GB2336071A - Null periods in a communication channel allow scanning for alternative handover channel - Google Patents
Null periods in a communication channel allow scanning for alternative handover channel Download PDFInfo
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- GB2336071A GB2336071A GB9806613A GB9806613A GB2336071A GB 2336071 A GB2336071 A GB 2336071A GB 9806613 A GB9806613 A GB 9806613A GB 9806613 A GB9806613 A GB 9806613A GB 2336071 A GB2336071 A GB 2336071A
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- 230000006854 communication Effects 0.000 title claims abstract description 52
- 238000004891 communication Methods 0.000 title claims abstract description 52
- 230000001360 synchronised effect Effects 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 34
- 230000005540 biological transmission Effects 0.000 claims description 30
- 230000007175 bidirectional communication Effects 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 6
- 238000013459 approach Methods 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000008054 signal transmission Effects 0.000 description 2
- 230000011664 signaling Effects 0.000 description 2
- 108010003272 Hyaluronate lyase Proteins 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/16—Discovering, processing access restriction or access information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
- H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
Abstract
In a communication system, a frequency division duplex (FDD) channel is set up between first and second stations. The up- and down-link channels are each divided into sequential time segments 2. Null periods 4 are provided in the channel A (or C) from the first to the second station during which the communication signal from the first station to the second station is interrupted, and the second station is operated to survey alternative communication channels B, D during the null periods 4 for the purposes of deciding whether handover is appropriate. The null periods 4 have a duration which is a fraction of the duration of a time segment 2 and different null periods 4, 4a, 4b may be positioned at different timings relative to their respective time segment 2. This ensures that data of alternative channels B, D can be captured. Alternatively, for changeover from a frequency division duplex (FDD) mode to a time division duplex (TDD) mode (figure 2), the position of the null period 4 may be the same in each frame while different control data portions 6 in the TDD channel are positioned at different relative timings within the frames 2. The duration of the null period 4 may be shorter than a time frame and then the time frame may correspond to the time segment 2. If the duration of the null period 4 is equal to or greater than a time frame, the time segment 2 is defined as the average repetition for the null periods 4 and may comprise a number of time frames. Null periods are preferably also provided in the channel from the second to the first station and synchronised with the null periods in the channel from the first station to the second station.
Description
1
DESCRIPTION
2336071 A METHOD OF CONTROLLING A COMMUNICATION SYSTEM AND THE SYSTEM EMPLOYING THE METHOD This invention relates to a method of controlling a communication system, and particularly to enable interrogation of other channels so that a handover request may be generated. In particular, the invention is concerned with handover from an established channel operating in a frequency division mode.
The need for handover control in cellular systems is well known, and many techniques for changing the base station with which a mobile unit is communicating have been proposed. The present invention is particularly concerned with the handover of communication signals between different systems, or within a single system which supports different types of communication in different areas.
For a mobile station to determine when handover is appropriate, some monitoring must be made of afternafive available channels so that a correct handover decision can be made. A particular problem arises if an existing communication channel is operafing in a frequency division duplex (FDD) mode, because user data is assigned to virtually the full duration of each time frame of the communication channel, so that there is no available time for the mobile station to monitor alternative communication channels. One possible solution to this problem is to provide each mobile station with two receivers, one for receiving the user data transmitted by the base station, and the other for monitoring the condition of other possible channels. It is, of course, desirable to avoid the need for each mobile station to have two receivers.
An alternative approach is to provide a slotted transmission mode in which for some or all time frames, the base station transmits all of the data for the frame, but in part of the frame duration. This would normally require that the information rate is increased during transmission, for example by reducing 2 PHB34239 the spreading factor in a spread spectrum system. No information is sent to the mobile station during the remainder of the frame, which comprises a null period. There could be information sent in the null period, but of a nature which can be ignored by the mobile station. The null periods enable the mobile station to use a single receiver to perform signal measurements during the null periods in order to analyse alternative channels or frequency bands. This analysis then enables evaluation of whether handover is appropriate.
In order to evaluate whether an alternative channel is appropriate for handover, the mobile station needs to obtain information concerning other channels, which information may be transmitted only at specific times. For example control data defining a channel may be provided at an allocated timing within each time frame, for example in the header of each time frame. A system operating using time division duplex (TIDID) will only produce base station transmissions during a fraction of the time slots in a time frame.
Therefore, for the mobile station to evaluate whether an alternative possible channel is appropriate, it needs to interrogate alternative channels at specific but unknown times.
A particular problem may arise if the time frame duration of the alternative channel is the same as the time frame duration of the channel being operated, because the null periods during which the mobile station interrogates alternative channels may not correspond with the control data which is required to make a handover decision.
According to the present invention there is provided a method of controlling a communication system in which a communication signal is established between first and second stations and using a channel configuration in which outward and return channels are each divided into time segments with the channels defining a substantially continuous transmission, comprising:
providing in the channel from the first to the second station recurring null periods during which the communication signal from the first station to the 3 PHB34239 second station is interrupted; and operating the second station to survey alternative communication channels during the null periods, wherein the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different timings relative to their time segment.
in the following description and claims, references to the null periods being "recurring" is not intended to signify any regularity or sequence to the timing of null periods, but merely that more than one null period are provided at different times during the course of a communication channel.
In the method of the invention, the position of the null period may be periodically adjusted relative to the time segment boundary. This allows measurements to be taken at different timings of alternative channels. The alternative channel to be surveyed may comprise a channel of a different communication system, or may comprise a channel of the same system, but operating according to a different mode of communication.
Null periods are preferably also provided in the channel from the second to the first station, and synchronised with the null periods in the channel from the first to the second station. This ensures that the survey of alternative channels performed by the second station does not suffer from interference arising from the return signal being transmitted by the second station.
Thus, in accordance with a second aspect of the invention there is provided a method of controlling a communication system in which a communication signal is established between first and second stations and using a channel configuration in which outward and return channels are each divided into time segments wfth the channels defining a substantially continuous transmission, comprising:
providing in the channel from the first to the second station recurring null periods during which the communication signal from the first station to the second station is interrupted; and operating the second station to survey alternative communication 4 PHB34239 channels during the null periods, wherein null periods are also provided in the channel from the second to the first station, and are synchronised with the null periods in the channel from the first to the second station.
Preferably, the first station is a base station, and the second station is a mobile station. The second station is preferably operated to generate a handover request in response to the survey, if a more appropriate channel is identified during the survey. The time segments preferably comprise the predetermined time frames of the system.
In accordance with a third aspect of invention, there is provided a telecommunication station for transmitting a signal over an allocated channel which is divided into time segments, comprising transmitting means and means for providing in the transmission channel recurring null periods during which the transmission signal is interrupted, wherein the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different timings relative to their respective time segment.
The station is preferably a base station. This arrangement of null periods enables the method of the invention to be employed.
In a fourth aspect, the invention provides a telecommunication station for receiving a signal from a transmitting station over an allocated channel which is divided into time segments, comprising receiving means and means for interrupting operation of the receiving means during recurring null periods of the received signal, and means for operating the receiving means to survey other communication channels during the null periods, wherein the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different relative timings relative to their respective time segments.
The station is preferably a mobile station, and which is capable of implementing the method of the invention.
The station is preferably also capable of transmitting a signal to the transmitting station, and means is then provided for interrupting the PHB34239 transmission during the null periods.
The invention is also aimed at the particular situation in which a telecommunication system supports different modes of communication, for example a frequency division duplex mode and a time division multiple access mode, with different base stations being set up according to different modes depending upon the environmental condition. For example, a time division multiple access system may be appropriate for signal transmissions requiring high bit rates, whereas a frequency division duplex system may be more appropriate for larger cell areas. In a system which supports both possible modes of operation, it will be desirable to enable handover from a base station operating according to one mode to a base station operating according to the other mode. The invention is again particularly aimed at the handover from system using a frequency division duplex signal which requires null periods.
Thus, according to a fifth aspect of the invention, there is provided a method of effecting handover of a communication signal established between first station and second stations from a channel configuration corresponding to a first mode of communication to a channel configuration corresponding to a second mode of communication, each mode permitting bidirectional communication over a channel divided into time frames, the first mode defining substantially continuous signals arranged with outward and return signals separated in frequency, recurring null periods being provided in the channel from a transmitting to a receiving station during which the transmission signal is interrupted, the second mode allocating different time slots of each time frame to outward and return signals, control data being provided in an allocated portion of each time frame, the method comprising:
operating the receiving station to survey the control data generated by transmitting stations operating according to the second mode of communication during the null periods, and to generate a handover request when appropriate, wherein the control data is provided at different relative timings within time frames of the second mode.
6 PHB34239 In the method according to this aspect of the invention, the control data is provided at different timings within the time frames to ensure that there will be cyclic overlap of the null periods with the control data portions. Again, this may not be the case for unsynchronised systems having equal frame durations. The invention also provides a communication station employing a frame structure in which user data is allocated to time slots within each time frame, each time frame comprising a control data portion, and wherein the control data portion is provided at different relative timings within different time frames.
The invention will now be described by way of example, with reference to and as shown in the accompanying drawings, in which Figure 1 shows frame timing data using one possible slotted transmission mode, and using a slotted transmission mode in accordance with one aspect of the invention; Figure 2 shows frame timing diagrams for operation in accordance with the second aspect of the invention; Figure 3 shows a schematic architecture for a base station capable of operating according to the method of the invention; and Figure 4 is a schematic diagram of one possible architecture for a mobile station capable of operating according to the method of the invention.
Figure 1 Part A shows one possible frame structure for the down-link communication between a base station and a mobile station. The signal comprises a number of time frames 2 arranged in sequence. Typically, a time frame may have a duration of 1 Orns. Each time frame 2 includes user data as well as control data. The user data and control data may be multiplexed together, or else each time frame may be divided into discrete sections. For example, each time frame may include a synchronisation sequence and a header in which control data is transmitted. This invention is particularly concerned with a communication system employing frequency division duplex, in which the transmission and reception signals are essentially continuous. Of 7 PHB34239 course, various coding and interleaving techniques are additionally possible.
The invention is directed at the particular problem of handover from a frequency division duplex system to alternative systems, or to other modes of communication supported by an individual system.
In order to make reliable handovers possible, it is necessary for the mobile station to make measurements of the potential replacement channels established by other base stations (or even by the same base station). For seamless handover to take place, these measurements must be carried out by the mobile station while the existing connection is maintained. This requires the mobile station to have a second receiver for monitoring alternative channels, or else requires the mobile station to interrupt use of its single receiver periodically. For this purpose, null periods 4 are possible in the transmission from the base station to the mobile station during which time the mobile station receiver can be allocated to tasks other than reception of information from the base station. One possible arrangement of the null periods 4 is shown in Figure 1A, in which each null period 4 occupies approximately half of the frame duration, and is positioned at the beginning of a time frame 2 with a null period for every fourth time frame.
Although in the example above, and in the following examples, a null period is associated with a repsective time frame, and the null period has a duration shorter than a time frame, other configurations are possible. For example, the null period may be as long as or longer than the time frame duration of the system. In this case, time segments will be defined as the average repetition period for the null periods. The time segments will then comprise a number of time frames, and the timing of the null period will be adjusted with respect to the time segment boundaries. This will of course require different processing to ensure that the receieving station can construct an uninterrupted signal.
One possible problem with the base station transmission of Figure 1A arises if the monitoring by the mobile station during the null periods 4 does not coincide with control information transmitted by other base stations. In this 8 PHB34239 case, the null periods 4 may coincide with a period during which other base stations make no transmissions. For example, Figure 113 shows a possible frame structure for a different base station which operates using time frames 2' of the same duration. The bold lines in Figure 113 at the beginning of each time frame 2' represent control data portions 6 of each time frame, during which the base station may be set up to transmit various control information, such as identification of the base station, information concerning which alternative systems are authorised to use the channel, and the type of signal transmissions which the base station can support. The null periods 4 of Figure 1A do not coincide with any of the control data portions 6 so that the mobile station will not receive any of the control information required to determine whether it may be appropriate to handover to the base station using the channel represented in Figure 1B.
This particular problem may arise with unsynchronised systems having the same frame duration, or it may equally arise in a single system which supports different communication modes. For example in the proposed U1VITS system, there are proposals for the system to support a frequency division duplex mode as well as a time division duplex mode. In this case, the channel represented in Figure 1 B may comprise a time division duplex channel offered by a different base station within the U1VITS system, or even by the same base station. In this case, the null period must coincide with a period of base station transmission in the TDID system for measurements to be possible by the mobile.
In one aspect of the invention, the null periods 4 are positioned at different timings relative to their respective time frames. Thus, as shown in Figure 1C, each null period is again provided in every fourth time frame 2 but in successive time frames in which the null period 4 appears, the null period is retarded so that it progresses from the beginning of the time frame to the end of the time frame. In 9 PHB34239 other words, the position of the null interval in the base station transmission is periodically adjusted relative to the frame boundary. This allows measurements taken by the mobile station to cover all time slots of the other channels being monitored. In Figure 1C, the null period is shown to have a duration of approximately half of the time frame duration, and five different positions of the null period relative to the time frame are shown. One position of the null period overlaps the boundary between adjacent time frames, to cover the possibility that data is required from an alternative channel at a time coinciding with the frame boundary. Of course numerous other possible arrangements can be envisaged. With the base station channel configured as shown in Figure 1C it can be seen that two of the null periods 4a, 4b now overlap Mh control data 6 from the channel being monitored represented in Figure 1B. The relative timing of successive null periods in the down-link transmission may be set to follow a repeating sequence, so that the mobile station can independently calculate when the null periods will arrive. A synchronisation message will be required to initialise a channel set up, which specifies the timing of at least one null period. 20 Alternatively, the mobile may request a specific timing for null periods, for example if one particular timing reveals a greater number of alternative channels to interrogate. This request may be achieved using dedicated signalling. Flexibility for the mobile to select the timing of null periods also enables the mobile to dictate that two or more base stations transmit null periods at the same time, for example in the case that the mobile is receiving user data from two base stations simultaneously. Such an approach may be implemented in some systems to increase diversity. The timing of the null periods may alternatively be varied by the 30 infrastructure rather than following a predetermined pattern. Figure 1D shows a base station transmission of a possible PHB34239 alternative base station to which handover may be effected, in which the time frames 2" have longer duration than the time frames of the existing communication channel. In this case, the null periods 4 from both possible base station channel configurations align with the control data portion 6, and the potential problem of null periods failing to overlap control data portion 6 does not arise. In accordance with another aspect of the invention, the up-link signal from the mobile station to the base station is also arranged to be interrupted with null periods corresponding and coinciding with the null periods 4 of the base station transmission. This enables the mobile station to monitor channels operating in the same or adjacent frequency bands to the channel presently operating. This situation may arise in the U1VITS system, in which the TDID and FDD communication modes may be deployed in the adjacent frequency bands. Without switching off the transmitter of the mobile station, high performance filters would be required to prevent the transmission signal from the mobile station interfering with the monitored signals from alternative channels. The possibility of discontinuous operation of the mobile station thereby simplifies the hardware required in order to implement the method of the invention. The timing of the up-link null periods may also be used as a request to the base station to alter the timing of future down-link null periods. Of course, various schemes can be envisaged for governing the timing adjustment, and for selecting signalling methods for transmitting timing requests between 25 the mobile and base station. Figure 2 shows an alternative approach which again ensures that at least some of the null periods 4 in the base station transmission overlap with control data portions of alternative channels being monitored. In Figure 2A, the null period 4 is provided every third time frame 2 and again occupies 30 approximately half of the time frame duration. This aspect of the invention is directed at the particular situation where the communication system supports PHB34239 two modes of communication, an FIDID mode and a TIDD mode. Figure 213 represents a possible time frame structure for the TIDID mode, in which each time frame 2 is divided into time slots, which are allocated to different channels. In Figure 213, the control data portions 6 are provided at different relative timings within each time frame 2. In the example shown in Figure 2B, the control data portions 6 can occupy five different relative positions within their respective time frame 2, and the control data portions cycle through these different relative timings. The time frames 2 in Figures 2A and 213 again have the same durations, but are not synchronised, so that the problem explained with reference to Figure 1 may also arise. The cyclic shifting of the control data portion 6 in Figure 213 results in overlap of the control data portion 6a with a respective null period 4a. Thus, in the time frame structure shown in Figure 2B, each time frame comprises a control data portion which is provided at different relative timings within different time frames. Of course, this approach requires control of the configuration of the time frames generated by both stations, and the control of both systems must therefore be governed by a single overall system architecture.
Figure 3 shows, in schematic form, a possible architecture for a base station to generate a channel structure as described with reference to Figure 1 or 2 The base station 10 comprises a transmitter 12 and a receiver 14. The signal for transmission is prepared by a coding unit 16 which performs the necessary modulation and generates the frame structure, including headers and synchronisation sources as well as performing any coding or interleaving of the transmitted signals. Similarly, a decoding unit 18 is provided for the received signal. The overall control of the station is governed by a controller 20 which controls the operation of the coder 16, decoder 18 and an inputloutput interface 22. The base station additionally comprises a timing controller 24 which gives information to the controller 20 to influence the frame generation process. In particular, for the method described with reference to Figure 1, the timing unit 24 dictates the position of the null periods in the transmitted signal during which the receiving mobile station can survey other channels. Alternatively, to 12 PHB34239 implement the method described with reference to Figure 2, the timing unit 24 dictates the positioning of control data portions within each time frame as described with reference to Figure 2.
The structure and operation of the hardware required to implement the method of the invention will not be described in further detail, since more specific details will be apparent to those skilled in the art, and the method of the invention can be implemented using conventional equipment.
Figure 4 schematically shows a possible system architecture for a mobile station which can operate in accordance with the method of the invention. The mobile station 30 again includes a transmitter 32 and a receiver 34 with associated coders and decoders 36, 38 performing the same functions as in the circuit of Figure 3, and coupled to an inputloutput circuit 38. In the mobile station 30 a switch 40 enables the receiver 34 to cease normal operation and to survey other communication channels during the null periods defined in the down-link channel. During this time the receiver 34 provides information to a control analysis circuit 42 which provides information to an overall controlling unit 44 which controls the overall system to generate a handover request in a subsequent up-link transmission. The controller can also implement the interruption to the transmitted signal from the mobile station 30 corresponding with the null periods in the base station channel. Again, specific details of the possible architecture will not be described, since conventional hardware is appropriate for producing a system operating in accordance with the method of the invention.
13
Claims (15)
- PHB34239 1. A method of controlling a communication system in which a communication signal is established between first and second stations and using a channel configuration in which outward and return channels are each divided into sequential time segments with the channels defining a substantially continuous transmission, comprising: providing in the channel from the first to the second station recurring null periods during which the communication signal from the first station to the second station is interrupted; and operating the second station to survey alternative communication channels during the null periods, characterised in that the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different timings relative to their respective time segment.
- 2. A method as claimed in claim 1, characterised in that null periods are also provided in the channel from the second to the first station, and at least some of which are synchronised with null periods in the channel from the first to the second station.
- 3. A method of controlling a communication system in which a communication signal is established between first and second stations and using a channel configuration in which outward and return channels are each divided into sequential time segments with the channels defining a substantially continuous transmission, comprising: providing in the channel from the first to the second station recurring null periods during which the communication signal from the first station to the second station is interrupted; and t, 14 PHB34239 operating the second station to survey alternative communication channels during the null periods, characterised in that null periods are also provided in the channel from the second to the first station, and are synchronised with the null periods in the channel from the first to the second station.
- 4. A method as claimed in claim 3, characterised in that the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different timings relative to their respective time segment.
- 5. A method as claimed in any preceding claim, wherein the second station is operated to generate a handover request in response to the survey, if a more appropriate channel is identified during the survey.
- 6. A method as claimed in any preceding claim, wherein the first station is a base station, and the second station is mobile station.
- 7. A method as claimed in any preceding claim, wherein the timing of different null periods relative to the respective time segment is controlled by the second station.
- 8. A telecommunication system employing a method as claimed in any preceding claim.
- 9. A telecommunication station for transmitting a signal over an allocated channel which is divided into time segments, comprising transmitting means and means for providing in the transmission channel recurring null periods during which the transmission signal is interrupted, wherein the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different relative timings relative to their respective time segment.PHB34239
- 10. A telecommunication station as claimed in claim 9, comprising a base station.
- 11. A telecommunication station for receiving a signal from a transmitting station over an allocated channel which is divided into time segments, comprising receiving means and means for interrupting operation of the receiving means during recurring null periods of the received signal, and means for operating the receiving means to survey other communication channels during the null periods, wherein the null periods have a duration which is a fraction of the duration of a time segment, and different null periods are positioned at different timings relative to their respective time segment.
- 12. A telecommunications station as claimed in claim 11, characterised in that the station is also capable of transmitting a signal to the transmitting station, and means is provided for interrupting the transmission during the null periods.
- 13. A telecommunications station as claimed in claim 11 or 12, comprising a mobile station.
- 14. A method of effecting handover of a communication signal established between first station and second stations from a channel configuration corresponding to a first mode of communication to a channel configuration corresponding to a second mode of communication, each mode permitting bidirectional communication over a channel divided into time frames, the first mode defining substantially continuous signals arranged with outward and return signals separated in frequency, recurring null periods being provided in the channel from a transmitting to a receiving station during which the transmission signal is interrupted, 16 PHB34239 the second mode allocating different time slots of each time frame to outward and return signals, control data being provided in an allocated portion of each time frame, the method comprising:operating the receiving station to survey the control data generated by transmitting stations operating according to the second mode of communication during the null periods, and to generate a handover request when appropriate, wherein the control data is provided at different relative timings within time frames of the second mode.
- 15. A communication station employing a frame structure in which user data is allocated to time slots within each time frame, each time frame comprising a control data portion, and characterised in that the control data portion is provided at different relative timings within different time frames.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9806613A GB2336071A (en) | 1998-03-28 | 1998-03-28 | Null periods in a communication channel allow scanning for alternative handover channel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9806613A GB2336071A (en) | 1998-03-28 | 1998-03-28 | Null periods in a communication channel allow scanning for alternative handover channel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9806613D0 GB9806613D0 (en) | 1998-05-27 |
| GB2336071A true GB2336071A (en) | 1999-10-06 |
Family
ID=10829399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9806613A Withdrawn GB2336071A (en) | 1998-03-28 | 1998-03-28 | Null periods in a communication channel allow scanning for alternative handover channel |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2336071A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2354671A (en) * | 1999-09-24 | 2001-03-28 | Nokia Mobile Phones Ltd | Inter-frequency measurement during a predetermined frame of a common channel which has omitted access channel data |
| GB2369957A (en) * | 2000-07-27 | 2002-06-12 | Motorola Inc | Generating handover cell parameter information to avoid need for scanning |
| GB2370191A (en) * | 2000-12-13 | 2002-06-19 | Motorola Inc | Monitoring radio signals for handover in a mobile station |
| WO2002049377A1 (en) | 2000-12-15 | 2002-06-20 | Motorola, Inc. | Method and apparatus to enable background scanning |
| WO2006103618A1 (en) * | 2005-03-31 | 2006-10-05 | Koninklijke Philips Electronics N.V. | Method and apparatus for transmitting data, and a communication system |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2246490A (en) * | 1990-07-23 | 1992-01-29 | Philips Electronic Associated | Fdm-tdd cordless telephone system measures channel quality for handover |
| WO1994001974A1 (en) * | 1992-07-01 | 1994-01-20 | Motorola Inc. | A method of performing mobile assisted hand-off in a communication system |
| GB2271039A (en) * | 1992-02-06 | 1994-03-30 | Motorola Inc | Apparatus and method for alternative radiotelephone system selection |
| GB2300999A (en) * | 1995-05-16 | 1996-11-20 | Nec Corp | Method of Soft Handoff in a Mobile Radio Communication System |
| WO1997029611A1 (en) * | 1996-02-06 | 1997-08-14 | Ericsson Inc. | A method and apparatus for determining an optimal communications channel without loss of channel messages on a current communications channel |
| WO1997040593A1 (en) * | 1996-04-23 | 1997-10-30 | Telefonaktiebolaget Lm Ericsson (Publ) | Code-rate increased compressed mode ds-cdma systems and methods |
-
1998
- 1998-03-28 GB GB9806613A patent/GB2336071A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2246490A (en) * | 1990-07-23 | 1992-01-29 | Philips Electronic Associated | Fdm-tdd cordless telephone system measures channel quality for handover |
| GB2271039A (en) * | 1992-02-06 | 1994-03-30 | Motorola Inc | Apparatus and method for alternative radiotelephone system selection |
| WO1994001974A1 (en) * | 1992-07-01 | 1994-01-20 | Motorola Inc. | A method of performing mobile assisted hand-off in a communication system |
| GB2300999A (en) * | 1995-05-16 | 1996-11-20 | Nec Corp | Method of Soft Handoff in a Mobile Radio Communication System |
| WO1997029611A1 (en) * | 1996-02-06 | 1997-08-14 | Ericsson Inc. | A method and apparatus for determining an optimal communications channel without loss of channel messages on a current communications channel |
| WO1997040593A1 (en) * | 1996-04-23 | 1997-10-30 | Telefonaktiebolaget Lm Ericsson (Publ) | Code-rate increased compressed mode ds-cdma systems and methods |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2354671A (en) * | 1999-09-24 | 2001-03-28 | Nokia Mobile Phones Ltd | Inter-frequency measurement during a predetermined frame of a common channel which has omitted access channel data |
| GB2354671B (en) * | 1999-09-24 | 2003-10-01 | Nokia Mobile Phones Ltd | Inter-frequency measurement |
| GB2369957A (en) * | 2000-07-27 | 2002-06-12 | Motorola Inc | Generating handover cell parameter information to avoid need for scanning |
| GB2369957B (en) * | 2000-07-27 | 2003-11-19 | Motorola Inc | Communication system,radio unit and method of performing a handover |
| GB2370191A (en) * | 2000-12-13 | 2002-06-19 | Motorola Inc | Monitoring radio signals for handover in a mobile station |
| WO2002049377A1 (en) | 2000-12-15 | 2002-06-20 | Motorola, Inc. | Method and apparatus to enable background scanning |
| EP1344412A1 (en) * | 2000-12-15 | 2003-09-17 | Motorola, Inc. | Method and apparatus to enable background scanning |
| EP1344412A4 (en) * | 2000-12-15 | 2007-01-24 | Motorola Inc | Method and apparatus to enable background scanning |
| WO2006103618A1 (en) * | 2005-03-31 | 2006-10-05 | Koninklijke Philips Electronics N.V. | Method and apparatus for transmitting data, and a communication system |
| US8261146B2 (en) | 2005-03-31 | 2012-09-04 | Koninklijke Philips Electronics N.V. | Method and apparatus for transmitting data, and a communication system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9806613D0 (en) | 1998-05-27 |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |