CN112314041B

CN112314041B - Transmission resource sharing

Info

Publication number: CN112314041B
Application number: CN201980037481.4A
Authority: CN
Inventors: 乌莫·萨利姆; 维吉尔·加西亚; 布鲁诺·杰裘克斯
Original assignee: JRD Communication Shenzhen Ltd
Current assignee: JRD Communication Shenzhen Ltd
Priority date: 2018-08-09
Filing date: 2019-08-06
Publication date: 2024-06-11
Anticipated expiration: 2039-08-06
Also published as: GB201812954D0; WO2020029977A1; GB2576198B; CN112314041A; GB2576198A

Abstract

A method for sharing resource utilization information between base stations to facilitate resource sharing. When the first base station acquires the access of transmission resources, the first base station transmits the indication of the resources to the adjacent base station. These neighboring base stations may share resources if they do not collide with other devices.

Description

Transmission resource sharing

Technical Field

The present application relates to the field of transmission resource sharing in cellular wireless networks, and more particularly to unlicensed transmission resource sharing between base stations of a cellular wireless network.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and technologies, are well known. Such 3G standards and techniques are established by the third generation partnership project (3 GPP). Third generation wireless communications are commonly used to support macrocell mobile telephone communications and continue to evolve. Communication systems and networks have evolved to broadband and mobile systems.

In cellular wireless communication systems, user Equipment (UE) is connected to a Radio Access Network (RAN) via a radio link. The RAN comprises a set of base stations and an interface to a Core Network (CN). The base station provides a radio link for UEs located in a cell covered by the base station. The CN provides overall network control. It is readily understood that the RAN and CN each perform functions related to the overall network. For convenience, the term "cellular network" will be used in this disclosure to refer to the combination of RAN and CN. It is to be understood that the terminology is used to refer to the respective systems performing the disclosed functions.

The 3GPP has developed a so-called Long Term Evolution (LTE) system, i.e. an evolved universal mobile telecommunications system territory radio access network (E-UTRAN). The LTE is used to implement a mobile access network in which one or more macro cells are supported by a base station called an eNodeB or eNB (evolved NodeB). Recently, LTE is further evolving towards so-called 5G or NR (new radio) systems, where one or more cells are supported by a base station called a gNB. NR intends to employ an Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

The NR protocol is intended to provide the option of operating in the unlicensed radio frequency range, the so-called NR-U. While operating in the unlicensed radio band, the gNB and UE must compete for physical medium/resource access with other devices. For example, wi-Fi, NR-U, and LAA may utilize the same physical resources.

To share resources, a Listen Before Talk (LBT) protocol is proposed. Wherein the gNB or UE monitors the available resources and starts transmission only if there is no collision with another device that has already used the resources. Once the LBT procedure is successful (the resource is "won"), the gNB or UE gains access to the resource, up to a Maximum Channel Occupancy Time (MCOT), provided that there is no interruption of transmission beyond a predefined time interval (e.g., 16 s).

Transmissions in the unlicensed spectrum must adhere to various current regulations for that spectrum. For example, many regulations specify an Occupied Channel Bandwidth (OCB) and a Nominal Channel Bandwidth (NCB) that must be complied with. NCB defines the widest frequency band allocated to a channel, including guard bands. While OCB defines a bandwidth that contains a specified fraction (typically 99%) of the signal power. OCB must typically be between 80% and 100% of NCB. For example, ETSI EN 301.893 defines the requirements of the european union for the 5GHZ band.

LBT procedures are effective for sharing transmission of unauthorized resources, thus allowing various devices to use these resources. Regulations and other transmission restrictions for fair use vary from country to country. Frequency reuse of unlicensed resources is not straightforward, as the resources do not essentially belong to the ownership of a device, group of devices, or an operator. Thus, clear channel access procedures for agreed upon specific areas must be used to gain access and ownership of the transmission. This may result in difficulty in achieving high frequency reuse of unlicensed resources even though a base station of a cellular operator is able to access the resources in one area. For example, multiple Wi-Fi stations have no coordination, so transmissions must be coordinated through an LBT procedure to avoid interference, provided only one station can use the resources at a time. In contrast, cellular systems have evolved to share resources with a frequency reuse factor of 1. However, in the conventional LBT procedure, one cellular base station gains access to and transmits on resources, and may block many neighboring base stations even without other devices.

As the technology of managing interference is mature, base stations with overlapping transmission areas of the same cellular network (same operator) can operate in the same frequency band. Thus, the application of conventional LBT procedures to cellular systems may result in inefficient use of transmission resources.

Thus, there is a need for improved LBT procedures for cellular systems.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the application, nor is it intended to be used to identify the scope of the application.

The present application provides a resource sharing method in a cellular communication system, the method being performed by a first base station and comprising: obtaining access to transmission resources of a prescribed transmission interval; and transmitting an indication of the transmission resources accessed by the first base station to a second base station of the cellular communication system.

The transmission resource is an unlicensed spectrum resource.

The access to the transmission resources by the first base station is obtained by a listen-before-talk procedure.

The indication includes scheduling resources from the first base station.

The indication of the transmission resources is given in the form of physical resource blocks.

The indication comprises a bitmap; wherein each bit relates to one of said physical resource blocks.

The method also includes transmitting an indication of transmission power used by the first base station for the transmission resource.

The method further includes transmitting an indication of the prescribed transmission interval.

The method further comprises transmitting an indication of the end of the prescribed transmission interval.

The method also includes transmitting an indication of the transmission resources obtained by the first base station.

The indication of the transmission resource comprises an indication of a carrier index of the transmission resource.

The present application also provides a resource sharing method in a cellular communication system, the method being performed by a second base station, comprising: receiving an indication of transmission resources obtained by a first base station; sensing the transmission power received by the second base station; comparing the sensed transmission power with an indication of the transmission resource; and initiating transmission of the second base station if the comparison result shows that the sensed transmission power is from the first base station only.

The transmission resource is an unlicensed spectrum resource.

The indication includes scheduling resources from the first base station.

The method also includes receiving an indication of transmission power used by the transmission resource by the first base station.

The method also includes estimating a path loss between the first base station and the second base station.

The method also includes receiving an indication of a prescribed transmission interval.

The method further includes receiving an indication of an end of the prescribed transmission interval.

The method also includes receiving an indication of the transmission resources obtained by the first base station.

The method also includes transmitting the received indication to a third base station.

The method further comprises indicating an identity of the base station receiving the indication.

And if the first base station stops transmitting the indicated transmission resource, the second base station stops transmitting the transmission resource.

The comparing the sensed transmission power with the indication of the transmission resource comprises: the method further includes comparing energy received in transmission resources indicated as being utilized by the first base station with a first threshold and comparing energy received in transmission resources indicated as not being utilized by the first base station with a second threshold.

The first threshold is higher than the second threshold.

The comparing the sensed transmission power with the indication of the transmission resource is performed between an indicated physical resource block and the sensed transmission power in the physical resource block.

If the sensed physical resource blocks are a subset of the indicated physical resource blocks, determining that the sensed transmission power is from only the first base station.

The application also provides a base station for the method.

The non-transitory computer readable medium may include at least one of the group of: hard disks, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory.

Drawings

The details, aspects and embodiments of the application will be described, by way of example only, with reference to the accompanying drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the various figures to facilitate understanding

Fig. 1 is a schematic diagram of a typical cellular network.

Fig. 2 is a schematic diagram of a pair of base stations that may be used to share resources.

FIG. 3 is a flow chart of a method of resource sharing.

Fig. 4 is a schematic diagram of three base stations that may be used to share resources.

FIG. 5 is a flow chart of a method of resource sharing.

Fig. 6 is a schematic diagram of a set of cells for simulation.

Fig. 7 is a schematic diagram of simulation results.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative scenarios.

The application discloses an improved mechanism, which aims to realize more effective sharing of transmission resources among related base stations.

Fig. 1 is a schematic diagram of three base stations (e.g., enbs or gnbs, depending on the particular cellular standard and terminology) making up a cellular network. Typically, each base station will be deployed by one cellular network operator, providing geographic coverage for UEs in that region. These base stations form a Radio Area Network (RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected by an X2 structure and connected to the core network by an S1 interface. As will be appreciated, only basic details are shown here in order to illustrate the main features of the cellular network.

Each base station includes hardware and software implementing RAN functions. The functions include communication with the core network and other base stations, transmission of control and data signals between the core network and the UE, and maintaining wireless communication of the UE with respect to each base station. The core network includes hardware and software that implement network functions. Including overall network management and control, and routing of calls and data.

Fig. 2 is a schematic diagram of 2 base stations 20 and 21. The base stations 20 and 21 serve areas 22 and 23, respectively. However, the base station 20 is transmitted farther from the service area 22, as indicated by the ring 24. If these base stations use unlicensed resources and base station 20 is transmitting, then base station 21 will monitor for transmissions from base station 20 and be prevented from transmitting when it performs an LBT procedure, as it appears that a device has taken up transmission resources. In reality, however, since these transmissions come from base stations of the same cellular network, the communication between the base station 21 and the UE connected to the base station 21 may enable resource sharing. Most modern cellular systems, like 3G WCDMA, 4G LTE, LTE-a, and the originally released 5G NR, have a designed frequency reuse factor of 1, which means that they use the same frequency resources for transmission in all base stations.

As shown in fig. 1, the base stations of the cellular network are interconnected, and data communication between them can be performed with the core network through an X2 interface or through an S1 interface. These interfaces may be utilized to share information about the amount of resource utilization between base stations in order to more efficiently share unauthorized resources.

Fig. 3 illustrates a collaboration of resource sharing. When a base station performs an LBT procedure and gains access to transmission resources, it has access to use those resources for a Maximum Channel Occupancy Time (MCOT). The base station (e.g., base station 20) gains access to the transmission resources at step 30 and may indicate its access to the neighboring base station via the X2/S1 interface or other suitable communication mechanism at step 31. For example, messages may be transmitted wirelessly over a shared spectrum. Specific time and/or frequency resources may be agreed upon on which resource utilization information is broadcast so that neighboring base stations may listen to, accept information when it may be useful to them. For example, techniques similar to transmitting DRS or SRBs on a particular portion of a carrier may be utilized. However, this solution makes use of transmission resources and thus may reduce access to the streaming transmission resources. Another way to share this information may be through other licensed carriers if the base stations are also using licensed carriers.

For convenience of explanation, the present application names a base station that obtains an unlicensed transmission resource as an originating base station, and names a base station that receives the indication as a receiving base station.

The receiving base station (e.g., base station 21) receives the indication at step 32 and thus learns of the signal that may be detected when executing its own LBT procedure at step 33. The results of this LBT procedure may be validated with details received from other base stations at step 34. If there is a correlation (as described in detail below), the base station may determine that transmission resources are available and continue transmission at step 35. If the LBT result and the received details are not correlated (as described in detail below), the base station may conclude that the detected transmission is from a different resource and thus decide at step 36 that the transmission resource cannot be utilized.

Therefore, according to the method shown in fig. 3, the base station can share detailed information of the transmission resources it is using after a successful LBT procedure, thereby sharing with other base stations of the cellular network using the existing resource sharing technology and improving the utilization of resources.

The indication of resource utilization information may include various information items to assist other base stations in associating their LBT results with the information and to allow efficient utilization of resources. When the unlicensed resource has a wide bandwidth and consists of many channels or carriers, the initiating base station may transmit a carrier index in the indication so that neighboring base stations can identify the carrier that the initiating base station obtained access to. To help facilitate frequency reuse of channels/carriers, an initiating base station may transmit information of narrowband frequency resources that it transmits within the carrier bandwidth. The narrowband frequency resources may be in the form of a set of Physical Resource Blocks (PRBs), the size of which may be selected to make the indication meaningful. Specifically, a group of size 1 may be selected, meaning that the initiating base station transmits utilization information for each individual PRB. In principle any indication may be utilized that allows the receiving base station to determine the channel details. This enables the receiving base station to determine whether the detected signal is from the initiating base station. For example, if the receiving base station detects power over a wide range of frequency resources, but the initiating base station only indicates that a subset of those resources are utilized, it will be determined that the detected transmission is from another device (e.g., wi-Fi device).

The initiating base station may also share other relevant parameters such as the Contention Window Size (CWS), MCOT, and the remaining time of the current transmission opportunity (TxOP) used by the initiating base station. The latter value may be important because if the receiving base station decides to also utilize the resources guaranteed by the initiating base station, these resources should only be utilized until the end of the MCOT, according to the provision at the time the initiating base station gets access. Both the initiating and receiving base stations must stop transmitting after this period of time and perform a new LBT procedure as specified with appropriate gaps and rollbacks to acquire unauthorized resources. If each receiving base station starts a new MCOT when starting transmission, a very long continuous occupation time may occur between base stations of the same operator, prohibiting other devices from accessing the transmission resources. However, the initiating base station may have gained access before the receiving base station receives the indication, so within the MCOT value of the initiating base station, the receiving base station does not know when the TxOP ends. Thus, each receiving base station sharing a TxOP obtained by the initiating base station must be made aware of when the current TxOP ends.

For the case where the initiating base station plans to use the resources for a shorter time than its MCOT, from a regulatory point of view, the neighboring base stations sharing the resources may continue to use the resources until the initiating base station MCOT expires, treating each base station as part of a group. In this case, a mechanism for correctly updating the sensing-related parameters after TxOP must be ensured. And in view of fairness, the initiating base station should not have the right to perform LBT again if its initiated TxOP is still activated by the neighboring base station. The time when the neighboring base station stops using resources should not be later than the originating base station in general from the point of view of system control, signaling and fairness, even before the TxOP ends.

As described above, details of transmission access may be shared with neighboring base stations. Depending on the particular network configuration, it may be flexible to define which base stations qualify as neighboring base stations. For example, in some cases, which may be dense small cells, information may be shared among a wider range of receiving base stations. In other cases, the neighboring base stations may be only those base stations that share a boundary with the initiating base station. In another example, the neighboring base stations may be those base stations that have a handoff relationship with the initiating base station.

In addition to more broadly defining neighboring base stations, the receiving base station may retransmit the utilization information to other base stations to achieve a broad sharing of resources. This may be particularly useful for deploying dense small cells. However, the propagation of information should be limited to only those base stations that are expected to detect the initiating base station transmission, to ensure that the transmissions detected during LBT are those in the indication, rather than coincidentally the same other transmissions. For example, the receiving base station may be allowed to share information only if the information is received directly from the initiating base station (i.e., to limit propagation between base stations to two "hops"). To implement the above scheme, the initiating base station may include its identity in the information, or each base station may indicate whether the information is original or retransmitted. For example, a flag may be included to indicate whether the message is from an initiating base station. Additional flexibility may be achieved by limiting the number of possible retransmissions to a specific number and tracking the number of retransmissions in each message.

If a base station resends a message, the base station should ensure that the details remain up to date. For example, if the remaining time of the TxOP is included in the message, an update should be made to ensure that all receiving base stations know the absolute expiration time.

To avoid the need to update the remaining time, the end of the TxOP may be designated as an absolute time, provided that all relevant base stations have the same reference time (e.g., the actual absolute time, or a common reference time). This may be due to the fact that in the main example all base stations belong to the same cellular network.

As described above, when the receiving base station receives the utilization information, the LBT procedure should be performed. In some cases, the receiving base station may begin transmitting directly without performing the LBT procedure. However, this is based on the assumption that no other devices within range of the receiving base station use the same resources. As shown in fig. 4, the case is not necessarily: because the first base station may use resources, the second base station may also use resources.

As shown in fig. 2, base station 40 provides coverage for area 42 and base station 41 provides coverage for area 43. Base station 41 may detect transmissions of base station 40 that extend into region 44. In one example case, the UE 45 connects to the base station 40 using unlicensed resources. The base station 40 sends an indication of its use to the base station 41 as described above.

A device 46, such as a Wi-Fi device having a coverage area 47, is located within the coverage area of base station 41 but outside the range of base station 40. If base station 41 takes action only in accordance with the instructions from base station 40, its transmissions will collide with device 46. Instead, the base station 48 does not have any other equipment within its coverage area 49 and therefore will be free to transmit based on information from the initiating base station 40 without any further inspection. However, this is not known until the inspection is performed.

The basic LBT procedure performed by base station 41 cannot help to resolve whether base station 41 is free to transmit because it does not distinguish between signals of base station 40 and device 46.

As described above, this difficulty may be overcome if the indication from the base station 40 includes details of the resources being utilized, and the details may be associated with the signals sensed by the base station 41. The base station 41 must also perform detailed sensing procedures to determine the power distribution in the frequency band of interest or in the relevant channel. For example, the indication may include details of the channels utilized, and the sensing procedure may sense the power on each channel. The correlation between the two indicates that the sensed signal is from the base station 40, while the lack of correlation indicates that the signal may be from a different device.

The information sent by the initiating base station may include details of the PRBs being utilized. For example, a bitmap may be utilized, where each bit represents the state of one PRB. Many different subcarrier spacings (SCS) are possible and the variation in the number of PRBs is a function of the SCS for a given bandwidth. Thus, the information must include enough information so that the receiving base station can decode and understand the information. To reduce the number of bits required for large bandwidth carriers and a large number of PRBs, the PRBs may be indicated in groups. Typically, the resource utilization information may be indicated for the duration of a period. However, more or less granular information may be transmitted if desired, such as at the sub-period or symbol level.

In practice, the base station 41 is applying a comparison to determine whether the sensed signal is a signal from the initiating base station or a signal from another device. The comparison may be made using any suitable data, and any suitable comparison may be made.

In some cases, the signal from the initiating base station occupies the same or very similar frequency as the signal from another device. For example, the base station and device 46 may be using all available resources. In another case, there may be partial resource overlap between the base station 40 and the device 46. Further information may be provided by the initiating base station to assist the receiving base station in identifying the source of the sensing signal. For example, the provided information may include a transmission power of a signal from the initiating base station. The power received at the receiving base station from the transmission of the initiating base station will vary due to channel variations, but due to the fixed location of the base station, a good estimate of the path loss and statistical variations should be obtained. In this way, the receiving base station can more accurately identify whether the sensed signal is from the initiating base station (if the sensed power is desired at the indicated transmission power and estimated path loss). The base station may use a Discovery Reference Signal (DRS), a Synchronization Sequence Block (SSB), or any known preamble/initial/reserved signal to improve the accuracy of the sensing power. These signals enable the receiving base station to make an estimate of the instantaneous implementation of the channel fading process connecting the receiving base station to the initiating base station, thereby enabling the receiving base station to make a very accurate estimate of the receiving power of the initiating base station.

If the sensed occupancy of resources is a subset of the utilization information indicated by the initiating base station, then it may be decided that only the initiating base station is utilizing transmission resources and that the receiving base station may transmit. In the example shown in fig. 4, the base station 41 detects more resources than the resource utilization information indicated by the base station 40 and decides that it cannot transmit accordingly. However, the base station 48 will detect the same or fewer resources as indicated (if some resources are attenuated and cannot be detected) and so the base station can transmit. The own technical families apply to frequency channels, PRBs or other suitable parameters.

The sensing procedure of the receiving base station may estimate the power spectral density of the entire spectrum. This means that the receiving base station can measure the power of each narrow channel over the bandwidth. This allows a more accurate estimation of the transmission power and a comparison with the utilization information of the initiating base station. The granularity of a PRB or a group of PRBs may be utilized. Such an estimate may be compared to an indication from the indicated base station, indicating which channels the base station is utilizing, to determine whether the sense signal is from the initiating base station.

While the estimated power spectral density analysis at the neighboring base station may provide some indication of which resource blocks may be used by other incumbent devices after receiving the ownership indication and the indicated resource occupancy, this procedure may complement the beginning of use of unlicensed resources without interfering with other incumbent device transmissions and may not be sufficient to fairly utilize the unlicensed resources. A more robust approach is to apply an energy detection based channel sensing mechanism and learn the frequency resources used by the initiating base station. The receiving base station may apply an energy detection threshold to both sets of frequency resources. The first group includes resources that are indicated as being in use by the initiating base station, while the second group includes resources that are not indicated as being in use. The energy received in each of these groups may then be estimated and each value compared to a different Energy Detection (ED) threshold. The time to measure the energy may be the same as the time used in the energy detection of the conventional LBT procedure. The ED threshold of the first group (used by the initiating base station) may be higher than the ED threshold of the second group (not used). The ED thresholds applied to the second set may be thresholds for single channel sensing or thresholds specified by the local regulatory authorities to access unauthorized resources. The ED thresholds applied to the first set of resources may be calculated from the respective thresholds by combining them with the received power from the initiating base station. The simplest approach is to add the receive power of the initiating base station to each ED threshold, although some offset may be applied to control the level of sharing between neighboring base stations.

In summary, the energy in the frequency resources indicated as utilized by the initiating base station is compared to a first ED threshold and the energy in the frequency resources not indicated as utilized resources is compared to a second threshold. The first threshold may be higher than the second threshold, and the first ED threshold may be determined based on the transmission power indicated by the initiating base station and the estimated path loss.

The above-described technique of applying two different energy detection thresholds to two complementary frequency resources may be implemented by energy subtraction and applying one ED threshold. The receiving base station may subtract the estimated accepted energy from the initiating base station from the sum of the energies in the received indication indicating the set of occupied resources. The technique may combine this subtracted energy with the energy of the complementary set of frequency resources that are not indicated to be occupied. Thus, in practice the technique has made an estimate of the received energy over the entire channel bandwidth, subtracting the energy received from the initiating base station that sent the indication. Thereafter, the technique may apply a single conventional energy detection threshold to this energy value to determine a clear channel assessment of the unlicensed resource.

Techniques that apply two different ED thresholds to unlicensed channel resources may identify potential devices that may use a small portion of the channel bandwidth. The technique can also more finely control how much interference conditions are allowed between the shared base stations. Currently in LAA-based schemes, energy calculation does not take into account any possibility of agreeing to other base stations of the operator to own resources. A single ED threshold is applied, the choice of which is based on whether the presence/absence of other RATs (Wi-Fi) can be established. If it can be determined that there are no other devices, for example by specification, a higher ED threshold is selected and applied. Thus, the current scheme facilitates frequency reuse only if no other devices are present by specification. In contrast thereto, the proposed solution of the application facilitates frequency reuse between neighboring base stations even in case of competitors from other RATs or different operators from the same RAT. Enhanced channel sensing based on the estimate and the received ownership indication ensures shared channel access when base stations, mainly unified operators, are transmitting nearby and ensures fairness by leaving resources according to the access rights of the initiating base station.

When a base station gains access to transmission resources, the base station may use the resources for Downlink (DL), uplink (UL), or DL and UL transmissions. The intended use of the resources may also be indicated to the receiving base station to further assist in determining whether the receiving base station may share the resources. The method of indicating the utilization information may vary between UL and DL. For example, for the UL, a bitmap representing the use of a space may be used to provide a compact representation. Similarly, the same interlace representation method can be used for DL.

The TxOP duration that the initiating base station obtains for the resource that may reach the duration of the MCOT may be longer than the transmission that may be scheduled the first time the channel access is obtained. Thus, the base station may send an initial indication of the resources to be utilized and then send a further indication when more resources are scheduled. For example, a new indication may be arranged at the beginning of each period or when a change in schedule occurs.

To limit the variables available when sharing resources, sharing can only be allowed to begin at a predetermined time, such as the beginning of a period or subframe. Such a limitation also allows time for message propagation for base stations desiring to share resources so that transmission details can be sent to other base stations for the remaining time interval during the TxOP.

In the example shown in fig. 4, the base station 48 may begin sharing resources with the base station 40 as indicated by the resource utilization information. The base station 41 will then sense the transmissions from the base stations 40 and 41. Even if the device has stopped transmitting, it may still occur that the base station 41 cannot transmit because it will detect more available resources and more accepted energy than the base station 40 indicates in its initial indication. However, since base stations 40 and 48, including 41, are both part of the same cellular network, base station 41 may be able to share these resources.

This problem can be alleviated if the base station 48 also transmits its resource utilization information (i.e. it is also an initiating base station in terms of its transmission) and the base station 41 compiles both indications. However, this may increase signaling load and create problems in the shared area because the neighbor base stations of base station 48 may be different from the neighbor base stations of initiating base station 40. In addition, the base station 48 may return an indication to the base station 40 that it intends to share resources and update its own indication in subsequent transmissions. The indication may include its resource occupancy, transmit power, and the duration that it intends to share the resource. This enables the initiating base station 40 to send an accurate indication of the resource occupancy and transmission power of the unlicensed resources to its neighboring base stations in the next interval. The base station 40 may include detailed information about the base station 48 or include a flag indicating that at least one other base station is sharing resources. Such an indication is useful because it facilitates better application of the receive power threshold, as the channels connecting the receiving base station and base stations 40 and 48 may be different. The base station 41 thus receives the improved data for comparison with the sensed condition.

Fig. 5 shows a more detailed process for sharing transmission resources applying the principles described above. The base station wishes to acquire transmission resources at step 50 and initiates an LBT procedure at step 51. If the base station gains access to the transmission resources at step 51, then the use of these resources is started at step 52 and an indication of its use information is transmitted to the neighbouring base station at step 53. The base station continues to transmit until it reaches the MCOT of the resource or no more utilization of the channel is made and returns to standard behavior.

If the base station does not successfully gain access to the transmission resources, it may attempt to share the resources with the initiating base station. At step 54, the base station checks whether it has received information from the neighboring base station to win transmission rights and indicates the utilization of the transmission resources.

If there are resources that may be available for sharing, the base station may check the remaining time in the TxOP at step 55 to ensure that the opportunity is appropriate. For example, if there is only a very short time available, or less time than is required for a scheduled transmission, it may be inefficient to start the transmission, stop and later attempt to acquire resources with a conventional LBT procedure. Waiting and later attempting to acquire resources may be more efficient.

If there is sufficient time remaining, the base station performs an appropriate form of LBT at step 56, at step 55. For example, as described above, the power in two sets of channels may be calculated and compared to two different thresholds. In addition, any of the procedures described above may be utilized. If the LBT procedure shows that the resources are being utilized by different devices, the base station cannot share the resources and seek other transmission options.

The LBT procedure in step 51 is a conventional energy detection over the channel bandwidth without regard to which parts of the resources the energy propagates over and which devices may be using these resources. As will be appreciated, the LBT of step 56 is more complex than the LBT of step 51 in that it needs to determine which portions of transmission resources may be available for transmission, even if the conventional LBT procedure indicates that transmission is not possible.

If access is available, the base station shares resources until TXoP ends at step 57 (or its transmission is complete) and then returns to the idle state for subsequent operations. Thus, in the case where the conventional LBT procedure does not allow the base station to transmit, the procedure allows transmission resources to be shared and used more efficiently.

Simulations have been utilized to show the possible advantages of the above-described techniques. In particular, a cell arrangement as shown in fig. 6 may be utilized. It takes into account the configuration that the gNB1 is surrounded by M neighboring base stations of the same network and assumes that there are N devices in the vicinity (e.g., wi-Fi or other cellular devices) competing for the same transmission resources.

Without coordination, from the perspective of base station gNB1, there are N competing devices plus neighboring base stations of the same network. This is also assumed that transmissions of neighboring base stations are detectable on gNB 1. This is an effective assumption for most urban deployments, as well as higher frequencies and higher path losses as the spectrum moves to. The gNB1 will compete with N devices (Wi-Fi or other operators) and M neighboring base stations.

If it is assumed that each device has full buffered traffic so that each device has traffic available for transmission all the time, then the target base station gNB1 and all the m+n other nodes will have a view of gaining access to the transmission resources. All devices will have equal channel access opportunities in the long term due to the contention window and the random decimation based channel sensing procedure (e.g. the LBT of LAA/ELAA in 3 GPP). Therefore, the resource access rate is 1/(m+n) for the target base station gNB 1.

In the case where the base stations share utilization information, the probability of the target (initiating) base station gNB1 accessing the channel is not greater than 1/(m+n) where the legacy channel sensing mechanism still exists. But once it has gained access to the resources, it indicates utilization information to its neighboring base stations. The information also includes the time remaining, channel resource occupancy, and power of occurrence within the COT, helping other base stations to find the time remaining for the COT, and determining that no other users are transmitting on the same unlicensed resource. If the other base station recognizes that there are other devices transmitting, the other base station does not transmit.

Assuming that gNB1 shares resources only with directly neighboring base stations, gNB1 shares some of the neighboring base stations in M with each directly neighboring base station. When the gNB1 is able to gain access to the resources, these neighboring base stations must not be transmitting. For this hexagonal layout, this number is exactly M/2=3. Thus, each neighboring base station that receives the indication of the resource utilization information sent by the gNB1 may still have M/2 neighboring base stations that may be transmitting because it is not in the vicinity of the gNB 1. For the other "N" competitors, if each base station is assumed to have the same device density, then each neighboring base station will have half of the N/2 devices silent. These devices are all adjacent to gNB 1. While the other half of the N/2 devices may transmit. Thus, each neighboring base station can see the success probability that no other devices are active except gNB1 as:

p_s＝1/(M/2+N/2)＝2/(M+N)

The probability of failure, i.e. the probability of at least one active device being active except the gNB1 is:

p_f＝1-p_s＝(M+N-2)/(M+N)

sharing can be achieved when one, two or M neighboring base stations can account for the probability of success, considering that the probability of each neighboring base station is random. Thus, the overall probability of sharing an unlicensed resource is:

The results are shown in fig. 7, which shows the variation of the channel access amount of each base station with different number of competing devices (N). The solid curve (down) is a conventional channel usage mechanism, where the base station does not share resources with neighboring base stations. The dashed curve (upper) indicates the effective channel access situation of each base station, when the base station that obtains channel access sends an instruction to the neighboring base stations of the same operator, these neighboring base stations can share resources under appropriate conditions.

Both schemes show a reduction in the amount of channel access as the number of neighboring devices increases. This is normal in view of the fair usage principle enforced by the channel sensing mechanism. In case of different numbers of competitors trying to access the same resource, an advantage of the spectral efficiency of the proposed solution of the application can be observed to be between 200% and 300%. The results show the obvious advantage of sharing unauthorized resource access with neighboring base stations.

Any device or means not specifically shown as forming part of a network in the present application may include at least a processor, a memory unit and a communication interface, wherein the processing unit, the memory unit and the communication interface are configured to perform any of the methods described in the present application. Further options are described below.

The signal processing functions of embodiments of the present application, particularly the gNB and the UE, may be implemented using computing systems or architectures well known to those skilled in the art. For example, a desktop, notebook or computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device may be used as may be desirable or appropriate for a particular application or environment. A computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computing system may also include a main memory, such as Random Access Memory (RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. The main memory may also be used for storing temporary variables or other intermediate information during execution of instructions by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism that supports fixed or removable storage media, such as a hard disk drive, floppy disk drive, magnetic tape drive, optical disk drive, compact Disk (CD) or Digital Video Drive (DVD), read or write drive (R or RW), or other removable or fixed media drive. The storage medium may include, for example, a hard disk, floppy disk, such a single, optical disk, CD or DVD, or other fixed or removable medium, which is read by and written to by a media drive. The storage medium may include a computer-readable storage medium having stored therein specific computer software or data.

In other embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. The components may include, for example, removable storage units and interfaces (e.g., program cartridges and cartridge interfaces), removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

The computing system may also include a communication interface. The communication interface may be used to allow software and data to be transferred between the computer system and an external device. Examples of communication interfaces may include a modem, a network interface (e.g., an ethernet or other NIC card), a communication port (e.g., a universal serial bus (USB port), a PCMCIA slot and card, etc., software and data transferred via the communication interface may be transmitted in the form of signals, which may be electronic, electromagnetic, and optical or other signals capable of being received by a communication interface medium.

In the present disclosure, the terms "computer program product," "computer-readable medium," and the like may be used to generally refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. Such instructions, which are commonly referred to as "computer program code" (which may be in the form of a computer program or other groupings), when executed, enable the computing system to perform functions of embodiments of the present application. It is noted that the code may directly cause the processor to perform specified operations, be compiled for execution, and/or be executed in conjunction with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions).

The non-transitory computer readable medium may include at least one of the group of: hard disks, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments in which the elements are implemented using software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. When a processor in a computer system executes a control module (in this example, software instructions or executable computer program code), the processor performs the described functions of the application.

Furthermore, the inventive concept may be applied to any circuit that performs signal processing functions within a network element. It is further contemplated that the concept may be employed, for example, by a semiconductor manufacturer in the design of a stand-alone device, such as a microcontroller of a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC) and/or any other subsystem element.

It will be appreciated that for clarity, the above description has described embodiments of the application with reference to a single processing logic. However, the inventive concept may equally be implemented by a number of different functional units and processors to provide signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Aspects of the application may be implemented in any suitable form including hardware, software, firmware or any combination of these. The application may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors or configurable module components, such as FPGA devices.

The elements and components of an embodiment of the application may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the application has been described in connection with certain embodiments, the application is not limited to the specific embodiments described. Rather, the scope of the application is limited only by the appended claims. Furthermore, although features have been described in connection with specific embodiments, those skilled in the art will recognize that various features of the described embodiments may be combined in accordance with the application. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may be combined. The inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a," "an," "the first," "the second," etc. do not exclude a plurality.

Although the application has been described in connection with certain embodiments, the application is not limited to the specific embodiments described. Rather, the scope of the application is limited only by the appended claims. Furthermore, although features have been described in connection with specific embodiments, those skilled in the art will recognize that various features of the described embodiments may be combined in accordance with the application. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Claims

1. A method of resource sharing in a cellular communication system, the method performed by a first base station and comprising:

obtaining access to transmission resources of a prescribed transmission interval; and

Transmitting an indication of the transmission resources accessed by the first base station to a second base station of the cellular communication system; the second base station is used for comparing the indication of the transmission resource with the sensed transmission power, and responding to the comparison result to display that the sensed transmission power is only from the first base station, and the second base station is also used for initiating transmission, wherein the transmission power is the transmission power received by the second base station.

2. The method of claim 1, wherein the transmission resource is an unlicensed spectrum resource.

3. A method according to claim 1 or 2, characterized in that the access to the transmission resources by the first base station is obtained by means of a listen-before-talk procedure.

4. The method of claim 1, wherein the indication comprises scheduling resources from the first base station.

5. The method of claim 1, wherein the indication of transmission resources is given in the form of physical resource blocks.

6. The method of claim 5, wherein the indication comprises a bitmap; wherein each bit relates to one of said physical resource blocks.

7. The method of claim 1, further comprising transmitting an indication of transmission power used by the first base station for the transmission resources.

8. The method of claim 1, further comprising transmitting an indication of the prescribed transmission interval.

9. The method of claim 1, further comprising transmitting an indication of the end of the prescribed transmission interval.

10. The method of claim 1, further comprising transmitting an indication of the transmission resources obtained by the first base station.

11. The method of claim 1, wherein the indication of transmission resources comprises an indication of a carrier index of the transmission resources.

12. A method for resource sharing in a cellular communication system, the method performed by a second base station comprising:

Receiving an indication of transmission resources obtained by a first base station;

sensing the transmission power received by the second base station;

comparing the sensed transmission power with an indication of the transmission resource; and

And if the comparison result shows that the sensed transmission power is only from the first base station, initiating transmission of the second base station.

13. The method of claim 12, wherein the transmission resource is an unlicensed spectrum resource.

14. The method of claim 12 or 13, wherein the indication comprises scheduling resources from the first base station.

15. The method of claim 12, wherein the indication of transmission resources is given in the form of physical resource blocks.

16. The method of claim 15, wherein the indication comprises a bitmap; wherein each bit relates to one of said physical resource blocks.

17. The method of claim 12, further comprising receiving an indication of a transmission power used by the transmission resource by the first base station.

18. The method of claim 17, further comprising estimating a path loss between the first base station and the second base station.

19. The method of claim 12, further comprising receiving an indication of a prescribed transmission interval.

20. The method of claim 12, further comprising receiving an indication of an end of the prescribed transmission interval.

21. The method of claim 12, further comprising receiving an indication that the transmission resource was obtained by the first base station.

22. The method of claim 12, wherein the indication of the transmission resource comprises an indication of a carrier index of the transmission resource.

23. The method of claim 12, further comprising transmitting the received indication to a third base station.

24. The method of claim 23, further comprising indicating an identity of a base station receiving the indication.

25. The method according to any of claims 23 to 24, wherein the second base station stops transmitting the transmission resources if the first base station stops transmitting the indicated transmission resources.

26. The method of claim 12, wherein the comparing the sensed transmission power with the indication of transmission resources comprises: the method further includes comparing energy received in transmission resources indicated as being utilized by the first base station with a first threshold and comparing energy received in transmission resources indicated as not being utilized by the first base station with a second threshold.

27. The method of claim 26, wherein the first threshold is higher than the second threshold.

28. The method of claim 12, wherein the comparing the sensed transmission power with the indication of transmission resources is between an indicated physical resource block and the sensed transmission power in the physical resource block.

29. The method of claim 28, wherein the sensed transmission power is determined to be from only the first base station if the sensed physical resource blocks are a subset of the indicated physical resource blocks.

30. A base station comprising one or more processors to perform the method of any of claims 1 to 29.