Method of maintaining an established connection in a mobile radio system comprising both analog and digital radio channels

Claim 2

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection started on the digital radio channel comprising the steps of: estimating time dispersion of the digital radio channel used by the mobile radio station for the connection; and comparing the estimated time dispersion with criteria for handoff to an available analog radio channel and when the estimated time dispersion corresponds to the criteria for handoff, transmitting to the mobile station information on the available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 3

A method according to claim 1, comprising the further steps of: estimating time dispersion of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; and comparing the estimated time dispersion of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated time dispersion corresponds to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel,

Claim 4

The method of claim 2 wherein the digital radio channel, the analog radio channels and the possible digital radio channel are of different frequencies.

Claim 5

The method of claim 1 wherein the digital radio channel and the analog radio channels are of different frequencies.

Claim 6

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of the digital radio channel used by the mobile radio station for an ongoing connection; and comparing the estimated radio propagation properties with criteria for handoff from the digital radio channel and when the estimated radio propagation properties correspond to the criteria for handoff, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 7

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of the digital radio channel used by the mobile radio station for an ongoing connection; and comparing the estimated radio propagation properties with criteria for handoff from the digital radio channel and when the estimated radio propagation properties correspond to the criteria for handoff, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 8

A method according to claim 5, comprising the further steps of: estimating radio propagation properties of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; and comparing the estimated radio propagation properties of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated radio propagation properties of the possible digital radio channel correspond to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel.

Claim 9

The method of claim 6 wherein the digital radio channel, the analog radio channels and the possible digital radio channel are of different frequencies.

Claim 10

The method of claim 5 wherein the digital radio channel and the analog radio channels are of different frequencies.

Claim 11

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated radio propagation properties of the first and second digital radio channels and when the estimated radio propagation properties of the first and second digital radio channels correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated radio propagation properties of the first and second digital radio channels do not correspond to the criteria for handoff to the second digital radio channel, estimating the radio propagation properties of an analog radio channel available to the mobile radio station and comparing the estimated radio propagation properties of the first digital radio channel and the analog radio channel with criteria for handoff to the analog radio channel, and when the estimated radio propagation properties of the first digital radio channel and the analog radio channel correspond to criteria for handoff to the analog radio channel, transmitting to the mobile station information on the analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 12

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated radio propagation properties of the first and second digital radio channels and when the estimated radio propagation properties of the first and second digital radio channels correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated radio propagation properties of the first and second digital radio channels do not correspond to the criteria for handoff to the second digital radio channel, estimating the radio propagation properties of an analog radio channel available to the mobile radio station and comparing the estimated radio propagation properties of the first digital radio channel and the analog radio channel with criteria for handoff to the analog radio channel, and when the estimated radio propagation properties of the first digital radio channel and the analog radio channel correspond to criteria for handoff to the analog radio channel, transmitting to the mobile station information on the analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 13

A method according to claim 9, comprising the further steps of: estimating the radio propagation properties of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; and comparing the estimated radio propagation properties of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated radio propagation properties of the possible digital radio channel correspond to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel.

Claim 14

The method of claim 10 wherein the first digital radio channel, the second digital radio channel, the analog radio channels and the possible digital radio channel are of different frequencies.

Claim 15

The method of claim 9 wherein the first digital radio channel, the second digital radio channel and the analog radio channels are of different frequencies.

Claim 16

In a multiple channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on any of a plurality of digital radio channels and for analog transmission of information using analog-modulated radio signals on any of a plurality of analog radio channels, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating a signal level and bit error rate of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel and, when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel do not correspond to the criteria for handoff to the second digital radio channel, estimating the radio propagation properties of an analog radio channel available to the mobile radio station and comparing the estimated radio propagation properties of the first digital radio channel and the analog radio channel with criteria for handoff to the analog radio channel and when the estimated radio propagation properties of the first digital radio channel and the analog radio channel correspond to criteria for handoff to the analog radio channel, transmitting to the mobile station information on the analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 17

In a multiple channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on any of a plurality of digital radio channels and for analog transmission of information using analog-modulated radio signals on any of a plurality of analog radio channels, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating a signal level and bit error rate of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel and, when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel do not correspond to the criteria for handoff to the second digital radio channel, estimating the radio propagation properties of an analog radio channel available to the mobile radio station and comparing the estimated radio propagation properties of the first digital radio channel and the analog radio channel with criteria for handoff to the analog radio channel and when the estimated radio propagation properties of the first digital radio channel and the analog radio channel correspond to criteria for handoff to the analog radio channel, transmitting to the mobile station information on the analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 18

A method according to claim 13, comprising the further steps of: estimating radio propagation properties of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; comparing the estimated radio propagation properties of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated radio propagation properties of the possible digital radio channel correspond to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel.

Claim 19

The method of claim 14 wherein the first digital radio channel, the second digital radio channel, the analog radio channel and the possible digital radio channel are of different frequencies.

Claim 20

The method of claim 13 wherein the first digital radio channel, the second digital radio channel and the analog radio channel are of different frequencies.

Claim 21

In a mobile radio system having a mobile station and a base station having use of analog radio channels and digital radio channels subject to time dispersion whereby signal intelligence is smeared over a wider time interval during the course of transmission, a method of maintaining a connection established on a digital radio channel, comprising the steps of: determining when time dispersion on said digital radio channel exceeds a predetermined maximum acceptable time dispersion; and transmitting to the mobile station, when the time dispersion of said digital radio channel exceeds the predetermined maximum acceptable time dispersion, information on an available analog channel, and performing handoff of the connection to the available analog channel.

Claim 22

In a mobile radio system having a mobile station and a base station having use of analog radio channels and digital radio channels subject to time dispersion whereby signal intelligence is smeared over a wider time interval during the course of transmission, a method of maintaining a connection established on a digital radio channel, comprising the steps of: determining when time dispersion on said digital radio channel exceeds a predetermined maximum acceptable time dispersion; and transmitting to the mobile station, when the time dispersion of said digital radio channel exceeds the predetermined maximum acceptable time dispersion, information on an available analog channel, and performing handoff of the connection to the available analog channel.

Claim 23

The method of claim 17 wherein said determining step comprises estimating said time dispersion of said digital radio channel at said mobile station and reporting estimates to said base station.

Claim 24

The method of claim 17 wherein said digital radio channel is an uplink channel and said determining step comprises the base station estimating said time dispersion of said digital radio channel.

Claim 25

The method of claim 17 wherein the digital radio channel and the analog radio channel are of different frequencies.

Claim 26

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection started on the digital radio channel comprising the steps of: estimating time dispersion of the digital radio channel used by the mobile radio station for the connection; estimating radio propagation of an analog radio channel available to the mobile station; and comparing the estimated time dispersion and radio propagation properties with criteria for handoff to the available analog radio channel and when the estimated time dispersion and radio propagation properties correspond to the criteria for handoff, transmitting to the mobile station information on the available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 27

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection started on the digital radio channel comprising the steps of: estimating time dispersion of the digital radio channel used by the mobile radio station for the connection; estimating radio propagation of an analog radio channel available to the mobile station; and comparing the estimated time dispersion and radio propagation properties with criteria for handoff to the available analog radio channel and when the estimated time dispersion and radio propagation properties correspond to the criteria for handoff, transmitting to the mobile station information on the available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 28

The method of claim 21 wherein the digital radio channel and the analog radio channels are of different frequencies.

Claim 29

A method according to claim 21, comprising the further steps of: estimating time dispersion of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; and comparing the estimated time dispersion of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated time dispersion of the possible digital radio channel substantially corresponds to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel.

Claim 30

The method of claim 23 wherein the digital radio channel, the analog radio channels and the possible digital radio channel are of different frequencies.

Claim 31

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of the digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of an analog radio channel available to the mobile radio station; and comparing the estimated radio propagation properties of the digital radio channel and the available analog radio channel with criteria for handoff from the digital radio channel to the available analog radio channel and when the estimated radio propagation properties of the digital radio channel and the available analog radio channel correspond to the criteria for handoff, transmitting to the mobile station information on the available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 32

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating radio propagation properties of the digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of an analog radio channel available to the mobile radio station; and comparing the estimated radio propagation properties of the digital radio channel and the available analog radio channel with criteria for handoff from the digital radio channel to the available analog radio channel and when the estimated radio propagation properties of the digital radio channel and the available analog radio channel correspond to the criteria for handoff, transmitting to the mobile station information on the available analog radio channel and performing handoff of the connection to the available analog radio channel.

Claim 33

The method of claim 25 wherein the digital radio channel and the analog radio channels are of different frequencies.

Claim 34

A method according to claim 25, comprising the further steps of: estimating radio propagation properties of a possible digital radio channel available to the mobile station during the time the connection continues on the analog radio channel; and comparing the estimated radio propagation properties of the possible digital radio channel with criteria for handoff to the possible digital radio channel and when the estimated radio propagation properties of the possible digital radio channel correspond to the criteria for handoff to the possible digital radio channel, transmitting to the mobile station information on the possible digital radio channel and performing handoff of the connection to the possible digital radio channel.

Claim 35

The method of claim 27 wherein the digital radio channel, the analog radio channels and the possible digital radio channel are of different frequencies.

Claim 36

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating ratio propagation properties of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated radio propagation properties of the first and second digital radio channels and when the estimated radio propagation properties of the first and second digital radio channels correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated radio propagation properties of the first and second digital radio channels do not correspond to the criteria for handoff to the second digital radio channel, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 37

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on a digital radio channel and for analog transmission of information using analog-modulated radio signals on an analog radio channel, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating ratio propagation properties of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated radio propagation properties of the first and second digital radio channels and when the estimated radio propagation properties of the first and second digital radio channels correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated radio propagation properties of the first and second digital radio channels do not correspond to the criteria for handoff to the second digital radio channel, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 38

The method of claim 29 wherein the first digital radio channel, the second digital radio channel and the analog radio channels are of different frequencies.

Claim 39

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on any of a plurality of digital radio channels and for analog transmission of information using analog-modulated radio signals on any of a plurality of analog radio channels, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating a signal level and bit error rate of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating the radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel do not correspond to the criteria for handoff to the second digital radio channel, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 40

In a multi-channel mobile radio system comprising a base station and a mobile station designed both for digital transmission of information using digitally modulated radio signals on any of a plurality of digital radio channels and for analog transmission of information using analog-modulated radio signals on any of a plurality of analog radio channels, which mobile station comprises an equalizer designed for a particular maximum time dispersion of digitally modulated radio signals, a method of maintaining a connection comprising the steps of: estimating a signal level and bit error rate of a first digital radio channel used by the mobile radio station for an ongoing connection; estimating the radio propagation properties of a second digital radio channel available to the mobile station; comparing the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel correspond to criteria for handoff to the second digital radio channel, transmitting to the mobile station information on the second digital radio channel and performing handoff of the connection to the second digital radio channel; and when the estimated signal level and bit error rate of the first digital radio channel and the estimated radio propagation properties of the second digital radio channel do not correspond to the criteria for handoff to the second digital radio channel, transmitting to the mobile station information on an available analog radio channel and performing handoff of the connection to the analog radio channel.

Claim 41

The method of claim 31 wherein the first digital radio channel, the second digital radio channel and the analog radio channel are of different frequencies.