best channel within the remaining sequence interval, these channels forming a second best channel jump sequence ; selection of successively worse channel jump sequences according to the same principle as for the best and the second best channel jump sequence where the choice of channels takes place from the remaining channels within the respective sequence interval. A method according to any one of claims 4 and 6, wherein the radio communication system is a TDMA system, wherein the generation of the channel jump sequences further comprises: selecting the best frequency with respect to the channel quality parameter (I, C / I, BER) within each sequence interval (T1-T3 ), these best frequencies forming a best frequency hopping sequence; selecting the best frequency with respect to the channel quality parameter of the remaining frequencies within each sequence interval (T1-T3), these frequencies successively forming inferior frequency hop sequences with respect to the channel quality parameter compared to the best frequency hop sequence; selection of 'at least one time slot in one. TDMA frame to the respective frequency hop sequence, each combination of a time slot and a frequency hop sequence constituting a channel jump sequence. A method according to any one of claims 4 and 6, wherein the radio communication system is a TDMA system, wherein the generation of the channel jump sequences further comprises: selecting the best frequency with respect to the channel quality parameter (I, C / I, BER) within a number of sequence intervals, and selecting the second best frequency within the remaining sequence range, these frequencies forming a best frequency hopping sequence; selection of the second best frequency with respect to the channel quality parameter of (I, C / I, BER) within the sequence intervals where the best frequencies are included in the first frequency hopping sequence, and selection of the best frequency within the remaining sequence interval, these frequencies forming a second best frequency hopping sequence ; selection of successively inferior frequency hop sequences according to the same principle as for the best and the second best frequency hop sequence where the selection of frequencies takes place from the remaining frequencies within the respective sequence range. selecting at least one time slot in a TDMA runx for each frequency hopping sequence, each combination of a time slot and a frequency hopping sequence constituting a channel hopping sequence. 11. ll. A method according to any one of claims 7 and 8, which comprises: sorting the channels (chl-chy) for the respective sequence intervals (T§-T3) with respect to the channel quality parameter (I, C / I, BER); storing the sorted channels in a sorted channel list 5 (407a-4070) for each sequence interval (IQ-T3), the channels for each sequence interval being stored sorted depending on the channel quality parameter. A method according to any one of claims 9 and 10, which comprises: sorting the frequencies (f1-fn) for each sequence interval (TI-T3), with respect to the channel quality parameter (I, C / I, BER); storing the sorted frequencies in sorted channel lists (307a-307c) for each sequence interval (T1-Ty, the frequencies for each sequence interval being stored sorted depending on the channel quality parameter. A method according to claim 11, wherein said selection of channels for the respective channel jump sequences takes place depending on the position of the channels 20 in the respective sorted channel list (307a-307c, 407a-407c). A method according to claim 12, wherein said selection of frequencies to the respective channel jump sequences takes place depending on the position of the frequencies in the respective sorted channel list (307a-307c). z.'25 A method according to any one of claims 7-14, wherein the assignment of channel jump sequences to the respective connections m ... comprises: selecting the worst connection with respect to the 518 262 51 .u .. signal attenuation parameter (Ö); assigning the best channel jump sequence to the worst connection; selection of successively better connections with respect to the signal attenuation parameter (Ö); assigning the successively inferior channel jump sequences 10 to the successively better connections. A method according to claim 15, comprising: sorting the connections with respect to the signal attenuation parameter (ö); Storing the sorted connections in a sorted connection list (215), the connections being stored sorted depending on the signal attenuation parameter (5) A method according to claim 16, wherein said selection of the respective connections (F1-F3) takes place depending on their position in the sorted connection list (215). The method of any of claims 6-17, wherein the generating the channel jump sequences further comprises: generating a second channel jump sequence for each already generated channel jump sequence by utilizing a .H ,. duplex spacing, wherein pairs of channel hop sequences are generated for the connections (F1-F3) and wherein the channels in a pair of channel jump sequences are mutually separated by the duplex spacing. -ßsno 10 15 20 518 262 52 u | v o u u »I The method of any of claims 6-17, wherein the generation of the channel jump sequences further comprises: generating two channel jump sequences for the respective compounds (F1-F3), the generation taking place depending on the channel quality parameters (I, C / I, BER) within the the respective sequence intervals (T1-T,) for both channel jump sequences. A method according to any one of claims 18 and 19, wherein the (Ö) connections (F1-F3) comprise measuring the signal attenuation in the generation of the uplink signal attenuation parameters. A method according to any one of claims 18 and 19, wherein the generation of the signal attenuation parameters (Ö) for the connections (F1-F3) comprises measuring the signal attenuation in the downlink. A method according to any one of claims 18-21, wherein the generation of the channel quality parameters (I, C / I, BER) comprises measuring the C / I value and the bit error content value some of the interference value, (BER) in the uplink. A method according to any one of claims 18-21, wherein the generation of the channel quality parameters (I, C / I, BER) comprises measuring the C / I value and the bit error content value some of the interference value, (BER) in the downlink and. averaging the generated values of the channel quality parameter for each sequence interval (IQ-T3) with respect to the same frequency and the same generation interval (ATQ). A method according to any one of claims 18-21, wherein the generation of the channel quality parameters (I, C / I, BER) comprises measuring ø n o ø u u o | now n »0 ~ 518 262 en Que v '53 any of the interference value, C / I value and bit error content value (BER) in both the uplink and downlink and averaged for the generated values of the channel quality parameter for each sequence interval (TI-T3) with respect to the same frequency and the same 5 generation intervals (ATQ. A method according to any one of claims 22-24, wherein the generation of the channel quality parameter (I, C / I, BER) comprises measuring said values for all input frequencies and channels in the radio communication system, respectively. A method according to any one of claims 22-24, wherein the generation of the channel quality parameter (I, C / I, BER) comprises measuring said values for a subset of all input frequencies and channels in the radio communication system, respectively. A method according to any one of claims 22-24, wherein the generation of the channel quality parameter (I, C / I, BER) comprises measuring said values for the channels and frequencies assigned to the base station, respectively. The method of any of claims 8-27, wherein assigning the channel jump sequences to the jump sequence lists (307a-307c, 407a-407c) comprises transmitting either of the channel jump sequences in said pair to a respective jump sequence list (201-203, 204-206) in the base station (BS1) and the mobile stations (MS1-MS3), respectively. The method of claim 28, comprising transmitting the ÉÉf25 channel hop sequences to the hop sequence lists (204-206) of the mobile stations (MS1-MS3) via a control channel (SACCH). / \\ _ A device in radio communication system comprising a first radio station (BS1), which communicates with at least a second vnvvonuu of radio station (MS1-MS3) over channels (fl-fn, chl-chy), wherein channel jumping is performed according to channel jump sequences, each of which is divided into a number of sequence intervals (Ti), for connections (F1 ~ F3) between the first radio station and each of the 5 radio stations, and the connections being subjected to signal attenuation and interference, which device comprises : means (212) for generating a signal attenuation parameter (8) for each of the respective connections (F1-F3); Means (216) for generating a channel quality parameter (I, C / I, BER) within each sequence interval (Ti) for each of said frequencies (f1-f6) and for different generation intervals (ATk), where a generation interval comprises the time for all or parts of a sequence interval (Ti); means (220) for 'generating' at least one. channel jump sequence for each of the respective connections, a channel jump sequence comprising a channel (fl-fn, ch1-chy) for each sequence interval (Ti), which respective channel within each sequence interval is selected depending on the generated values of the channel quality parameter (I , C / I, BER), which means (220) assigns to each connection (F1-F3) a channel hop sequence depending on the generated signal attenuation parameter (Ö) for 525 respective connection (F1-F3) and depending on the generated values of the channel quality parameter (I, C / I, BER) for the channels included in the channel jump sequences. m-ua f an. 10 l5 20 'y 30 | | u. - v n | no 518 262 u | n ~ u 55 An apparatus according to claim 30, comprising: at least one receiver (207) in the first radio station (BS1) and at least one receiver (208-210) in each second radio station (MS1-MS3), for receiving signal values, which signal values are supplied to said means (216) for generating said channel quality parameter and said means for (212) generating said signal attenuation parameter; means (CPU) for controlling the channel hopping in the radio communication system. An apparatus according to claim 31, comprising: means (214) for sorting the connections with respect to the signal attenuation parameter (Ö), means (215) for storing the sorted connections, the connections being stored sorted depending on the signal attenuation parameter (8). The apparatus of claim 31, wherein the channel quality parameter generating means (216) comprises: a sequence counter (303,403) indicating which sequence interval Ti the channel jump sequence is within; at least one averaging means (304a-304c, 404a-404c), which respective means. during each generation interval (ATR) averages the obtained measured values of the channel quality parameter (I, C / I, BER) for each frequency (fl-fn) and stores the values in a channel quality list (305a-305c, 405a-405c) for each v. - . -, u-u ...- 10 15 ø v o a o I v o un o 518 262 ïš. 56 sequence interval (TQ; a multiplexer means (302,402) which, depending on which sequence interval Ti indicated by the sequence counter (302,403), connects the receiver (207) to any of a plurality of averaging means (304a-304c, 404a-404c), sorting means (306a). -306c, 406a-406c), which sorting means for each sequence interval (TQ sorts frequencies (fl-fn) and channels (chl-chy) in the radio communication system with respect to the channel quality parameter (I, C / I, BER) means (307a-307c, 407a-407c) for storing the sorted frequencies (fl-fn) and the channels (chl-chy) respectively depending on the channel quality parameter (I, C / I, BER) for each sequence interval (TQ.