CN111165059B - Handover procedure for wireless networks using beamforming - Google Patents

Abstract

Various communication systems could benefit from improved methods for switching when using beamforming. For example, in the case of an intra-network handover or an inter-network handover, it may be advantageous to use a method comprising: receiving a dedicated random access channel configuration associated with at least one first downlink beam, determining the The device is not in the coverage area of at least one first downlink beam, and based on the determination, using the dedicated random access channel configuration associated with the at least one first downlink beam to transmit information for at least one first downlink beam Random access messages for two downlink beams.

Description

Handover procedure for wireless networks using beamforming

technical field

The present invention generally relates to apparatus, methods and computer programs for handover procedures of wireless networks using beamforming.

Background technique

Embodiments of the present invention relate to wireless or mobile communication networks such as but not limited to Global System for Mobile Communications, GSM, Wideband Code Division Multiple Access, WCDMA, Long Term Evolution, LTE and/or 5G radio access technologies, which may also be referred to as New Radio Access technology NR. Since its inception, LTE has been widely deployed in various environments involving data communications, and LTE is still being developed by the 3rd Generation Partnership Project 3GPP. Likewise, 3GPP has also developed standards for 5G/NR. In general, the goal of 3GPP is to further develop and improve wireless cellular systems.

One of the topics related to LTE and 5G/NR in 3GPP discussions is mobility. As the mobile terminal moves, it may be necessary to hand off the mobile terminal from one base station to another to maintain connectivity. Such switching may be required within a network (intra-network handover) or between networks (inter-network handover). Often, switching procedures need to be improved for efficient operation.

Beamforming may be used in wireless networks to steer transmission and/or reception in a certain direction for better performance than omnidirectional transmission and/or reception. However, if the user equipment moves, a continuous connection should be maintained even with beamforming.

For example, similar enhancements can also be employed in other wireless cellular systems such as GSM and WCDMA. In addition to different wireless cellular systems, these enhancements can also be utilized in relation to or in combination with a number of other wireless systems, such as wireless local area networks, WLANs, and Worldwide Interoperability for Microwave Access WiMAX systems.

Contents of the invention

According to some embodiments, an apparatus may include at least one processor and at least one memory including computer program code. At least one memory and computer program code may be configured to, with at least one processor, cause the apparatus to at least: receive a dedicated random access channel configuration associated with at least one first downlink beam, determine that the apparatus is not in the at least one in the coverage area of a first downlink beam, and based on the determination, transmitting a message for at least one second downlink beam using a dedicated random access channel configuration associated with the at least one first downlink beam Random access messages.

According to some embodiments, the first method may comprise: receiving a dedicated random access channel configuration associated with at least one first downlink beam, determining that the apparatus is not covered by the at least one first downlink beam In the region, and based on the determination, a random access message for at least one second downlink beam is transmitted using a dedicated random access channel configuration associated with the at least one first downlink beam.

According to some embodiments, an apparatus may include at least one processor and at least one memory including computer program code. At least one memory and computer program code may be configured to, together with at least one processor, cause the apparatus to at least: transmit to a user equipment a dedicated random access channel configuration associated with at least one first downlink beam, and communicate with at least one first downlink beam A random access message for at least one second downlink beam is received from the user equipment on a dedicated random access channel associated with one first downlink beam.

According to some embodiments, the second method may include: transmitting to the user equipment a dedicated random access channel configuration associated with at least one first downlink beam, and when associated with the at least one first downlink beam A random access message for at least one second downlink beam is received from the user equipment on a dedicated random access channel of .

According to some embodiments, a computer program product may be configured to control an apparatus to perform a process according to the first or second method.

According to some embodiments, an apparatus may comprise means for performing a first or a second method.

Description of drawings

For a more complete understanding of example embodiments of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 illustrates the general procedure for handover;

Figure 2 illustrates an example of a handover procedure according to an embodiment of the invention;

Figure 3 illustrates a process according to some embodiments of the invention;

Figure 4 illustrates a flow chart of a method according to an embodiment of the invention;

Figure 5 illustrates a flow chart of a method according to an embodiment of the invention;

Figure 6 illustrates an apparatus according to an embodiment of the invention.

Detailed ways

Embodiments of the present invention relate to handover procedures for wireless networks using beamforming and provide an improved solution for handover when beamforming is used.

In the case of wireless communication, radio resources can be allocated in two ways. Dedicated resources can be used by only one device, thus avoiding conflicts. On the other hand, shared resources can be shared among multiple devices, which can lead to situations where conflicts arise.

For example, the Random Access Channel RACH may be utilized to access a wireless communication system, or when a mobile station is handed over from one base station to another within a network or between networks. Depending on the situation, both dedicated and shared resources can be used for random access. Contention-free random access (CFRA) refers to the use of dedicated resources, while contention-based random access (CBRA) refers to the use of shared resources. RACH resources may be, for example, preambles, sequences, frequency resources or time resources. For example, a preamble may include a cyclic prefix CP, a sequence and a guard time. The sequence may be a Zadoff-Chu sequence or another suitable sequence. Moreover, RACH resources may also refer to a group of resources, such as two or more preambles, two or more sequences, two or more frequency resources, or two or more time resources. In some embodiments, the RACH resource may be a physical random access channel, a PRACH resource or a set of PRACH resources.

Dedicated and shared resources can also be utilized with beamforming. By using beamforming, transmission and/or reception can be directed directly by adjusting the radiation pattern of the antenna array at the transmitter and/or receiver side to optimize communication. Therefore, beamforming can be bi-directional. For example, beamforming can be thought of as steering lobes of power in a certain direction. In the case of beamforming, a RACH resource or set of resources may be associated with a downlink beam or set of downlink beams.

If beamforming or any other similar technique is used, the user equipment UE may report measurement information per beam or per set of beams to the base station. The reported information may be based on the synchronization signal SS and/or the channel state indication reference signal CSI-RS. In some embodiments, this information may be transmitted to the base station BS in a measurement report. For example, the received information can be used at the BS to adjust resource allocations accordingly.

Figure 1 illustrates the procedure for inter-BS handover (ie intra-network handover). The invention is described in the context of this architecture, but the invention may be employed in any suitable alternative network architecture, such as for inter-network handover. As a starting point, the UE may be in a connected state, eg, in RRC-CONNECTED state. In case of an upcoming handover of the UE, the source base station and the target base station may also utilize the reporting information related to beams or sets of beams. The source BS may receive reporting information from the UE related to the beam or set of beams, for example in a measurement information message (110).

Also, the source BS may transmit or forward information about the beam or set of beams to the target BS, for example in a handover request message (120). After receiving this information, the target BS can perform admission control and select the most appropriate beam for the UE. The target BS can also correspondingly allocate dedicated random access channel resources associated with the most appropriate beam for the UE. If a set of RACH resources is allocated, those resources may be associated with a set of downlink beams.

Thereafter, the target BS may transmit a message to the source BS, eg, an acknowledgment message related to the upcoming handover (130). The target BS may also generate an RRCConnectionReconfiguration message for the UE, which may be part of the message. The RRCConnectionReconfiguration message may also include mobilityControlInfo related information elements.

The source BS may transmit the information included in the received message to the UE, possibly in the form of a handover command (140). That is, the message may be transmitted from the target BS to the UE via the source BS. In some embodiments, the handover command (140) may include at least the cell identity of the target BS. Alternatively or additionally, the handover command (140) may include information required to access the target BS. Such information may be sufficient for the UE to access the target BS. For example, in some cases, the handover command (140) may include information required by CBRA and/or CFRA. In the case of beamforming, the handover command (140) may also include information about the beam or set of beams.

For example, the target BS may provide the UE with a common RACH configuration as a shared resource and/or a dedicated RACH configuration as a dedicated resource. In some embodiments, a common RACH configuration may be a common RACH resource associated with an SS block that all UEs can use. Additionally, in some embodiments, a dedicated RACH configuration may be a dedicated RACH resource associated with a dedicated SS block and/or associated with a dedicated CSI-RS that only one UE may use.

The common RACH configuration may be equivalent to the configuration information broadcast in the system information block. Therefore, UEs can use a common RACH configuration for performing CBRA. On the other hand, a dedicated RACH configuration may only be allocated to one specific UE for performing CFRA.

If the target BS uses beamforming, a dedicated RACH resource configuration may be associated with a beam or set of beams. The configuration may be associated with SS block(s) and/or CSI-RS(s). In some embodiments, one RACH resource may be allocated to a UE for performing CFRA, and in some embodiments, a set of RACH resources may be allocated. If a set of RACH resources is allocated, the dedicated RACH resource configuration may include one RACH resource per beam. For example, if three dedicated RACH resources are configured to be associated with three beams, the dedicated RACH configuration may include one resource per beam.

After receiving the handover command, the UE can handover or access the target BS. To this end, the UE may utilize information received in the handover command (140), such as, for example, information required by CBRA and/or CFRA. Once the UE has decided to handover to the target BS, it may send a message to the target BS, eg, a handover complete message (150), to access the target BS. Transmission of messages may be accomplished by utilizing information required by CBRA and/or CFRA.

However, one issue may be that if beamforming is used at the target BS, the UE may move after it has reported beam measurement information, at least in some cases. In this case, it may happen that one or more beams indicated in the handover command (140) are no longer suitable for accessing the target BS, ie the indicated one or more beams may be invalid. For example, the target BS may allocate dedicated RACH resources related to the first downlink beam or the first set of downlink beams to the UE. However, if the UE has moved, the quality of the first downlink beam or the first set of downlink beams may decrease due to the UE's movement. On the other hand, it may happen that the quality of the second downlink beam or the second set of downlink beams has improved and at this time the second downlink beam or the second set of downlink beams will be better for the UE.

Therefore, if in this case, the UE will use the configured dedicated RACH resources associated with the first downlink beam(s) to transmit a message to the target BS, the target BS will send a message to the target BS by using A downlink beam sends a message in response. Therefore, the UE will not correctly receive the message from the target BS. Therefore, the random access procedure will continue and after a few attempts, the UE will fall back to CBRA. This will introduce a noticeable delay to the switching procedure. One possible solution might be to configure the UE such that it falls back to CBRA as soon as it notices that the first downlink beam(s) are not suitable for communication. However, CBRA should generally be avoided, as CBRA is a shared resource, so collisions may occur, which will again increase latency. That is, compared to CBRA, dedicated RACH resources (ie, CFRA) should be preferred to provide better success rate and lower delay.

In view of the above disadvantages, certain embodiments of the present invention may improve the handover procedure, especially when beamforming is used at the target BS. Embodiments of the present invention support faster random access for mobile UEs. Furthermore, embodiments of the present invention also provide a robust solution, wherein even if the UE has moved from the coverage area of the first downlink beam(s) to the second downlink beam(s) coverage area, the UE does not need to fall back to CBRA.

For example, if the UE has moved away from the coverage area of the first downlink beam(s) associated with the indicated dedicated RACH resource, the UE may continue to use the dedicated RACH resource, for example, if the target BS can omnidirectionally receive . To this end, even if the target BS does not move out of the coverage area of the first downlink beam(s), it can indicate to the UE that it can use dedicated RACH resources. In this case, the UE may indicate the index of the second downlink beam(s) to the target BS, so that the target BS may send a response message to the UE using the second downlink beam(s).

Alternatively, if the UE knows that the target BS is capable of receiving dedicated RACH resources only in a certain direction, the UE can quickly fall back to using CBRA for the second downlink beam(s). This may be beneficial, for example, if the uplink is beamed in the target BS, ie the target BS uses beamforming in reception. For this option, even if the target BS moves out of the coverage area of the first downlink beam(s), it can indicate to the UE that it cannot use dedicated RACH resources. That is, even if the target BS moves out of the coverage area of the first downlink beam(s), it can indicate to the UE whether it can use dedicated RACH resources.

Even though the allocated dedicated RACH resources may be a set of resources, one consideration is how many resources should be included in the set. This results in a tradeoff between RACH resource consumption and the UE's likelihood to use CFRA. Once a dedicated RACH resource is allocated to a UE, any other UE will not be able to use it temporarily. Therefore, a network implementation may configure a small number of dedicated RACH resources, for example, only one. However, in that case, the possibility of the UE moving out of the coverage of dedicated RACH resources increases compared to a case where a large amount of RACH resources would be allocated. In practice, RACH resources are limited, therefore, it may not be desirable to reserve many dedicated RACH resources for handover of a single UE. Certain embodiments of the present invention support resource saving of dedicated RACH resources, since fewer resources can be allocated to a UE, while also minimizing latency.

An example of how this can be achieved is provided below. Fig. 2 represents an example of a network scenario according to an embodiment of the present invention. The network may comprise a core network, two or more base stations BS (210, 220) and at least one user equipment UE (230). BS (210) may be a source BS for handover, and BS (220) may be a target BS for handover.

In the context of 5G/NR and intra-network handover, the BS (210, 220) may be referred to as a gNB. On the other hand, in the context of LTE and intra-network handover, a BS (210, 220) may be referred to as an eNB. In case of inter-network handover, the BS (210) may be a gNB and the BS (220) may be an eNB, or vice versa. However, the invention is not limited to any particular definition of BS, ie those skilled in the art will understand how to apply the invention in different wireless systems which may have various names for BS (210, 220). Likewise, even though the present invention has been described using UE (230) as an example, other names may be used, such as mobile station or wireless terminal.

As a starting point, a UE (230) may associate with a BS (210). In some embodiments, the UE may be in RRC_CONNECTED state. The UE (230) may perform measurements related to one or more beams and report information related to the measurements to the BS (210). If the received power of the first downlink beam (240) is above a threshold (A4 event) or better offset than the received power of the serving beam (A3 event), the UE (230) may report e.g. Measurements related to an uplink beam (240), where the serving beam is associated with the BS (210).

After detecting that a handover is required, the BS (210) may transmit a message to the BS (220) via a fixed backhaul connection. The message may include information related to beam measurements reported by the UE (230). Based on this information, the BS (220) can determine the dedicated RACH resources that the UE (230) can use to access the BS (220). Dedicated RACH resources can be used for beams or sets of beams. Referring to Figure 2, dedicated RACH resources may be associated with a first downlink beam (240).

Then, the BS (220) may transmit a message including information on the dedicated RACH to the BS (210). In some embodiments, this message may be in the form of an RRCConnectionReconfiguration message, possibly including a mobilityControlInfo information element. The message may also include an indication or instruction as to whether the UE (230) should continue to use the dedicated RACH resources even if it finds that it has moved away from the coverage area of the first downlink beam (240) associated with the dedicated RACH resources. The BS (210) may transmit or forward the message to the UE (230). That is, the message is transmitted from the BS (220) to the UE (230) via the BS (210).

Referring again to FIG. 2, the UE may have moved along the trajectory (260) during the handover procedure. Accordingly, the UE (230) can determine whether the first downlink beam (240) associated with the dedicated RACH is still suitable for communication. In other words, the UE (230) determines whether it has moved away from the coverage area of the first downlink beam (240). This determination can be based on the latest measurement results.

For example, the UE (230) may compare the received power of the first downlink beam (240) to a threshold or offset between the received power of the first downlink beam (240) and the serving beam. For example, if the received power (eg, reference signal received power RSRP) is above a threshold, the first downlink beam (240) may be determined to be suitable for communication. However, if the received power is below a threshold, the first downlink beam (240) may be determined to be unsuitable for communication.

In some embodiments, the received power of the first downlink beam (240) may be compared to the received power of the second downlink beam (250). For example, if the received power of the first downlink beam (240) is much lower than the received power of the second downlink beam (250), it may be determined that the first downlink beam (240) is not suitable for communication, Whereas the second downlink beam (250) is suitable for communication.

If it is determined that the first downlink beam (240) is not suitable for communication, but the second downlink beam (250) is, the UE (230) may indicate this by transmitting a first message to the BS (220), to access the BS (220). The first message may include information related to the second downlink beam (250). Such information may include, for example, measurement information related to the second downlink beam (250), an index related to the second downlink beam (250), or a measurement report related to the second downlink beam (250). A measurement report may also include information related to one or more other beams. After transmitting the first message to the BS (220), the UE (230) may start monitoring or receiving random access response messages from the BS (220) on the second downlink beam (250).

Based on the received information about the second downlink beam (250), the BS (220) may then select the second downlink beam (250) as the appropriate beam instead of the first downlink beam (240 ), and notify the UE accordingly (230). The BS (220) can also transmit subsequent downlink messages to the UE (230) by using the selected beam. That is, after receiving the Random Access Response message, the UE (230) can use it to configure for accessing the BS (220) and receive transmissions accordingly.

The new information measured in the first message may be related to one or more downlink beams measured by the UE, or other assistance information that the target BS can use to identify the UE's (230) current location and the best beam, and /or related to the offset between the assigned beam index and the best beam index. In the scenario of Figure 2, the best beam may be the second downlink beam (250), while the assigned beam index is related to the first downlink beam (240).

The transmission of the first message from the UE (230) to the BS (220) may depend on an indication as to whether the UE (230) should continue to use dedicated RACH resources even if it is found to have moved away from the first downlink beam (240) coverage area. For example, the BS (220) may instruct the UE (230) not to use dedicated RACH resources. In this case, the UE (230) can immediately start the random access procedure using CBRA, i.e., if the BS (220) finds that it has moved away from the coverage area of the first downlink beam (240), it can instruct the UE ( 230) Use CBRA. Therefore, the UE may use CBRA with the common RACH resource associated with the beam for which it is measured to be suitable (eg, the second downlink beam (250) in FIG. 2). In this case, if dedicated RACH resources associated with the first downlink beam (240) would be used, the BS (220) would not be able to receive the first message correctly anyway, since the BS would receive using beamforming.

Also, the BS (220) may instruct the UE (230) to continue using the dedicated RACH resources even if it finds that it has moved away from the coverage area of the first downlink beam (240). In this case, the UE (230) may use dedicated RACH resources to transmit random access messages for the appropriate beam (eg, the second downlink beam (250) in Figure 2). The UE may indicate in the first message eg the index of a suitable beam or some other information about a suitable beam. In some embodiments, if the UE (220) is using transmit beamforming, it may form beams according to which downlink beams it has measured to be suitable.

Figure 3 illustrates a process according to some embodiments of the invention. During or before the handover procedure, in step 310, the UE may receive a dedicated RACH configuration associated with the first downlink beam(s). Additionally, if the UE finds that it has moved away from the coverage area of the first downlink beam(s) in step 320, the UE may receive an instruction related to using a dedicated RACH configuration. In some embodiments, dedicated signaling may be used to receive instructions. However, although such instructions may be optional. In some embodiments, the UE may be configured to use a dedicated RACH configuration if the UE finds that it has moved away from the coverage area of the first downlink beam(s) by default, eg based on the UE's own capabilities. In this case, the UE may receive the information in a broadcast message such as eg in a System Information Block SIB.

Thereafter, at step 330, the UE may determine whether it is in the coverage area of the first downlink beam(s). If yes, the UE may transmit a random access RA message for the first downlink beam(s) in step 340 using the dedicated RACH configuration associated with the first downlink beam. Thereafter, the UE may start monitoring, receiving random access response messages on the first downlink beam(s).

However, if the UE determines that it is not in the coverage area of the first downlink beam(s), the process may proceed to step 350, where, for example, if the UE finds that it has moved away from the first downlink(s) The coverage area of the downlink beam, then based on the received instruction regarding the use of the dedicated RACH configuration, the UE may determine whether the dedicated RACH configuration can be used for the second downlink beam(s). If yes, then in step 360 the UE may transmit a random access message for the second downlink beam(s) using the dedicated RACH configuration. On the other hand, if it is determined that the dedicated RACH configuration may not be used for the second downlink beam(s), then in step 360, the UE may directly transmit the RA message for the second downlink beam using CBRA. Thereafter, the UE may start monitoring, receiving random access response messages on the second downlink beam(s). Once the UE has received the random access response message, it can use the information therein to receive subsequent downlink transmissions.

Figure 4 then illustrates a method according to some embodiments. In some embodiments, a UE may perform the method. As shown in Fig. 4, the method may comprise, in 410, receiving a dedicated random access channel configuration associated with at least one first downlink beam. In some embodiments, the UE may receive a dedicated random access channel configuration from the BS. In case of handover, the BS may be a source BS for handover. The at least one first downlink beam and/or the at least one second downlink beam may include one, but not all, downlink beams or sets of downlink beams of the target BS.

The method may further comprise determining at 420 that the UE is not in the coverage area of the at least one first downlink beam. Furthermore, the method may comprise determining that the UE is not in the coverage area of the at least one first downlink beam, eg by checking measurements related to the at least one first downlink beam. Alternatively or additionally, the method may comprise determining that the UE is not in the coverage area of the at least one first downlink beam by comparing received power of the at least one first downlink beam with a threshold. Likewise, the method may further comprise determining that the UE is within the coverage area of at least one second downlink beam, which may be done using the same procedure as determining that the UE is not within the coverage area of at least one first downlink beam .

In some embodiments, the method may further comprise: if or when it is determined that the apparatus is not in the coverage area of the at least one first downlink beam, i.e., the at least one first downlink beam is not suitable for communication, then Instructions are received to use a dedicated random access channel configuration configured to transmit random access messages for at least one second downlink beam.

Additionally or alternatively, the method may further comprise: if or when it is determined that the UE is not in the coverage area of the at least one first downlink beam, receiving Instructions for random access channel configuration. In other words, the method may further comprise: if or in case it is determined that the UE is not in the coverage area of the at least one first downlink beam, receiving a contention-based random Access instructions.

The method may further comprise, at step 430, transmitting a random access message for at least one second downlink beam based on determining to use a dedicated random access channel configuration associated with the at least one first downlink beam. In case of handover, the method may include receiving a dedicated random access channel configuration for at least one first downlink beam from a source base station, and transmitting a random access message to a target base station for handover.

The method may also include transmitting a random access message using a dedicated random access channel based on the received instruction. In some embodiments, the method may further comprise: following the transmission of the random access message, starting to monitor or receive a random access response message from the base station on the at least one second downlink beam. Also, the method may include receiving subsequent downlink transmissions based on information contained in the random access response message.

Alternatively or additionally, the method may comprise transmitting the random access message using contention based random access. The decision to use contention-based random access to transmit the random access message may be based on a received instruction not to use a dedicated random access channel configuration for transmission of at least one second downlink Random access messages for beams.

The random access message may include a preamble associated with the dedicated random access channel configuration and information related to the at least one second downlink beam. This information may include, for example, an index associated with the at least one second downlink beam, any other information that may be used to calculate an index associated with the at least one second beam, measurement information or new measurement report.

Figure 5 illustrates another method in accordance with certain embodiments. In some embodiments, the method may be performed by a base station. For example, in case of handover, the method can be performed by the target base station. The method may include: in 510, transmitting a dedicated random access channel configuration associated with at least one first downlink beam to a user equipment. Alternatively or additionally, the method may comprise transmitting an instruction not to use a dedicated random access channel configuration for transmitting random access messages for the at least one second downlink beam. For example, such an instruction may be given for a scenario where the user equipment may determine that the UE is not in the coverage area of the at least one first downlink beam.

In step 520, the method may include: for example, if an instruction to use a dedicated random access channel configuration has been transmitted to transmit a random access message for at least one second downlink beam, and the user equipment determines that it is not in at least In the coverage area of a first downlink beam, a random access for at least one second downlink beam is received from the user equipment on a dedicated random access channel associated with the at least one first downlink beam enter the message. Likewise, the method may further include: for example, if an instruction not to use a dedicated random access channel configuration has been transmitted to transmit a random access message for at least one second downlink beam, and the user equipment has determined that it is not in In the coverage area of the at least one first downlink beam, the random access message is received using contention-based random access.

Figure 6 illustrates a device (10) according to an embodiment of the invention. For example, the apparatus (10) may be a wireless device such as a user equipment. In other embodiments, such (10) may be, for example, a base station, an access point, a software-defined network, an SDN controller, a cloud base station controller, or a centralized base station controller.

The wireless device or user equipment may be a mobile station, an MS provided with wireless communication capabilities (such as a mobile phone or smart phone or a multimedia device), a computer provided with wireless communication capabilities (such as a tablet computer), a wireless Communication capable personal data or digital assistants PDAs, portable media players, digital cameras, camcorders, navigation units provided with wireless communication capabilities or any combination thereof. A wireless device or user device may be a sensor or smart meter or other device that may generally be configured for a single location. Additionally, the wireless device or user equipment may be a device-to-device user equipment or a device for machine type communication.

The apparatus (10) may include a processor (22) to process information and execute instructions or operations. Processor (22) may be any type of general purpose or special purpose processor. Although a single processor (22) is shown in Figure 6, multiple processors may be used according to other embodiments. As an example, the processor (22) can also include a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor DSP, a field programmable gate array FPGA, an application-specific integrated circuit (SIC, and a processor based on a multi-core processor architecture) one or more.

The apparatus (10) may also include a memory (14) coupled to the processor (22) to store information and instructions executable by the processor (22). The memory (14) may be one or more memories and may be of any type suitable for the local application environment and may use any suitable volatile or non-volatile data storage technology such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory). For example, memory (14) may include any combination of random access memory RAM, read only memory ROM, static storage devices such as magnetic or optical disks, or any other type of non-transitory machine or computer readable medium. Instructions stored in memory (14) may include program instructions or computer program code which, when executed by processor (22), enable apparatus (10) to perform the tasks described herein.

The device (10) may also include one or more antennas (not shown) to transmit signals and/or data to and/or receive signals and/or data from the device (10). The device (10) may further include a transceiver (28) that modulates information onto a carrier waveform for transmission by the antenna(s) and demodulates information received via the antenna(s) for the device The other elements of (10) are further processed. In other embodiments, the transceiver (28) may be capable of directly transmitting and receiving signals or data.

The processor (22) may perform functions associated with operation of the apparatus (10), including but not limited to precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming communication messages, formatting of information, and Overall control of the device (10), including processes related to communication resource management.

In some embodiments, memory (14) stores software modules that provide functionality when executed by processor (22). The modules may include an operating system (15) that provides operating system functionality for the device (10). The memory may also store one or more functional modules (18), such as applications or programs, to provide additional functionality to the device (10). The components of the device (10) may be implemented in hardware or as any suitable combination of hardware and software.

The described features, advantages, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

Furthermore, those of ordinary skill in the art will readily appreciate that the invention discussed above may be practiced in a different order of steps and/or with different configurations of hardware elements than that disclosed. Therefore, although the invention has been described based on these preferred embodiments, it will be apparent to those skilled in the art that certain modifications, variations and alternative constructions will be apparent while remaining within the spirit and scope of the invention of.

In an exemplary embodiment, an apparatus such as a user equipment or a base station may include components for performing the above-described embodiments and any combination thereof.

In another exemplary embodiment, an apparatus such as a user equipment or a base station may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code may be configured to communicate with the at least one processor Together the apparatus is caused to perform at least the above-described embodiments and any combination thereof.

In another exemplary embodiment, the computer program product may be configured to control the apparatus to execute the processes according to the above-mentioned embodiments and any combination thereof. A computer program product may be embodied on a non-transitory computer readable medium.

Claims (15)

1. A device for communication comprising: means for receiving a dedicated random access channel configuration associated with at least one first downlink beam; means for determining that the apparatus is not within the coverage area of the at least one first downlink beam; and means for transmitting a random access message for at least one second downlink beam based on said determining using said dedicated random access channel configuration associated with said at least one first downlink beam. 2. The apparatus of claim 1, further comprising: means for determining that the apparatus is within the coverage area of the at least one second downlink beam. 3. The apparatus of claim 1, further comprising: for receiving an instruction to use the dedicated random access channel configuration to transmit the components of the random access message for each beam. 4. The apparatus of claim 3, further comprising, means for transmitting said random access message using said dedicated random access channel based on said instruction received. 5. The apparatus according to any one of claims 1-4, wherein the random access message comprises: a preamble associated with the dedicated random access channel configuration and a link to the at least one second downlink Information about road beams. 6. The apparatus according to any one of claims 1-4, further comprising: Means for starting monitoring or receiving a random access response message from a base station on said at least one second downlink beam after said transmission of said random access message. 7. The apparatus according to any one of claims 1-4, further comprising: Means for receiving an instruction to use contention-based random access when it is determined that the apparatus is not in the coverage area of the at least one first downlink beam. 8. The apparatus according to any one of claims 1-4, further comprising: means for transmitting the random access message using contention based random access. 9. The apparatus according to any one of claims 1-4, further comprising: means for receiving said dedicated random access channel configuration for said at least one first downlink beam from a source base station; and means for transmitting said random access message to a target base station for handover. 10. The apparatus according to any of claims 1-4, wherein the random access message comprises measurement information related to the at least one second downlink beam. 11. The apparatus according to any one of claims 1-4, further comprising: means for determining that the apparatus is not in the coverage area of the at least one first downlink beam by comparing a received power of the at least one first downlink beam to a threshold. 12. An apparatus for communicating comprising: means for transmitting a dedicated random access channel configuration associated with at least one first downlink beam to a user equipment; and means for receiving a random access message for at least one second downlink beam from said user equipment on said dedicated random access channel associated with said at least one first downlink beam, The random access message is transmitted by the user equipment based on determining that the user equipment is not in the coverage area of the at least one first downlink beam. 13. The apparatus of claim 12, further comprising: means for transmitting an instruction to use said dedicated random access channel configuration when it is determined that said user equipment is not in said coverage area of at least one first downlink beam for transmitting said random access message for said at least one second downlink beam; and/or means for transmitting an instruction not to use the dedicated random access channel configuration when it is determined that the user equipment is not in the coverage area of the at least one first downlink beam, the dedicated random access A channel is configured for transmitting said random access message for said at least one second downlink beam. 14. A method of communication comprising: receiving a dedicated random access channel configuration associated with at least one first downlink beam; determining that the device is not in the coverage area of the at least one first downlink beam; and Based on said determining, a random access message for at least one second downlink beam is transmitted using said dedicated random access channel configuration associated with said at least one first downlink beam. 15. A method of communication comprising: transmitting a dedicated random access channel configuration associated with the at least one first downlink beam to the user equipment; and receiving a random access message for at least one second downlink beam from the user equipment on the dedicated random access channel associated with the at least one first downlink beam, the random access An incoming message is transmitted by the user equipment based on determining that the user equipment is not within the coverage area of the at least one first downlink beam.

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