Abstract:
The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for switching resource pools by a device arranged to transmit according to a first resource pool is provided. The method includes sensing a second resource pool, determining whether the second resource pool has been sensed sufficiently long to apply sensing based resource selection, and selecting resources from an exceptional pool by using random resource selection, if the second resource pool has not been sensed sufficiently long to apply sensing based resource selection.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of a United Kingdom patent application filed on Jul. 18, 2016 in the United Kingdom Patent Office and assigned Serial number 1612391.1 and a United Kingdom patent application filed on Sep. 30, 2016 in the United Kingdom Patent Office and assigned Serial number 1616646.4, the entire disclosure of each of which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to resource arrangement or configuration for devices and to methods and apparatuses for arranging resources. More particularly, the present disclosure relates to switching resource pools for devices. 
       BACKGROUND 
       [0003]    To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
         [0004]    The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications. 
         [0005]    In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology. 
         [0006]    Long term evolution (LTE) has been proposed for safety critical communications for safety critical systems, including group communications and proximity based services. The proximity based services may be provided when devices, such as user equipment (UE), are relatively proximal. The proximity based services may include: ProSe Direct Discovery, in which two devices are identified as relatively proximal; ProSe Direct Communication, in which two devices communicate directly using reserved LTE resources; and Network-level Discovery and Network Support for WLAN Direct Discovery and Communication. 
         [0007]    ProSe Direct Communication may also be known as device-to-device (D2D) communication. D2D communication may be provided for vehicle-to-everything (V2X) communication, which may involve a vehicle as a source or a destination of a message, for example. V2X communication may include, for example, vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, for example road infrastructure, vehicle-to-network (V2N) communication, for example the Internet and vehicle-to-pedestrian (V2P) communication. 
         [0008]    D2D communication requires resources for communication, for example bandwidth for transmission. However, devices may contend for the same resources and/or use the same resources. Interference, for example due to data collisions, between communicating D2D devices may reduce a quality of service (QoS). Retransmission of the data may be required though this may further increase interference. Furthermore, safety critical systems may be compromised by data lost as a result of the data collisions or by data delayed as a result of retransmission of the data. In addition, devices may transition between cells and/or geographic zones within a cell, for example due to movement of a vehicle. Such transitions may require that the devices switch from the resources to other resources, for example due to use of the same resources by other devices. However, such transitions may not be predictable and/or may be out-of-coverage, requiring autonomous resource configuration by the devices. In addition, such transitions may be associated with latencies that may result in interruption of transmission, which may also compromise safety critical systems. 
         [0009]    Hence, there is a need to improve resource arrangements for devices, particularly with respect to autonomous resource arrangement. In this way, for example, latency and/or interruption of transmission may be reduced or avoided. In this way, for example, the QoS may be improved. In this way, for example, compromise of safety critical systems may be lowered or averted. 
         [0010]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. 
       SUMMARY 
       [0011]    Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide switching resource pools for devices which at least partially obviates or mitigates at least some of the disadvantages of the prior art, whether identified herein or elsewhere. For example, the present disclosure may provide for switching resource pools for devices, in which latency and/or interruption of transmission may be reduced or avoided. In this way, a quality of service (QoS) may be improved such that, for example, compromise of safety critical systems may be lowered or averted. 
         [0012]    In accordance with an aspect of the present disclosure, a method of switching resource pools by a device, is provided. The method includes transmitting according to a first resource pool, sensing a second resource pool, switching from the first resource pool to the second resource pool, based on a result of the sensing the second resource pool, and transmitting according to the second resource pool. 
         [0013]    In accordance with another aspect of the present disclosure, a method of switching from the first resource pool to the second resource pool is provided. The method includes determining if the second resource pool has been sensed longer than an amount of time to apply sensing based resource selection, and based on a result of the determining, using sensing based resource selection if the second resource pool has been sensed for longer than an amount of time to apply the sensing based resource selection, and using random resource selection for the second resource pool if the second resource pool has not been sensed for longer than an amount of time to apply the sensing based resource selection. 
         [0014]    If the switching from the first resource pool to the second resource pool comprises using the random resource selection for the second resource pool, the method may comprise changing, for the second resource pool, from using the random resource selection to using the sensing based resource selection based on the result of the sensing the second resource pool. 
         [0015]    The method may comprise receiving information related to the second resource pool. 
         [0016]    The sensing of the second resource pool may comprise sensing the second resource pool according to the received information related to the second resource pool. 
         [0017]    The method may comprise determining an expected cell change, and starting the sensing of the second resource pool based on the determining the expected cell change. 
         [0018]    The method may comprise determining a cell change, and wherein the switching from the first resource pool to the second resource pool is based on the result of the sensing of the second resource pool and the determining of the cell change. 
         [0019]    The method may comprise determining an expected zone change, and starting the sensing of the second resource pool based on the determining of the expected zone change. 
         [0020]    The method may comprise determining a zone change, and wherein the switching from the first resource pool to the second resource pool is based on the result of the sensing of the second resource pool and the determining of the zone change. 
         [0021]    The method may comprise receiving a command, and starting the sensing of the second resource pool based on the received command, and wherein the switching from the first resource pool to the second resource pool is based on the result of the sensing of the second resource pool and the command. 
         [0022]    The method may comprise determining a state transition of the device, starting the sensing of the second resource pool based on the determining of the state transition, and wherein the switching from the first resource pool to the second resource pool is based on the result of the sensing of the second resource pool and the determining of the state transition. 
         [0023]    The method may comprise sensing a third resource pool, switching from the second resource pool to the third resource pool, based on a result of the sensing the third resource pool, and transmitting according to the third resource pool. 
         [0024]    The sensing may be performed according to scheduling assignment (SA), decoding. 
         [0025]    The sensing may be performed according to an energy measurement. 
         [0026]    The method may comprise pre-sensing a reception resource pool. 
         [0027]    The method may comprise receiving a bit indicating that the first resource pool continues across a cell border. 
         [0028]    The method may comprise pre-sensing the second resource pool based on at least one of a time to trigger (TTT) or a treselection timer. 
         [0029]    In accordance with another aspect of the present disclosure, a device comprising a transmitter and a receiver is provided. The device is arranged to transmit according to a first resource pool, sense a second resource pool, switch from the first resource pool to the second resource pool, based on a result of the sensing the second resource pool, and transmit according to the second resource pool. 
         [0030]    The device may be arranged to switch from the first resource pool to the second resource pool by determining if the second resource pool has been sensed for longer than an amount of time to apply sensing based resource selection, and based on a result of the determining, using sensing based resource selection if the second resource pool has been sensed for longer than an amount of time to apply the sensing based resource selection, and using random resource selection for the second resource pool if the second resource pool has not been sensed for longer than an amount of time to apply the sensing based resource selection. 
         [0031]    If the switch from the first resource pool to the second resource pool comprises using random resource selection for the second resource pool, the device may be configured to change, for the second resource pool, from using the random resource selection to using the sensing based resource selection based on the result of the sensing the second resource pool. 
         [0032]    The device may be configured to receive information related to the second resource pool. 
         [0033]    The device may be configured to sense the second resource pool according to the received information related to the second resource pool. 
         [0034]    The device may be configured to determine an expected cell change, and start the sensing of the second resource pool based on the determined expected cell change. The device may be configured to determine a cell change, and switch from the first resource pool to the second resource pool based on the result of the sensing of the second resource pool and the determined cell change. 
         [0035]    The device may be configured to determine an expected zone change, and start the sensing of the second resource pool based on the determined expected zone change. 
         [0036]    The device may be configured to determine a zone change, and switch from the first resource pool to the second resource pool based on the result of the sensing of the second resource pool and the determined zone change. 
         [0037]    The device may be configured to receive a command, start sensing the second resource pool based on the received command, and switch from the first resource pool to the second resource pool based on the result of the sensing of the second resource pool and the command. 
         [0038]    The device may be configured to determine a state transition of the device, start sensing the second resource pool based on the determined state change, and switch from the first resource pool to the second resource pool based on the result of the sensing of the second resource pool and the determined state transition. 
         [0039]    The device may be configured to sense a third resource pool, switch from the second resource pool to the third resource pool, based on a result of the sensing the third resource pool, and transmit according to the third resource pool. 
         [0040]    The device may be configured to sense according to SA decoding. 
         [0041]    The device may be configured to sense according to an energy measurement. 
         [0042]    The device may be configured to pre-sense a reception resource pool. 
         [0043]    The device may be configured to receive a bit indicating that the first resource pool continues across a cell border. 
         [0044]    The device may be configured to pre-sense the second resource pool based on at least one of a TTT or a Treselection timer. 
         [0045]    Throughout this specification, the term “comprising” or “comprises” means including the component(s), unit(s), module(s), feature(s) or integer(s) specified but not to the exclusion of the presence of other components, units, modules, features or integers. 
         [0046]    The term “consisting of” or “consists of” means including the component(s), unit(s), module(s), feature(s) or integer(s) specified but excluding other components, units, modules, features or integers. 
         [0047]    Whenever appropriate, depending upon the context, the use of the term “comprises” or “comprising” may also be taken to include the meaning “consists essentially of” or “consisting essentially of”, and also may also be taken to include the meaning “consists of” or “consisting of”. 
         [0048]    The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or embodiment of the present disclosure, as set out herein are also applicable to all other aspects or various embodiments of the present disclosure, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or embodiment of the present disclosure as interchangeable and combinable between different aspects and various embodiments. 
         [0049]    In accordance with another aspect of the present disclosure a method of switching resource pools is provided. The method implemented by a device, wherein the device is arranged to transmit according to a first resource pool, the method comprising sensing a second resource pool, and switching from the first resource pool to the second resource pool, based on a result of the sensing the second resource pool, wherein the device is arranged to transmit according to the second resource pool. 
         [0050]    In this way, the device may, for example, transmit data according to, for example via or using, the first resource pool. In parallel, simultaneously, concurrently or interleavingly to transmitting the data, the device may also sense the second resource pool. Based on a result of the sensing, the device may switch, for example directly, indirectly, conditionally, subsequently, autonomously or in response to a request, to the second resource pool. By switching, for example reconfiguring, changing, swapping, exchanging, migrating or moving, from the first resource pool to the second resource pool, the device may be arranged to transmit according to, for example via or using, the second resource pool. In other words, by switching, the device may start transmitting according to the second resource pool. In addition, by switching, the device is arranged to not transmit according to, for example via or using, the first resource pool. In other words, by switching, the device stops transmitting according to the first resource pool. That is, the device may be arranged to transmit according to only one resource pool, for example the first resource pool or the second resource pool. In this way, the device may, for example, transmit data according to the arranged, for example newly-arranged, second resource pool. 
         [0051]    Switching from the first resource pool to the second resource pool may comprise determining if the second resource pool has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool if the second resource pool has not been sensed sufficiently long to apply sensing based resource selection. 
         [0052]    If switching from the first resource pool to the second resource pool comprises using random resource selection for the second resource pool, the method may comprise: changing, for the second resource pool, from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool. 
         [0053]    For example, if the device has not performed sufficient sensing of the second resource pool, as described below, the device may switch initially from the first resource pool to the second resource pool, using random resource selection of the second resource pool. Subsequently, when the device has performed sufficient sensing of the second resource pool, the device may change, for the second resource pool, from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool. 
         [0054]    In other words, if the device does not manage to complete sensing of the second resource pool (for example, a temporary or fallback or exceptional resource pool) for long enough, the device temporarily uses the second resource pool with random selection. The second resource pool may be broadcast. Random selection may initially, when the device was unable to perform sensing for long enough prior to switching to the second resource pool (i.e., sufficient pre-sensing), for example upon zone change, connection establishment, radio link failure (RLF) and/or connection re-establishment. The second resource pool may also be used upon cell re-selection and/or moving out of coverage, with sensing based resource selection if possible and with random selection otherwise. 
         [0055]    Upon moving out of coverage, the device may sense, for example pre-sense, similarly as when moving to another zone, i.e., a zone change. The device may sense, for example pre-sense, one or more candidate resource pools, for example a set of multiple potential candidates and may change the set depending on movement of the device, for example. The second resource pool (for example, a temporary or fallback or exceptional resource pool) may be pre-configured, for example as part of SL-V2X-Preconfiguration. 
         [0056]    By sensing the second resource pool while transmitting according to the first resource pool and switching from the first resource pool to the second resource pool after sensing the second resource pool, latency and/or interruption of transmission arising from sensing, for example, may be reduced or avoided according to the related art. In this way, a QoS may be improved such that, for example, compromise of safety critical systems may be lowered or averted. 
         [0057]    Generally, in communication in a network, for example over an Uu interface, a node for example an enhanced node B (eNB) may communicate with a device via a downlink (DL) and/or an uplink (UL) according to the related art. For D2D communication, two devices may communicate via a sidelink (SL). The SL may correspond, for example, to a PC5 interface. Resources for the SL may be from the UL. For example, resources for the SL may be from subframes on a UL frequency in frequency division duplex (FDD) or from subframes assigned to the UL in time division duplex (TDD). 
         [0058]    Two SL logical channels may be defined for D2D communication: a SL traffic channel (STCH) and a SL broadcast control channel (SBCCH). The STCH may be used for data transmission and may be connected with a SL shared channel (SL-SCH). The STCH may interface with a physical SL shared channel (PSSCH), which may transport data wirelessly. The SBCCH may be used for synchronization in out-of-coverage and/or partial coverage situations, as described below, and/or synchronization between devices located in different cells. The STCH may be connected with a SL broadcast channel (SL-BCH) which may interface with a physical SL broadcast channel (PSBCH). A Physical SL Control Channel may be equivalent to a physical downlink control channel (PDCCH) in communication according to related art. The PDCCH contains sidelink control information (SCI), which carries information that devices require to receive and demodulate the PSSCH. 
         [0059]    A resource pool (RP) may be a set of resources assigned to the SL. The RP may comprise subframes and resource blocks within the subframes. A subframe bitmap may indicate whether a subframe may be used by the SL. Within a usable subframe, resources used by the SL may be arranged in two frequency bands or physical resource block (PRB) bandwidth units, each having a frequency range defined in terms of PRBnum resource blocks. A first band may start at a frequency PRBstart and a second band may end at a frequency PRBend. This arrangement may allow nesting of a plurality of RPs within a subframe, while other resource blocks in the subframe may be used by other devices for cellular traffic. A device may use a subframe in a given carrier for either cellular traffic or for SL. 
         [0060]    Hence, the RP may be defined in a frequency domain by the three parameters: PRBnum, PRBstart and PRBend. Additionally and/or alternatively, the RP may be defined in a time domain by a bitmap that indicates subframes used for PSCCH transmission. 
         [0061]    Information needed to define the RP, for example the frequency domain parameters and/or the time domain bitmap, may be broadcast by the network, for example by an access point (AP), in a system information block (SIB). The device receives this information and may be arranged or configured to use, for example sense and/or receive and/or transmit, the RP according to this received information. 
         [0062]    There may be two types of RPs: reception resource pools (Rx RPs) and transmission resource pools (Tx RPs). 
         [0063]    D2D communication may handle resource configuration for in-coverage, out-of-coverage and/or partial coverage situations. 
         [0064]    In the in-coverage situation, a network may control resources allocated to and/or selected by the devices. For example, in Mode 1 (also known as Scheduled Resource Allocation), the network may allocate a specific resource to a device. The device must be in a connected state, for example in a RRC_CONNECTED state. The allocation of the specific resource to the device may be according to a request from the device. Alternatively, in Mode 2 (also known as Autonomous Resource Selection), the network may allocate a resource pool to the device and the device may select a resource from the allocated resource pool. The device may be in an idle state, for example in a RRC_IDLE state, or may be in the out-of-coverage situation. In this way, interference and/or collisions with transmissions from other devices may be reduced. 
         [0065]    In the out-of-coverage situation, control of resources by the network may not be possible. The device may select pre-configured resources, for example. 
         [0066]    In the partial coverage situation, coordination between the network and the pre-configured resources may be necessary. 
         [0067]    It should be understood that the device may comprise, for example, user equipment (UE). In the universal mobile telecommunications system (UMTS) and 3GPP LTE, UE allows a user to access network services. In other words, a UE is any device used by the user to communicate on a network. The UE may be, for example, a device comprising a transmitter and a receiver or a transceiver, such as a mobile telephone or a laptop computer equipped with a mobile broadband adapter, as described below. The user may be a human user or a non-human user, for example a vehicle or infrastructure. The device may connect to or communicate with or via an AP for example an universal terrestrial radio access network (UTRAN) AP such as a base station Node B (Node B or NB) and/or an evolved base station Node B (eNodeB or eNB), as specified in ETSI 125/136-series and/or 3GPP 25/36-series of specifications. That is, the device may transmit data to and/or receive data from the AP, as described below. Furthermore, the device may connect to or communicate with or via another such device. That is, the device may transmit data to and/or receive data from the AP, as described below. In one example embodiment, the device comprises a UE. In one example embodiment, the device is a UE. 
         [0068]    It should be understood that an UTRAN AP may be a conceptual point within the UTRAN performing radio transmission and reception. The UTRAN AP may be associated with one specific cell. That is, there may exist one UTRAN AP for each cell. The UTRAN AP may be the UTRAN-side end point of a radio link. 
         [0069]    It should be understood that a cell may be a radio network object that may be uniquely identified by a UE from a cell identification that is broadcast over a geographical area from one UTRAN AP. A cell may be in either frequency division duplex (FDD) or time division duplex (TDD) mode. 
         [0070]    It should be understood that an inter-cell handover may be a handover (HO) between different cells. The inter-cell handover may require network connections to be altered. 
         [0071]    It should be understood that a sector may be a sub-area of a cell. All sectors within the cell may be served by the same AP. A radio link within the sector may be identified by a single logical identification belonging to the sector. 
         [0072]    It should be understood that an intra-cell handover may be a HO within one sector or between different sectors of the same cell. 
         [0073]    In an example embodiment, the method comprises determining a cell. For example, the device may determine a current cell, that is, a cell in which the device is currently located. Additionally and/or alternatively, the device may determine an adjacent cell, that is, a cell adjacent to the current cell. For example, if the device is moving in the current cell towards a border of the current cell, the device may determine a target cell, that is, the adjacent cell towards which the device is moving. The device may determine that the border of the current cell will be and/or is being and/or has been crossed. That is, the device may determine a cell change and/or an expected cell change, for example from the current cell to the target cell. The device may for example determine a cell change and/or an expected cell change based on measurement of radio signals. Additionally and/or alternatively, the device may determine a cell change and/or an expected cell change based on receiving a command. In an example embodiment, the method comprises determining a cell change. In an example embodiment, the method comprises determining an expected cell change. In an example embodiment, the method of switching resource pools comprises determining a target cell, as described above. In an example embodiment, the method of switching resource pools comprises sensing the second resource pool, wherein the second resource pool is allocated to the target cell. 
         [0074]    It should be understood that the world may be divided into geographical zones. The zones may correspond with cells. Alternatively, the zones may not correspond with the cells. That is, a zone may comprise one or more cells. Additionally and/or alternatively, a cell may comprise one or more zones. For example, a zone may be included wholly within a cell. Additionally and/or alternatively, a zone may extend across one or more cells. For example, a zone may be included partly within a cell and/or partly within an adjacent cell and/or a plurality of adjacent cells. 
         [0075]    The zones may be contiguous, that is, borders or boundaries or edges or perimeters of a zone may be common with adjacent or neighboring zones. The zones, for example adjacent zones, may not overlap. That is, a geographical area may be in only one zone. Alternatively, the zones, for example adjacent zones, may overlap. The zones may be of similar shape and/or size, for example the same shape and/or size. Alternatively, the zones may be of different shapes and/or sizes, for example different shapes and/or sizes. The zones may have a regular shape, for example the zones may be quadrilateral such as square or rectangular. However, other shapes may be provided for the zones, for example shapes that may afford tessellation, such as triangular or hexagonal zones. Additionally and/or alternatively, the zones may have other shapes that may not afford tessellation, such as circular or octagonal zones. The sizes and/or locations of the zones may be provided to the device by Aps such as eNBs, for example, for in-coverage situations. Additionally and/or alternatively, the sizes and/or locations of the zones may be pre-configured or stored in and/or for the device, for example, for out-of-coverage situations and/or partial coverage situations. That is, the zones may be configurable for in-coverage, out-of-coverage and/or partial coverage situations. For in-coverage situations, the zones may be configurable for Mode 1 and/or Mode 2 operation. A size of a zone may be defined by a length and a width, for example for a quadrilateral zone. A location of the zone may be defined by an origin, for example, a single fixed reference point such as (0, 0). An identification of the zone, for example a unique identifier of the zone, may be defined. In an example embodiment, the method comprises receives zone information, for example from an access point. That is, the access point may transmit zone information. If zone information is transmitted by the AP, zones may be contiguous across cells if the zone information provided in the cells controlled by the AP is consistent with contiguous zones. That is, zones may not be contiguous. Alternatively, zones may be contiguous if the zone information is consistent with contiguous zones. The zone information may comprise a size and/or location and or identification of a zone. The zone information may comprise sizes and/or locations and/or identifications of a plurality of zones. The device may store the received zone information. In an example embodiment, the method comprises providing with and/or storing zone information during manufacture, initialization, setup, updating, configuration or reconfiguration of the device. 
         [0076]    In an example embodiment, the method comprises determining a zone, for example according to a modulo operation. For example, the device may determine a current zone, that is, a zone in which the device is currently located. For example, the device may determine the current zone according to a location, for example a geolocation, of the device and the zone information. The device may determine the location of the device according to, for example, a global positioning system (GPS) location of the device. Additionally and/or alternatively, the device may determine the location of the device according to, for example, radiolocation. The device may transmit the determined location of the device, for example, in Mode 1. The device may transmit the current zone. Additionally and/or alternatively, the device may determine an adjacent zone, that is, a zone adjacent to the current zone. For example, if the device is moving in the current zone towards a border of the current zone, the device may determine a target zone, that is, the adjacent zone towards which the device is moving. The device may determine that the border of the current zone will be and/or is being and/or has been crossed. That is, the device may determine a zone change, for example from the current zone to the target zone. 
         [0077]    It should be understood that resource pools may be allocated or assigned to the zones. For example, a transmission resource pool may be allocated to a zone. The transmission resource pool may be allocated to the zone by an AP related to the zone. For example, different transmission resource pools may be allocated to adjacent zones. In this way, inter-zone interference may be reduced. For example, near-far or hearability problems may be avoided. A near-far problem may result if a first transmitting device relatively nearer a receiving device is not aware of a second transmitting device relatively further from the receiving device. So as to reduce interference, the first and the second transmitting devices should transmit according to different resource pools. The first and the second transmitting devices may be allocated different resource pools and/or the first and the second transmitting devices may select different resource pools from allocated resource pools. However, allocating resource pools to zones may restrict, limit or concentrate devices to the same resource pools, thereby increasing a risk of collisions. To avoid this increased risk of collisions, sensing in combination with resource use for a pre-determined time period, for example 0.1 s, 1 s, less than 0.1 s, more than 1 s, may be adopted. Additionally and/or alternatively, devices may be interested in receiving information regarding, for example, proximal or neighboring devices, such as proximal or neighboring vehicles. In an example embodiment, the method of switching resource pools comprises receiving information. In an example embodiment, the method of switching resource pools comprises receiving zone information. In an example embodiment, the method of switching resource pools comprises storing zone information. In an example embodiment, the method comprises receiving zone transmission resource pool information, for example from the AP. That is, the AP may transmit zone information that may comprise and/or further comprise, as described above, a transmission resource pool and/or transmission resource pools allocated to a zone. The device may store the received zone information. In an example embodiment, the method comprises receiving and/or storing zone information during manufacture, initialization, setup, updating, configuration or reconfiguration of the device. In an example embodiment, the method comprises receiving zone information. In an example embodiment, the method comprises storing zone information. As described above, the zone information may comprise size and/or location and/or allocated resource pool and/or allocated transmission resource pool information for one or more zones. For example, the zone information may include resource pool configurations for multiple zones, broadcast or transmitted via dedicated signaling by an AP, for idle and connected states of the device). The device may select a resource pool for transmission, for example, a resource pool corresponding to the current zone, as determined by the device. 
         [0078]    It should be understood that a zone change, for example a change from a current zone to a target zone, may be similar to an inter-cell handover, as described above. That is, the zone change may require network connections to be altered, as described above with reference to the inter-cell handover. That is, the zone change may require the device to switch from the first resource pool to the second resource pool. However, a delay in device the switching from the first resource pool to the second resource pool due to the zone change may, for example, result in near-far problems, as described previously. Thus, this delay should be reduced and/or minimized. 
         [0079]    In an example embodiment, the method of switching resource pools comprises determining a target zone, as described above. In an example embodiment, the method of switching resource pools comprises sensing the second resource pool, wherein the second resource pool is allocated to the target zone. In an example embodiment, the method of switching resource pools comprises sensing the second resource pool, wherein the second resource pool is a transmission resource pool allocated to the target zone. The second resource pool may be one of a plurality of resource pools allocated to the target zone. The plurality of resource pools allocated to the target zone may be received by and/or stored on the device, as described above. In an example embodiment, the method of switching resource pools comprises selecting the second resource pool from a plurality of resource pools allocated to the target zone. 
         [0080]    In an example embodiment, the method of switching resource pools comprises sensing the second resource pool, wherein the second resource pool is a reception resource pool. The reception resource pool may include, for example, transmission resources of neighboring cells and thus may include, for example, transmission resources of a candidate (HO) target cell, of which the device is not aware before a cell change. 
         [0081]    In an example embodiment, the result of the sensing the second resource pool is a result of sufficient sensing of the second resource pool. Sufficient sensing may be regarded as enough sensing for the device to select resources for which a likelihood of collisions is sufficiently low. The result of sufficient sensing may complete the sensing. Sufficient sensing may comprise, for example, measuring energy periodically for a duration over a time period. For example, sufficient sensing may comprise measuring energy for 200 ms every 1000 ms. Other durations, time periods and frequencies may be provided. Additionally and/or alternatively, sufficient sensing may be according to SA decoding, as described previously. For example, the device may switch based on the result of the sensing, comprising sufficient sensing. That is, a trigger to switch may be considered the result of the sensing, comprising sufficient sensing. In other words, the switch may be in response to the result of the sensing, comprising sufficient sensing. 
         [0082]    In an example embodiment, the switching from the first resource pool to the second resource pool may be further based on determining a zone change, as described previously. For example, the device may switch based on the result of the sensing and determining the zone change. That is, a trigger to switch may be considered the result of the sensing and determining the zone change. In other words, the switch may be in response to the result of the sensing and determining the zone change. 
         [0083]    In an example embodiment, the switching from the first resource pool to the second resource pool may be further based on determining a cell change, as described previously. For example, an idle device may switch based on the result of the sensing and determining the cell change. That is, a trigger to switch may be considered the result of the sensing and determining the cell change. In other words, the switch may be in response to the result of the sensing and determining the cell change. 
         [0084]    In an example embodiment, the switching from the first resource pool to the second resource pool may be further based on a command, for example, a network command received from an AP or in a HO command. For example, a connected device may receive such a command and switch based on the result of the sensing and the command. That is, a trigger to switch may be considered the result of the sensing and the command. In other words, the switch may be in response to the result of the sensing and the command. 
         [0085]    It should be understood that the switching from the first resource pool to the second resource pool may be, for example, due to or required by or based on or in response a cell change or a zone change or a received command. For example, for a HO, the device may receive a command, as described above. For example, the cell change may include cell reselection. In addition, an expected cell change may also apply to a HO. For example, the device may start to sense and/or pre-sense according to the expected cell change due to the HO. In particular, the UE may determine expected cell change to be starting TTT for a particular measurement (assumed to be configured for the purpose of HO, or including a particular indicator). 
         [0086]    It should be understood that the first resource pool may be known as a source resource pool. The first resource pool may be associated with a first cell, for example a source cell, and/or a first zone, for example a source zone. For example, the first resource pool may be associated with a first eNB of the first cell. In other words, the first resource pool may be associated with a source eNB of the source cell. Similarly, it should be understood that the second resource pool may be known, for example, as a target resource pool. 
         [0087]    It should be understood that the device may transmit based on a timing or synchronization of a cell, for example a current cell and/or a target cell, for which a transmission resource pool, for example the first resource pool and/or the second resource pool, is configured. That is, to transmit using a particular resource pool, the device may be required to maintain, for example, a timing reference of the corresponding cell. 
         [0088]    In an example embodiment, the method comprises receiving information related to the second resource pool. 
         [0089]    For example, the information related to the second resource pool may comprise information related to a specific resource allocated or assigned to the device. The information related to the second resource pool may be received from the network, for example from an AP such as an eNB or a source eNB. The information may be received in response to a request for information transmitted by the device. Alternatively, the information related to the second resource pool may be included on the device, for example, previously included on the device during manufacture, initialization, setup, updating, configuration or reconfiguration. 
         [0090]    Additionally and/or alternatively, the information related to the second resource pool may comprise information related to a resource pool allocated or assigned to the device. In Mode 2 (also known as Autonomous Resource Selection), the network may allocate a resource pool to the device and the device may select a resource from the allocated resource pool. The device may be in an idle state, for example in a RRC_IDLE state, or may be in the out-of-coverage situation. In this way, interference and/or collisions with transmissions from other devices may be reduced. 
         [0091]    Sensing may be used to obtain information for the device to predict interference conditions for future SL transmissions. Based on the sensing result, the device may autonomously select a suitable resource from the second resource pool. That is, the device may select the resource having a relatively lower expected interference for SL transmissions, for example, to improve system performance. 
         [0092]    In an example embodiment, sensing is according to SA decoding. That is, sensing may be based on a SA scan, for example, PSCCH decoding, of other devices. Locations of SA transmissions may be known and may be decodable by the device. For example, blind decoding may be used. If a SA of another device is decoded, the device may be informed of future SA and/or data transmissions and/or resource utilizations by that other device. Since a number of PSCCH in a subframe may be restricted, a complexity of decoding by the device may be relatively low. However, decoding of all SAs from all devices may be relatively complex under, for example, high interference or low signal to noise ratio (SNR) conditions, which may occur in dense traffic scenarios. 
         [0093]    In an example embodiment, sensing is according to energy measurement. Sensing according to energy measurement may be performed in the frequency domain. An energy threshold, for example, may be used to identify available resources for transmission. Compared with SA decoding, energy measurement may provide additional information on overall interference levels of a given resource, for example, in band emission and interferences from undetected SAs. Furthermore, energy measurement may still be useful even if SA decoding is not successful, for example, due to resource collision and/or misdetection of SAs. However, a reliability of the energy measurement may be relatively lower at low SNR and/or high mobility scenarios. 
         [0094]    In an example embodiment, sensing is according to SA decoding and energy measurement. 
         [0095]    In an example embodiment, the sensing the second resource pool during the first time period comprises sensing the second resource pool according to the received information related to the second resource pool. 
         [0096]    In an example embodiment, the method comprises pre-sensing one or more second resource pools, for example, one or more candidate target transmission resource pools allocated by a target zone and/or target cell. In an example embodiment, the sensing comprises pre-sensing one or more second resource pools, for example, one or more candidate target transmission resource pools allocated by a target zone and/or target cell. 
         [0097]    In an example embodiment, the method comprises pre-sensing one or more second resource pools, for example, one or more reception resource pools. In an example embodiment, the sensing comprises pre-sensing one or more second resource pools, for example, one or more reception resource pools. Such reception resource pools may cover neighboring transmission resource pools, for example. In this way, information related to candidate target transmission resource pools allocated by a target zone and/or target cell, for example, may not be required for the pre-sensing. 
         [0098]    In an example embodiment, the method comprises determining a state transition of the device; and wherein the switching from the first resource pool to the second resource pool is based on the result of the sensing the second resource pool and the determining the state transition. 
         [0099]    In accordance with another aspect of the present disclosure, a device is provided. The device includes a transmitter and a receiver, wherein the device is arranged to transmit according to a first resource pool, sense a second resource pool, and switch from the first resource pool to the second resource pool, based on a result of the sensing the second resource pool, wherein the device is arranged to transmit according to the second resource pool. 
         [0100]    The device may be arranged to switch from the first resource pool to the second resource pool by determining if the second resource pool has been sensed sufficiently long to apply sensing based resource selection, and based on a result of the determining: using sensing based resource selection if the second resource pool has been sensed sufficiently long to apply sensing based resource selection, and using random resource selection for the second resource pool if the second resource pool has not been sensed sufficiently long to apply sensing based resource selection. 
         [0101]    If the switch from the first resource pool to the second resource pool comprises using random resource selection for the second resource pool, the device may be arranged to change, for the second resource pool, from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool. 
         [0102]    The device may be arranged to implement any combination of the operations described above with respect to the method of switching resource pools. In an example embodiment, the device is arranged to implement any of the methods described herein. 
         [0103]    In an example embodiment, the device is arranged to receive information related to the second resource pool. 
         [0104]    In an example embodiment, the device is arranged to sense the second resource pool according to the received information related to the second resource pool. 
         [0105]    In an example embodiment, the device is arranged to determine an expected cell change; and to start sensing based on the determining the expected cell change. For example, the sensing may be in response to the determining the expected cell change. Such sensing based on the determining the expected cell change may be considered pre-sensing. Pre-sensing may also not be started upon expecting a cell or zone change but more continuous, i.e., in anticipation of any potential cell or zone changes, the UE may sense a pool it can use in exceptional cases/to avoid interruptions (as a ready to use fall-back pool). The expected cell change may, for example, be determined according to a measurement related to a cell change such as a start of a time to trigger (TTT) or treselection timer. In an example embodiment, the device is arranged to determine a cell change and the switching from the first resource pool to the second resource pool is based on the result of the sensing the second resource pool and the determining the cell change. 
         [0106]    In an example embodiment, the device is arranged to determine an expected zone change; and to start sensing based on the determining the expected zone change. For example, the sensing may be in response to the determining the expected zone change. Such sensing based on the determining the expected zone change may be considered pre-sensing. The expected zone change may, for example, be determined according to an approach to or a distance from a zone border. In an example embodiment, the device is arranged to determine a zone change; and switch from the first resource pool to the second resource pool based on the result of the sensing the second resource pool and the determined zone change. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 First 
                 Second 
                 Third 
                   
               
               
                   
                 resource 
                 resource 
                 resource 
                   
               
               
                 Case 
                 pool 
                 pool 
                 pool 
                 Notes 
               
               
                   
               
             
             
               
                 Zone change 
                 Pool of 
                 Pool of 
                 N/A 
                 Within cell, or when same 
               
               
                   
                 source 
                 target 
                   
                 configuration applies in 
               
               
                   
                 zone 
                 zone 
                   
                 neighboring cell. 
               
               
                   
                   
                   
                   
                 In case of inter-cell, device needs to 
               
               
                   
                   
                   
                   
                 apply timing of target cell. Device 
               
               
                   
                   
                   
                   
                 either synchronizes early, but 
               
               
                   
                   
                   
                   
                 maybe case would be limited to 
               
               
                   
                   
                   
                   
                 case source and target eNB are 
               
               
                   
                   
                   
                   
                 synchronized. 
               
               
                 Cell change 
                 Pool of 
                 Fall-back 
                 Pool of 
                 Exceptional pool of source cell 
               
               
                 (discontinuous 
                 source 
                 pool of 
                 target 
                 could be used as fall-back (or new 
               
               
                 pool or zone 
                 cell 
                 source 
                 cell 
                 dedicated pool). 
               
               
                 configuration) 
                   
                 cell 
                   
                 In idle state, device detects change 
               
               
                   
                   
                   
                   
                 of cell, while in connected state, the 
               
               
                   
                   
                   
                   
                 network indicates. 
               
               
                   
               
             
          
         
       
     
         [0107]    Table 1 Example of resource pool usage for zone and cell changes. 
         [0108]    In an example embodiment, the device is arranged to: receive a command; and switch from the first resource pool to the second resource pool based on the result of the sensing the second resource pool and the command. 
         [0109]    In an example embodiment, the device is arranged to determine a state transition of the device; and switch from the first resource pool to the second resource pool based on the result of the sensing the second resource pool and the determining the state transition. 
         [0110]    In an example embodiment, the device is arranged to sense a third resource pool; and switch from the second resource pool to the third resource pool, based on a result of the sensing the third resource pool, wherein the device is arranged to transmit according to the third resource pool. For example, the device may switch to the second resource pool, for example a temporary resource pool (also known as a fallback pool or an exceptional resource pool), according to an internal trigger, for example, indicating that the device is not permitted or allowed to use the first resource pool or that use of the third resource pool is not appropriate. The device may also receive information and/or a command to switch from the second resource pool to the third resource pool, as described above. 
         [0111]    In an example embodiment, the device is arranged to sense according to SA decoding. 
         [0112]    In an example embodiment, the device is arranged to sense according to energy measurement. 
         [0113]    In an example embodiment, the device is arranged to determine a cell. For example, the device may be arranged to determine a current cell, that is, a cell in which the device is currently located. Additionally and/or alternatively, the device may be arranged to determine an adjacent cell, that is, a cell adjacent to the current cell. For example, if the device is moving in the current cell towards a border of the current cell, the device may be arranged to determine a target cell, that is, the adjacent cell towards which the device is moving. The device may be arranged to determine that the border of the current cell will be and/or is being and/or has been crossed. That is, the device may be arranged to determine a cell change and/or an expected cell change, for example from the current cell to the target cell. In an example embodiment, the device is arranged to determine a cell change. In an example embodiment, the device is arranged to determine an expected cell change. In an example embodiment, the device is arranged determine a target cell, as described above. In an example embodiment, the device is arranged to sense the second resource pool, wherein the second resource pool is allocated to the target cell. 
         [0114]    In an example embodiment, the device is arranged to receive zone information. In an example embodiment, the device is arranged to store zone information. In an example embodiment, the device is arranged to store received zone information. In an example embodiment, the device is arranged to be provided with and/or store zone information during manufacture, initialization, setup, updating, configuration or reconfiguration. 
         [0115]    In an example embodiment, the device is arranged to determine a zone, for example according to a modulo operation. 
         [0116]    In an example embodiment, the device is arranged to receive zone transmission resource pool information, for example from the AP. The device may be arranged to store the received zone information. In an example embodiment, the device is provided with and/or store zone information during manufacture, initialization, setup, updating, configuration or reconfiguration. In an example embodiment, the device is arranged to receive zone information. In an example embodiment, the device is arranged to store zone information. As described above, the zone information may comprise size and/or location and/or allocated resource pool and/or allocated transmission resource pool information for one or more zones. 
         [0117]    In an example embodiment, the device is arranged to determine a target zone, as described above. In an example embodiment, the device is arranged to sense the second resource pool, wherein the second resource pool is a transmission resource pool allocated to the target zone. In an example embodiment, the device is arranged to select the second resource pool from a plurality of resource pools allocated to the target zone. 
         [0118]    Switching from the first resource pool RP 1  to the second resource pool RP 2  (e.g., a target pool, a temporary resource pool, a fallback pool, an exceptional resource pool) may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0119]    In an example embodiment, the device is arranged to start sensing the second resource pool relatively early, for example in mobility and/or non-mobility cases. 
         [0120]    The non-mobility cases, such as connection establishment, connection establishment following power up, connection re-establishment, reconfiguration, and/or radio link failure (RLF) may be covered by a second resource pool. For example, the device may pre-sense the second resource pool that may be provided by serving cell, to handle interruptions during connection establishment, reconfiguration of the pool of device autonomously-selectable transmission resources and/or RLF. 
         [0121]    However, some of the cases in which the second resource pool is to be used may be unpredictable, for example, connection establishment, connection establishment following power up, connection re-establishment and/or reconfiguration. The device may anticipate or predict the occurrence of a RLF before the RLF occurs. However, it may not be possible for the device to anticipate or predict all RLF cases, for example, is in advance. Similarly, it may not be possible for the device to anticipate or predict other cases in which the second resource pool is to be used. Instead, the device may be required to sense the second resource pool, for example continuously, intermittently, periodically, if the second resource pool is included or configured in SIB21, for example. 
         [0122]    The device may sense, for example continuously sense, the second resource pool, if the second resource pool is included or configured in SIB21, to enable use of sensing whenever using this second resource pool. Additionally and/or alternatively, one or more of the cases in which the second resource pool is to be used may be unpredictable, as described above and/or may be relevant to non-mobility related events. Sensing based resource selection may still be possible for such cases by requiring the device to sense the exceptional transmission pool if the second resource pool is included or configured in SIB21. For example, the device may perform sensing on the resources of the pool indicated by v2x-CommTxPoolExceptional within SystemInformationBlockType21, before the device transmits using the pool of resources. However, there may still be cases in which the device wants to transmit V2X communication while sensing, for example, power on. Random selection may not be allowed for a pool for which sensing is required, since this could reduce a benefit of sensing. However, for the second resource pool, such mixed approach (i.e., random selection and sensing) is may be acceptable. 
         [0123]    In an example embodiment, the device is arranged to use the second resource pool, for example included in SIB21, wherein the device has not performed sensing for a required duration, for example a pre-determined duration, of the second resource pool and wherein the device is allowed to use random selection for this second resource pool. 
         [0124]    However, while the device may be allowed to perform random selection of the second resource pool, sensing of this pool may not be determined by device implementation. That is, sensing of this pool may be required rather than optional, for example. A benefit of requiring the device to sense this pool may depend, for example, on a frequency of use of the second resource pool. For example, the frequency of use of the second resource pool may be determined by an average number of idle to active transitions. For example, if there is such an idle to active transition every 10 s, requiring pre-sensing could avoid that in 10%, less than 10%, more than 10% of the time, random selection is otherwise used. 
         [0125]    In an example embodiment, the device is configured to transmit V2X communication, wherein the device is required to continuously sense a second resource pool, for example an exceptional transmission pool, if the second resource pool is configured, for example pre-configured, configured in SIB21. 
         [0126]    The mobility cases, such as zone change, cell change, moving out of coverage and/or RLF may be covered by a second resource pool. Typically, the device may pre-sense a relevant neighboring transmission pool in advance of a zone change, for example. For a HO, the device may use random selection of the second resource pool. For example, E-UTRAN may include the second resource pool in an HO command, for example in a v2x-CommTxPoolExceptional within mobilityControlInfoV2X. 
         [0127]    For example, if T304 is running and the UE is configured with v2x-CommTxPoolExceptional included in mobilityControlInfoV2X in RRCConnectionReconfiguration, lower layers may be configured to transmit SCI and corresponding data using random selection using a pool of resources indicated by v2x-CommTxPoolExceptional. 
         [0128]    In a case of a cell change in RRC_IDLE, service interruption may exceed 1 s, for example due to covering SIB21 acquisition and/or initial sensing delay. Hence, the device may use the second resource pool in SIB21 combined with random selection to address, for example, the case of cell change and/or re-selection. This approach may cover connection establishment for a case in which the device employs a normal pool, for example a source pool or the first resource pool, in SIB21 but has not yet complete sensing (e.g., power on). 
         [0129]    In an example embodiment, the device is configured to use a normal pool, for example a source pool or the first resource pool, for example included in SIB21, wherein the device has not performed sensing for a required duration, for example following cell re-selection, wherein the device is configured to use the second resource pool, for example included in SIB21, with random selection. 
         [0130]    A size of a pool for which random selection is allowed may need to increase to obtain similar performance as, for example, a pool that is sensed. To avoid that sizes of all pools need to increase to accommodate random selection, it may be preferable to limit random selection to the second resource pool(s) only. 
         [0131]    Additionally and/or alternatively, for cell change in idle mode, a bit may be included in SIB21 indicating whether neighboring cells employ the same zone based transmission pool configuration. If the bit is set, the device may employ a pre-sensing operation in advance of a zone change, for example, as for a case of intra-cell. This option may be used in conjunction with wherein the device is configured to use a normal pool, for example included in SIB21, wherein the device has not performed sensing for a required duration, for example following cell re-selection, wherein the device is configured to use the exceptional pool, for example included in SIB21, with random selection. In this way, use of the exceptional pool (with random selection) may be controlled and/or reduced and/or minimized. 
         [0132]    In an example embodiment, a bit, for example in SIB21, indicates whether a neighboring cell and/or a plurality of neighboring cells employ a same zone based transmission pool configuration. 
         [0133]    If the device moves out of coverage, the device may switch to a preconfigured pool. Such a case can be regarded to be similar to change of zone within a cell, as described previously. That is, the device may pre-sense an appropriate preconfigured transmission pool in advance of moving out of coverage. Upon return to coverage, the device may temporarily employ a second resource pool, if included in SIB21, and optionally, initially using random selection, for example. This may be appropriate for when a transmission pool is provided in SIB21, for example by v2x-CommTxPoolNormalCommon. That is, random selection may be restricted to the second resource pool. 
         [0134]    In an example embodiment, upon return from out of coverage, a device configured to use a transmission pool provided in SIB21 is arranged to use, for example to temporarily use, the second resource pool included in SIB21 using random selection, for example until the device completes sensing of the normal pool, for example a source pool or the first resource pool. 
         [0135]    The device may be arranged to start sensing a transmission pool of a neighboring zone and/or transmission pools of neighboring zones relatively early, for example, according to a criterion. For example, the criterion may be when a distance to the neighboring zone is or becomes below a threshold distance or a pre-determined distance, such as a threshold or predetermined percentage of a size of the zone. By defining device requirements regarding pre-sensing due to device mobility, for example, may depend on an interval or an average interval between mobility related pool changes. For example, if a relatively poor device implementation does not employ pre-sensing (i.e., does not start sensing prior to zone change), the device would initially use random selection of resources from the second resource pool (i.e., an exceptional resource pool) and use the second resource pool during the first second (1 s) following a zone change. Subsequently, the device may use sensing based selection of resources from a normal pool (e.g., a target pool or a third resource pool) applicable in that zone. If however there is a zone change every 1 s, the relatively poor device implementation will never enter a mode in which it employs sensing based resource selection. 
         [0136]    If pre-sensing is not required, for example, the relatively poor device implementation may not employ sensing based selection when changing zone frequently, for example, every 1 s. 
         [0137]    In an example embodiment, device requirements are specified regarding pre-sensing of transmission pools of a neighboring zone and/or neighboring zones. 
         [0138]    Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0139]    The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0140]      FIG. 1  schematically depicts a device according to the prior art, in use according to an embodiment of the present disclosure; 
           [0141]      FIG. 2  schematically depicts the device of  FIG. 1 , in use according to an embodiment of the present disclosure; 
           [0142]      FIG. 3  schematically depicts a device according to an embodiment of the present disclosure; 
           [0143]      FIG. 4  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure; 
           [0144]      FIG. 5  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0145]      FIG. 6  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure; 
           [0146]      FIG. 7  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0147]      FIG. 8  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure; 
           [0148]      FIG. 9  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0149]      FIG. 10  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure; 
           [0150]      FIG. 11  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0151]      FIG. 12  schematically depicts a method of switching resource according to an embodiment of the present disclosure; 
           [0152]      FIG. 13  schematically depicts a device according to an embodiment of the present disclosure, in use; and 
           [0153]      FIG. 14  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0154]      FIG. 15  schematically depicts a device according to an embodiment of the present disclosure, in use; 
           [0155]      FIG. 16  schematically depicts signaling extensions for an embodiment of the present disclosure; 
           [0156]      FIGS. 17A and 17B  schematically depicts signaling extensions for an embodiment of the present disclosure; and 
           [0157]      FIG. 18  schematically depicts signaling extensions for an embodiment of the present disclosure. 
       
    
    
       [0158]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION 
       [0159]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0160]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents. 
         [0161]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
         [0162]      FIGS. 1 and 2  schematically depict a device  1  according to the prior art, in use. The device  1  is arranged to transmit according to a first transmission resource pool RP 1 . Particularly, the device  1  is arranged to switch from the first transmission resource pool RP 1  to a second transmission resource pool RP 2  before sensing the second transmission resource pool RP 2 . In this way, transmission interruption may result, as described previously. 
         [0163]    Referring to  FIG. 1 ,  FIG. 1  shows that at transmission time interval (TTI) N, resource selection is triggered in Mode 2 (i.e., Autonomous Resource Selection), as described above. Hence, at an earlier TTI N-a, the device  1  switches from the first transmission resource pool RP 1  to the second transmission resource pool RP 2 . For a time period from TTI N-a to TTI N-b, the device  1  senses the second transmission resource pool RP 2 . At TTI N+c, the device  1  transmits a scheduling assignment (SA), indicating associated data which are transmitted at TTI N+d. a-d are integer times, in milliseconds (ms). The values of a and b may be fixed and may be common for all V2V UE, for example. Particularly, a=1000+b ms. The values of c and/or d may be greater than 0 ms and/or less than or equal to 100 ms. Particularly, d&gt;=c ms. Thus, the data transmitted by the device  1  at TTI N+d according to the second transmission resource pool RP 2  are transmitted (a+b+c+d) ms after the switch from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at TTI N-a. Assuming b=c=d=0 ms and since a=1000 ms, a minimum delay or transmission interruption is 1000 ms (1 s). 
         [0164]    More generally,  FIG. 2  schematically shows the device  1  switching from the first transmission resource pool RP 1  to the second transmission resource pool RP 2 , as described above. Prior to a time T 0 , the device  1  is arranged to transmit and to sense according to, for example via, the first transmission resource pool RP 1 . The device  1  is arranged to switch from the first transmission resource pool RP 1  to a second transmission resource pool RP 2  at the time T 0 . From the time T 0 , the device  1  is not allowed to use, for example sense and/or transmit, according to the first transmission resource pool. For a time period from T 0  to T 0 +1 s (i.e., 1 s), the device  1  is arranged to sense the second transmission resource pool RP 2 . During this time period from T 0  to T 0 +1 s (i.e., 1 s), the device  1  is not arranged to transmit according to, for example via, the second transmission resource pool RP 2 . After sufficient sensing (i.e., at T 0 +1 s), the device  1  is arranged to transmit according to, for example via, the second transmission resource pool RP 2 . That is, when the device  1  is provided with a new transmission resource pool, such as the transmission resource pool RP 2 , a transmission interruption of 1 s may result before the device  1  may start to transmit via the new transmission resource pool. 
         [0165]    The transmission interruption, as described above, may arise in various scenarios. 
         [0166]    In a first scenario, related to a HO, an UE is configured with a first transmission resource pool RP 1  in a source cell. During HO from the source cell to a target cell, the UE is configured with a second transmission resource pool RP 2 , for use in the target cell. A transmission interruption of 1 s may result, as described above. Particularly, following a HO command, a source eNB of the source cell cannot schedule the UE until the HO has been successfully completed. Furthermore, after receiving the HO command, the UE is not allowed to continue to select resources from the first transmission resource pool RP 1  configured, for example, by the source eNB. In addition, reception resource pools provided by the source cell may not cover all transmission resource pools used in the target cell. Some may regard this, for example, as network misconfiguration, i.e., as reception pools should in general facilitate transmissions by nearly UEs using transmission pool of neighboring cells. This first scenario may similarly apply, for example, to a state transition. 
         [0167]    In a second scenario, related to a HO, an UE is configured with a first transmission resource pool RP 1  in a source cell. During HO from the source cell to a target cell, the UE is configured with a second transmission resource pool RP 2 , for use, during the HO. A first transmission interruption of 1 s may result, as described above. Subsequently, the UE is configured with a third transmission resource pool RP 3 , for use, during in the target cell. A second transmission interruption of 1 s may result, as described above. Particularly, synchronization and reception resource pool configurations for the target cell can be signaled in the HO command. 
         [0168]    In a variation of this scenario, related to a HO, either the network schedules the transmission resources of the UE (i.e., Mode 1) or the UE is configured with a first transmission resource pool RP 1  in a source cell, while in the target cell the network schedules transmission resources (i.e., Mode 1). In this case, a(n) (exceptional) transmission resource pool configuration for the target cell may be signaled in the HO command. If the (exceptional) transmission resource pool configuration is included in the HO command, the UE starts using the (exceptional) transmission resource pool from the reception of the HO command and continues to use this pool while a T304 HO time is running. 
         [0169]    For example, if the UE is configured with network scheduled resources (Mode 1) for a target cell, the UE may be provided with a pool of UE autonomously selectable (exceptional) transmission resources (Mode 2) that the UE may use while a T304 timer is running (i.e., from receiving a HO command until successful completion of random access). This (exceptional) pool may be intended to enable transmission while the T304 timer is running. However, due to RANI sensing requirements, it may take at least 1 s before the UE may transmit data via the transmission resource pool provided in the HO command. Hence, it will only reduce interruption of V2V sidelink communication transmission in a case that it would take longer than 1 s to complete HO. In addition, if the UE is configured for the target cell with a pool of UE autonomously selectable transmission resources, the RANI sensing requirements may result in V2V sidelink communication transmission being interrupted for at least 1 s. 
         [0170]    In a third scenario, related to a zone change, an UE is required to use a first transmission resource pool RP 1  in a first zone, prior to a time T 0 , as described above. Due to a mobility of the UE, the UE is required to use a second transmission resource pool RP 2  in an adjacent second zone, after the time T 0 , as described above. A transmission interruption of 1 s may result, as described above. 
         [0171]    For example, if E-UTRAN configures geographical zone specific transmission pools, the UE should switch to another transmission resource pool upon change of geographical zone, similar to HO. Correspondingly, given the RANI sensing requirements described above, a change of zone may result in an equally large interruption of V2V sidelink communication transmission as upon HO, when the UE is configured with a UE autonomously selectable resource pool. 
         [0172]    In a fourth scenario, related to a state transition, an UE is supposed to use a first transmission resource pool RP 1  in an IDLE state, prior to a time T 0 , as described above. Due to a state transition of the UE, the UE is required to change to a second transmission resource pool RP 2 , with dedicated signaling, in a CONNECTED state, after the time T 0 , as described above. A transmission interruption of 1 s may result, as described above. 
         [0173]    For example, the UE in idle Mode transmits sidelink communication using the pool of resources indicated by commTxPoolNormalCommon, if included in SystemInformationBlockType18. During connection establishment, E-UTRAN may either configure the UE with network scheduled resources (Mode 1), or with a pool of UE autonomously selectable (exceptional) transmission resources (Mode 2), to be used from the moment the UE receives the resources (i.e., by RRCConnectionReconfiguration including sl-CommConfig). Until the UE receives this message, the UE may continue using the normal transmission pool, for example a source pool or the first resource pool, for idle Mode (i.e., indicated by commTxPoolNormalCommon in SIB18) or, if not such pool is not configured, the exceptional pool indicated by commTxPoolExceptional in SIB18. In case E-UTRAN configures the normal transmission pool, for example a source pool or the first resource pool, for idle Mode and employs a similar transmission pool of UE autonomously selectable in connected mode, it may again take at least 1 s before the UE may transmit data via that transmission pool configured during connection establishment. In case E-UTRAN does not configure the normal transmission pool, for example a source pool or the first resource pool, for idle Mode but configures an exceptional pool of UE autonomously selectable transmission resources, this may not avoid interruption as due to sensing, it will take at least 1 s before the UE may transmit data via that transmission pool. 
         [0174]    For example, within a HO command, E-UTRAN may include an exceptional pool (also known as a temporary or fallback pool), for example an exceptional transmission or Tx pool. The UE may use this exceptional pool upon HO completion with random resource selection, for example. Additionally and/or alternatively, E-UTRAN may broadcast an exceptional pool, for example an exceptional transmission or Tx pool, in SIB21. The UE may use this broadcast exceptional pool with sensing based resource selection. 
         [0175]    In a fifth scenario, related to moving out of coverage, an UE may be required to use a new pool, which may be referred to as a target pool. The target pool may be a transmission pool for use when the UE is out of coverage. The UE may be pre-configured to use the target pool when the UE is out of coverage. In this scenario, transmission interruption may occur due to sensing the target pool. Specifically, if the UE has not completed sensing the target pool before moving out of coverage, transmission interruption may occur, as described previously. 
         [0176]      FIG. 3  schematically depicts a device  10  according to an embodiment of the present disclosure. The device  10  comprises a transmitter  11  and a receiver  12 . The device  10  is arranged to transmit according to a first resource pool. The device  10  is arranged to sense a second resource pool. The device  10  is arranged to switch from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2 , wherein the device  10  is arranged to transmit according to the second resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . In this way, a transmission interruption, as described above, may be reduced. 
         [0177]    Particularly, by sensing the second resource pool RP 2  while transmitting according to the first resource pool RP 1  and switching from the first resource pool RP 1  to the second resource pool RP 2  after sensing the second resource pool, latency and/or interruption of transmission arising from switching, for example, may be reduced or avoided according to the related art. In this way, a QoS may be improved such that, for example, compromise of safety critical systems may be lowered or averted. 
         [0178]    The device  10  is arranged to sense according to SA decoding and/or energy measurement, as described above. Based on the result of the energy sensing, the device  10  may autonomously select a suitable resource from the second resource pool RP 2 . 
         [0179]    The device  10  also comprises a processor and a memory (not shown). The device  10  may also comprise a storage  13  (not shown). The device  10  may be arranged to implement any of the methods of switching resources described herein. The device  10  may comprise an UE, as described above, for example, for D2D communication, including V2V. 
         [0180]      FIG. 4  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure, the method implemented by the device  10 , as described above. 
         [0181]    The device  10  is arranged to transmit according to a first resource pool RP 1 . At S 42 , the device  10  senses a second resource pool RP 2 . At S 43 , the device  10  switches from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2 , wherein the device  10  is arranged to transmit according to the second resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . In this way, a transmission interruption, as described above, may be reduced. 
         [0182]    The method may comprise any of the operations described herein. 
         [0183]    The method may comprise sensing according to SA decoding and/or energy measurement, as described above. Based on the result of the energy sensing, for example sufficient sensing, the method may comprise selecting a suitable resource from the second resource pool RP 2 . Sufficient sensing may comprise, for example, measuring energy periodically for a duration over a time period. For example, sufficient sensing may comprise measuring energy for 200 ms every 1000 ms. Other durations, time periods and frequencies may be provided. 
         [0184]      FIG. 5  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0185]    An optimal switching moment (OSM) may be defined. The OSM may be the moment, for example a time, an absolute time or a relative time, at which the device should, for example, be required to or ideally switch to using the second transmission resource pool RP 2 . For example, for a cell change, the OSM may correspond with the device  10  entering the target cell. For example, for a zone change, the OSM may correspond with the device  10  entering the target zone. For example, for continued use of the first transmission resource pool after the OSM may result in near-far problems, as described above. 
         [0186]    In principle, there may be two independent moments or times: a first moment or time when the device  10  switches resources pools, for example, stops using the first resource pool; and a second moment or time when the device  10  starts transmitting using the second resource pool. The first moment and the second moment may not be coincident, for example, a same moment or time. For example, it may be undesirable to continue to use the first resource pool for too long after the OSM because near-far problems may result. For example, in order for the device  10  to transmit according to the second resource pool, the device  10  must sense for sufficiently long. That is, sufficient sensing may be required, as described previously. In this way, for example, the device  10  may select resources for which the likelihood collisions occur is sufficiently low. 
         [0187]    In detail,  FIG. 5  shows three example cases: case A, comprising pre-sensing only; case B, comprising pre-sensing and continued use; and case C, comprising continued use only. 
         [0188]    In case A, the device  10  senses and/or transmits according to the first resource pool RP 1  during a time prior to the OSM. The device  10  pre-senses the second resource pool RP 2  for a time T a 1  prior to the OSM. At the OSM, the device  10  stops sensing and/or transmitting according to the first resource pool RP 1 . However, since the pre-sensing time T a 1  is less than a minimum sensing time T min-sense required for sufficient sensing, the device  10  continues to sense the second resource pool RP 2  for a further time T a 2  after the OSM. After sensing for a total time (T a 1 +T a 2 )&gt;=T min-sense, the device  10  starts transmitting according to the second resource pool RP 2 . That is, an interruption for the time T a 2  after the OSM results from the sensing. 
         [0189]    In case C, the device  10  senses and/or transmits according to the first resource pool RP 1  during a time prior to the OSM. At the OSM, the device  10  continues sensing and/or transmitting according to the first resource pool RP 1  for a further time until a time T max-continue, which may be a maximum time after the OSM during which the device  10  may continue sensing and/or transmitting according to the first resource pool RP 1 . At the OSM, the device  10  starts sensing the second resource pool RP 2  for a time T c 1  up to the time T max-continue. At the time T max-continue, the device  10  stops sensing and/or transmitting according to the first resource pool RP 1 . However, since the sensing time T c 1  is less than the minimum sensing time T min-sense required for sufficient sensing, the device  10  continues to sense the second resource pool RP 2  for a further time T c 2  after the time T max-continue. After sensing for a total time (T c 1 +T c 2 )&gt;=T min-sense, the device  10  starts transmitting according to the second resource pool RP 2 . That is, an interruption for the time T c 2  after the time T max-continue results. 
         [0190]    In case B, the device  10  senses and/or transmits according to the first resource pool RP 1  during a time prior to the OSM. The device  10  pre-senses the second resource pool RP 2  for a time T b 1  prior to the OSM. At the OSM, the device  10  continues sensing and/or transmitting according to the first resource pool RP 1  for a further time T b 2  less than the time T max-continue. Particularly, at the OSM, the device  10  continues sensing the second resource pool RP 2  for a time T b 2  after the OSM. That is, the further time T b 2  corresponds with sensing for a total time (T b 1 +T b 2 )&gt;=T min-sense. Hence at the time T b 2 , the device  10  stops sensing and/or transmitting according to the first resource pool RP 1  and the device  10  starts transmitting according to the second resource pool RP 2 . That is, no interruption results from the sensing. 
         [0191]    For example, upon an expected cell change, the device  10  may pre-sense the resources: 
         [0192]    a) Indicated by a reception resource pool (i.e., a broader pool including transmission resources used by nearby devices in neighboring cells, using transmission resources of those cells); 
         [0193]    b) Of the particular expected and/or candidate target cell(s). For this option, the device  10  needs information related to transmission resource pools of all neighbor cells; 
         [0194]    c) If zones are used, and the network or the AP indicates that the zone based pool configuration continues unchanged: the resources corresponding to the zone across the cell border, which the device  10  may determine based on the current configuration (if zone border coincide with cell border, for example). 
         [0195]      FIG. 6  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0196]    Prior to a time T 0 , the device  10  is arranged to transmit and to sense according to, for example via, a first transmission resource pool RP 1 . For a time period from T 0  to T 0 +1 s (i.e., 1 s), the device  10  is arranged to sense a second transmission resource pool RP 2 . In contrast to the device  1 , during the time period from T 0  to T 0 +1 s, the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the first transmission resource pool RP 1 . In contrast to the device  1 , the device  10  is arranged to switch from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 +1 s, based on a result of the sensing during the time period from T 0  to T 0 +1 s. From the time T 0 +1 s, the device  10  is arranged to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0197]    That is, when the device  10  is provided with a new transmission resource pool, such as the transmission resource pool RP 2 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 2 , may be reduced, minimized or avoided, in contrast with the device  1 . 
         [0198]    That is, the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 +1 s may be considered to be delayed with respect to the switch of the device  1 , as described above. However, in contrast to the device  1 , the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the first transmission resource pool RP 1  during the time period from T 0  to T 0 +1 s. In this way, delaying the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2 , as described, implementation may be relatively simple. However, by delaying the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2 , as described, use of an optimal transmission resource pool such as the second transmission resource pool RP 2  is delayed, which may result in near-far problems. 
         [0199]      FIG. 7  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure, the method implemented by the device  10 , as described above. 
         [0200]    The device  10  is arranged to transmit according to a first resource pool RP 1 . At S 71 , the device transmits according to, for example via, the first resource pool RP 1 . At S 72 , the device  10  senses a second resource pool RP 2 . At S 73 , the device  10  switches from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2  or using random resource selection of the second resource pool RP 2 , wherein at S 74  the device  10  is arranged to transmit according to the second resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . In this way, a transmission interruption, as described above, may be reduced. 
         [0201]      FIG. 8  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0202]    Prior to a time T 0 -t, the device  10  is arranged to transmit and to sense according to, for example via, a first transmission resource pool RP 1 . For a time period (i.e., a first time period) from T 0 -t to T 0  (i.e., t s), the device  10  is arranged to sense a second transmission resource pool RP 2 . In contrast to the device  1 , during the time period from T 0 -t to T 0 , the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the first transmission resource pool RP 1 . In contrast to the device  1 , the device  10  is arranged to switch from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 , based on a result of the sensing during the time period from T 0 -t to T 0 . During a time period (i.e., a second time period) from T 0  to T 0 +1 s, the device  10  is arranged to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0203]    That is, when the device  10  is provided with a new transmission resource pool, such as the transmission resource pool RP 2 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 2 , may be reduced, minimized or avoided, in contrast with the device  1 . During the time period (i.e., the second time period) from T 0  to T 0 +1 s, the device  10  is arranged to sense a third transmission resource pool RP 3 . During the time period from T 0  to T 0 +1 s, the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . The device  10  is arranged to switch from the second transmission resource pool RP 2  to the third transmission resource pool RP 3  at the time T 0 , based on a result of the sensing during the time period from T 0  to T 0 +1 s. From the time T 0 +1 s, the device  10  is arranged to use, for example sense and/or transmit, according to the third transmission resource pool RP 3 . That is, when the device  10  is provided with another new transmission resource pool, such as the transmission resource pool RP 3 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 3 , may be reduced, minimized or avoided, in contrast with the device  1 . 
         [0204]    That is, for example, a temporary (also known as a fallback or exceptional) transmission resource pool (i.e., the second transmission resource pool RP 2 ) may be provided for use by the device  10  during a time period of potential transmission interruption. Furthermore, the temporary transmission resource pool may be provided early, before the temporary transmission resource pool is required. That is, the device  10  may sense, the temporary transmission resource pool early, before the time period of potential transmission interruption. The temporary transmission resource pool may be continuously configured or provided for use by the device  10 , for example, rather than only upon and/or before the switch and/or during the time period of potential transmission interruption. For such continuous configuration, the device  10  may sense the temporary transmission resource pool continuously, for example, periodically, intermittently. Additionally and/or alternatively, for such continuous configuration, the device  10  may sense the temporary transmission resource pool when a resource pool switch or change is expected, for example based on an expected cell change or an expected zone change, as described previously. That is, the device  10  may pre-sense the temporary transmission resource pool. 
         [0205]    For example, the first transmission resource pool RP 1  may be associated with a current cell, the second transmission resource pool RP 2  may be the temporary transmission resource pool provided for use during a HO to a target cell and the third transmission resource pool RP 3  may be associated with the target cell. 
         [0206]    To ensure consistent performance by devices, such as the device  10 , a criterion may define a time (i.e., T-t) when the device  10  is to start sensing the temporary transmission resource pool. For example, for the HO as described above, the criterion may be from when a HO related measurement event criterion is first met. Additionally and/or alternatively, the device  10  may define the criterion, for example, the criterion may be defined by an implementation of the device  10 . 
         [0207]    Furthermore, use of the temporary transmission resource pool by the device  10  may be defined, for example, restricted, limited or bound. 
         [0208]    For example, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of successfully completing the HO. 
         [0209]    Additionally and/or alternatively, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of completing sensing of the third transmission resource pool, for example, provided by the target cell. 
         [0210]    Additionally and/or alternatively, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of expiry of a T304 HO timer, corresponding with a HO failure. 
         [0211]    However, the temporary transmission resource pool may be used by different devices in different zones, potentially resulting in near-far problems. In addition, definition of when the device  10  starts sensing the temporary transmission resource pool may be required, which may be difficult. Furthermore, the temporary transmission resource pool must be allocated, for example, by a cell for this use. 
         [0212]      FIG. 9  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure, the method implemented by the device  10 , as described above. 
         [0213]    The device  10  is arranged to transmit according to a first resource pool RP 1 . At S 91 , the device transmits according to, for example via, the first resource pool RP 1 . At S 92 , the device  10  senses a second resource pool RP 2 . At S 93 , the device  10  switches from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2 , wherein the device  10  is arranged to transmit according to the second resource pool RP 2 . At S 94 , the device  10  transmits according to, for example via, the second resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the method may comprise changing, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . At S 95 , the device  10  senses a third resource pool RP 3 . At S 96 , the device  10  switches from the second resource pool RP 2  to the third resource pool RP 3 , based on a result of the sensing the third resource pool RP 3 , wherein the device  10  is arranged to transmit according to the third resource pool RP 3 . At S 97 , the device  10  transmits according to, for example via, the third resource pool RP 3 . In this way, transmission interruptions, as described above, may be reduced. 
         [0214]      FIG. 10  schematically depicts the device  10  according to an embodiment of the present disclosure, in use.  FIG. 10  shows two different cases: a first case in which the device  10  is configured with a transmission pool RP 3  for use in a target cell and a second case in which a network schedules the transmission resources of the device  10  while connected to the target cell. 
         [0215]    For both cases, prior to a time T 0 -t, the device  10  is arranged to transmit and to sense according to, for example via, a first transmission resource pool RP 1  or scheduled Mode 1 resources. For a time period (i.e., a first time period) from T 0 -t to T 0  (i.e., t s), the device  10  is arranged to sense a second transmission resource pool RP 2 . In contrast to the device  1 , during the time period from T 0 -t to T 0 , the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the first transmission resource pool RP 1 . In contrast to the device  1 , the device  10  is arranged to switch from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 , based on a result of the sensing during the time period from T 0 -t to T 0 . During a time period (i.e., a second time period) from T 0  to T 0 +1 s, the device  10  is arranged to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0216]    That is, when the device  10  is provided with a new transmission resource pool, such as the transmission resource pool RP 2 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 2 , may be reduced, minimized or avoided, in contrast with the device  1 . 
         [0217]    That is, for example, a temporary transmission resource pool (the second transmission resource pool RP 2 ) may be provided for use by the device  10  during a time period of potential transmission interruption. Furthermore, the temporary transmission resource pool may be provided early, before the temporary transmission resource pool is required. That is, the device  10  may sense, the temporary transmission resource pool early, before the time period of potential transmission interruption. The temporary transmission resource pool may be continuously configured or provided for use by the device  10 , for example, rather than only upon and/or before the switch and/or during the time period of potential transmission interruption. For such continuous configuration, the device  10  may sense the temporary transmission resource pool continuously, for example, periodically, intermittently. Additionally and/or alternatively, for such continuous configuration, the device  10  may sense the temporary transmission resource pool when a resource pool switch or change is expected, for example based on an expected cell change or an expected zone change, as described previously. That is, the device  10  may pre-sense the temporary transmission resource pool. The temporary transmission resource pool may be an exceptional transmission resource pool, as described herein. The device  10  may perform random selection of the exceptional resource pool, as described herein. 
         [0218]    For example, the first transmission resource pool RP 1  may be associated with a current cell, the second transmission resource pool RP 2  may be the temporary transmission resource pool provided for use during a HO to a target cell, in which either a third transmission resource pool RP 3  is used, or in which the network schedules the transmission resources of the UE. 
         [0219]    To ensure consistent performance by devices, such as the device  10 , a criterion may define a time (i.e., T-t) when the device  10  is to start sensing the temporary transmission resource pool. For example, for the HO as described above, the criterion may be from when a HO related measurement event criterion is first met. Additionally and/or alternatively, the device  10  may define the criterion, for example, the criterion may be defined by an implementation of the device  10 . 
         [0220]    Furthermore, use of the temporary transmission resource pool by the device  10  may be defined, for example, restricted, limited or bound. 
         [0221]    For example, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of successfully completing the HO. 
         [0222]    Additionally and/or alternatively, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of completing sensing of the third transmission resource pool, for example, provided by the target cell. 
         [0223]    Additionally and/or alternatively, for the HO as described above, use of the temporary transmission resource pool by the device  10  may be allowed, for example permitted or required, from a time of receiving a HO command until a time of expiry of a T304 HO timer, corresponding with a HO failure. 
         [0224]    However, the temporary transmission resource pool may be used by different devices in different zones, potentially resulting in near-far problems. In addition, definition of when the device  10  starts sensing the temporary transmission resource pool may be required, which may be difficult. Furthermore, the temporary transmission resource pool must be allocated, for example, by a cell for this use. 
         [0225]    For the first case, during the time period (i.e., the second time period) from T 0  to T 0 +1 s, the device  10  is arranged to sense a third transmission resource pool RP 3 . During the time period from T 0  to T 0 +1 s, the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . The device  10  is arranged to switch from the second transmission resource pool RP 2  to the third transmission resource pool RP 3  at the time T 0 , based on a result of the sensing during the time period from T 0  to T 0 +1 s. From the time T 0 +1 s, the device  10  is arranged to use, for example sense and/or transmit, according to the third transmission resource pool RP 3 . That is, when the device  10  is provided with another new transmission resource pool, such as the transmission resource pool RP 3 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 3 , may be reduced, minimized or avoided, in contrast with the device  1 . 
         [0226]    For the second case, additionally and/or alternatively, for example after completion of HO to the target cell, the device  10  may be scheduled with Mode 1 resources from a time T 0 +˜200 ms. That is, during handover, the network may be temporarily unable to schedule transmission resources and it may take ˜200 ms for the handover procedure to complete successfully. 
         [0227]      FIG. 11  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure, the method implemented by the device  10 , as described above. 
         [0228]    The device  10  is arranged to transmit according to a first resource pool RP 1 . At S 111 , the device transmits according to, for example via, the first resource pool RP 1  or scheduled Mode 1 resources. At S 112 , the device  10  senses a second resource pool RP 2 . At S 113 , the device  10  switches from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2 , wherein the device  10  is arranged to transmit according to the second resource pool RP 2 . At S 114 , the device  10  transmits according to, for example via, the second resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the method may comprise changing, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . At S 115 , the device  10  senses a third resource pool RP 3  if not configured with Mode 1 (in which resources are not scheduled by the network). At S 116 , the device  10  switches from the second resource pool RP 2  to the third resource pool RP 3 , based on a result of the sensing the third resource pool RP 3 , wherein the device  10  is arranged to transmit according to the third resource pool RP 3  if not configured with Mode 1 resources. At S 117 , the device  10  transmits according to, for example via, the third resource pool RP 3  if not configured with Mode 1 resources. At S 118 , the device transmits according to, for example via, the scheduled Mode 1 resources. In this way, transmission interruptions, as described above, may be reduced. 
         [0229]      FIG. 12  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0230]    Prior to a time T 0 -t, the device  10  is arranged to transmit and to sense according to, for example via, a first transmission resource pool RP 1 . For a time period (i.e., a first time period) from T 0 -t to T 0  (i.e., t s), the device  10  is arranged to sense a second transmission resource pool RP 2 . In contrast to the device  1 , during the time period from T 0 -t to T 0 , the device  10  is allowed to use and/or may continue to use, for example sense and/or transmit, according to the first transmission resource pool RP 1 . In contrast to the device  1 , the device  10  is arranged to switch from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 , based on a result of the sensing during the time period from T 0 -t to T 0 . From the time T 0 , the device  10  is arranged to use, for example sense and/or transmit, according to the second transmission resource pool RP 2 . Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0231]    That is, when the device  10  is provided with another new transmission resource pool, such as the transmission resource pool RP 2 , a transmission interruption before the device  10  may start to transmit via the new transmission resource pool, such as the transmission resource pool RP 2 , may be reduced, minimized or avoided, in contrast with the device  1 . 
         [0232]    That is, the device  10  is arranged to start sensing the second transmission resource pool RP 2  relatively early, compared with the device  1 , prior to the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  at the time T 0 . Furthermore, if sensing is completed before the time T 0 , which may be considered an intended switching point, the device  10  may be arranged to switch when sensing is completed, for example, before the time T 0 . In this way, an optimal transmission resource pool, such as the second transmission resource pool RP 2 , may be used as early as possible, for example, reducing and/or minimizing near-far problems. 
         [0233]    The device  10  may require information related to the second transmission resource pool relatively early, for example, before T 0  or before T 0 -t. Furthermore, the device  10  may require a criterion indicating from when the device  10  should start sensing the second transmission resource pool. 
         [0234]      FIG. 13  schematically depicts a method of switching resource pools according to an embodiment of the present disclosure, the method implemented by the device  10 , as described above. 
         [0235]    The device  10  is arranged to transmit according to a first resource pool RP 1 . At S 131 , the device transmits according to, for example via, the first resource pool RP 1 . At S 132 , the device  10  senses a second resource pool RP 2 . At S 133 , the device  10  switches from the first resource pool RP 1  to the second resource pool RP 2 , based on a result of the sensing the second resource pool RP 2 , wherein the device  10  is arranged to transmit according to the second resource pool RP 2 . At S 134 , the device  10  transmits according to, for example via, the second resource pool RP 2 . In this way, transmission interruptions, as described above, may be reduced. Switching from the first resource pool RP 1  to the second resource pool RP 2  may comprise: determining if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool RP 2  has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool RP 2  if the second resource pool RP 2  has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool RP 1  to the second resource pool RP 2  comprises using random resource selection for the second resource pool RP 2 , the device  10  may be arranged to change, for the second resource pool RP 2 , from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool RP 2 . 
         [0236]      FIG. 14  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0237]    In detail,  FIG. 14  shows a network  2  comprising three cells  200 A,  200 B,  200 C, defined by APs  20 A,  20 B and  20 C, respectively. The APs  20  may be eNBs, for example. The cells  200  define in-coverage, out-of-coverage and partial coverage situations, as described previously. The cells  200  are shown as hexagonal cells, for convenience. A border  200 AB between the cell  200 A and the adjacent cell  200 B is oriented in an X direction. 
         [0238]    The device  10  is in the cell  200 A (i.e., a current cell) and is moving towards the border  200 AB with the adjacent cell  200 B (i.e., a target cell) in a direction Y, transverse to the border  200 AB. The device  10  is arranged to transmit according to the first resource pool RP 1 , as described previously, in which the first resource pool RP 1  is allocated by the cell  200 A. 
         [0239]    The device  10  may determine the current cell  200 A according to a location of the device  10  and cell information received from the AP  20 A. Additionally, the device  10  may determine the adjacent, target cell  200 B, as described previously. The device  10  may also determine that the border  200 AB of the current cell will be and/or is being and/or has been crossed. That is, the device  10  may determine a cell change or an expected cell change, for example from the current cell  200 A to the target cell  200 B. 
         [0240]    In response to the determination of the cell change, as described above, the device  10  may switch resource pools, as described previously with respect to  FIGS. 6 and 7 . That is, the device  10  may continue to use the first transmission resource pool RP 1  within the target cell  200 B until sensing of the second resource pool RP 2 , allocated by the target cell  200 B, is complete, for example. That is, the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  may be considered to be delayed with respect to the switch of the device  1 , as described above. In this way, a transmission interruption, as described above, may be reduced. 
         [0241]    In response to the determination of the expected cell change, as described above, the device  10  may pre-sense one or more second resource pools, for example, one or more candidate target transmission resource pools allocated by the target cell  200 B. Additionally and/or alternatively, the device  10  may sense one or more reception resource pools, as described previously. Additionally and/or alternatively, the device  10  may sense a temporary resource pool, as described previously. 
         [0242]    In response to the determination of the cell change, as described above, the device  10  may switch resource pools, as described previously with respect to  FIGS. 8 and 9 . The device  10  may receive information related to the second resource pool RP 2 , which may be the temporary resource pool, before crossing the border  200 AB, for example. That is, the device  10  may sense the second resource pool RP 2  relatively early, for example, while moving towards and/or before crossing the border  200 AB. After crossing the border  200 AB and/or within the cell  200 B, the device  10  may receive information related to a third resource pool, allocated by the cell  200 B, and/or switch to the third resource pool RP 3 , or be scheduled with Mode 1 resources, as described previously. In this way, a transmission interruption, as described above, may be reduced. 
         [0243]    In response to the determination of the cell change, as described above, the device  10  may switch resource pools early, as described previously with respect to  FIGS. 12 and 13 . The device  10  may receive information related to the second resource pool RP 2  before crossing the border  200 AB, for example, in a handover (HO) command. That is, the device  10  may sense the second resource pool RP 2 , allocated by the cell  200 B, relatively early, for example, while moving towards and/or before crossing the border  200 AB. In this way, a transmission interruption, as described above, may be reduced. 
         [0244]    In response to the determination of the cell change, as described above, the device  10  may switch resource pools early, as described previously with respect to  FIGS. 12 and 13 . The device  10  may sense one or more reception resource pools, as described previously. That is, the device  10  may sense the second resource pool RP 2 , corresponding to the one or more reception resource pools, relatively early, for example, while moving towards and/or before crossing the border  200 AB. In this way, a transmission interruption, as described above, may be reduced. 
         [0245]    The device  10  may switch based on the result of the sensing and determining the cell change. That is, a trigger to switch from the first resource pool RP 1  to the second resource pool RP 2  may be the result of the sensing and determining the cell change. 
         [0246]    Alternatively, the device  10  may switch based on the result of the sensing and a command received, for example, from the AP  20 A. That is, a trigger to switch from the first resource pool RP 1  to the second resource pool RP 2  may be the result of the sensing and the command. 
         [0247]    In response to the determination of the cell change, as described above, additionally and/or alternatively, the device  10  may not switch from the first resource pool RP 1  to the second resource pool RP 2 . For example, the device  10  may receive information indicating that the second resource pool RP 2  is the same as the first resource pool RP 1 . That is, the first resource pool RP 1  allocated by the cell  200 A may be the same as the second resource pool RP 2  allocated by the cell  200 B. 
         [0248]    Particularly, there may be two examples related to information received by the device before a handover (HO). 
         [0249]    In a first example, zones may not be defined and/or used. Thus, it is unlikely that neighboring or target cells use the same transmission resource pool as the current cell. In this example, the device  10  would need to receive information about transmission resource pools of all neighbor in cells. Alternatively, the device  10  would need to receive information about a general broader resource pool covering transmission resource pools of neighboring cells, for example, the device may use the reception resource pools of which it already has all the required information. 
         [0250]    In a second example, zones may be defined and/or used. In this case, it would be beneficial if the network would indicate that the zone based pool configuration continues unchanged across the border of neighboring cells, for example by a single bit as described previously (i.e., the bit indicating that the first resource pool continues across a cell border). 
         [0251]    Additionally and/or alternatively, for cell change in idle mode, the bit may be included in SIB21 indicating whether neighboring cells employ the same zone based transmission pool configuration. If the bit is set, the device may employ a pre-sensing operation in advance of a zone change, for example, as for a case of intra-cell. This option may be used in conjunction with wherein the device is configured to use a normal pool, for example a source pool or the first resource pool, for example included in SIB21, wherein the device has not performed sensing for a required duration, for example following cell re-selection, wherein the device is configured to use the second resource pool, for example included in SIB21, with random selection. In this way, use of the second resource pool (with random selection) may be controlled and/or reduced and/or minimized. 
         [0252]    In an example embodiment, a bit, for example in SIB21, indicates whether a neighboring cell and/or a plurality of neighboring cells employ a same zone based transmission pool configuration. 
         [0253]      FIG. 15  schematically depicts the device  10  according to an embodiment of the present disclosure, in use. 
         [0254]    In detail,  FIG. 15  shows the network  2  comprising the three cells  200 A,  200 B,  200 C, defined by the APs  20 A,  20 B and  20 C, respectively, as described previously with respect to  FIG. 14 . In addition, three rectangular, contiguous zones  300 A,  300 B,  300 C are shown. The zone  300 A is partly within the cell  200 A and partly in an out-of-coverage area. The zone  300 B is partly within the two cells  200 A and  200 B and partly in an out-of-coverage area. The zone  300 C is partly within the three cells  200 A,  200 B and  200 C. A border  300 AB between the zone  300 A and the adjacent zone  300 B is oriented in an X direction, partly within the cell  200 A and partly in an out-of-coverage area. 
         [0255]    The device  10  is in the cell  200 A (i.e., the current cell) and is moving towards the border  200 AB with the adjacent cell  200 B (i.e., the target cell) in a direction Y, transverse to the border  200 AB, as described previously. The device  10  is arranged to transmit according to the first resource pool RP 1 , as described previously, in which the first resource pool RP 1  is allocated by the cell  200 A. 
         [0256]    The device  10  is also in the zone  300 A (i.e., a current zone) and is moving towards the border  300 AB with the adjacent zone  300 B (i.e., a target zone) in a direction Y, transverse to the border  300 AB. The device  10  is relatively more proximal the border  300 AB than the border  200 AB. 
         [0257]    The device  10  may determine the current cell  200 A according to the location of the device  10  and cell information received from the AP  20 A, as described previously. 
         [0258]    Additionally, the device  10  may determine the current zone  300 A according to the location of the device  10  and zone information received from the AP  20 A and/or zone information received previously, for example during setup or updating, as described previously. The device  10  may also determine the adjacent, target zone  300 B, as described previously. The device  10  may also determine that the border  300 AB of the current zone will be and/or is being and/or has been crossed. That is, the device  10  may determine a zone change or an expected zone change, for example from the current zone  300 A to the target zone  300 B. 
         [0259]    In response to the determination of the zone change, as described above, the device  10  may switch resource pools, as described previously with respect to  FIGS. 5 and 6 . That is, the device  10  may continue to use the first transmission resource pool RP 1  within the target zone  300 B until sensing of the second resource pool RP 2 , allocated for the target zone  300 B, is complete, for example. That is, the switch of the device  10  from the first transmission resource pool RP 1  to the second transmission resource pool RP 2  may be considered to be delayed with respect to the switch of the device  1 , as described above. In this way, a transmission interruption, as described above, may be reduced. 
         [0260]    In response to the determination of the expected zone change, as described above, the device  10  may pre-sense one or more second resource pools, for example, one or more candidate target transmission resource pools allocated for the current zone  300 A. It should be noted that, based on the resource configuration information acquired or received upon entering cell  200 A, the device  10  in the zone  300 A is typically made aware of the second resource pool RP 2  used in the zone  300 B. Hence, in particular, the device  10  may start sensing the second resource pool RP 2  upon determining that the device  10  is approaching the zone  300 B. Additionally and/or alternatively, the device  10  may sense one or more reception resource pools, as described previously. Additionally and/or alternatively, the device  10  may sense a temporary resource pool, as described previously. 
         [0261]    In response to the determination of the zone change, as described above, the device  10  may switch resource pools, as described previously with respect to  FIGS. 7 and 8 . The device  10  may receive information related to the second resource pool RP 2 , which may be the temporary resource pool, before crossing the border  300 AB, for example. That is, the device  10  may sense the second resource pool RP 2  relatively early, for example, while moving towards and/or before crossing the border  300 AB. After crossing the border  300 AB and/or within the zone  300 B, the device  10  may receive information related to the third resource pool, allocated for the zone  300 B, and/or switch to the third resource pool RP 3 , as described previously. In this way, a transmission interruption, as described above, may be reduced. 
         [0262]    In response to the determination of the zone change, as described above, the device  10  may switch resource pools early, as described previously with respect to  FIGS. 11 and 12 . The device  10  may receive information related to the second resource pool RP 2  before crossing the border  300 AB, for example, from the AP  20 A. That is, the device  10  may sense the second resource pool RP 2 , allocated by the cell  200 A for the zone  300 A, relatively early, for example, while moving towards and/or before crossing the border  300 AB. In this way, a transmission interruption, as described above, may be reduced. 
         [0263]    In response to the determination of the zone change, as described above, the device  10  may switch resource pools early, as described previously with respect to  FIGS. 11 and 12 . The device  10  may sense one or more reception resource pools, as described previously. That is, the device  10  may sense the second resource pool RP 2 , corresponding to the one or more reception resource pools, relatively early, for example, while moving towards and/or before crossing the border  300 AB. In this way, a transmission interruption, as described above, may be reduced. 
         [0264]    The device  10  may switch based on the result of the sensing and determining the zone change. That is, a trigger to switch from the first resource pool RP 1  to the second resource pool RP 2  may be the result of the sensing and determining the zone change. 
         [0265]    A particular case of interest is when the device  10  moves from the zone  300 B in the cell  200 A to the cell  200 B i.e., crossing the cell border  200 AB. In response to the determination of the cell change or the expected cell change, i.e., from the cell  200 A to the cell  200 B, additionally and/or alternatively, the device  10  may not switch from the first resource pool RP 2  to the second resource pool RP 3 . For example, the device  10  may receive information indicating that the zone based resource configuration used by the cell  200 B is the same as used by the cell  200 A (i.e., continues across the cell border  200 AB). Such indication implies that the resource pool used in the zone  300 B is the same on both sides of the cell border  200 AB, i.e., does not change upon changing cell. Moreover, if the zone border  300 AB were approximately coincident with the cell border  200 AB, the bit indicating that the zone based resource configuration continues across the cell border  200 AB would enable the device  10  to know the resource pool used in the zone  300 B (and hence which resources to pre-sense). 
         [0266]      FIG. 16  shows relevant broadcast signaling as may be included in a system information block (SIB), such as SIB18. In detail,  FIG. 16  shows a number of existing fields that are relevant for this present disclosure, i.e., commRxPool-r12  161 , commTxPoolNormalCommon-r12  162 , commTxPoolExceptional-r12  163  and commTxPoolNormalCommonExt-r13  164  as well as some extensions that would be introduced in accordance with the proposals in this present disclosure: neighCellTxInfoList-r14  165  and neighCellCommTxPoolSame-r14  166 . 
         [0267]      FIGS. 17A and 17B  shows relevant dedicated signaling as may be included in a dedicated message, such as RRCConnectionReconfiguration according to an embodiment of the present disclosure. In detail,  FIGS. 17A and 17B  shows an existing field sl-CommConfig-r12  171 , as well as some extensions that would be introduced in accordance with the proposals in this present disclosure: neighCellTxInfoList-r14  172  and neighCellCommTxPoolSame-r14  173 . 
         [0268]      FIG. 18  shows extensions that may be used in both broadcast and dedicated signaling according to an embodiment of the present disclosure. In detail,  FIG. 18  shows an extension SL-CommNeighCellInfoList-r14  181 , an extension SL-CommNeighCellInfo-r14  182  and an extension SL-CommTxPoolList-r14  183 . 
         [0269]    Particularly, upon expecting cell change, the device  10  may pre-sense the second resource pool: 
         [0270]    a) The second resource pool may be indicated by a reception resource pool (i.e., a broader pool covering transmission resources used by nearby devices in neighboring cells, using transmission resources of such cells). In both idle and connected states, the device may use the communication reception resource pool provided by broadcast signaling, for example included in SIB18 as field  161  (commRxPool-r12). It may however be that a V2X specific reception pool is provided, possibly within another SIB. 
         [0271]    b) The second resource pool may be the transmission pool used by the expected/candidate target cell(s). For this option, the device needs to be informed about the details of the transmission resource pools of all neighbor cells. To support this case for use by devices that are in an idle state, E-UTRAN needs to provides the neighboring information (i.e., the transmission resource pool of neighbors) in SIB18. Although provision of information of neighboring cells on other frequencies should not be excluded, it may be less attractive given a signaling overhead. As an example, the extensions  165 ,  172  (neighCellTxInfoList-r14) and/or the extension  181  (SL-CommNeighCellInfoList-r14) included in SIB18 may thus only cover intra-frequency neighbors. The same extension may be used in a connected state. Alternatively and/or additionally, the neighboring information may be added to dedicated signaling, for example the field  171  (SL-CommConfig-r12). The extensions  165 ,  172  (neighCellTxInfoList-r14) and/or the extension  181  (SL-CommNeighCellInfoList-r14) may be the same, and may for example again only cover intra-frequency neighbors. 
         [0272]    c) If zones are used, the network may indicate that in neighboring cells the zone based pool configuration continues unchanged. In such case, the transmission resources to be used by the device only change upon change of zone, but not necessarily upon change of cell. In such case, upon cell change the UE only needs to use another transmission pool if a zone border coincides with the cell border, for example. The UE can, from the zone based pool configuration, always determine the transmission pool used by the expected target zone. Hence, if the network indicates that the same zone based pool configuration continues in neighboring cells, the UE can also determine the transmission pool to be used in such neighboring cells beforehand (e.g., before it actually changes to such cells). For the same or similar reasons as indicated for b), the indication may for example be included in SIB18. It may however also be included elsewhere for example should a V2X specific reception pool is specified within another SIB. Although it may be unlikely that same resource configuration is used on other frequencies, provision of an indicator for other frequencies need not be excluded. As an example, the SIB18 extension  166  (neighCellCommTxPoolSame-r14) only covers intra-frequency neighbors. The same extension may be used for devices in connected states. Alternatively and/or additionally, the neighboring information may be added to dedicated signaling, for example, by the RRCConnectionReconfiguration extension  173  (SL-CommConfig-r12). The extension  166 ,  173  (neighCellCommTxPoolSame-r14) may be the same and may for example again only cover intra-frequency neighbors. 
         [0273]    Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the present disclosure, as defined in the appended claims and as described above. 
         [0274]    In summary, the present disclosure provides a method of switching resource pools, implemented on a device. The present disclosure also provides the device. The device is arranged to transmit according to a first resource pool. A second resource pool is sensed. The device switches from the first resource pool to the second resource pool, based on a result of the sensing. Switching from the first resource pool to the second resource pool may comprise: determining if the second resource pool has been sensed sufficiently long to apply sensing based resource selection; and based on a result of the determining: using sensing based resource selection if the second resource pool has been sensed sufficiently long to apply sensing based resource selection; and using random resource selection for the second resource pool if the second resource pool has not been sensed sufficiently long to apply sensing based resource selection. If switching from the first resource pool to the second resource pool comprises using random resource selection for the second resource pool, the device may be arranged to change, for the second resource pool, from using random resource selection to using sensing based resource selection based on a result of the sensing the second resource pool. By switching in this way, the device is arranged to transmit according to the second resource pool and transmission interruptions associated with switching resource pools may be reduced or avoided according to the related art. 
         [0275]    In this way, the device may, for example, transmit data according to, for example via or using, the first resource pool. In parallel, simultaneously, concurrently or interleavingly to transmitting, the device may also sense the second resource pool. The device may switch, for example directly, indirectly, conditionally, subsequently, autonomously or in response to a request, to the second resource pool, based on a result of the sensing or using random resource selection of the second resource pool. By switching, for example reconfiguring, changing, swapping, exchanging, migrating or moving, from the first resource pool to the second resource pool, the device may be arranged to transmit according to, for example via or using, the second resource pool. In this way, the device may, for example, transmit data according to the arranged, for example newly-arranged, second resource pool. 
         [0276]    By sensing the second resource pool while transmitting according to the first resource pool and switching from the first resource pool to the second resource pool after sensing the second resource pool and switching subsequently after sensing the second resource pool, latency and/or interruption of transmission arising from switching, for example, may be reduced or avoided. In this way, a QoS may be improved such that, for example, compromise of safety critical systems may be lowered or averted according to the related art. 
         [0277]    In other words, the present disclosure may provide an improved method of and apparatus for switching resource pools. Particularly, by sensing the second resource pool while transmitting according to the first resource pool and switching from the first resource pool to the second resource pool after sensing the second resource pool and switching subsequently after sensing the second resource pool, latency and/or interruption of transmission arising from switching, for example, may be reduced or avoided. In this way, a QoS may be improved such that, for example, compromise of safety critical systems may be lowered or averted. In this way, a transmission interruption that may arise in various scenarios, as described above, may be overcome according to the related art. 
         [0278]    In the first scenario, related to a cell change (cell re-selection or handover, HO), the device  10  is configured with a first transmission resource pool RP 1  in a source cell. During change from the source cell to a target cell, the device  10  is configured with a second transmission resource pool RP 2 , for use in the target cell. As described above, by sensing the second resource pool RP 2  while transmitting according to the first resource pool RP 1  and switching from the first resource pool RP 1  to the second resource pool RP 2  after sensing the second resource pool, the transmission interruption of 1 s arising from switching, for example, may be reduced or avoided according to the related art. 
         [0279]    In the second scenario, related to a cell change (cell re-selection or handover, HO), the device  10  is configured with a first transmission resource pool RP 1  in a source cell. During change from the source cell to a target cell, the device  10  is configured with a second transmission resource pool RP 2 , for use, during the cell change. As described above, the first transmission interruption of 1 s may be similarly reduced or avoided. Subsequently, the device  10  is configured with a third transmission resource pool RP 3 , for use, during in the target cell. As described above, the second transmission interruption of 1 s may be similarly reduced or avoided. 
         [0280]    In the third scenario, related to a zone change, the device  10  is required to use a first transmission resource pool RP 1  in a first zone, prior to a time T 0 , as described above. Due to a mobility of the device  10 , the device  10  is required to use a second transmission resource pool RP 2  in an adjacent second zone, after the time T 0 , as described above. As described above, the transmission interruption of 1 s may be similarly reduced or avoided. 
         [0281]    In the fourth scenario, related to a state transition, the device  10  is supposed to use a first transmission resource pool RP 1  in an IDLE state, prior to a time T 0 , as described above. Due to a state transition of the device  10 , the device  10  is required to change to a second transmission resource pool RP 2 , with dedicated signaling, in a CONNECTED state, after the time T 0 , as described above. As described above, the transmission interruption of 1 s may be similarly reduced or avoided. 
         [0282]    Additionally and/or alternatively, the device  10  may be configured to use an exceptional transmission pool (i.e., a second resource pool) using random resource selection if the device  10  has not completed sensing-based resource selection, as described above. For example, the device  10  may be configured to use the exceptional transmission pool during connection establishment, RLF and/or Radio Resource Control (RRC) reselection. The device  10  may pre-sense the exceptional transmission pool. 
         [0283]    Additionally and/or alternatively, the device  10  may be configured to use the first transmission resource pool RP 1  (i.e., a normal transmission pool) in the IDLE state and/or if there is no Primary Serving Cell (PCell). However, if the device  10  has not performed sensing for sufficiently long so as to use sensing-based resource selection for the normal pool, for example a source pool or the first resource pool RP 1 , the device  10  may instead use the exceptional transmission pool. The exceptional transmission pool may be in SIB21. The device  10  may use the exceptional transmission pool with random resource selection. The device  10  may pre-sense the exceptional transmission pool. 
         [0284]    In this way, by using the exceptional transmission pool, sensing-based pools may not be polluted or interfered with random resource selection. That is, only the exceptional transmission pool would be polluted or interfered with random resource selection. Furthermore, pool sizes may be controlled and/or reduced and/or minimized. For example, random resource selection may require a relatively larger pool so as to provide similar and/or the same performance as sensing-based resource selection. By limiting random resource selection to one pool (i.e., the exceptional transmission pool), a size of this exceptional transmission pool only may be relatively larger and/or increased while resource transmission pools associated with zones may be relatively smaller and/or reduced. Particularly, the resource transmission pools associated with the zones may be numerous and thus these numerous zones may be each relatively smaller and/or reduced compared with the single exceptional transmission pool. 
         [0285]    In the fifth scenario, related to moving out of coverage, the device  10  is required to use a first transmission resource pool RP 1  in a first zone, prior to a time T 0 , as described above. Due to a mobility of the device  10  in which the device  10  moves out of coverage of the first zone, the device  10  is required to use a second transmission resource pool RP 2 , after the time T 0 , as described above. That is, this scenario related to moving out of coverage may be considered covered by and/or similar to and/or the same as the scenario related to a zone change, as described above. Particularly, when moving out of coverage from the first zone, the device  10  may estimate a second zone (i.e., a target zone) towards which the device  10  is moving and start pre-sensing corresponding resources of the second zone (i.e., the second transmission resource pool RP 2 ) in advance, for example a period of time in advance such as 1 s in advance. However, it may not be possible for the device  10  to estimate the second zone well enough in the period of time such as 1 s in advance. Therefore, the device  10  may additionally and/or alternatively start sensing resources (i.e., transmission resource pools) of a plurality of candidate zones in advance, for example a period of time in advance such as 1 s in advance. For example, the device  10  may start sensing the resources of 2, 3 or more candidate zones in advance. Furthermore, the device  10  may stop sensing the resource of 1 or more of the candidate zones if the device  10  determines that these candidate zones are not relevant, for example, if the device  10  is not moving towards these candidate zones such that these candidate zones will not be the second zone. If the device  10  is not able to estimate the second zone well enough in the period of time such as 1 s in advance, the device  10  may instead use an exceptional pool when the device  10  is out of coverage. The device  10  may be pre-configured to use the exceptional pool in this scenario. 
         [0286]    Table 2 summarizes these scenarios for an example practical application, in which four approaches described herein are compared: 
         [0287]    Approach A: Allow an UE to continue using a first resource pool txPool 1  (i.e., RP 1 ) until sensing is completed for a second resource pool txPool 2  (i.e., RP 2 ). That is, the UE switches upon having sensed txPool 2  (i.e., RP 2 ) for long enough. 
         [0288]    Approach B: Require the UE to temporarily employ another pool, that the UE starts sensing before the UE is (re-) configured to use the third resource pool txPool 2  (i.e., RP 3 ). For example, the UE may start sensing a source exceptional pool, or a dedicated fallback pool txPoolFB (i.e., RP 2 ) before HO, or continuously. That is, the UE switches to txPoolFB (i.e., RP 2 ) at a time to start using the target pool txPool 2  (i.e., RP 3 ) if txPool 2  (i.e., RP 3 ) has not been sensed long enough. Switch to txPool 2  (i.e., RP 3 ) upon having sensed txPool 2  (i.e., RP 3 ) long enough. 
         [0289]    Approach C: Require the UE to start sensing the second resource pool txPool 2  (i.e., RP 2 ) in advance of the UE being (re-) configured to use the second resource pool txPool 2  (i.e., RP 2 ) (i.e., pre-sense a target pool). For example, the UE switches upon a command or detecting zone or pool change. 
         [0290]    Approach D: Pre-sense fallback/intermediate pool txPoolFB (i.e., RP 2 ) and use txPoolFB (i.e., RP 2 ) while target pool txPool 2  (i.e., RP 3 ) has not been sensed long enough. Switch to txPoolFB (i.e., RP 2 ) at time to start use target pool txPool 2  (i.e., RP 3 ) if that pool has not been sensed long enough. Use random selection for txPoolFB (i.e., RP 2 ) while txPoolFB (i.e., RP 2 ) has not been sensed long enough to use sensing based selection (i.e., pre-sensing was too short). Switch to txPool 2  (i.e., RP 3 ) upon having sensed txPool 2  (i.e., RP 3 ) long enough. 
         [0000]    
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Approach D: 
               
               
                   
                   
                   
                   
                   
                 Pre-sense 
               
               
                   
                   
                   
                   
                   
                 second resource 
               
               
                   
                   
                   
                 Approach B: 
                   
                 pool txPool FB   
               
               
                   
                   
                   
                 temporarily 
                   
                 and use 
               
               
                   
                   
                 Approach A: 
                 use pre- 
                 Approach C: 
                 txPool FB  while 
               
               
                   
                   
                 continue 
                 sensed 
                 pre-sense 
                 target pool 
               
               
                   
                   
                 using first 
                 second 
                 second 
                 txPool2 has not 
               
               
                   
                   
                 resource 
                 resource pool 
                 resource pool 
                 been sensed 
               
               
                 Scenario 
                 Description 
                 pool txPool1  
                 txPool FB   
                 txPool2 
                 long enough 
               
               
                   
               
             
             
               
                 1 
                 Upon HO, for 
                 If UE is 
                 If UE is 
                 Not 
                 Upon HO 
               
               
                   
                 target cell UE 
                 configured 
                 configured 
                 applicable 
                 exceptional pool 
               
               
                   
                 is configured 
                 with Mode 2 
                 with Mode 1 
                   
                 of target cell 
               
               
                   
                 with network 
                 resources: 
                 resources: 
                   
                 may be 
               
               
                   
                 scheduled 
                 UE 
                 UE starts 
                   
                 configured, that 
               
               
                   
                 transmission 
                 continues 
                 sensing 
                   
                 UE temporarily 
               
               
                   
                 resources and 
                 using source 
                 source cell 
                   
                 uses, initially 
               
               
                   
                 exceptional 
                 cell 
                 exceptional 
                   
                 with random 
               
               
                   
                 pool for use 
                 transmission 
                 transmission 
                   
                 resource 
               
               
                   
                 while T304 is 
                 pool during 
                 pool early so 
                   
                 selection. As 
               
               
                   
                 running 
                 T304 
                 it can be used 
                   
                 HO should 
               
               
                   
                   
                   
                 during T304. 
                   
                 complete before 
               
               
                   
                   
                   
                 Note 1 
                   
                 sensing, UE will 
               
               
                   
                   
                   
                   
                   
                 normally only 
               
               
                   
                   
                   
                   
                   
                 apply random 
               
               
                   
                   
                   
                   
                   
                 selection 
               
               
                 2 
                 Upon HO, for 
                 If UE is 
                 UE starts 
                 Solution 
                 Same as 
               
               
                   
                 target cell UE  
                 configured 
                 sensing 
                 requires UE 
                 scenario 1. As 
               
               
                   
                 is configured 
                 with Mode 2 
                 source cell 
                 to know 
                 UE cannot start 
               
               
                   
                 with pool of 
                 resources: 
                 exceptional 
                 txPool2 
                 sensing of 
               
               
                   
                 UE 
                 UE 
                 transmission 
                 details, i.e.,  
                 temporary pool 
               
               
                   
                 autonomously 
                 continues 
                 pool early so 
                 transmission 
                 earlier than 
               
               
                   
                 selectable 
                 using source 
                 it can be used  
                 resources 
                 target pool, UE 
               
               
                   
                 transmission 
                 cell 
                 until it is 
                 used in target  
                 will only apply 
               
               
                   
                 resources 
                 transmission 
                 ready to 
                 cell. UE 
                 random 
               
               
                   
                   
                 pool until 
                 transmit via 
                 might start 
                 selection in this 
               
               
                   
                   
                 UE is ready 
                 target cell 
                 sensing  
                 scenario (upon 
               
               
                   
                   
                 to transmit 
                 transmission 
                 txPool2, e.g.,  
                 sensing long 
               
               
                   
                   
                 via target 
                 pool (i.e., 
                 from the 
                 enough UE 
               
               
                   
                   
                 cell 
                 sensing 
                 moment it  
                 switches to 
               
               
                   
                   
                 transmission 
                 completed). 
                 starts TTT 
                 target pool) 
               
               
                   
                   
                 pool (i.e., 
                 Note 1 
                 for the HO 
                   
               
               
                   
                   
                 sensing 
                   
                 related 
                   
               
               
                   
                   
                 completed) 
                   
                 measurement 
                   
               
               
                   
                   
                   
                   
                 event. 
                   
               
               
                 3 
                 Change of 
                 UE 
                 UE starts 
                 It is assumed  
                 If UE did not 
               
               
                   
                 geographical 
                 continues 
                 sensing 
                 the UE 
                 start pre-sensing 
               
               
                   
                 zone (with 
                 using source 
                 source cell 
                 knows 
                 target pool of 
               
               
                   
                 Mode 2 Tx 
                 zone Tx pool 
                 fallback 
                 txPool2  
                 target zone long 
               
               
                   
                 resources), 
                 until it is 
                 transmission 
                 details, i.e., 
                 enough in 
               
               
                   
                 i.e., while 
                 ready to 
                 pool early so 
                 transmission 
                 advance, UE 
               
               
                   
                 staying within 
                 transmit via 
                 it can be used 
                 resources 
                 will use source 
               
               
                   
                 cell 
                 target zone 
                 until it is 
                 used in the 
                 cell fallback 
               
               
                   
                   
                 Tx pool (i.e.,  
                 ready to 
                 target zone 
                 transmission 
               
               
                   
                   
                 sensing 
                 transmit via 
                 (as long as 
                 pool. If that 
               
               
                   
                   
                 completed) 
                 target cell 
                 cell does not 
                 fallback pool 
               
               
                   
                   
                   
                 transmission 
                 change). UE 
                 has not yet been 
               
               
                   
                   
                   
                 pool (i.e., 
                 might start 
                 sensed long 
               
               
                   
                   
                   
                 sensing 
                 sensing 
                 enough, random 
               
               
                   
                   
                   
                 completed). 
                 txPool2 
                 selection is used 
               
               
                   
                   
                   
                 Note 1 
                 when 
                 (and otherwise 
               
               
                   
                   
                   
                   
                 distance to 
                 sensing based 
               
               
                   
                   
                   
                   
                 zone border 
                 resource 
               
               
                   
                   
                   
                   
                 is below 
                 selection) 
               
               
                   
                   
                   
                   
                 some limit 
                   
               
               
                 4a 
                 Upon 
                 If normal 
                 If only 
                 Not 
                 During 
               
               
                   
                 connection 
                 transmission 
                 exceptional 
                 applicable 
                 connection 
               
               
                   
                 establishment, 
                 pool is 
                 transmission 
                   
                 establishment, 
               
               
                   
                 UE is 
                 configured 
                 pool is 
                   
                 UE employs 
               
               
                   
                 configured 
                 for idle 
                 configured 
                   
                 exceptional 
               
               
                   
                 with network 
                 Mode 
                 (SIB18), UE 
                   
                 pool. If that 
               
               
                   
                 scheduled 
                 (SIB18), UE 
                 could sense 
                   
                 fallback pool 
               
               
                   
                 transmission 
                 continues 
                 exceptional 
                   
                 has not yet been 
               
               
                   
                 resources 
                 using this 
                 Tx pool 
                   
                 sensed long 
               
               
                   
                   
                 pool during 
                 continuously 
                   
                 enough (e.g., 
               
               
                   
                   
                 T300. Note 
                 so it can be 
                   
                 power on), 
               
               
                   
                   
                 2 
                 used during 
                   
                 random 
               
               
                   
                   
                   
                 T300. Note 1 
                   
                 selection is used 
               
               
                   
                   
                   
                   
                   
                 (and otherwise 
               
               
                   
                   
                   
                   
                   
                 sensing based 
               
               
                   
                   
                   
                   
                   
                 resource 
               
               
                   
                   
                   
                   
                   
                 selection) 
               
               
                 4b 
                 Upon 
                 If normal 
                 If only 
                 Not 
                 Same as for 
               
               
                   
                 connection 
                 transmission 
                 exceptional 
                 applicable, 
                 scenario 4a. 
               
               
                   
                 establishment, 
                 pool is 
                 transmission 
                 i.e., may not 
                   
               
               
                   
                 UE is 
                 configured 
                 pool is 
                 be possible to 
                   
               
               
                   
                 configured 
                 for idle 
                 configured 
                 predict 
                   
               
               
                   
                 with 
                 Mode 
                 (SIB18), UE 
                 connection 
                   
               
               
                   
                 dedicated 
                 (SIB18), UE 
                 could sense 
                 establishment 
                   
               
               
                   
                 pool of UE 
                 continues 
                 exceptional 
                   
                   
               
               
                   
                 autonomously 
                 using this 
                 transmission 
                   
                   
               
               
                   
                 selectable 
                 pool until it 
                 pool 
                   
                   
               
               
                   
                 transmission 
                 is ready to 
                 continuously 
                   
                   
               
               
                   
                 resources 
                 transmit via 
                 so it can be 
                   
                   
               
               
                   
                   
                 dedicated 
                 used until it 
                   
                   
               
               
                   
                   
                 transmission 
                 is ready to 
                   
                   
               
               
                   
                   
                 pool (i.e., 
                 transmit via 
                   
                   
               
               
                   
                   
                 sensing 
                 dedicated 
                   
                   
               
               
                   
                   
                 completed) 
                 transmission 
                   
                   
               
               
                   
                   
                   
                 pool (i.e., 
                   
                   
               
               
                   
                   
                   
                 sensing 
                   
                   
               
               
                   
                   
                   
                 completed). 
                   
                   
               
               
                   
                   
                   
                 Note 1, Note 
                   
                   
               
               
                   
                   
                   
                 2 
               
               
                   
               
             
          
         
       
     
         [0291]    Note 1: Instead of starting sensing before a particular event (e.g., radio quality going down, so HO or RLF may occur), UE may continuously monitor the fallback/exceptional transmission pool so that the UE may use this during any sudden unforeseen event (connection establishment is difficult to predict). Such an approach may drain UE batteries, but power saving options could be left to UE implementation. 
         [0292]    Note 2: Exceptional pool may only be intended to be used as fallback pool when using Mode 1 resources. 
         [0293]    Table 3 summarizes time periods during which device is configured, for example allowed, permitted and/or required, to use an exceptional pool (i.e., a temporary pool). The device may be configured to stop using the exceptional pool upon completing sensing of a target pool for a required duration, as described previously. 
         [0000]    
       
         
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 Until (scheduled 
                 Until (UE selected 
               
               
                   
                   
                 resources in target 
                 resources in target 
               
               
                   
                 From 
                 state) 
                 state) 
               
               
                   
               
             
             
               
                 Establishment 
                 Initiation of 
                 Switch to network 
                 Sensing completed for 
               
               
                   
                 connection 
                 scheduled resource 
                 newly received UE 
               
               
                   
                 establishment 
                 (end usage of 
                 selected resources 
               
               
                   
                   
                 exceptional pool as 
                   
               
               
                   
                   
                 today) 
                   
               
               
                 Reconfiguration 
                 Receipt of 
                 N/A 
                 Sensing completed for 
               
               
                   
                 reconfiguration 
                   
                 newly received UE 
               
               
                   
                 message 
                   
                 selected resources 
               
               
                 RLF with re- 
                 Detection of RLF 
                 Switch to network 
                 Sensing completed for 
               
               
                 establish 
                   
                 scheduled resource 
                 newly received UE 
               
               
                   
                   
                 upon reconfiguration 
                 selected resources 
               
               
                   
                   
                 following re- 
                   
               
               
                   
                   
                 establishment (end 
                   
               
               
                   
                   
                 usage of exceptional 
                   
               
               
                   
                   
                 pool as today) 
                   
               
               
                 Release/RLF 
                 Receipt of release 
                 N/A 
                 Sensing completed for 
               
               
                 resulting in idle 
                 message/ 
                   
                 broadcasted UE 
               
               
                   
                 Detection of RLF 
                   
                 selected resources 
               
               
                 HO 
                 Receipt of 
                 Switch to network 
                 Sensing completed for 
               
               
                   
                 handover 
                 scheduled resource 
                 newly received UE 
               
               
                   
                 message/start 
                 (end usage of 
                 selected resources 
               
               
                   
                 T304 
                 exceptional pool as 
                   
               
               
                   
                   
                 today) 
                   
               
               
                 Cell reselection 
                 Unspecified 
                 Unspecified 
                 Unspecified 
               
               
                   
               
             
          
         
       
     
         [0294]    As a summary regarding use by the device of an exceptional pool: 
         [0295]    1) Following RLF, the device may be required to use sensing for the exceptional pool, as described previously; 
         [0296]    2) Use of exceptional transmission resources upon HO for a case in which the device is configured with scheduled resources, for example by a target cell, may be allowed only during T304. For a case in which the device is configured with a pool, the exceptional resources may be used, for example with random selection, until the device has sensed the pool for long enough, as described previously. However, in case of a subsequent pool reconfiguration, the device may not use the exceptional pool included in the HO command, but rather, should use a pool in SIB21; 
         [0297]    3) During connection establishment, the device uses either a normal transmission pool or, if that is not included in SIB21, an exceptional pool. For both the normal transmission pool and the exceptional pool, sensing is used. However, if the device has not performed sensing for long enough as described previously, the device should use the exceptional pool with random selection, as described previously; and 
         [0298]    4) In case of release, the device should use the transmission resources in SIB21. If sensing has not been completed, the device should use exceptional pool with random selection, as described previously. 
         [0299]    Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. 
         [0300]    All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the operations of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or operations are mutually exclusive. 
         [0301]    Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0302]    At this point it should be noted that various embodiments of the present disclosure as described above typically involve the processing of input data and the generation of output data to some extent. This input data processing and output data generation may be implemented in hardware or software in combination with hardware. For example, specific electronic components may be employed in a mobile device or similar or related circuitry for implementing the functions associated with the various embodiments of the present disclosure as described above. Alternatively, one or more processors operating in accordance with stored instructions may implement the functions associated with the various embodiments of the present disclosure as described above. If such is the case, it is within the scope of the present disclosure that such instructions may be stored on one or more non-transitory processor readable mediums. Examples of the processor readable mediums include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The processor readable mediums can also be distributed over network coupled computer systems so that the instructions are stored and executed in a distributed fashion. Also, functional computer programs, instructions, and instruction segments for accomplishing the present disclosure can be easily construed by programmers skilled in the art to which the present disclosure pertains. 
         [0303]    While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.