CN112314041A

CN112314041A - Transmission resource sharing

Info

Publication number: CN112314041A
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: Jiekai Communications Shenzhen Co Ltd
Current assignee: JRD Communication Shenzhen Ltd; Jiekai Communications Shenzhen Co Ltd
Priority date: 2018-08-09
Filing date: 2019-08-06
Publication date: 2021-02-02
Also published as: WO2020029977A1; GB201812954D0; GB2576198A; GB2576198B

Abstract

A method for sharing resource utilization information between base stations to facilitate resource sharing. When the first base station obtains the access of the 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 no collision occurs 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 in particular 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 techniques are well known. Such 3G standards and techniques are set by the third generation partnership project (3 GPP). Third generation wireless communications are commonly used to support macrocell mobile telephone communications and are constantly evolving. Communication systems and networks have evolved towards broadband and mobile systems.

In a cellular wireless communication system, User Equipment (UE) is connected to a Radio Access Network (RAN) over 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 will be readily appreciated that the RAN and CN each perform functions related to the overall network. For convenience, the term "cellular network" will be used herein to refer to the combination of the RAN and the CN. It is to be understood that the term is used to refer to the respective system performing the disclosed function.

The 3GPP has developed a so-called Long Term Evolution (LTE) system, the evolved universal mobile telecommunications system, the terrestrial 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 base stations called enodebs or enbs (evolved nodebs). 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 is intended to use an Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

The NR protocol aims to provide a choice for operating in unlicensed radio bands, the so-called NR-U. When operating in the unlicensed radio band, the gNB and UE must contend with other devices for physical medium/resource access. For example, Wi-Fi, NR-U, and LAA may utilize the same physical resources.

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

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

The LBT procedure is effective for sharing the transmission unlicensed resources, thus allowing various devices to use these resources. The regulations for fair use and other transmission restrictions vary from country to country. Frequency reuse of unlicensed resources is not straightforward, as the resources do not inherently belong to the ownership of a device, a group of devices, or an operator. Thus, agreed clear channel access procedures for specific areas must be used to gain access and ownership of the transmission. This may result in difficulties in achieving high frequency reuse of unlicensed resources even if the base station of the cellular operator is able to access resources within an area. For example, multiple Wi-Fi stations do not have coordination, and therefore transmissions must be coordinated through LBT procedures to avoid interference, provided that only one station can use resources at a time. In contrast, cellular systems have evolved to share resources with a frequency reuse factor of 1. However, in conventional LBT procedures, one cellular base station gains access to resources and transmits on those resources, even without other devices, may block many neighboring base stations.

As the technology for managing interference is well developed, base stations with overlapping transmission areas of the same cellular network (same operator) can operate in the same frequency band. Therefore, the application of the conventional LBT procedure to the cellular system may result in inefficient utilization of transmission resources.

Therefore, cellular systems need to improve the LBT procedure.

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 subject matter of the disclosure, nor is it intended to be used to identify the scope of the disclosure.

The present application provides a method of resource sharing 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 sending an indication to a second base station of the cellular communication system that the first base station has gained access to the transmission resources.

The transmission resources are unlicensed spectrum resources.

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

The indication comprises scheduling resources from the first base station.

The indication of 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 a transmission power used by the first base station for the transmission resource.

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

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

The method also includes transmitting an indication that the transmission resources were 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 method of 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 a transmission power received by the second base station; comparing the sensed transmission power to an indication of the transmission resource; and initiating transmission by the second base station if the comparison shows that the sensed transmission power is only from the first base station.

The transmission resources are unlicensed spectrum resources.

The indication comprises scheduling resources from the first base station.

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

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 specifying a transmission interval.

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

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

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

The method also includes indicating an identity of a base station receiving the indication.

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

The comparing the sensed transmission power to the indication of the transmission resource comprises: comparing the energy received in transmission resources indicated to be utilized by the first base station with a first threshold and comparing the energy received in transmission resources indicated to not be 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 to the indication of the transmission resource is between an indicated physical resource block and the sensed transmission power in the physical resource block.

Determining that the sensed transmission power is only from the first base station if the sensed physical resource block is a subset of the indicated physical resource block.

The application also provides a base station for the method.

The non-transitory computer readable medium may comprise at least one of the group of: hard disk, optical storage device, magnetic storage device, 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 present 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 drawings 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 illustrating a resource sharing method.

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

Fig. 5 is a flow chart illustrating a resource sharing method.

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

Fig. 7 is a schematic diagram of the simulation results.

Detailed Description

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

The application discloses an improved mechanism aiming at realizing more effective sharing of transmission resources among related base stations.

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

Each base station includes hardware and software that implement the RAN functionality. The functions include communication with the core network and other base stations, transfer of control and data signals between the core network and the UEs, and maintaining wireless communication with the UEs associated with 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 has a transmission distance that is far beyond 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 20's transmissions will be monitored and blocked from transmitting when base station 21 performs the LBT procedure, as it appears that there is a device that has seized transmission resources. In fact, however, since these transmissions come from base stations of the same cellular network, the communication between the base station 21 and the UEs connected to the base station 21 may achieve resource sharing. Most modern cellular systems, such as 3G WCDMA, 4G LTE, LTE-a, and the originally released 5G NR, are designed with a 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 may communicate data with the core network via an X2 interface or via an S1 interface. These interfaces can be utilized to share information about resource utilization between base stations in order to more efficiently share unauthorized resources.

Fig. 3 illustrates a cooperative manner of resource sharing. When a base station performs the LBT procedure and gains access to transmission resources, it has access to these resources within the Maximum Channel Occupancy Time (MCOT). A base station (e.g., base station 20) gains access to transmission resources at step 30 and may indicate its access to neighboring base stations at step 31 over an X2/S1 interface or other suitable communication mechanism. For example, messages may be wirelessly transmitted over a shared spectrum. Certain time and/or frequency resources may be agreed upon on which to broadcast resource utilization information so that neighboring base stations can listen to, and accept the information as may be useful to them. For example, techniques similar to transmitting DRSs or SRBs on specific portions of a carrier may be utilized. However, this solution utilizes transmission resources and may therefore reduce access to traffic transmission resources. Another way to share this information may be through other licensed carriers if these base stations are also using licensed carriers.

For ease of explanation, the base station that obtains the unlicensed transmission resources is referred to herein as the initiating base station and the base station that receives the indication is referred to herein as the receiving base station.

The receiving base station (e.g. base station 21) receives the indication at step 32 and thus learns of the possible detected signals when performing its LBT procedure at step 33. The results of the LBT procedure may be verified at step 34 with details received from other base stations. 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 is not relevant to the received details (as described in detail below), the base station may conclude that the detected transmission is from a different resource and therefore decide at step 36 that the transmission resource cannot be utilized.

Therefore, according to the method shown in fig. 3, the bs can share the detailed information of the transmission resource it is using after the successful LBT procedure, so as to share with other bss of the cellular network by using the existing resource sharing technology, thereby improving the resource utilization.

The indication of resource utilization information may include various items of information to help other base stations associate their LBT results with the information and to make efficient use 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 gains access to. To help facilitate frequency reuse of channels/carriers, the initiating base station may transmit information of the 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 originating base station transmits utilization information for each individual PRB. In principle, any indication that allows the receiving base station to determine the channel details may be utilized. 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 indicates that only a subset of these resources are utilized, then it will be determined that the detected transmission is from another device (e.g., a Wi-Fi device).

The initiating base station may also share other relevant parameters such as Contention Window Size (CWS), MCOT and 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 provisions when the initiating base station gains access. Both the initiating base station and the receiving base station must stop transmitting after the end of this period of time and perform a new LBT procedure as specified with appropriate gaps and backoff to acquire the unlicensed resources. If each receiving base station starts a new MCOT at the beginning of the transmission, a very long continuous time of occupancy between the base stations of the same operator may occur, prohibiting other devices to access the transmission resources. However, the initiating base station may have gained access before the receiving base station receives the indication, so the receiving base station does not know when the TxOP ends within the MCOT value of the initiating base station. Therefore, it is necessary for each receiving base station sharing a TxOP obtained by the initiating base station to know when the current TxOP ends.

For the case where the time for which the initiating base station plans to use the resource is shorter than its MCOT, from a regulatory perspective, neighboring base stations sharing the resource may continue to use the resource until the initiating base station MCOT expires, treating each base station as part of a group. In this case, it is necessary to ensure a mechanism for correctly updating the sensing-related parameter after the TxOP. And in consideration 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. So generally from the system control, signaling and fairness point of view, the time when the neighboring base station stops using resources should be no later than the initiating base station, even before the TxOP ends.

As described above, details of the 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. While in other cases the neighboring base stations may be only those that share a boundary with the originating base station. In another example, the neighboring base stations may be those base stations that have a handover relationship with the initiating base station.

In addition to defining the neighboring base stations more broadly, the receiving base station can retransmit the utilization information to other base stations to achieve a wide sharing of resources. This may be particularly useful for deploying densely populated small cells. However, the propagation of information should be limited to only those base stations that are expected to detect the originating base station transmission to ensure that the transmissions detected during LBT are those in the indication, rather than coincidently other transmissions that are the same. For example, the receiving base station may be allowed to share information (i.e., restrict propagation between base stations to two "hops") only when the information is received directly from the initiating base station. 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 information. For example, a flag may be included to indicate whether the message is from the initiating base station. Additional flexibility may be achieved by limiting the number of possible retransmissions to a particular number and tracking the number of retransmissions in each message.

If a base station resends the message, the base station should ensure that the details are kept 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 the absolute expiration time is known to all receiving base stations.

To avoid the need to update the remaining time, the end of the TxOP may be specified as an absolute time, provided that all relevant base stations have the same reference time (e.g., an actual absolute time, or a common reference time). This may be because 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 start transmission directly without 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 situation is not necessarily: since the first base station may use resources, the second base station may also use.

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, which extend into area 44. In one example case, the UE 45 connects to the base station 40 using unlicensed resources. The base station 40 sends its usage indication 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 acts solely on the indication from base station 40, its transmissions will collide with device 46. In contrast, the base station 48 does not have any other equipment within its coverage area 49 and will therefore be free to transmit based on information from the initiating base station 40 without any further examination. However, this is not known until the inspection is performed.

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

As described above, this difficulty can be overcome if the indication from the base station 40 includes details of the resources being utilized, which can 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 associated channel. For example, the indication may include details of the channels being 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 transmitted 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 spacing (SCS) are possible, and the variation in the number of PRBs at a given bandwidth is a function of the SCS. Thus, the information must include enough information so that the receiving base station can decode and understand the information. In order to reduce the number of bits required for a large bandwidth carrier and a large number of PRBs, the PRBs may be grouped and indicated. Typically, the resource utilization information may be indicated for the duration of a time 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. Any suitable data may be used for this comparison, and any suitable comparison may be made.

In some cases, the signal from the initiating base station and the signal from another device occupy the same or very similar frequencies. 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 the 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 variations in the channel, but due to the fixed location of the base station, a good estimate of the path loss and statistical variation should be available. 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 expected 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 sensing power. These signals enable the receiving base station to estimate the instantaneous realization of the channel fading process connecting the receiving base station and 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 resource occupancy is a subset of the utilization information indicated by the initiating base station, it may be decided that only the initiating base station is utilizing the transmission resource and the receiving base station may transmit. In the example shown in fig. 4, the base station 41 may detect more resources than the resource utilization information indicated by the base station 40 and decide that it cannot transmit accordingly. However, the base station 48 will detect the same or fewer resources as the indication (if some resources are attenuated and cannot be detected) and therefore the base station may transmit. The own technical skill applies to frequency channels, PRBs or other suitable parameters.

The sensing procedure of the receiving base station can 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 comparison with the utilization information of the initiating base station. The granularity of a PRB or a group of PRBs may be utilized. This estimate may be compared to indications from the indicating base station, indicating which channels the base station is utilizing, and having determined whether the sensed signal is from the initiating base station.

Although 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 possibility of starting to use the unlicensed resources without interfering with the transmission of other incumbent devices, and may not be sufficient to make fair use of the unlicensed resources. A more robust approach is to apply a channel sensing mechanism based on energy detection and to know the frequency resources used by the initiating base station. The receiving base station may apply energy detection thresholds to the two sets of frequency resources. The first group includes resources indicated as being used by the initiating base station, while the second group includes resources not indicated as being used. 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 values of the first group (used by the initiating base station) may be higher than the ED threshold values of the second group (unused). The ED threshold applied to the second group may be a threshold for single channel sensing or a threshold specified by a local regulatory authority to access the unlicensed resources. The ED threshold values applied to the first set of resources may be calculated from the respective threshold values 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 in various ED thresholds, 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 with the first ED threshold, and the energy in the frequency resources not indicated as utilized is compared with the 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 energy that does not indicate an occupied set of complementary frequency resources. Thus, in effect the technique has made an estimate of the received energy over the entire channel bandwidth, minus the energy received from the originating base station that sent the indication. The technique may then apply a single conventional energy detection threshold to this energy value to determine a clear channel estimate for the unlicensed resource.

Techniques for applying two different ED thresholds to unlicensed channel resources may identify potential devices that may use a fraction of the channel bandwidth. The technique may also more finely control how much interference conditions are allowed between the shared base stations. Currently in LAA-based schemes, energy calculations do not take into account any possibility of granting the operator's other base stations possession of resources. A single ED threshold is applied, the threshold being chosen according to whether the presence/absence of other RATs (Wi-Fi) can be established. If it can be determined that there are no other devices, e.g. by specification, a higher ED threshold is selected and applied. Thus, current solutions only facilitate frequency reuse by specifying that no other devices are present. In contrast, the proposed scheme facilitates frequency reuse between neighboring base stations even in the presence of competitors from other RATs or from different operators of the same RAT. Enhanced channel sensing based on the estimation and received ownership indication ensures shared channel access when base stations, which are mainly unified operators, transmit nearby and ensures fairness by leaving resources according to the access rights of the originating 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 UL, a bitmap indicating interlace usage can be used to provide a compact representation. Similarly, the same interlace representation method can be used for DL.

The TxOP duration, which may be up to the duration of the MCOT, obtained by the initiating base station for the resource may be longer than the transmission that may be scheduled when channel access is first obtained. Thus, the base station may send an initial indication of resources to be utilized and then send further indications when more resources are scheduled. For example, a new indication may be scheduled 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 restriction also allows time for message propagation for base stations that wish to share resources so that transmission details can be sent to other base stations for the remaining time interval during 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. Base station 41 will then sense the transmissions from

base stations

40 and 41. Even if the device has stopped transmitting, it may still happen that the base station 41 is not able to transmit, since it will detect more active resources and more received energy than the base station 40 indicates in its initial indication. However, since

base stations

40 and 48, including 41, are part of the same cellular network, base station 41 may be able to share these resources.

This problem can be alleviated if base station 48 also transmits its resource utilization information (i.e., it is also an initiating base station in terms of its transmissions), and base station 41 compiles both indications. However, this may increase the signaling load and create problems in the shared area, as the neighboring base stations of the base station 48 may be different from the neighboring base station of the originating base station 40. In addition, the base station 48 may transmit back to the base station 40 an indication 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 for which it intends to share resources. 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 neighbouring 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 received power threshold since the channels connecting the receiving base station to the

base stations

40 and 48 may be different. The base station 41 thus receives improved data for comparison with the sensed condition.

Fig. 5 shows a more detailed procedure for sharing transmission resources applying the above principles. At step 50 the base station wishes to obtain transmission resources and initiates an LBT procedure at step 51. If the base station gains access to the transmission resources at step 51, then the utilisation of these resources is commenced at step 52 and an indication of its utilisation information is transmitted to the neighbouring base station at step 53. The base station continues to transmit until it reaches the MCOT of resources or there is no further utilization of the channel and reverts 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 information for winning the transmission right is received from the neighboring base station and indicates the utilization of the transmission resource.

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 required for a scheduled transmission, it may be inefficient to start the transmission, stop and attempt to acquire resources later using conventional LBT procedures. Waiting and then 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 reveals that resources are utilized by different devices, the base stations cannot share the resources and seek other transmission options.

The LBT procedure in step 51 is a regular energy detection over the channel bandwidth without concern for which parts of the resources the energy is spread 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, since it needs to determine which portions of the transmission resources may be available for transmission, even if conventional LBT procedures indicate that transmission is not possible.

If it is accessible, the base station will share the resources until the TXoP at step 57 ends (or its transmission is complete) and then return 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 techniques. In particular, a cell arrangement as shown in fig. 6 may be utilized. It considers the configuration where the gNB1 is surrounded by M neighboring base stations of the same network and assumes that there are N devices (e.g., Wi-Fi or other cellular devices) in the vicinity contending 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 also assumes that transmissions of neighboring base stations are detectable at the gNB 1. This is a valid assumption for most urban deployments, and as the spectrum moves towards higher frequencies and higher path losses. The gNB1 will compete with N devices (Wi-Fi or other operators) and M neighbor base stations.

If it is assumed that each device has full buffered traffic so that each device always has traffic to transmit, the target base station gNB1 and all M + N other nodes will view access to the transmission resources. Due to the contention window and the channel sensing procedure based on random extraction (e.g. LBT of LAA/ELAA in 3GPP), it is long-term that all devices will have equal channel access opportunities. Thus, for the target base station gNB1, the resource access rate is 1/(M + N).

In the case of base stations sharing utilization information, the probability of the target (originating) base station gNB1 accessing the channel is no greater than 1/(M + N) with legacy channel sensing mechanisms still present. However, once it has gained access to the resources, it indicates the utilization information to its neighboring base stations. This information also includes the remaining time in the COT, the channel resource occupancy and the power of occurrence, which helps other base stations to find the remaining time of the COT and determine that no other users are transmitting on the same unlicensed resource. If other base stations recognize that other devices are transmitting, the other base stations do not transmit.

Assuming that the gNB1 only shares resources with directly neighboring base stations, the gNB1 shares some of the M's neighboring base stations with each directly neighboring base station. When the gNB1 is able to gain access to resources, these neighboring base stations must not be transmitting. For this hexagonal layout, this number is exactly M/2-3. Therefore, each neighboring base station receiving the resource utilization indication from 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 the device density of each base station is assumed to be the same, then half N/2 devices per neighbouring base station will be silent. These devices are all adjacent to the gNB 1. While the other half of N/2 devices may transmit. Thus, each neighboring base station can see a success probability of no other devices being active than the 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 other than the gNB1 being active, is:

p_f＝1-p_s＝(M+N-2)/(M+N)

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

the result is shown in fig. 7, which shows the variation of the channel access amount of each base station with different numbers of competing devices (N). The solid curve (lower) is the conventional channel usage mechanism, and the base station does not share resources with neighboring base stations. The dashed curve (upper) is the effective channel access situation for each base station, and when the base station obtaining channel access sends an indication 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 use 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 present application of 200% -300% can be observed. The results show the clear advantage of sharing unlicensed resource access with neighboring base stations.

This application does not specifically show that any device or apparatus forming part of a network may comprise 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 herein. Further alternatives are described below.

The signal processing functions of the embodiments of the present application, and in particular of the gNB and UE, may be implemented using computing systems or architectures that are well known to those skilled in the art. For example, a desktop, laptop or computer, handheld 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, for example, a microprocessor, microcontroller or other control module.

The computing system may also include a main memory, such as a 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 to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a Compact Disk (CD) or Digital Video Drive (DVD), a 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, compact disk, CD or DVD, or other fixed or removable medium that is read by and written to by the media drive. The storage media may include a computer-readable storage medium having stored therein particular computer software or data.

In other embodiments, information storage systems 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, a removable storage unit and interface (e.g., a program cartridge and cartridge interface), a removable memory (e.g., a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to the computing system.

The computing system may also include a communications interface. The communication interface may be used to allow software and data to be transferred between the computer system and external devices. Examples of a communication interface 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 transmitted over a communication interface are transmitted in the form of signals, which may be electronic, electromagnetic, and optical signals or other signals capable of being received by the communication interface medium.

In this application, the terms "computer program product," "computer-readable medium," and the like may generally refer to a tangible medium, such as a memory, a storage device, or a storage unit. 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. The instructions, generally 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 should be 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 comprise at least one of the group of: hard disk, optical storage device, magnetic storage device, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into the computing system using, for example, a removable storage drive. When a processor in the computer system executes a control module (in this example, software instructions or executable computer program code), the processor performs the functions described herein.

Furthermore, the concepts of the present application may be applied to any circuit that performs signal processing functions within a network element. It is further contemplated that, for example, a semiconductor manufacturer may employ the concept 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 the above description, for clarity, has described embodiments of the application with reference to a single processing logic. However, the inventive concept may equally be implemented by a plurality of different functional units and processors to provide the signal processing functions. Hence, 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 present application may be implemented in any suitable form including hardware, software, firmware or any combination of these. The present 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 modular components such as FPGA devices.

Thus, 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 present application has been described in connection with some embodiments, the present application is not limited to the specific embodiments described. Rather, the scope of the present application is limited only by the accompanying claims. In addition, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. 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 possibly 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", "first", "second", etc., do not preclude a plurality.

Although the present application has been described in connection with some embodiments, the present application is not limited to the specific embodiments described. Rather, the scope of the present application is limited only by the accompanying claims. In addition, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. 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 being performed by a first base station and comprising:

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

sending an indication to a second base station of the cellular communication system that the first base station obtained the accessed transmission resources.

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 said first base station's access to said transmission resources is obtained by a listen-before-talk procedure.

4. The method according to any of the preceding claims, wherein the indication comprises scheduling of resources from the first base station.

5. The method according to any of the preceding claims, 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 according to any of the preceding claims, further comprising transmitting an indication of the transmission power used by the first base station for the transmission resource.

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

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

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

11. The method according to any of the preceding claims, wherein the indication of the transmission resources comprises an indication of a carrier index of the transmission resources.

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

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

sensing a transmission power received by the second base station;

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

initiating transmission by the second base station if the comparison shows that the sensed transmission power is only from the first base station.

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

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

15. The method according to any of claims 12 to 14, 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 according to any of claims 12 to 16, further comprising receiving an indication of a transmission power used by the first base station for the transmission resource.

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 any of claims 12 to 17, further comprising receiving an indication specifying a transmission interval.

20. The method of any of claims 12 to 19, further comprising receiving an indication of an end of the prescribed transmission interval.

21. The method according to any of claims 12 to 20, further comprising receiving an indication that the transmission resources were obtained by the first base station.

22. The method according to any of claims 12 to 21, characterised in that said indication of transmission resources comprises an indication of a carrier index of said transmission resources.

23. The method of any of claims 12 to 22, 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, characterized in that the second base station stops transmitting the transmission resources if the first base station stops transmitting the indicated transmission resources.

26. The method according to any of claims 12 to 25, wherein said comparing the sensed transmission power with the indication of the transmission resource comprises: comparing the energy received in transmission resources indicated to be utilized by the first base station with a first threshold and comparing the energy received in transmission resources indicated to not be 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 to the indication of the transmission resource 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 transmission power sensed is determined to be from only the first base station if the physical resource block sensed is a subset of the indicated physical resource block.

30. A base station for performing the method of any one of claims 1 to 29.