WO2021050060A1

WO2021050060A1 - Adaptive guard period for beam switching for wireless networks

Info

Publication number: WO2021050060A1
Application number: PCT/US2019/050578
Authority: WO
Inventors: Kari Pekka Pajukoski; Karri Markus Ranta-Aho; Mark Cudak; Rapeepat Ratasuk; Arto Lehti; Oskari TERVO
Original assignee: Nokia Technologies Oy; Nokia Of America Corporation
Priority date: 2019-09-11
Filing date: 2019-09-11
Publication date: 2021-03-18

Abstract

According to an example embodiment, a method may include determining, by a base station, a beam switching time for the base station; determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

Description

Adaptive Guard Period For Beam Switching For Wireless Networks

TECHNICAL FIELD

[0001]This description relates to wireless communications.

BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3^rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments. Aspects of LTE are also continuing to improve.

[0004] 5G New Radio (NR) development is part of a continued mobile broadband evolution process to meet the requirements of 5G, similar to earlier evolution of 3G & 4G wireless networks. 5G is also targeted at the new emerging use cases in addition to mobile broadband. A goal of 5G is to provide significant improvement in wireless performance, which may include new levels of data rate, latency, reliability, and security. 5G NR may also scale to efficiently connect the massive Internet of Things (IoT) and may offer new types of mission-critical services. For example, ultra-reliable and low- latency communications (URLLC) devices may require high reliability and very low latency. SUMMARY

[0005] According to an example embodiment, a method may include: determining, by a base station, a beam switching time for the base station; determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

[0006] According to an example embodiment, an apparatus may include means for determining, by a base station, a beam switching time for the base station; means for determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; means for determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and means for adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

[0007] According to an example embodiment, an apparatus 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 configured to, with the at least one processor, cause the apparatus at least to: determine, by a base station, a beam switching time for the base station; determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; determine that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and add a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

[0008] According to an example embodiment, a non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform a method of: determining, by a base station, a beam switching time for the base station; determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

[0009] According to an example embodiment, a method may include: determining, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam; and receiving, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam.

[0010] According to an example embodiment, an apparatus may include means for determining, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam; and means for receiving, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam. [0011] According to an example embodiment, an apparatus 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 configured to, with the at least one processor, cause the apparatus at least to: determine, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam; and receive, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam.

[0012] According to an example embodiment, a non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform a method of: determining, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam; and receiving, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam.

[0013] The details of one or more examples of embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a block diagram of a wireless network according to an example embodiment.

[0015] FIG. 2 is a diagram illustrating example numerologies according to an example embodiment.

[0016] FIG. 3 is a diagram illustrating a transmitter in which a guard period may be added according to an example embodiment. [0017] FIG. 4 is a diagram illustrating a symbol in which a guard period is added as zero (or very low power) resource elements (REs) are added to either a beginning and/or end of the symbol.

[0018] FIG. 5 is a diagram illustrating a symbol in which a guard period is added as zero (or very low power) resource elements (REs) where the symbol includes known resource elements according to an example embodiment.

[0019]FIG. 6 is a diagram illustrating an added guard period according to an example embodiment.

[0020] FIG. 7 is a flow chart illustrating operation of a base station according to an example embodiment.

[0021] FIG. 8 is a flow chart illustrating operation of a user equipment according to an example embodiment.

[0022] FIG. 9 is a flow chart illustrating operation of a base station according to an example embodiment.

[0023]FIG. 9 is a block diagram of a wireless station (e.g., AP, BS, RAN node, UE or user device, or other network node) according to an example embodiment.

DETAIFED DESCRIPTION

[0024] FIG. 1 is a block diagram of a wireless network 130 according to an example embodiment. In the wireless network 130 of FIG. 1, user devices 131, 132, 133 and 135, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB), a BS, next generation Node B (gNB), a next generation enhanced Node B (ng-eNB), or a network node. The terms user device and user equipment (UE) may be used interchangeably. A BS may also include or may be referred to as a RAN (radio access network) node, and may include a portion of a BS or a portion of a RAN node, such as (e.g., such as a centralized unit (CU) and/or a distributed unit (DU) in the case of a split BS). At least part of the functionalities of a BS (e.g., access point (AP), base station (BS) or (e)Node B (eNB),

BS, RAN node) may also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices (or UEs) 131, 132, 133 and 135. Although only four user devices (or UEs) are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a SI interface or NG interface 151. This is merely one simple example of a wireless network, and others may be used.

[0025]A base station (e.g., such as BS 134) is an example of a radio access network (RAN) node within a wireless network. A BS (or a RAN node) may be or may include (or may alternatively be referred to as), e.g., an access point (AP), a gNB, an eNB, or portion thereof (such as a centralized unit (CU) and/or a distributed unit (DU) in the case of a split BS or split gNB), or other network node.

[0026] According to an illustrative example, a BS node (e.g., BS, eNB, gNB, CU/DU,

...) or a radio access network (RAN) may be part of a mobile telecommunication system. A RAN (radio access network) may include one or more BSs or RAN nodes that implement a radio access technology, e.g., to allow one or more UEs to have access to a network or core network. Thus, for example, the RAN (RAN nodes, such as BSs or gNBs) may reside between one or more user devices or UEs and a core network. According to an example embodiment, each RAN node (e.g., BS, eNB, gNB, CU/DU,

...) or BS may provide one or more wireless communication services for one or more UEs or user devices, e.g., to allow the UEs to have wireless access to a network, via the RAN node. Each RAN node or BS may perform or provide wireless communication services, e.g., such as allowing UEs or user devices to establish a wireless connection to the RAN node, and sending data to and/or receiving data from one or more of the UEs. For example, after establishing a connection to a UE, a RAN node (e.g., BS, eNB, gNB, CU/DU, ... ) may forward data to the UE that is received from a network or the core network, and/or forward data received from the UE to the network or core network.

RAN nodes (e.g., BS, eNB, gNB, CU/DU, ...) may perform a wide variety of other wireless functions or services, e.g., such as broadcasting control information (e.g., such as system information) to UEs, paging UEs when there is data to be delivered to the UE, assisting in handover of a UE between cells, scheduling of resources for uplink data transmission from the UE(s) and downlink data transmission to UE(s), sending control information to configure one or more UEs, and the like. These are a few examples of one or more functions that a RAN node or BS may perform. A base station may also be DU (Distributed Unit) part of IAB (Integrated Access and Backhaul) node (a.k.a. a relay node). DU facilitates the access link connection(s) for an IAB node.

[0027] A user device (user terminal, user equipment (UE), mobile terminal, handheld wireless device, etc.) may refer to a portable computing device that includes wireless mobile communication devices operating either with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, a vehicle, a sensor, and a multimedia device, as examples, or any other wireless device. It should be appreciated that a user device may also be (or may include) a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A user device may be also MT (Mobile Termination) part of IAB (Integrated Access and Backhaul) node (a.k.a. a relay node). MT facilitates the backhaul connection for an IAB node.

[0028] In LTE (as an illustrative example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility/handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, and other control functions or blocks. Other types of wireless networks, such as 5G (which may be referred to as New Radio (NR)) may also include a core network.

[0029] In addition, by way of illustrative example, the various example embodiments or techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types. New Radio (5G) development may support a number of different applications or a number of different data service types, such as for example: machine type communications (MTC), enhanced machine type communication (eMTC), Internet of Things (IoT), and/or narrowband IoT user devices, enhanced mobile broadband (eMBB), and ultra-reliable and low-latency communications (URLLC). Many of these new 5G (NR) - related applications may require generally higher performance than previous wireless networks.

[0030] IoT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status, and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC, or Machine to Machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without intervention of humans. Enhanced mobile broadband (eMBB) may support much higher data rates than currently available in LTE.

[0031] Ultra-reliable and low-latency communications (URLLC) is a new data service type, or new usage scenario, which may be supported for New Radio (5G) systems. This enables emerging new applications and services, such as industrial automations, autonomous driving, vehicular safety, e-health services, and so on. 3GPP targets in providing connectivity with reliability corresponding to block error rate (BLER) of 10⁵ and up to 1 ms U-Plane (user/data plane) latency, by way of illustrative example. Thus, for example, URLLC user devices/UEs may require a significantly lower block error rate than other types of user devices/UEs as well as low latency (with or without requirement for simultaneous high reliability). Thus, for example, a URLLC UE (or URLLC application on a UE) may require much shorter latency, as compared to a eMBB UE (or an eMBB application running on a UE).

[0032] The various example embodiments may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-A, 5G (New Radio (NR)), cmWave, and/or mm Wave band networks, IoT, MTC, eMTC, eMBB, URLLC, etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples.

[0033] According to an illustrative example embodiment, New Radio (NR) or 5G, and possibly other wireless networks, may use much higher frequencies than used previously. According to an illustrative example, NR Rel-15 may use or define operation for frequencies up to 52.6GHz, and possibly higher. Such high frequencies may contain large spectrum allocations and may support many high capacity use cases.

[0034] The next generation of wireless systems may operation at relatively high frequencies (e.g., such as frequencies near and/or above 52.6 GHz) may have to cope with increased path loss, larger antenna arrays, and less efficient RF (radio frequency) components like power amplifiers (PAs). The beam forming (BF) with large antenna array is one of the capabilities that may be used to compensate for large path-loss. The large bandwidths may mean that the analog to digital and digital to analog converters may use significantly more power. This may, for example, drive wireless systems towards use of analogue beamforming where beams are steered in RF (radio frequency) instead of at digital baseband.

[0035] According to an example embodiment, a wireless transmitter (e.g., at a base station (BS) or other wireless node) may be required to switch the beam between multiple UE’ s scheduled in different directions or switch between different beams to transmit different signals or symbols to the same UE if the channel conditions for the UE change. An antenna (or antenna array) may include multiple antenna elements, where a specific beam (e.g., including a beam direction and/or beam width) may be generated or obtained by applying a set of antenna weights (e.g., each antenna weight including an amplitude and phase) to the antenna array, with a different weight applied to each antenna element. The direction of the beam from a phased antenna array may be changed by adjusting the phase of the signal applied to each of the elements in the antenna array. This analog beamforming may be implemented in a number of ways, such as for example: 1) by use of analog phase shifters - devices which implement a controllable phase shift such as PIN diodes. This is probably the slowest reacting method of phase shift, such circuits have a reaction time in the 10s (tens) of ns (tens of nanoseconds), for example, and a worst case of 100ns can be considered, as an illustrative example embodiment; and/or 2) use of switched phase shifters - RF (radio frequency) switches are used to switch different transmission line delays, such circuits will react based on the RF switching time, GaAs switches react in approximately 10ns, according to an example embodiment. Thus, for example, a BS antenna array may have beam switching time, which may be a worst case beam switching time. In an example embodiment, a worst case beam switching time may be 100 ns, as an illustrative example, although other beam switching times may be used; and/or 3) use of hybrid beam forming - mixture of analogue and digital beam forming, worst case will have similar switching time to the analog part. Thus, according to an illustrative example embodiment, a worst-case beam switching time may for example be based on the analog implementation and is estimated as less than 100ns. This is merely an example and other beam switching times may be used.

[0036] According to an example embodiment, a numerology may refer to a numerical configuration, where each numerology may include different values for one or more parameters. According to an example embodiment, a numerology may be defined by or associated with a subcarrier spacing (SCS) used for a wireless system or for a transmitted signal. Thus, for example, different numerologies may have a different SCS (Af). According to an example embodiment, some wireless systems may allow different numerologies (e.g., different SCS) to be used, and which may be configured by the BS. For example, different SCS may be used for different symbols, and/or for different channels. For example, for NR or 5G, BSs and/or UEs may be required to support multiple or different numerologies (e.g., multiple or different SCS).

[0037] Table 1 indicates some example numerologies that may be used or supported, where Af is subcarrier spacing (SCS). In this example, there may be two different lengths of CP, including a normal CP and an extended CP.

[0038]

Table 1 - some example numerologies

[0039] According to an example embodiment, larger subcarrier spacing (SCS) may lead to:

[0040]· larger carrier bandwidth for a given FFT (Fast Fourier Transform) size, [0041]· reduced sensitivity to phase noise, and/or [0042] · reduced CP (cyclic prefix) length. [0043] The term cyclic prefix (CP) may, for example, refer to or may include a prefixing of a symbol, with a repetition (or copy) of a sample(s) of the end of the symbol (e.g., copying a sample(s) from the end of the symbol, and placing those sample(s), as a cyclic prefix, at the beginning of the symbol). The receiver is typically configured to discard the cyclic prefix (CP) samples, but the cyclic prefix may serve one or more purposes, such as, for example: 1) the CP may provide a guard interval to reduce or eliminate intersymbol interference from the previous symbol; 2) the CP repeats the end of the symbol so the linear convolution of a frequency-selective multipath channel can be modeled as circular convolution, which in turn may transform to the frequency domain via a discrete Fourier transform. This approach accommodates simple frequency domain processing, such as channel estimation and equalization; and/or 3) the CP may provide a guard interval or guard band (samples or portion of the symbol where no actual data is transmitted, or samples that may be discarded at the receiver, or which are duplicative, or which convey no information) so that the CP or guard interval or guard band may be discarded at the receiver) to provide sufficient time, at least in some cases, for a BS or other wireless node to perform beam switching between symbols (e.g., to provide time for the BS or node to switch or change transmit beams from a first beam to transmit to a first UE to a second beam to transmit to a second UE, or to perform beam switching between beams for transmission to the same UE, e.g., as channel conditions change for that UE).

[0044]

Table 1 - some example numerologies

[0045] According to an illustrative example embodiment, NR/5G may support BWP (bandwidth part) size of 275 PRBs (physicals resource blocks). In such an example case, a maximum BWP size according to may be 792 MHz (0.24 MHz* 12*275). This is not enough for scenarios above 52.6 GHz where channel bandwidth can be as high as 10 GHz. Additionally, phase noise and the Doppler effect in case the UE is moving will also be increased. Thus, larger SCS may be required, e.g., to tackle phase noise, and to provide larger carrier bandwidth with reasonable FFT size. This can be achieved by extending the numerology to support additional (higher) values for m . Different SCS are associated with different values for m.

[0046] FIG. 2 is a diagram illustrating example numerologies according to an example embodiment. As shown in the numerologies shown in FIG. 2, three frequency ranges are shown, e.g., including FR (Frequency range) 1 (e.g., with m = 0, 1 or 2), FR2 (with m= 1, 2 or 3) and FR3 (with m=4, 5, 6, 7 or 8). Note that for m between 0 and 5, the CP is greater than the beam switching time (e.g., maximum beam switching time), and thus offers a sufficient guard period or guard interval to allow a BS or other node to switch beams between two symbols. On the other hand, for m = 6, 7, or 8, the associated CP of 73 ns, 37 ns and 18 ns, respectively, is less than the BS beam switching time of 100 ns. Thus, in this illustrative example, it can be seen that there may be some situations, e.g., some SCS or numerologies, in which the CP associated with such SCS will be insufficient to allow beam switching to be performed within or during the CP.

[0047] Thus, according to an example embodiment, it may be useful for the BS to switch or change beams (change beam steering directions) within the CP (or other guard interval), e.g., so that downlink (DF) transmission performance will not be negatively impacted (e.g., to avoid negatively impacting downlink data rate, signal to interference plus noise ratio (SINR), or other performance characteristic) when at least a portion of a beam switching occurs outside of the CP or other guard period/guard interval. Thus, it is advantageous for the BS and other nodes to be able to perform beam switching within the CP or other guard period or guard interval of a symbol(s).

[0048] Also, according to an example embodiment, in order to prevent the DF performance degradation, the switching time should be less than a predetermined fraction (or predetermined portion), e.g., 80%, of the CP length and/or guard period. Thus, some example values of the predetermined fraction or predetermined portion of the CP length may include 65%, 70%, 75%, 80%, 85%, 90%, or 100%, of the CP length. The remaining portion of the CP and/or guard period may accommodate or provide time or room for channel spreading, for example. A guard period may include, e.g., one or more consecutive samples or resource elements within one (or more) symbols (e.g., that are not data or that may be discarded by the receiving node). However, as noted, the required increased subcarrier spacings for some higher frequencies, such as beyond 52.6 GHz may mean that the symbol and CP lengths become very short. In some cases, this may cause performance degradation because, in some cases, the CP length may be shorter than beam switching time. For example, CP length for SCSs between 960-3840kHz (see FIG. 2) may be significantly shorter than the worst-case example beam switching time of 100 ns. Thus, for example, without additional guard period, such short CPs, as compared to longer beam switching time, may cause a significant decrease in transmission performance.

[0049] According to an example embodiment, a BS may control various parameters of a wireless network, e.g., such the frame and slot timing, allocations of resources to various UEs for UL and DL transmissions. Also, a BS may determine or select a SCS for each symbol and/or each slot that will be transmitted. Also, for example, the SCS may be determined based on the carrier frequency that is used, e.g., whether within FR1, FR2 or FR3. Thus, higher carrier frequencies may typically have or be associated with greater (or higher) SCS and shorter CP lengths (e.g., see FIG. 2).

[0050] Therefore, according to an example embodiment, e,g., in a case where a beam switching time (e.g., a maximum or worst case beam switching time) exceeds (or is greater than) a predetermined fraction of the CP, a BS or other wireless node may add a guard period to one or more symbols, such that the beam switching time (e.g., maximum beam switching time of the BS or transmitting node) will not exceed a predetermined fraction (e.g., 80% or other fraction) of the sum or total length of the CP length and the added guard period.

[0051]For example, a BS may transmit a first set of one or more symbols via a first beam (e.g., to a first UE), and then perform beam switching from the first beam to a second beam, and then transmit a second set of one or more symbols via the second beam (e.g., to a second UE). Each, of one or more, of the transmitted symbols may include a cyclic prefix (CP). For example, the first symbol of the second set of one or more symbols (transmitted via the second beam) may include a CP, e.g., which may be defined based on the numerology or SCS used for transmission of the last symbol. According to an example embodiment, the BS may perform beam switching at the end of the last symbol of the first set of one or more symbols and/or at the beginning of the first symbol of the second set of one or more symbols.

[0052] According to an example embodiment, in order to avoid a decrease in DL transmission performance, the beam switching (from the first beam to the second beam) may (or should) be performed within the CP (or within the predetermined fraction of the CP) of the first symbol of the second set of one or more symbols. According to an example embodiment, if the beam switching time of the BS is greater than or exceeds the predetermined fraction (e.g., 80%) of the CP length of the CP of the first symbol of the second set of one or more symbols transmitted via the second beam, then the BS may add a guard period to one or both of the last symbol of the first set of one or more symbols (associated with the first beam) or the first symbol of the second set of one or more symbols (associated with the second beam). The BS may then perform beam switching within the CP and/or added guard period without negatively impacting transmission performance, e.g., since after adding the guard period, the beam switching period will be less than or equal to the predetermined fraction the sum or total (total period of time) of the CP length and the added guard period. Thus, by adding a sufficient guard period, the total period of the CP and added guard period will be sufficient to allow beam switching from the first beam to the second beam.

[0053] As noted, the added guard period may be added at or on or near the inter-symbol border (e.g., at an end of the last symbol of the first set of one or more symbols associated with the first beam and/or a beginning of the first symbol of the second set of one or more symbols associated with the second beam). In this manner, the combination of the CP and the added guard period (which may be contiguous with the CP) may provide sufficient time for the BS to perform beam switching.

[0054]Thus, for example, if the beam switching time (e.g., 100ns) is greater than .8*CP for the SCS (where .8 is an example predetermined fraction), then the BS may add a guard period. Hence the predetermined fraction , e.g., .8*CP may be compared to beam switching time (e.g., compared to maximum or worst case beam switching time), and a guard period may be added to one or both of the last symbol of the first set of one or more symbols or the first symbol of the second set of one or more symbols, such that the beam switching time (e.g., 100 ns) is less than or equal to .8*(CP + added guard period), e.g., in order to provide a sufficient period for the BS to perform beam switching.

[0055] According to an example embodiment, the guard period may be one full symbol(s), a fraction of symbol or an extended CP. Whether the guard period includes a full symbol(s) or a fraction of a symbol may depend on the configured subcarrier spacing (SCS). The fraction of symbol guard period may include zero power or very low power samples located at least one of (or both) at the end of the last symbol for the first beam or at the beginning of the first symbol of the next (e.g., second) transmitted beam.

[0056] A UE may determine the added guard period (e.g., which may include determining a presence, a location, and/or length of the added guard period) based on either downlink control information (DCI) received by the UE from the gNB, implicitly based on configured subcarrier spacing (e.g., there may be a specific guard period to be added for each SCS), or a guard period may exist in predefined intervals or at predetermined locations/resources (e.g., for each SCS). Thus, the UE may determine the added guard period based on, e.g., 1) receiving, by the user equipment from the base station, control information indicating the guard period added by the base station; 2) determining, by the user equipment, the guard period added by the base station based on a subcarrier spacing configured by the base station for one or more of the symbols; and/or 3) determining, by the user equipment, a predefined guard period, or the guard period provided at predefined or preconfigured locations or intervals.

[0057] According to an example embodiment, the added guard period may depend on the channel. On PDCCH (physical downlink control channel), the guard period may be implicitly tied to the configured subcarrier spacings. On PDSCH (physical downlink shared channel or data channel), the presence of the guard period may be signaled in the DCI. On SSB (synchronization signal block or synch channel), the guard period may exist in predefined intervals.

[0058] According to an example embodiment, a guard period may be added to a symbol by adding zero power (or low power) resource elements (REs), either at the beginning of the symbol (zero head REs) or at the end or tail of a symbol (zero tail REs). Or, a guard period may be added to a symbol by adding known REs or by repeating data resource elements. Or, the guard period, when added as a further or extended CP, may be added by CP block 318 (see FIG. 3). Thus, in an example embodiment, a guard period may be added by adding zero Res or known REs, either at the beginning of symbol or end of symbol) based on the fraction of symbol may be applicable for single carrier (SC) symbols, while extended CP added by CP block 318 or symbol level guards may be applied to symbols for both SC symbols and multicarrier (e.g., cyclic prefix Orthogonal frequency division multiplexed (CP-OFDM)).

[0059] FIG. 3 is a diagram illustrating a transmitter in which a guard period may be added according to an example embodiment. FIG. 4 is a diagram illustrating a symbol in which a guard period is added as zero (or very low power) resource elements (REs) are added to either a beginning and/or end of the symbol. With reference to FIG. 3, a Discrete Fourier Transform (DFT) block 312, with a DFT of size Ns, may receive inputs as data REs (d), zero (or very low power) REs (0), and/or known REs (k), where a cyclic prefix Res or samples are an example of a known (k) REs or input to the DFT block 312. The transmitter of FIG. 3 also includes an Inverse Discrete Fourier Transform (IDFT) which performs an inverse DFT on the outputs from the DFT block 312 to output samples. A parallel to serial block 316 performs a parallel to serial conversion on received inputs. A CP (cyclic prefix) block 318 may add a cyclic prefix to a beginning of the symbol. As noted, a guard period may also be added (for example, to provide additional period for beam switching), e.g., to one or more symbols, if the CP is not sufficient. As shown in FIG. 4, the symbol may include Ns resource elements (REs).

The Ns resource elements (REs) may include N_D data REs. Also, the symbol may include a guard period of one or more zero REs, e.g., including N_H zero head REs located at the beginning of the symbol, and/or NT zero tail REs located at the end of the symbol. Thus, a guard period (e.g., as zero REs or known REs) may be added to a symbol.

[0060] FIG. 5 is a diagram illustrating a symbol in which a guard period is added as zero (or very low power) resource elements (REs) or known resource elements. For example, as shown in FIG. 5, may include N_D data REs, and N_K known (k). If the CP is not sufficient, then a guard period may be added, as noted herein. Thus, for example, the symbol may include N_K, and Nz zero REs that may be added at the beginning of the symbol (e.g., zero head REs) and/or at the end of the symbol (e.g., zero tail REs). Also, as part of the added guard period, some known REs may be added to the end of the symbol. A known RE is a RE that is a known value or RE. Thus, in the example shown in FIG. 5, N_K RES plus an added guard period of Nz zero REs may provide sufficient time for beam switching. Or, a guard period may be added to the beginning and/or the end of the symbol that may include one or more guard REs, such as, e.g., one or more zero REs, known (k) REs, and/or repeated data REs. As noted, the zero REs may include zero power or very low power REs. Known REs may be a RE that is a known value or known RE. And, a repeated data RE may include, for example, a copy of a known data RE, e.g., a copy of which may be provided as a guard RE or part of the added guard period.

[0061] An amount (or number) of zero REs, known REs and/or repeated data REs to be added as the added guard period can be defined based on relations (or a relationship) between beam switching time, cyclic prefix length and symbol length. An amount of guard REs added may be zero if beam switching time is less than predefined fraction (e.g., 80%, or other fraction value) of cyclic prefix length. Depending on the beam switching time, an amount of guard REs (e.g., either zero REs, known REs and/or repeated data REs) may, for example, occupy, e.g., up to 50% of the DFT size of DFT block 312. According to an illustrative example embodiment, a number of added guard REs may be ¼, or ½ (as illustrative examples) of the REs of a symbol. The guard REs may be located either/both at the end of the last symbol (guard tail REs) in the previous beam or at the beginning of the first symbol (guard head REs) in the next beam. Both guard head REs and guard tail REs may exist with symbol wise beam switching. Note that DFT block 312 may be implemented as a Fast Fourier Transform (FFT) block, and IDFT block 314 may be implemented as an Inverse FFT block.

[0062] Thus, after IDFT block 314, there may be 1 symbol, with (or including) a group of guard samples.

[0063] Also, the guard period may be added to symbols with CP-less waveforms wherein CP is replaced with an internal guard interval prior to DFT that include zero power (or very low power) REs.

[0064] FIG. 6 is a diagram illustrating an added guard period according to an example embodiment. FIG. 6 is a sample level (e.g., showing samples after output from IDFT/IFFT block 314). As shown in FIG. 6, two symbols are shown, including a last symbol (612) of beam 1, and a first symbol (620) of beam 2. Symbols 612 and 620 are adjacent to each other, with symbol 620 transmitted immediately after symbol 612. As noted, symbol 612 may be a last symbol of a first set of one or more symbols transmitted via beam 1 , while symbol 620 may be a first symbol of a second set of one or more symbols transmitted via beam 2. The first symbol 620 of beam 2 may include a cyclic prefix (CP) 624. The BS may determine that the beam switching time may be greater than a predetermined fraction (e.g., .8) of the CP 624. Thus, to provide additional time for the BS to perform beam switching from beam 1 to beam 2, the BS may add a guard period 630, e.g., which may include guard samples 614 that are added to an end of last symbol 612, and/or guard samples 622 added to first symbol 620. As noted, REs are input to DFT block 312, while samples are output from IDFT block 314.

[0065] Example 1. FIG. 7 is a flow chart illustrating operation of a base station (BS) according to an example embodiment. Operation 710 includes determining, by a base station, a beam switching time for the base station. Operation 720 includes determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols. Operation 730 includes determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length. And, operation 740 includes adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

[0066]Example 2. The method of example 1 wherein the adding comprises: adding a guard period to at least one of a last symbol associated with the first beam and/or a first symbol associated with the second beam, such that the beam switching time for the base station will not exceed the predetermined fraction of the guard period plus cyclic prefix length

[0067]Example 3. The method of any of examples 1-2, wherein the adding comprises: adding, by the base station based on at least the beam switching time and the predetermined fraction of the cyclic prefix length, a guard period to at least one of the last symbol associated with the first beam and/or the first symbol associated with the second beam, to provide additional time for beam switching between transmission of the last symbol and transmission of the first symbol.

[0068] Example 4. The method of any of examples 1-3 further comprising: transmitting the last symbol via the first beam; performing, by the base station beam switching from the first beam to the second beam within the cyclic prefix and/or the guard period; and transmitting, by the base station, the first symbol via the second beam.

[0069]Example 5. The method of any of examples 1-4, wherein the adding comprises: adding guard period at an end of the last symbol associated with the first beam or after transmission of the last symbol via the first beam.

[0070]Example 6. The method of any of examples 1-5, wherein the adding comprises: adding guard period at a beginning of the first symbol or before transmission of the first symbol via the second beam.

[0071]Example 7. The method of any of examples 1-6, wherein the adding comprises: adding cyclic prefix or an extended cyclic prefix to the second symbol or before transmission of the second symbol.

[0072] Example 8. The method of any of examples 1-7, wherein the adding comprises: adding one or more guard resource elements, including one or more zero power resource elements or low power resource elements, one or more known resource elements, and/or one or more repeating data resource elements to at least one of the last symbol and/or the first symbol.

[0073]Example 9. The method of example 8, wherein the adding a number of guard resource elements is based on the beam switching time, the cyclic prefix length, and a symbol length.

[0074]Example 10. The method of any examples 1-9, wherein the adding comprises at least one of: adding one or more zero power resource elements or low power resource elements at an end of the last symbol associated with the first beam; or adding one or more zero power resource elements or low power resource elements at a beginning of the first symbol associated with the second beam.

[0075] Example 11. The method of any of examples 1-10 wherein the guard period comprises at least one of the following: a fraction of a symbol; or a full symbol. [0076] Example 12. The method of any of examples 1-11 wherein the beam switching time is a maximum beam switching time for the base station.

[0077]Example 13. The method of any of examples 1-12, wherein the determining, by the base station, of a predetermined fraction of a cyclic prefix length comprises: determining a cyclic prefix length based on a subcarrier spacing or numerology to be used for transmission by the base station; and determining the predetermined fraction or portion.

[0078] Example 14. An apparatus comprising means for performing the method of any of examples 1-13.

[0079] Example 15. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform the method of any of examples 1-13.

[0080] Example 16. An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform the method of any of examples 1-13.

[0081] Example 17. FIG. 8 is a flow chart illustrating operation of a user equipment according to an example embodiment. Operation 810 includes determining, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam. And, operation 820 includes receiving, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam.

[0082]Example 18. The method of example 17, wherein the determining comprises at least one of the following: receiving, by the user equipment from the base station, control information indicating the guard period added by the base station; determining, by the user equipment, the guard period added by the base station based on a subcarrier spacing configured by the base station for one or more of the symbols; and/or determining, by the user equipment, a predefined guard period, or the guard period provided at predefined or preconfigured locations or intervals.

[0083]Example 19. The method of any of examples 17-18, wherein at least the first symbol associated with the second beam includes a cyclic prefix that has a cyclic prefix length based on a subcarrier spacing for one or more of the symbols, wherein the determining a guard period comprises: determining, the user equipment, the guard period added by the base station, such that a beam switching time for the base station will not exceed a predetermined fraction of both of or sum of the cyclic prefix length of the first symbol associated with the second beam and the added guard beam.

[0084]Example 20. The method of any of examples 17-19, wherein the added guard period provides additional time for the base station to perform beam switching between transmission of the last symbol and transmission of the first symbol.

[0085] Example 21. The method of any of examples 17-20, wherein the added guard period is provided at an end of the last symbol associated with the first beam or after transmission of the last symbol via the first beam.

[0086] Example 22. The method of any of examples 17-21, wherein the added guard period is provided at a beginning of the first symbol or before transmission of the first symbol via the second beam.

[0087] Example 23. The method of any of examples 17-22, wherein the guard period comprises: a cyclic prefix or an extended cyclic prefix added to the second symbol or before transmission of the second symbol.

[0088] Example 24. The method of any of examples 17-23, wherein the guard period comprises at least one of: one or more zero power resource elements or low power resource elements added at an end of the last symbol associated with the first beam; or one or more zero power resource elements or low power resource elements added at a beginning of the first symbol associated with the second beam.

[0089] Example 25. The method of example 24, wherein the number of zero power resource elements or low power resource elements added to at least one of the last symbol and/or the first symbol is based on, or may be determined from, a beam switching time of the base station, the cyclic prefix length, and a symbol length for one or more of the symbols.

[0090] Example 26. The method of any of examples 17-25 wherein the guard period comprises at least one of the following: a fraction of a symbol; or a full symbol.

[0091]Example 27. The method of any of examples 17-26 wherein the beam switching time is a maximum beam switching time (e.g., a maximum beam switching time of the base station (BS).

[0092]Example 28. The method of any of examples 17-27, wherein the added guard period comprises: one or more guard resource elements, including one or more zero power resource elements or low power resource elements, one or more known resource elements, and/or one or more repeating data resource elements.

[0093] Example 29. An apparatus comprising means for performing the method of any of examples 17-28.

[0094] Example 30. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform the method of any of examples 17-28.

[0095] Example 31. An apparatus comprising: at least one processor; and

[0096] at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform the method of any of examples 17-28.

[0097] FIG. 9 is a block diagram of a wireless station (e.g., AP, BS or user device/UE, or other network node) 1000 according to an example embodiment. The wireless station 1000 may include, for example, one or more (e.g., two as shown in FIG. 9) RF (radio frequency) or wireless transceivers 1002 A, 1002B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) 1004 to execute instructions or software and control transmission and receptions of signals, and a memory 1006 to store data and/or instructions.

[0098] Processor 1004 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 1004, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 1002 (1002A or 1002B). Processor 1004 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 1002, for example). Processor 1004 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 1004 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor 1004 and transceiver 1002 together may be considered as a wireless transmitter/receiver system, for example.

[0099]In addition, referring to FIG. 9, a controller (or processor) 1008 may execute software and instructions, and may provide overall control for the station 1000, and may provide control for other systems not shown in FIG. 9, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station 1000, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

[00100] In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 1004, or other controller or processor, performing one or more of the functions or tasks described above.

[00101] According to another example embodiment, RF or wireless transceiver(s) 1002A/1002B may receive signals or data and/or transmit or send signals or data. Processor 1004 (and possibly transceivers 1002A/1002B) may control the RF or wireless transceiver 1002A or 1002B to receive, send, broadcast or transmit signals or data.

[00102] The embodiments are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems. Another example of a suitable communications system is the 5G system. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

[00103] It should be appreciated that future networks will most probably utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

[00104] Embodiments of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Embodiments may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Embodiments may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Embodiments of the various techniques may also include embodiments provided via transitory signals or media, and/or programs and/or software embodiments that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, embodiments may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

[00105] The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

[00106] Furthermore, embodiments of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the embodiment and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,...) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various embodiments of techniques described herein may be provided via one or more of these technologies.

[00107] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[00108] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[00109] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data.

Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[00110] To provide for interaction with a user, embodiments may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[00111] Embodiments may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an embodiment, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.

[00112] While certain features of the described embodiments have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the various embodiments.

Claims

WHAT IS CLAIMED IS:

1. A method comprising: determining, by a base station, a beam switching time for the base station; determining, by the base station, a predetermined fraction of a cyclic prefix length of a cyclic prefix to be used by the base station for transmission of one or more symbols; determining that the beam switching time for the base station exceeds the predetermined fraction of the cyclic prefix length; and adding a guard period to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is transmitted after and adjacent to the last symbol associated with the first beam.

2. The method of claim 1 wherein the adding comprises: adding a guard period to at least one of a last symbol associated with the first beam and/or a first symbol associated with the second beam, such that the beam switching time for the base station will not exceed the predetermined fraction of the guard period plus cyclic prefix length

3. The method of any of claims 1-2, wherein the adding comprises: adding, by the base station based on at least the beam switching time and the predetermined fraction of the cyclic prefix length, a guard period to at least one of the last symbol associated with the first beam and/or the first symbol associated with the second beam, to provide additional time for beam switching between transmission of the last symbol and transmission of the first symbol.

4. The method of any of claims 1-3 further comprising: transmitting the last symbol via the first beam; performing, by the base station beam switching from the first beam to the second beam within the cyclic prefix and/or the guard period; and transmitting, by the base station, the first symbol via the second beam.

5. The method of any of claims 1-4, wherein the adding comprises: adding guard period at an end of the last symbol associated with the first beam or after transmission of the last symbol via the first beam.

6. The method of any of claims 1-5, wherein the adding comprises: adding guard period at a beginning of the first symbol or before transmission of the first symbol via the second beam.

7. The method of any of claims 1-6, wherein the adding comprises: adding cyclic prefix or an extended cyclic prefix to the second symbol or before transmission of the second symbol.

8. The method of any of claims 1-7, wherein the adding comprises: adding one or more guard resource elements, including one or more zero power resource elements or low power resource elements, one or more known resource elements, and/or one or more repeating data resource elements to at least one of the last symbol and/or the first symbol.

9. The method of claim 8, wherein the adding a number of guard resource elements is based on the beam switching time, the cyclic prefix length, and a symbol length.

10. The method of any of claims 1-9, wherein the adding comprises at least one of: adding one or more zero power resource elements or low power resource elements at an end of the last symbol associated with the first beam; or adding one or more zero power resource elements or low power resource elements at a beginning of the first symbol associated with the second beam.

11. The method of any of claims 1-10, wherein the guard period comprises at least one of the following: a fraction of a symbol; or a full symbol.

12. The method of any of claims 1-11, wherein the beam switching time is a maximum beam switching time.

13. The method of any of claims 1-12, wherein the determining, by the base station, of a predetermined fraction of a cyclic prefix length comprises: determining a cyclic prefix length based on a subcarrier spacing or numerology to be used for transmission by the base station; and determining the predetermined fraction or portion.

14. An apparatus comprising means for performing the method of any of claims 1-13.

15. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform the method of any of claims 1-13.

16. An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform the method of any of claims 1 - 13.

17. A method comprising: determining, by a user equipment, a guard period added by a base station to at least one of a last symbol, of a first set of one or more symbols, associated with a first beam and/or a first symbol, of a second set of one or more symbols, associated with a second beam, wherein the first symbol associated with the second beam is after and adjacent to the last symbol associated with the first beam; and receiving, by the user equipment from the base station, at least one of the last symbol associated with the first beam or the first symbol associated with the second beam.

18. The method of claim 17, wherein the determining comprises at least one of the following: receiving, by the user equipment from the base station, control information indicating the guard period added by the base station; determining, by the user equipment, the guard period added by the base station based on a subcarrier spacing configured by the base station for one or more of the symbols; and/or determining, by the user equipment, a predefined guard period, or the guard period provided at predefined or preconfigured locations or intervals.

19. The method of any of claims 17-18, wherein at least the first symbol associated with the second beam includes a cyclic prefix that has a cyclic prefix length based on a subcarrier spacing for one or more of the symbols, wherein the determining a guard period comprises: determining, the user equipment, the guard period added by the base station, such that a beam switching time for the base station will not exceed a predetermined fraction of both of or sum of the cyclic prefix length of the first symbol associated with the second beam and the added guard beam.

20. The method of any of claims 17-19, wherein the added guard period provides additional time for the base station to perform beam switching between transmission of the last symbol and transmission of the first symbol.

21. The method of any of claims 17-20, wherein the added guard period is provided at an end of the last symbol associated with the first beam or after transmission of the last symbol via the first beam.

22. The method of any of claims 17-21, wherein the added guard period is provided at a beginning of the first symbol or before transmission of the first symbol via the second beam.

23. The method of any of claims 17-22, wherein the guard period comprises: a cyclic prefix or an extended cyclic prefix added to the second symbol or before transmission of the second symbol.

24. The method of any of claims 17-23, wherein the guard period comprises at least one of: one or more zero power resource elements or low power resource elements added at an end of the last symbol associated with the first beam; or one or more zero power resource elements or low power resource elements added at a beginning of the first symbol associated with the second beam.

25. The method of claim 24, wherein the number of zero power resource elements or low power resource elements added to at least one of the last symbol and/or the first symbol is based on, or may be determined from, a beam switching time of the base station, the cyclic prefix length, and a symbol length for one or more of the symbols.

26. The method of any of claims 17-25, wherein the guard period comprises at least one of the following: a fraction of a symbol; or a full symbol.

27. The method of any of claims 17-26, wherein the beam switching time is a maximum beam switching time.

28. The method of any of claims 17-27, wherein the added guard period comprises: one or more guard resource elements, including one or more zero power resource elements or low power resource elements, one or more known resource elements, and/or one or more repeating data resource elements.

29. An apparatus comprising means for performing the method of any of claims 17-28.

30. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform the method of any of claims 17-28.

31. An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform the method of any of claims 17-28.