GB2501420A

GB2501420A - Switching to alternative communication channels to enhance reliability in shared bands

Info

Publication number: GB2501420A
Application number: GB1312715.4A
Authority: GB
Inventors: Timo Koskela; Sami-Jukka Hakola; Samuli Turtinen
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2011-04-14
Filing date: 2011-04-14
Publication date: 2013-10-23
Also published as: GB201106358D0; GB2490110A; GB2490185A; GB201120064D0; GB201312715D0

Abstract

Channel reliability for mobile communications deployed on shared bands (e.g. TV white space) is enhanced by switching to alternative channels in the event that a current channel becomes unusable. A list of channels useable for communication is maintained and if a currently used channel becomes unusable, for example due to interference, a switch to one of the channels in the list is prompted. The list is constructed at a network node S10 and includes channel bandwidths and centre frequencies (fig. 3), wherein at least one of the bandwidth and centre frequency are configured by the node. At least one entry on the list comprises a code indicative of a relationship between a centre frequency of a channel on the list and a centre frequency of another channel (e.g. TV channel). The channel list may be updated and distributed to communication terminals.

Description

Enhancements on channel reliability in scenarios operating on shared bands

Field of the Invention

The present invention generally relates to enhancements on channel S reliability in scenarios operating on shared bands. More particularly, the present invention addresses methods, devices and computer readable memories for systems operated on shared bands, which enhance reliability of channels.

Background of the Invention

Mobile data transmission and data services are constantly making progress. With the increasing penetration of such services, a need for increased bandwidth for conveying the data is emerging. In hitherto known scenarios, networks operated on reserved bands (licensed bands) within the available spectrum, which were reserved for the particular network. As licensed band operation has been increasingly utilized, portions of the radio spectrum that remain available have become limited. Thus, operators, service providers, communication device manufacturers, and communication system manufacturers, are all seeking efficient solutions to utilize unlicensed shared band operation. Communication on an unlicensed shared band is generally based on sharing an available channel between different communication devices. The different communication devices may utilize a common radio access technology (RAT). However, in certain scenarios, the different communication devices may utilize different RATs. In an unlicensed shared band, channel access can be distributed, where communication devices can detect a channel, and utilize a channel reservation scheme known to other communication devices in order to reserve a right to access the channel. In distributcd channcl access, a transmitting communication device and a receiving communication device are generally not synchronized to a global reference.

Currently, a system known as Long Term Evolution, LTE, is being further developed. When the LTE system concept is further extended in a way that it can be deployed also on unlicensed bands, the devices and local access points (AP5) have potentially more spectrum available. That spectrum can be used opportunistically as explained above. This setting can be considered as a kind of non-contiguous carricr aggrcgation, in which unlicensed spectrum is used as resources or "ground" for secondary carriers/cells for the licensed spectrum primary and secondary carriers/cells, controlled by the network transceiver station (or access node) known as Evolved Node_B (eNB). One step further would be to deploy an eNB totally on some shared band, like in television white space (TVWS) or in the industrial, scientific and medical (ISM) band without any anchor in licensed spectrum (in EUTRAN level) (Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network) similar to WLAN deployments to make LTE an alternative solution against widely adopted IEEE technologies.

As a future LTE-A system may be deployed on unlicensed bands (e.g. TVWS or ISM bands), such an environment sets further requirements / challenges for the system to operate appropriately.

In particular, the dynamic interference environment is very peculiar to the shared bands such as ISM and TVWS. The quality of the communication link may change quite rapidly due to an unknown interferer (e.g. another system's device or devices occupying the band) or if the incumbent user decides to deploy the channel. Although the Quality of Service (Q0S) cannot be guaranteed on the shared bands where the available resource is shared between secondary users, the service continuity should be protected in case of a sudden degradation of the signal quality or if the used channel becomes occupied. In particular, the re-establishment of control channels on secondary channels is crucial in order to guarantee the service continuity on shared bands.

In one approach, secondary communication channels of an unlicensed band are e.g. derived based on GPS information for direct communication between communication devices without network node(s) being involved.

Thus, there is still a need to further improve such systems, in particular it is crucial to have reliable control channels so as to maintain and enable control of thc systcm.

Summary of the Invention

Various aspccts of cxamples of the invcntion arc set out in the claims.

Exemplary embodiments include a method, apparatus and computer program for configuring channels for use in communications between a network node aild a communications terminal operatillg in a shared frequency baild. The method comprises: constructing, at the network node, a list comprising a plurality of channels uscabic for said communications, thc list comprising data indicative of bandwidth and centre frequency of individual said channels, wherein at least one of the bandwidth and centre frequency of individual ones of the plurality of channels are configured by the network node transmitting, to the communication tcrniinal, data indicativc of the list of the plurality of channels; and communicating with the communication terminal via one of the plurality of channels of the list of channels.

Respcctivc advantagcous furthcr dcvelopments of the mcthod and!or apparatus are as set out in the corresponding dependent claims.

The above computer program product may be embodied as a (volatile or non-volatile) computer-readable storage medium.

The methods, apparatus and computer program products described in this document, at lcast in cxcmplary embodimcnts, use an auxiliary channel list (ACL) to thereby enable quick changing to an auxiliary channel if the current channel becomes un-useable. A quick change can be accomplished by merely signalillg the channel index of thc new auxiliary channel that is maintained in the ACL. Moreover, even if the connection between a communication terminal such as a user equipment (tiE) and a network node such as an eNB breaks, both devices have a common understanding about the new channel to be used in view of the ncccssary information bcing kept up-to-date in the ACL maintaincd in both devices.

By virtue thereof; a terminal UE is prevented from having to always blindly try to find the network node eNB from the shared spectrum. Offering auxiliary channels thus also speeds up the re-deployment of the shared spectrum. In addition, configuring virtual channels also speeds up the device S attachment to eNB and clarifies the deployment on shared bands.

Brief Description of the Drawings

For a more complete understanding of example embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which: FIGURE 1 illustrates procedures related to the auxiliary channel list ACL as performed at a network node side, e.g. at an eNB; FIGURE 2 illustrates an example of virtual and!or free channelization on a shared spectrum with reference to the ISM band; FIGURE 3 illustrates an exemplary example of an auxiliary channel list ACL while referring to the example of Figure 2; FIGURE 4 illustrates an example of channelization on a shared spectrum with reference to the TYWS band; FIGURE 5 illustrates procedures related to the auxiliary channel list ACL as performed at a communication terminal device side, e.g. at a UE, and FIGURE 6 shows a basic block circuit diagram illustrating exemplary network nodes as well as an exemplary communication terminal.

Detailed Description of the Invention

Exemplary aspects of the invention will be described herein below.

Generally, according to onc (at least partial) aspect, the invention is implemented in a network node such as an evolved Node_B, eNB. Likewise, according to another (at least partial) aspect, the invention is implemented in a communication terminal device such as an user equipment UE. Both aspects are at least partly interrelated. The invention is mainly implemented in a device such as a processor or chipset residing at the eNB side or at the UE side. Such processor of chipset may be implemented hardware independent, i.e. independent of the hardware technology such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), or ECL (Emitter coupled Logic),or any others. The chipset may be implemented as a DSP (digital signal S processor) or as an ASIC (application specific integrated circuit) or the like.

Alternatively, the functionality thereof may be realized, at least in part, as software or computer program product. If implemented as software, the software implementation may be independent of the programming language such as C++, or any other, as long as the functionality is preserved. Embodiments of the present invention may be implemented in software, hardware, application logic or even a combination of software, hardware and application logic.

In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or smart phone, or user equipment or evolved Node_B eNB.

The present invention relates in particular but without limitation to mobile communications, for example to environments under WCDMA, LTE, LTE-A, WIMAX and WLAN and can advantageously be implemented in user equipments or smart phones, or personal computers connectable to such networks. Also, it can be implemented in network devices such as network nodes like an evolved Node_B eNB or an access point AP, or the like.

That is, the present invention can be implemented as/in chipsets to connected devices, network nodes and/or respective modems thereof More generally, all products which contain an auxiliary channel list ACL managed and exploited as described in relation to at least exemplary embodiments will see performance improvement with the invention being implemented thereto.

The present invention is particularly useful in environments that operate at least not fully on a licensed band or even operate fully on an unlicensed band.

A licensed band denotes a band or bandwidth of spectrum reserved for a particular application or system (such as IJMTS), whereas an unlicensed band denotes a band or bandwidth of spectrum not reserved for a particular application/system and on which bandwidth users of more than one system may compete to obtain access to and use the available unreserved (shared) bandwidth.

It will be understood from the following description, that if desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

FIGURE 1 illustrates procedures related to the auxiliary channel list ACL as performed at a network node side, e.g. at an eNB.

The description starts with step 510. In this exemplary embodiment, the eNB operating on a shared band constructs, 510, an auxiliary channel list. The auxiliary channel list (ACL) determines the back-up channels to which the eNB (and an IJE) will move once a currently used channel becomes unusable. The channel may become unusable due to interference with other users of the same or different systems, or due to occupancy of the channel by a primary user, e.g. an industrial, scientific, or medical user (in case of the ISM shared band). Or, the coexistence protocol (which may determine that it is more beneficial to change the channel) has determined that the channel has to be changed for those or other reasons.

The eNB constructs the auxiliary channel list based on measurements (own measurements or reported measurements from UE5) or any other evaluation process. The eNB determines which channels are most suitable for its operation and thus for the auxiliary channel list ACL.

Such an evaluation process takes into account e.g. one or more of the following factors: -the channel position in the spectrum e.g. whether it is located close to the current channel (e.g. if close, the probability of interference maybe higher), -channels which are adjacent to TV channels should be avoided if the eNB occupies TV WS, -channels which may become occupied by an incumbent user soon (this information is provided by a TV WS data base) should be avoided.

The eNB, in step SI!, indicates and/or assigns a priority order for the channels listed in the ACL (e.g. based on a current interference level or on a predicted interference level, etc.) and allocates an index for each channel for quick reference. The eNB (optionally) maintains the auxiliary channel list in coordination with other eNBs, as illustrated in step 5!! a. Such a process may include a preferred channel list query to other eNBs in the vicinity, using an established inter-eNB interface for such communication, or with a (local) coexistence manager/coexistence server, or an MME (mobility management entity).

As shown in step S12, the eNB informs the attached terminals UEs about the backup channels by transmitting the ACL. Likewise, newly attaching or registering terminals liE receive the ACL list, e.g. upon entry to the eNB serving area, as shown in step SI 2a.

Depending on the offered service level, the ACL can be broadcasted or unicasted to the attached UEs. If broadcasted to all attached UEs, a common signaling channel is used, if unicasted to individual UEs, a respective dedicated signaling channel is used, as illustrated in step 513.

If a liE newly registers or attaches to the eNB, the ACL can either be pushed to the UE from the eNB, or the UE issues a pull request to the eNB, responsive to which the eNB then responds by transmitting the ACL list, as shown in step S13a.

Also, as shown in step SI4, the eNB regularly runs the ACL selection process to update its preferred backup channels. In connection thereto, the eNB notifies the attached liEs about the changes in the channel list. This can be the content of the changes themselves, or an indication of the change(s). If the content is transmitted, the receiving UE incrementally updates its "copy" of the ACL. If an indication of the change is signaled, the UE thereafter requests the content, either incrementally or a completely updated ACL, from the eNB.

For example, the eNB optionally sets an expiry timer (as an example of a validity attribute) for the list to prevent old information being maintained in the liE memory. Then, if the UE keeps an "old" ACL for which the expiry timer is close to expiry (e.g. more than 75% of the ACL lifetime expired), a complete update of the ACL is requested, whilst if the liE keeps a relatively "fresh" ACL (e.g. less than 75% of the ACL lifetime expired) an incremental update of the ACL is requested. Altematively or additionally, a validity attribute may be defined as a number of occasions a channel was used or attempted to be used.

Variations for updating the ACL may contribute to balance the payload transmitted in the system, and/or to speed up the ACL update.

The ACL list can optionally include the prefened cell IDs' of the eNBs belonging to the same network.

The ACL thus mainly serves two purposes: it provides a means to change the channel quickly if it becomes unusable by simply signaling the channel index in the ACL, and, if a connection between an eNB and a tiE breaks, they have a common understanding about the new channel to be used for maintaining communication, at least for a control channel, as both entities keep a record of the updated ACL list.

FIGURE 2 illustrates an example of virtual and/or free channelization on a shared spectrum with exemplary reference to the ISM band.

Typically, examples of shared bands arc the TV White Space spectrum, TV WS, and the ISM (industrial, scientific, medical) band.

While in TV WS channelization requirements are strict, in some bands such as ISM 2.4Ghz there is no strict channelization requirement.

The ISM 2.4GHz band provides for 83 MHz bandwidth in the range from 2.4 GHz to 2.483GHz, as shown in Fig. 2. This bandwidth can be utilized somewhat freely, taking into account the general regulation (transmit power limitation, duty cycle etc.). The most utilized channclization on ISM 2.4GHz band is the channelization (conformant to IEEE 802.11) which enables three 20Mhz channels 011 83Mhz bandwidth (the loose channelization is due to the relaxed outband transmission requirements specified in IEEE 802.11). With for example LTE, the ISM band could be utilized more effectively and with virtual channelization the network (effectively the operator) can control frequency S utilization and deploy its systems as preferred and needed. Figure 2 also illustrates such an example, in which the network, represented by an evolved Node_B eNB has configured a 20Mhz channel denoted by ID#1 as a main carrier configured to the shared ISM band and three 5Mhz channels close to the upper frequency bound, denoted by ID#2, ID#3, and ID#4, respectively, as auxiliary channels or carriers virtually configured to the shared ISM band.

Of course, other channelization can be deployed, as long as the ISM bandwidth is not exceeded, e.g. one or more channels with 20 MHz or 10 MHz in addition to one or more channels of 5 MHz can be configured. The number of 5MHz channels is not limited to three but can be configured freely while taking into account the remaining channels and ISM bandwidth. Also, a bandwidth of auxiliary channels can differ from the example of 5 MHz, e.g. when using a main carrier of 20MHz bandwidth, the auxiliary channels may be configured to MHz.

FIGURE 3 illustrates an exemplary example of an auxiliary channel list ACL while referring to the example illustrated in Figure 2.

As explained above in relation to an exemplary embodiment with reference to the ISM band, the eNB / network may generate virtual channelization on the shared band. Considering e.g. a femto eNB as an exemplary eNB of very small coverage area ("similar" to a "pico eNB"), limited in its coverage to, for example, private homes or offices, deployment to shared band and such "femto" or "pico" cNB would be under an operator's control.

Upon deployment of such eNB, the eNB requests a preferred channel configuration list from the network (either from a new logical element or from an added functionality feature, added to e.g. a mobility management entity MME acting as a local spectrum manager).

The format of such ACL list can be as exemplarily illustrated in Fig. 3.

Namely, -"Carrier ID" denotes a specific carrier, -"center frequency" denotes around what frequency the carrier is deployed, -"bandwidth" denotes the bandwidth of the channel/carrier, and -"priority" in the priority field denotes priority assigned to such channel, and is added to indicate network preferences.

By configuring the virtual channelization in such way, the eNB and UE or TJEs have consensus of the possible channels and deployment in case e.g. the current channel becomes occupied or interfered with, or more generally unusable. Naturally, the eNB initiates proactive actions to change the channel upon detecting rising intcrfcrcncc; the prcconfigurcd channclization then reduces the signaling overhead and speeds up the selection of a new communication channel. In addition, it provides options for a fallback channel if the current channel suddenly becomes occupied or the connection breaks and the channel reselection signaling is not possible.

FIGURE 4 illustrates an example of channelization on a shared spectrum with reference to the TVWS band.

For exemplary embodiments in relation to TV WS, those should conform to TV WS regulations as laid down e.g. in FCC 10-174 Appendix B Final Rules. Accordingly, a MODE I device (i.e. a terminal such as a user equipment liE) is required to obtain the available channel list' from a MODE II / Fixed device (i.e. a network node such as an cNB) before initiating the communication.

Hence, in one exemplary embodiment, the eNB signals in addition to the available channel list', the auxiliary channel list ACL mentioned above.

Such ACL list is similar to thc onc indicatcd in Fig. 3. The priority ordcr indicated in the ACL, as in the case of Fig. 3, determines the next preferred channel where the AP or eNB will deploy its carrier if the current carrier (primary) will become occupied or the communication degrades too much due to interference, or even breaks.

Optionally, together with the priority order, the position of the new center frequency relative to the TV Channel center frequency is also included, e.g. "0" denotes "TV channel center frequency", while "+ 1" denotes "between the TV channel center frequencies of the present one and the adjacent channel with higher frequency". Likewise, "-1" denotes "between the TV channel center frequencies of the present one and the adjacent channel with lower frequency".

This is graphically illustrated in Fig. 4.

By indicating the center frequency and its relation to the adjacent channel center frequency, flexible deployment options may be utilized in that it is possible to span the carrier over multiple adjacent channels. The initial dcploymcnt bandwidth may thus vary if thc carrier can be spanned ovcr multiple adjacent free channels (e.g. it should not always be fixed). Stated in other words, if the "center frequency indicates the center frequency of Ch_Aux and parameter "center=0", then the auxiliary channel has the bandwidth of Ch_Aux only (the one illustrated in the middle of Fig.4). However, if the "center frequency" indicates the center frequency of Ch_Aux and parameter "high = +1", then the auxiliary channel has the bandwidth of "Ch Aux" and "Ch Aux+l", thus doubling bandwidth in this example and as illustrated by the dotted envelope curve labeled Ch_Aux*.

The eNB and/or another network entity can configure the parameters for indicating the high and low values. For example, if only one bit is used, the parameter can have values center' and high', or alternatively center' and low'.

Using multiple bits, the parameter has more values as e.g. in the illustrated example, in which the values low, center, and high (3 values) need to bc distinguished and thus appropiiately coded, for which typically 2 bits arc required. A possible exemplary coding scheme could reside in lO=low,00=center,andol =high.

Optionally dwell time on each channel (i.e. how long the eNB will stay on the backup channel before trying another backup channel) can be indicated in the table. Such an indication can optionally also be added to the table shown in Fig. 3 for the ISM band.

In addition according to exemplary FCC regulations mentioned above, a MODE I device (UE is required to hear the Contact Verification Signal, CVS' S from the fixed/MODE II device (eNB) which provided the available channel list regularly, at least once every 60sec. Other update intervals may be applied in case other rules have to be met, or a shorter interval may be applied.

In an exemplary embodiment, the eNB thus informs in the contact verification signal with one flag bit if the channel preference list, i.e. the auxiliary channel list (ACL) has changed. On the UE side, upon reception of the flagged CVS, the TiE requests a new preferred channel list that is thus pulled from the eNB. Altematively the new channel preference list is fully retransmitted (pushed to the associated TiEs by the eNB).

FIGURE 5 illustrates procedures related to the auxiliary channel list ACL as performed at a communication terminal device side, e.g. at a UE.

The liE side actions in ACL procedure are illustrated in Figure 5. The procedure exemplarily specifies fault cases where the eNB cannot be found from the auxiliary channel list and the TIE is forced to reconnect via a licensed band (if such option exists) or to remain on a shared band and try to blindly decode e.g. the operator preferred default channels.

It is to be noted that features and/or stages illustrated in Figure 5 are not all carried out in a consecutive order. Rather, Fig. S illustrates certain states of a terminal device such as a user equipment or similar device and certain stages carried out starting in a specific stage or state leading to a subsequent stage or state.

In order to describe this transmission, the description of Fig. S is started with stage S60. In stage S60, the user equipment stores the auxiliary channel list ACL as signaled by a network node such as an eNB. Either the complete list is signaled and stored, or an update thereof is signaled and stored. The UE then updates its own ACL list which generally is a complete copy or mirror of the ACL list maintained at the eNB.

Using such a list, the UE communicates via a currently assigned channel, which in a normal condition is a so called main channel or channel of highest priority. If in such a stage, an ACL list is updated at the eNB, the process at the TiE advances to stage SM where an indication of changed channel list is S received.

Subsequently, in stage S62, the TIE obtains an ACL update, either by pulling the list from the eNB in a pull mode upon issuing a corresponding request to the eNB, or by receiving an ACL update from the eNB in a push mode. Such an update may be a complete copy of the ACL list or an incremental update of the ACL list as mentioned herein above.

After stage 562, the process returns to stage 560 described before. In another scenario, the process may advance from stage S60 to stage S63 when it is detected that the current channel becomes unusable. A channel may become unusable due to increased interference or due to another systems user accessing the channel, e.g. in an ISM band, or the like. Also, the channel is evaluated as unusable if the connection with the eNB is completely lost.

If the current channel becomes unusable, under "normal conditions" the cNB signals a "change channel" indication that is received with the channel ID reference in a stage 568 at the user equipment. The channel ID is similar or identical to the carrier ID illustrated in Fig. 3, for example. Then, in a stage S66 the channel is changed to the indicated channel denoted by the channel ID and the tiE reconnects the eNB. If the connection is thus successful, the process returns to stage S60.

Optionally, at a later point of time, the same stages may be transited again if the new channel as the current channel becomes unusable.

On the other hand, if the current channel is found to be unusable because the connection to the eNB is completely lost, the process advances from stage S63 to stage S64 where a situation of a lost connection to the eNB is handled. In such a stage, no signaling can be received from the eNB so that the liE then in stage S65 checks the ACL that it maintains in its memory for a next channel.

The next channel is thus the channel having the highest following priority. If for example the previous communication was carried on a channel of priority 2, the next channel checked is for example the one of priority 3.

Alternatively, also a channel with higher priority can be checked although, if communication has been conducted on a channel of priority 2, it can be assumed that channel of priority 1 may have failed beforehand. However, after a certain time since changing to a channel of priority 2 has elapsed, an attempt can be made to find out whether higher priority channels have become available again.

In any case, after checking the ACL for a next channel, the procedure advances to stage S66 where the liE changes the channel to the next channel and reconnects to the cNB. If connection was successful, the process advances again to stage S60. If however the reconnection was not successful, the process goes back to stage S65 and a next channel is checked for. Normally, the next channel is then the next channel of even lower priority.

In this way, the process loops via stage S65 and stage S66 until no further channel is on the ACL and a reconnection was not successful. Thus, if based on the available ACL channels on the list a reconnection to an eNB was not possible and no eNB was found, the process advances to stage S67 where the lIE tries to reestablish connection either via a licensed band or blindly decodes for example the operators preferred channels as a further and potentially final fallback position.

If connection was successful, the process advances to stage S60.

Alternatively, as mentioned before, the ACL list may be attributed with an expiry date. Therefore, if the channel list expired while reconnection was attempted using channels on the ACL list, connection is reestablished via stage S67 using either a licensed band or blindly decoding for example operators preferred channels.

If also via this stage, no successful reconnection is obtained, an error processing (not shown) is performed or, simply the connection to the eNB remains lost until a later point of time.

Fig. 6 shows a basic block circuit diagram illustrating an eNB#1 and an eNB#x as exemplary network nodes as well as illustrating a user equipment tiE as an exemplary communication terminal.

Basically, each eNB has a substantially similar internal construction, and S can be represented by a transmitter/receiver interface TX/RX-I/F, a memory MEM and a processor Proc. A network node communicates via the Tx/Rx-T/F with other network nodes as well as with a communication terminal UE. Also internally, the processor Proc. May access and read and/or write data ftomlto the memory via that interface, which may comprise e.g. a databus.

In terms of a network node as a device, such a device thus comprises a processor configured to construct, at a network node, a list of channels useable for communication, and a memory configured to store the consfructed list of channels, the processor being further configured to obtain, at the network node, information on the usability of a currently used channel, and to instruct a communication terminal to switch to one of the channels of the list of useable channels if the currently used channel becomes unusable.

The processor is further configured to re-connect to a communication terminal via the channel to which it was instructed to be switched, and/or optionally to detect at the network node that a connection to a communication terminal is lost. In the memory, the stored list of channels is associated with a validity attribute (and other attributes as shown e.g. in and described in relation to Fig. 3), and the processor is further configured to re-establish a connection to a communication terminal via a predetermined channel or blindly via an arbitrary channel, in the event that the validity of the list of channels expires and a currently used channel becomes unusable. The processor is further configured to update the list of channels in case an update criterion is fulfilled, wherein said update criterion is an indication of a changed channel list to be coordinated being available at another network node, or an expiry of a validity attribute associated with the list of channels. Moreover, in such a device, the processor is further configured to distribute the list of channels to communication terminals using a push mode or a pull mode.

In terms of a communication terminal as a device, such a device thus comprises a memory configured to maintain a list of channels useable for communication, a processor, configured to obtain information on the usability of a currently used channel, and configured to switch to one of the channels of the S list of useable channels if the currently used channel becomes unusable. The processor is further configured to re-connect to a network node via the channel to which switching was performed.

Also, the processor is further configured to switch to another one of the channels of the list of useable channels, if the re-connecting via the channel to which switching was performed was unsuccessful.

Likewise, the processor is further configured to re-establish a connection to the network node via a predetermined channel or blindly via an arbitrary channel, in the event that the re-connecting failed for each channel of the list.

The list of channels is associated with a validity attribute (and other attributes as shown e.g. in and described in relation to Fig. 3), and the processor is further configured to re-establish a connection to a network node via a predetermined channel or blindly via an arbitrary channel, in the event that the validity of the list of channels expired and a currently used channel becomes unusable. In addition, the processor is further configured to update the list of channels from a network node if an update criterion is fulfilled. Such an update criterion can comprise an indication of a changed channel list being available at the network node, or an cxpiry of a validity attribute associated with the list of channels.

Also, the processor is further configured to pull, from the network node, the updated list of useable channels, or to receive, from the network node, a pushed list of useable channels. The processor is further configured to receive a request from a network node to switch to onc of the channels of the list, or detect that a connection to a network node is lost.

Although the description of the block circuit diagrams has been given in brief only, it is understood that the processor and the memory, respectively, with the respective computer program products as described and disclosed herein, in cooperation accomplish the respective method aspects at the communication terminal side and the network node side, respectively. Those have been described in detail herein above so that a repeated and description thereof is dispensable here.

Thus, as has been described herein before with reference to one or more S exemplary embodiments, one or more of the following advantages are realized: -it is prevented that the TIE blindly attempts to find the eNB from the shared spectrum, -the re-deployment is speeded up by offered auxiliary channels, -the device attachment to the eNB is speeded up by configuring virtual channels and -the deployment on shared bands is clarified.

Also, the method, devices and computer program products presented herein are generally applicable to all scenarios and/or systems which operate on non-licensed and/or shared bands. Other systems can benefit also from the principles presented herein.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there arc several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Some examples of other embodiments, dcscribcd in summary form include a method, apparatus and computer program for configuring channels for use in communications between a network node and a communications terminal operating in a shared frequency band, the method comprising: updating, at the network node, a list comprising a plurality of channels useable for said communications; responsive to a change to the list, distributing the updated list of the plurality of channels to the communication terminal, the distributing comprising at least transmitting a signal from the network node to the communications terminal; and communicating with the communication terminal via one of the plurality of channels of the updated list of channels.

The updated list of channels maybe distributed to communication terminals using a push mode or a pull mode. The signal may inform the communications terminal that the list has changed, and the distributing may comprise: receiving a request for the updated list from the communications terminal; and transmitting at least a part of the updated list to the communications terminal. The signal may comprise a contact verification signal.

Furthcrmorc, the contact verification signal may comprisc a flag bit indicating if the list has changed.

As described above, the present invention proposes methods and devices for mobile communication deployed on shared bands, which enhance reliability of channels such as control channels. According to an aspect thereof, at a communication terminal, a list of channels useable for communication is maintained, information on the usability of a currently used channel is obtained, and it is switched to one of the channels of the list of useablc channels if the currently used channel becomes unusable. The invention encompasses also corresponding computer products as well as methods, devices and computer products residing at a network node.

Claims

Claims 1. A method of configuring channels for use in communications between a network node and a communications terminal operating in a shared frequency band, the method comprising: constructing, at the network node, a list comprising a plurality of channels useable for said communications, the list comprising data indicative of bandwidth and centre frequency of individual said channels, wherein at least one of the bandwidth and centre frequency of individual ones of the plurality of channels are configured by the nctwork node; transmitting, to the communication terminal, data indicative of the list of the plurality of channels; and communicating with the communication terminal via one of the plurality of channels of the list of channels.
2. The method according to claim I comprising: obtaining, at the network node, information on the usability of a currently used channel, said currently used channel being one of said plurality of the list of channels; and instructing the communication terminal to switch to one of the channels of the list ofuseable channels if the currently used channel becomes unusable.
3. The method according to claim 2, comprising re-connecting to the communication terminal via the channel to which the communication terminal was instructed to be switched.
4. The method according to claim 2 or claim 3, wherein the obtaining comprises detecting at the network node that a connection to a communication terminal is lost.
5. The method according to any of the preceding claims, wherein the list of channels is associated with a validity attribute, said method further comprising re-establishing a connection to a communication terminal via a predetermined channel or blindly via an arbitrary channel, in the event that the S validity of the list of channels expires and a currently used channel becomes unusable.
6. The method according to any of the preceding claims, in which said individual ones of the plurality of channels are individually configured by the network node in dependence on an instruction from a network operator with which the network node is associated.
7. The method according to any of the preceding claims, in which the number of channels making up the plurality of channels is configured in dependence on the bandwidth of individual said channels in the list and the bandwidth of the shared frequency band.
8. The method according to any of the preceding claims, wherein at least one entry on the list comprises a code indicative of a relationship between a centre frequency of a first channel of the plurality and a centre frequency of a second channel.
9. The method according to claim 8, wherein the code indicates that the centre frequency of the first channel is the centre frequency of the second channel.
10. The method according to claim 9, wherein the code indicates that the first channel has a bandwidth equal to a bandwidth of the second channel.
11. The method according to claim 8, wherein the code indicates that the centre frequency of the first channel lies between the centre frequency of the second channel and a centre frequency of a channel adjacent to the second channel.
12. The method according to claim 11, wherein the code further indicates that the fir st channel has a bandwidth equal to the bandwidth of the second channel and the channel adjacent to the further channel.
13. The method according to claim 11 or claim 12, wherein the code indicates that the centre frequency of the channel adjacent to the second channel is higher than the centre frequency of the second channel.
14. The method according to claim 11 or claim 12, wherein the code indicates that the centre frequency of channel adjacent to the second channel is lower frequency than the centre frequency of the second channel.
15. The method according to claim 8, wherein the code indicates that the first channel spans multiple adjacent channels.
16. The method according to any of claims 8 to 15, wherein the code comprises one or more bits.
17. The method according to any of claims 8 to 16, wherein at least one of the centre frequency and a bandwidth of the second channel is preconfigured.
18. The method according to any of claims 8 to 17, wherein the centre frequency of the second channel is a centre frequency of a TV channel.
19. The method according to any of claims 8 to 18, wherein the bandwidth of the second channel is a bandwidth of a TV channel.
20. The method according to any of the preceding claims, wherein the shared frequency band comprises the TV White Space (TV WS) spectrum band.
21. The method according to any of claims 1 to 17, wherein the shared frequency band comprises the Industrial, Scientific, Medical (ISM) band.
22. The method according to any of the preceding claims, comprising: updating the list, at the network node; and responsive to a change to the list, distributing the updated list of the plurality of channels to the communication terminal, the distributing comprising at least transmitting a signal from the network node to the communications terminal.
23. The method according to claim 22, further comprising distributing the updated list of channels to communication terminals using a push mode or a pull mode.
24. The method according to claim 22 or claim 23, wherein the signal informs the communications terminal that the list has changed, and the distributing comprises: receiving a request for the updated list from the communications terminal; and transmitting at least a part of the updated list to the communications terminal.
25. The method according to any of claims 22 to 24, wherein the signal comprises a contact verification signal.
26. The method according to claim 25, wherein the contact verification signal comprises a flag bit indicating if the list has changed.
27. The method according to any of claims 22 to 26, further comprising updating the list of chailnels if an update criterion is flilfilled, and wherein said update criterion comprises an indication of a changed channel list to be coordinated being available at another network node or an expiry of a validity attribute associated with the list of channels.
28. An apparatus for configuring channels for use in communications between the apparatus and a communications terminal operating in a shared frequency band, the apparatus comprising a processing system arranged to: construct a list comprising a plurality of channels useable for said communications, the list comprising data indicative of bandwidth and centre frequency of individual said channels, wherein at least one of the bandwidth and centre frequency of individual ones of the plurality of channels are configured by the apparatus; transmit, to the communication terminal, data indicative of the list of the plurality of channels; and communicate with the communication terminal via one of the plurality of channels of the list of channels.
29. The apparatus according to claim 28, wherein the processing system is arranged to: obtain information on the usability of a currently used channel, said currently used channel being onc of said plurality of the list of channcls; and instruct the communication terminal to switch to one of the channels of the list of useable channels if the currently used channel becomes unusable.
30. The apparatus according to claim 29, wherein the processing system is arranged tore-connect to the communication terminal via the channel to which the communication terminal was instructed to be switched.
31. The apparatus according to claim 29 or claim 30. wherein the processing system is arranged to detect that a connection to a communication terminal is lost whereby to obtain said information on the usability of a currently used channel.
32. Thc apparatus according to any of claims 28 to 31, wherein the list of channels is associated with a validity attributc, said processing system is further arranged to re-establish a connection to a communication terminal via a predetermined channel or blindly via an arbitrary channel, in the event that the validity of the list of channels expires and a currently used channel becomes unusable.
33. The apparatus according to any of claims 28 to 32, in which said individual ones of the plurality of channels are individually configured by the apparatus in dependence on an instruction from a network operator with which the apparatus is associated.
34. Thc apparatus according to any of claims 28 to 33, in which the numbcr of channels making up the plurality of channcls is configurcd in dependence on the bandwidth of individual said channels in the list and the bandwidth of the shared frequency band.
35. The apparatus according to any of claims 28 to 34, wherein at least one entry on the list comprises a code indicative of a relationship between a centre frequency of a first channel of the plurality and a centre frequency of a second channel.
36. The apparatus according to claim 35, wherein the code indicates that the centre frequency of the first channel is the centre frequency of the second channel.
37. The apparatus according to claim 36, wherein the code indicates that the first channel has a bandwidth equal to a bandwidth of the second channel.
38. The apparatus according to claim 35, wherein the code indicates that the centre frequency of the first channel lies between the centre frequency of thc sccond channel and a ccntrc frequency of a channel adjacent to the second channel.
39. The apparatus according to claim 38, wherein the code further indicates that the first channel has a bandwidth equal to the bandwidth of the second channel and the channel adjacent to the further channel.
40. The apparatus according to claim 38 or claim 39, wherein the code indicates that the centre frequency of the channel adjacent to the second channel is higher than the centre frequency of the second channel.
41. The apparatus according to claim 38 or claim 39, wherein the code indicates that the ccntrc frequency of channel adjacent to the second channel is lower frequency than the centre frequency of the second channel.
42. The apparatus according to claim 35, wherein the code indicates that the first channel spans multiple adjacent channels.
43. The apparatus according to any of claims35 to 42, wherein the code comprises one or more bits.
44. The apparatus according to any of claims 35 to 43, wherein at least one of the centre frequency and a bandwidth of the second channel is preconfigured.
45. The apparatus according to any of claims 35 to 44, wherein the centre frequency of the second channel is a centre frequency of a TV channel.
46. The apparatus according to any of claims 35 to 45, wherein the bandwidth of the second channel is a bandwidth of a TV channel.
47. The apparatus according to any of claims 28 to 46, wherein the shared frequency band comprises the TV White Space (TV WS) spectrum band.
48. The apparatus according to any of claims 28 to 44, wherein the shared frequency band comprises the Industrial, Scientific, Medical (ISM) band.
49. The apparatus according to any of claims 28 to 48, wherein the processing system is arranged to: update the list; and responsive to a change to the list, distribute the updated list of the plurality of channels to the communication terminal, wherein the processing system is arranged, at least, to transmit a signal to the communications terminal whereby to distribute the updated list.
50. The apparatus according to claim 49, wherein the processing system is farther arranged to distribute the updated list of channels to communication terminals using a push mode or a pull mode.
51. The apparatus according to claim 49 or claim 50, wherein the signal informs the communications terminal that the list has changed, and the processing system is ananged to: receive a request for the updated list from the communications terminal; and transmit at least a part of the updated list to the communications terminal whereby to distribute the updated list.S
52. The apparatus according to any of claims 49 to 51, wherein the signal comprises a contact verification signal.
53. The apparatus according to claim 52, wherein the contact verification signal comprises a flag bit indicating if the list has changed.
54. The apparatus according to any of claims 49 to 53, wherein the processing system is arranged to update the list of channels if an update criterion is fulfilled, and wherein said update criterion comprises an indication of a changed channel list to be coordinated being available at another network node or an expiry of a validity attribute associated with the list of channels.
55. A computer program product for use in communications between a network node and a communications terminal operating in a shared frequency band the computer program product comprising a set of instructions, which, when executed by a computing system within a network node, cause the computing system to pcrform thc stcps of: constructing a list comprising a plurality of channels useable for said conununications, the list comprising data indicative of bandwidth and centre frcqucncy of individual said channels, whercin at Icast one of the bandwidth and centre frequency of individual ones of the plurality of channels are configured by the computing system; transmitting, to the communication terminal, data indicative of the list of the plurality of channels; and communicating with the communication terminal via one of the plurality of channels of the list of channels.
56. The computer program product according to claim 55 wherein the set of instructions, when executed by the computing system, cause the computing system to perform the steps of: obtaining information on the usability of a currently used channel, said currently used channel being one of said plurality of the list of channels; and instructing the communication terminal to switch to one of the channels of the list ofuseable channels if the currently used channel becomes unusable.
57. The computer program product according to claim 56, wherein the set of instructions, when executed by the computing system, cause the computing system to perform the step of re-connecting to the communication terminal via the channel to which the communication terminal was instructed to be switched.
58. The computer program product according to claim 56 or claim 57, wherein the obtaining comprises detecting that a connection to a communication terminal is lost.
59. The computer program product according to any of claims 55 to 58, wherein the list of channels is associated with a validity attribute, and wherein the set of instructions, when executed by the computing system, cause the computing system to perform the step of re-establishing a connection to a communication terminal via a predetermined channel or blindly via an arbitrary channel, in the event that the validity of the list of channels expires and a currently used channel becomes unusable.
60. The computer program product according to any of claims 55 to 59, in which said individual ones of the plurality of channels are individually configured by the computing system in dependence on an instruction from a network operator with which the computing system is associated.
61. The computer program product according to any of claims 55 to 60, in which the number of channels making up the plurality of channels is configured in dependence on the bandwidth of individual said channels in the list and the bandwidth of the shared frequency band.
62. The computer program product according to any of claims 55 to 61, wherein at least one entry on the list comprises a code indicative of a rclationship bctwccn a ccntrc frcqucncy of a first channel of thc plurality and a centre frequency of a second channel.
63. The computer program product according to claim 62, wherein the code indicates that the centre frequency of the first channel is the centre frequency of the second channel.
64. The computer program product according to claim 63, wherein the code indicates that the first channel has a bandwidth equal to a bandwidth of the second channel.
65. The computer program product according to claim 62, wherein thc code indicates that the centre frequency of thc first channel lies bctwecn the centre frequency of the second channel and a centre frequency of a channel adjacent to the second channel.
66. The computer program product according to claim 65, wherein the code further indicates that the first channel has a bandwidth equal to the bandwidth of the second channel and the channel adjacent to the further channel. 3')
67. The computer program product according to claim 65 or claim 66, wherein the code indicates that the centre frequency of the channel adjacent to the second channel is higher than the centre frequency of the second channel.
68. The computer program product according to claim 65 or claim 66, wherein the code indicates that the centre frequency of channel adjacent to the second channel is lower frequency than the centre frequency of the second channel.
69. The computer program product according to claim 62, wherein the code indicates that the fimt channel spans multiple adjacent channels.
70. The computer program product according to any of claims 62 to 69, wherein the code comprises one or more bits.
71. The computer program product accothing to any of claims 62 to 70, wherein at least one of the centre frequency and a bandwidth of the second channel is preconfigured.
72. The computer program product according to any of claims 62 to 71, wherein the centre frequency of the second channel is a centre frequency of a TV channel.
73. The computer program product according to any of claims 62 to 72, wherein the bandwidth of the second channel is a bandwidth of a TV channcl.
74. The computer program product accothing to any of claims 55 to 73, wherein the shared frequency band comprises the TV White Space (TV WS) spectrum band.
75. The computer program product according to any of claims 55 to 71, wherein the shared frequency band comprises the Industrial, Scientific, Medical (ISM) band.
76. The computer program product according to any of claims 55 to 75, wherein thc set of instructions, whcn executed by thc computing system, cause the computing system to perform the steps of: updating the list; and responsive to a change to the list, distributing the updated list of the plurality of channels to the communication terminal, the distributing comprising at least transmitting a signal from the network node to thc communications terminal.
77. The computer program product according to claim 76, wherein the set of instructions, when executed by the computing system, cause the computing system to perform the step of distributing the updated list of channels to communication terminals using a push mode or a pull mode.
78. The computer program product according to claim 76 or claim 77, wherein the signal informs the communications terminal that the list has changed, and the distributing comprises: receiying a request for the updated list from the communications terminal; and transmitting at least a part of the updated list to the communications terminal.
79. The computer program product according to any of claims 76 to 78, wherein the signal comprises a contact verification signal.
80. The computer program product according to claim 79, wherein the contact verification signal comprises a flag bit indicating if the list has changed.
81. The computer program product according to any of claims 76 to 80, wherein the constructing further comprises updating the list of channels if an update criterion is flulfilled, and wherein said update criterion comprises an indication of a changed channel list to be coordinated being available at another network node or an expiry of a validity attribute associated with the list of channcls.