WO2019154507A1

WO2019154507A1 - Improved fronthaul communication system

Info

Publication number: WO2019154507A1
Application number: PCT/EP2018/053288
Authority: WO
Inventors: Robert Lindgren; Per-Arne Thorsén; Peter WINGARD; Peter Karlsson
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2018-02-09
Filing date: 2018-02-09
Publication date: 2019-08-15
Also published as: EP3750375A1

Abstract

The present disclosure relates to a method for providing fronthaul communication between one or more baseband units (130a, 130b, 130c) and at least one radio unit (170a, 170b, 170c) in a wireless communication system (100), over a shared communication link (150) arranged between a first shared communication link transceiver (140) connected to the one or more baseband units (130a, 130b, 130c) and a second shared communication link transceiver (160) connected to the at least one radio unit (170a, 170b, 170c). The method comprises obtaining information associated with a current data transmission capacity of the shared communication link (150), allocating an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link (150) at or below the current data transmission capacity of the shared communication link (150), and generating data for transmission over the shared communication link based on the allocated radio transmission resources.

Description

l

TITLE

IMPROVED FRONTHAUL COMMUNICATION SYSTEM

TECHNICAL FIELD

The present disclosure relates to a communication system for providing fronthaul communication between one or more baseband units and at least one radio unit over a shared communication link.

BACKGROUND

A fronthaul system in the context of a radio access network (RAN) refers to the intermediate links between radio controllers, also known as baseband units (BBU) and the radio heads, also known as radio units (RU). Fronthaul links are often implemented using dedicated optical fiber links, and fronthaul traffic is usually formatted using the known common public radio interface (CPRI) format, CPRI Specification V7.0, 2015-10-09, CPRI cooperation.

When transporting packet-based fronthaul traffic between BBUs and RUs in an access network it is often assumed that the fronthaul transport link is“perfect”. I.e., sufficient fixed transport capacity over the link is always provided and there are no packet drops or variations in transport capacity over time. This assumption is valid when using dedicated optical fiber for the transport, since this optical fiber can be overprovisioned.

High capacity microwave links offer an attractive alternative to dedicated optical fiber for fronthaul transport, at least partly due to the ease of deploying a microwave link in areas lacking optical fiber infrastructure. Microwave links may not always provide fixed transmission capacity, but may instead offer a variable transport capacity. However, with adequate link planning, microwave links have been known to operate with reduced capacity only during very short periods of time when, e.g., weather conditions drastically influence radio propagation. These conditions typically only persist for a few seconds to minutes each time, and accumulates to a few minutes to hours over a year.

There is a need for improved fronthaul communication techniques which can operate over variable transport capacity links. SUMMARY

It is an object of the present disclosure to provide a robust and efficient system for fronthaul communication between one or more baseband units and at least one radio unit in a wireless communication system.

This object is obtained by a method for providing fronthaul communication between one or more baseband units and at least one radio unit in a wireless communication system, over a shared communication link arranged between a first shared communication link transceiver connected to the one or more baseband units and a second shared communication link transceiver connected to the at least one radio unit. The wireless communication system is arranged for wireless communication between the radio units and one or more wireless devices using radio transmission resources. The method comprises obtaining information associated with a current data transmission capacity of the shared communication link, allocating an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link at or below the current data transmission capacity of the shared communication link, and generating data for transmission over the shared communication link based on the allocated radio transmission resources.

This way, the traffic over the shared fronthaul link is regulated to adjust for variations in capacity, since the amount of fronthaul traffic generated is a function of the amount of allocated radio transmission resources. Thus, when the capacity of the shared communication link goes down, a reduced amount of resources is allocated, which reduces requirements on fronthaul capacity to correspond to the reduced capacity. Radio transmission resources may according to different aspects comprise a number of different resource types, as will be discussed below. This provides for flexibility when adjusting operation of the fronthaul communication.

The use of a shared communication link for fronthaul enables statistical multiplexing gains, which is an advantage.

According to aspects, the allocating comprises de-allocating a sub-set of radio transmission resources in case a current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link in excess of the current data transmission capacity of the shared communication link. Thus, by the de-allocating, requirements on transmission capacity of the fronthaul system is reduced. This way a variable capacity of the fronthaul system is accommodated.

According to aspects, the allocating comprises allocating additional radio transmission resources only if the current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link below the current data transmission capacity of the shared communication link.

Thus, by allowing allocation of additional resources whenever possible, and when needed for communication with the one or more wireless devices, it is ensured that the current capacity of the shared communication link is always utilized. This way a variable capacity of the fronthaul system is accommodated which is efficient in the sense that the available fronthaul capacity is always utilized.

According to aspects, the radio transmission resources used for communication with the one or more wireless devices comprises any of a time resource, a frequency resource, a code resource, and a power resource.

According to aspects, the radio transmission resources used for communication with the one or more wireless devices comprises any of a spatial communication resource, an antenna beam resource, and an antenna array element resource.

The fact that different types of resources can be considered for allocating provides for a degree of flexibility in the utilization of the shared communications link.

According to aspects, the radio transmission resources used for communication with the one or more wireless devices comprises a quantization resolution resource in terms of number of bits per data sample communicated over the shared communication link.

Quantization resolution has an impact on required fronthaul capacity, thus by adjusting the quantization resolution the fronthaul capacity requirements can be adjusted.

According to aspects, the communication system comprises one or more centralized control units, wherein the obtaining and/or the allocating is performed by the one or more centralized control units.

It is advantageous in some scenarios to implement a centralized control. The disclosed techniques are suitable for centralized control, which is an advantage. There are also disclosed herein control units, baseband units, transceiver units, and computer programs associated with the above-mentioned advantages.

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described more in detail with reference to the appended drawings, where:

Figure 1 shows a schematic view of a communication system comprising fronthaul communication according to embodiments;

Figure 2 is a flowchart illustrating methods described herein;

Figure 3a is a schematic diagram showing a control unit;

Figure 3b is a schematic diagram showing a baseband unit;

Figure 3c is a schematic diagram showing a communication link transceiver;

Figures 4-6 show schematic views of communication systems comprising fronthaul communication according to prior art;

Figures 7-9 show schematic views of communication systems comprising fronthaul communication according to embodiments;

Figure 10 is a schematic diagram showing a control unit;

Figure 11 shows one example of a computer program product comprising computer readable means;

Figure 32 schematically illustrates a telecommunication network connected via an intermediate network to a host computer;

Figure 33 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection. DETAILED DESCRIPTION

Aspects of the inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. Aspects of the inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will help convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

In centralized RAN (CRAN) deployments, it is desirable to have the possibility of aggregating traffic from many baseband units (BBU) to many radio units (RU) over a common fronthaul connection, i.e., a shared communication link, and thus benefit from aggregation gains because of statistical multiplexing.

Statistical multiplexing refers to when many BBU communicate with many RU over a common link and the statistical risk of overprovisioning is assessed. This requires a method to cap utilization by controlling BBU resource allocation. If that method is adapted to be dynamic it can also be used when a link with variable capacity is assumed.

To be able to do that, transport over the fronthaul link must be resilient to occasional packet drops due to temporary overuse of the shared fronthaul link. Furthermore, if the shared fronthaul link has a variable capacity, as will be the case if the shared fronthaul link is implemented as a wireless microwave point-to-point link, then the transport over the fronthaul link must be able to cope with a variable data transmission capacity of the shared communication link.

To provide fronthaul communication which is resilient to both packet drops and variable data transmission capacity of the shared communication link, it is proposed herein to make BBUs at least indirectly aware of a current data transmission capacity of the shared communication link, and use the capacity information to control scheduling and resource allocation in the BBUs to avoid temporary overuse of data transmission capacity of the shared communication link.

Fig. 1 shows a schematic view of a communication system 100 comprising fronthaul communication according to embodiments. A connection to a core network 110 is operable to receive and to transmit data, optionally via a switch 120, to one or more baseband units 130a, 130b, 130c. The baseband units manage tasks like resource allocation, user scheduling, and the link. The baseband units are arranged to communicate with wireless devices 185. The communication system 100 uses a fronthaul link 150 to connect the baseband units to one or more radio units 180a, 170b, 170c. In the example shown in Fig. 1 , this connection between baseband units and radio units is via first and second shared communication link transceivers 140, 160, which are arranged to provide data transport over a shared communication link 150. Thus, the baseband units communicate with radio units using shared communications resources. This set-up is advantages, for instance in that statistical multiplexing gains are obtained. Since it is highly unlikely that all baseband units generate data for transmission at maximum rate at the same time, the shared communication link 150 can be provisioned for data transport at a lower capacity. This way, dedicated optical fiber may not be necessary for the fronthaul transport. Instead, a common set of optical fibers, and/or a common set of microwave radio links can be used, where the set of fibers or radio links may only comprise a single fiber or a single radio link. In summary, Fig. 1 illustrates a wireless communication system 100 comprising fronthaul communication between one or more baseband units 130a, 130b, 130c and at least one radio unit 170a, 170b, 170c over a shared communication link 150. The shared communication link is arranged between a first shared communication link transceiver 140 connected to the one or more baseband units 130a, 130b, 130c and a second shared communication link transceiver 160 connected to the at least one radio unit 170a, 170b, 170c. The wireless communication system 100 is arranged for wireless communication 180 between the radio units 170a, 170b, 170c and one or more wireless devices 185 using radio transmission resources.

A drawback of statistical multiplexing is that there may be times when traffic load at all baseband units is high, in which case the requirements on the fronthaul connection may exceed its capacity. If this happens data transmission over the fronthaul link will experience blockage, and data packets will either be queued for a long time or will be dropped. The same thing may happen if the fronthaul connection has a variable capacity, as will be the case if the shared communication link 150 is implemented by a microwave point-to-point wireless link. For instance, a microwave link may implement adaptive modulation, which, in case of signal degradation due to, e.g., rain, will reduce a spectral efficiency of communication, which in turn reduces transmission capacity in terms of bits/sec or packets/sec. To cope with such scenarios, and provide a robust fronthaul connection using a shared communication link with variable capacity, the communication system 100 is arranged to obtain 145 information associated with a current data transmission capacity of the shared communication link 150, and to allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link 150 at or below the current data transmission capacity of the shared communication link 150.

According to an example, the shared communication link transceivers 140, 160, may detect a fall in signal quality, such as a reduced signal to noise ratio, which may necessitate a reduction in spectral efficiency of communication over the shared communication link 150. The communication link transceivers 140, 160, may then report this reduced spectral efficiency to, e.g., the baseband units, which can accommodate the reduced capacity by re-allocating communication resources. For instance, baseband units may limit the frequency or time resources used for communication with the wireless devices 185. The communication system is then arranged to generate data for transmission over the shared communication link based on the allocated radio transmission resources. In configured correctly, the generated amount of data is not in excess of the current transport capacity of the shared communication link 150.

It is appreciated that the shared communications link 150 may comprise any of a single microwave link, a group of aggregated or bonded microwave links, or an in- band cellular backhaul communications link.

It is furthermore appreciated that the shared communications link may comprise one or more wireless links, optionally bonded or forming an aggregation group. The shared communications link may furthermore comprise both wireline and wireless links, bonded together or forming an aggregation group.

Fig. 2 is a flowchart illustrating methods described herein, which, e.g., the communication system in Fig. 1 may execute.

There is shown a method for providing fronthaul communication between one or more baseband units 130a, 130b, 130c and at least one radio unit 170a, 170b, 170c in a wireless communication system 100, over a shared communication link 150 arranged between a first shared communication link transceiver 140 connected to the one or more baseband units 130a, 130b, 130c and a second shared communication link transceiver 160 connected to the at least one radio unit 170a, 170b, 170c. The wireless communication system 100 is arranged for wireless communication 180 between the radio units 170a, 170b, 170c and one or more wireless devices 185 using radio transmission resources. The method comprises

obtaining S1 information associated with a current data transmission capacity of the shared communication link 150,

allocating S2 an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link 150 at or below the current data transmission capacity of the shared communication link 150, and

generating S3 data for transmission over the shared communication link based on the allocated radio transmission resources.

According to aspects, the allocating S2 comprises de-allocating S21 a sub-set of radio transmission resources in case a current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link 150 in excess of the current data transmission capacity of the shared communication link 150. In this case the scenario discussed above where the shared communication link

150 is overutilized has occurred. This is then compensated for by de-allocating a sub-set of radio transmission resources. By the de-allocating, the capacity requirements on the fronthaul link goes down, such that it is no longer overutilized. The de-allocation is preferably made before the shared communication link becomes overloaded.

According to aspects, the allocating S2 comprises de-allocating S22 at least part of radio transmission resources not used for wireless communication 180 between the at least one radio unit 170a, 170b, 170c and the one or more wireless devices 185. This action is a pre-emptive action. By de-allocating unused resources, room is made on the shared communications link for additional traffic from other BBUs. The radio transmission resources not used for wireless communication may for instance correspond to time-frequency communications resources not assigned for communication, or not scheduled for transmission of data from or to the wireless devices 185.

According to aspects, the allocating S2 comprises de-allocating S23 radio transmission resources used by a first baseband unit by an amount determined based on a fraction of the current data transmission capacity of the shared communication link 150 occupied by transmissions associated with the first baseband unit. This method of de-allocating provides a measure of fairness among the BBUs in the utilization of the shared communications link 150, in that baseband units associated with a large relative utilization of the shared communications link will de-allocate more resources than a baseband unit associated with a smaller relative utilization of the shared communications link. According to an example, the resource de-allocation may be performed as;

If (Maximum available - Currently utilized) < 0, then reduce capacity utilization, where reducing utilization entails;

Calculate own percentage of total utilization p=(Own utilization)/(Currently utilized), and

Reduce=p^*(Maximum available - Currently utilized), where“Maximum available” is now the reduced link speed. In other words, if the shared communications link 150 is over-loaded, then each baseband unit determined its corresponding relative utilization of the link 150, and reduces its own utilization by a corresponding percentage or fraction.

According to another example, knowledge of different traffic service quality levels for traffic constitutes additional capacity distribution criteria. Such criteria may be especially relevant in the context of network slicing.

According to aspects, the allocating S2 comprises allocating S24 additional radio transmission resources only if the current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link 150 below the current data transmission capacity of the shared communication link 150. According to aspects, the allocating S24 of additional radio transmission resources comprises allocating resources corresponding to a pre-determ ined fraction of the difference between the current data transmission capacity and a currently utilized data transmission capacity of the shared communication link. In other words, the maximum increase in capacity allocation by any BBU is lncrease=r*(Maximum available - Currently utilized), where r is a parameter 1 >r >1/N (N is the number of base band units) based on an acceptable risk of causing overuse or overloading of the shared communications link 150.

According to aspects, the radio transmission resources used for communication with the one or more wireless devices 185 comprises any of a time resource, a frequency resource, a code resource, and a power resource.

These resources are assigned or scheduled for transmission to and from the wireless devices 185 by, e.g., the BBUs 130a, 130b, 130c, or by an external control unit 190a, 190b. In case a sub-set of such resources are not assigned for transmission, or not scheduled, then the load on the fronthaul link, i.e., the shared communications link 150, goes down.

According to other aspects, the radio transmission resources used for communication with the one or more wireless devices 185 comprises any of a spatial communication resource, an antenna beam resource, and an antenna array element resource. These communications resources are comprised in advanced antenna systems (AAS), and are used to increase throughput in wireless networks according to known techniques. For instance, multiple-input multiple-output (MIMO) is a technique which can increase throughput in cellular systems by providing spatial multiplexing. However, using such AAS features increases the load on the fronthaul link, which is a drawback. Consequently, by not using such advanced features the fronthaul load can be reduced. As an example, consider a system which uses eight antenna elements for communication with a wireless device. All eight antenna elements require signal feed, so the fronthaul load is approximately eight times that of a single antenna system, at least if no advanced compression methods are applied. In case of, e.g., rain causing reduced capacity over the shared communications link 150, the system may skip using four of the antenna elements, and only operate using the remaining four antenna elements. By doing this the fronthaul load is cut in half, approximately, which can compensate for the reduced throughput over the shared communication link. When the rain stops, the system may revert back to full antenna usage.

According to other aspects, the radio transmission resources used for communication with the one or more wireless devices 185 comprises a quantization resolution resource in terms of number of bits per data sample communicated over the shared communication link 150.

Similar to the examples discussed above, quantization can be used to vary the load on the fronthaul link, i.e., the shared communications resource 150. Suppose each of the eight antenna elements are fed by signal samples at a resolution of 12 bits/sample. This relatively high resolution allows for accurate digital representation of transmitted and received radio signals, which in turn may allow for a high spectral efficiency for the radio transmission over the air to wireless devices 185. Should the shared communications link risk overloading, the quantization may be reduced to, e.g., 8 bits/sample. This reduction in quantization resolution would result in approximately 30% reduction in traffic load over the shared communication link 150. The information communicated from the shared communication link transceivers may vary according to different aspects, for instance, the information from a shared communication link transceiver 140, 160 associated with a current data transmission capacity of the shared communication link 150 may comprise any of; a current data throughput in terms of bits/second, an error rate associated with data transport via the shared communication link 150, an error condition associated with one or more components of the shared communication link 150, and a fading condition associated with the shared communication link 150.

It is appreciated that the above discussed methods, in particular the obtaining S11 and/or the allocating S25 may according to some aspects be performed by the one or more baseband units 130a, 130b, 130c shown in Fig. 1 .

It is furthermore appreciated that the communication system, according to aspects, comprises one or more centralized control units 190a, 190b. The obtaining S12 and/or the allocating S26 may then be at least partially performed by the one or more centralized control units 190a, 190b.

Fig. 3a is a schematic diagram showing a control unit 190a, 190b, 310 arranged to configure fronthaul communication between one or more baseband units 130a, 130b, 130c and at least one radio unit 170a, 170b, 170c in a wireless communication system 100, over a shared communication link 150 arranged between a first shared communication link transceiver 140 connected to the one or more baseband units 130a, 130b, 130c and a second shared communication link transceiver 160 connected to the at least one radio unit 170a, 170b, 170c. The wireless communication system 100 is arranged for wireless communication 180 between the radio units 170a, 170b, 170c and one or more wireless devices 185 using radio transmission resources. Thus, the control unit 310 is arranged to configure fronthaul communication such as discussed above in connection to Fig. 1 and Fig. 2.

The control unit comprises;

an obtaining unit Sa1 configured to obtain information associated with a current data transmission capacity of the shared communication link 150,

a resource allocation unit Sa2 arranged to allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link 150 below the current data transmission capacity of the shared communication link 150, and

a transmission unit Sa3 arranged to generate data for transmission over the shared communication link based on the allocated radio transmission resources.

Fig. 3b is a schematic diagram showing a baseband unit 130a, 130b, 130c, 320 arranged for fronthaul communication with at least one radio unit 170a, 170b, 170c in a wireless communication system 100, over a shared communication link 150. The baseband unit comprises

an obtaining unit Sb1 configured to obtain information associated with a current data transmission capacity of the shared communication link 150,

a resource allocation unit Sb2 arranged to allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link 150 below the current data transmission capacity of the shared communication link 150, and

a transmission unit Sb3 arranged to generate data for transmission over the shared communication link based on the allocated radio transmission resources.

Consequently, the baseband unit 320 is arranged to perform the various functions discussed in connection to Fig. 1 and Fig. 2 above.

Fig. 3c is a schematic diagram showing a communication link transceiver 140, 160, 330 arranged for fronthaul communication with a corresponding shared communication link transceiver in a wireless communication system 100, over a shared communication link 150. The shared communication link transceiver comprises

a capacity determining unit Sc1 arranged to determine information associated with a current data transmission capacity of the shared communication link 150,

a capacity reporting unit Sc2 arranged to report the determined information to a control unit of the wireless communications system, and

a transceiver Sc3 arranged to transmit and receive data over the shared communication link at the current data transmission capacity.

Thus, the communication link transceiver illustrated in Fig, 3c corresponds to the shared communication link transceivers discussed above in connection to Fig. 1 and Fig. 2.

In order to provide more detail about the proposed novel techniques, and to discuss differences between the proposed techniques and known technology, prior art will now be discussed. Figs. 4-6 show schematic views of communication systems comprising fronthaul communication according to prior art.

The dominating fronthaul transport technology for today’s 3G and 4G access networks is CPRI, or the more recently developed eCPRI. CPRI supports mainly transport of the digitized complex base band antenna signals, i.e., except for frequency translation, filtering and equalization, CPRI carries a replica of the signal fed to the antenna and received by the antenna. CPRI supports a point to point connection over a link with fixed bandwidth and have strict requirements on latency and delay variations microwave radio links have been used for CPRI fronthaul connections but since full capacity must be guaranteed always, link dimensioning is very demanding and challenging. A CPRI based system is illustrated in Fig. 4

With the advent of 5G, the usage of advanced antenna systems is expected to increase. This means that, in addition to increasing the channel bandwidth, beam forming spatial orthogonality will be heavily exploited to increase capacity in the access network. This implies feeding separate antenna signals to up to more than 1000 individual antenna elements, each requiring higher capacity than current 4G RUs. To handle this explosion in fronthaul bandwidth, new functional splits between base band units and radio units have been suggested as depicted in Fig. 5. Flere, data over the fronthaul interface 450a, 450b, 450c is mainly transported per beam direction and the synthesis of antenna signal per antenna element takes place in the radio unit. To handle this, there is also a need for extensive control signaling between the base band unit and the radio unit. Furthermore, the bandwidth required for control and data signaling depends closely on the user utilization of the access network and can vary heavily over time.

All this together speaks in favor of packet transport fronthaul and this has also been specified in eCPRI v1.0. eCPRI is an initiative handled by the very same community as CPRI. eCPRI is not depending on the new functional split, it also supports packet transport of digital base band data corresponding to current CPRI.

Since eCPRI can be carried over, e.g., Ethernet, also bridged connections as shown in Fig. 6 can be used.

Over a microwave link, capacity can be reduced to maintain connectivity during periods when the radio channel is affected by fading. For short hops and high frequencies, it’s mainly rain which is causing fading.

Since the provided capacity must always match the requirement, current CPRI do not support dynamic changes in capacity over the fronthaul link and it’s therefore not possible to use Adaptive Modulation over a CPRI fronthaul microwave link.

This makes dimensioning of the microwave link both demanding and challenging in this case.

In the eCPRI case it should be possible to sustain transport over the fronthaul link also when capacity is reduced if the link is not fully utilized. The problem is that there is no scheme like QoS for backhaul if link capacity would be exceeded. This is also the case for a bridged fronthaul network during temporary overuse even if the link capacity does not vary.

Figs. 7-9 show schematic views of communication systems comprising fronthaul communication according to embodiments.

Figure 7 illustrates a case where three base band units are connected to three radio units and share a common fronthaul link. We assume here that the capacity provided by the common link is less than the aggregated capacity of the base band units. A possible realization could then be;

Any base band unit shall always deallocate resources not used

The maximum increase in capacity allocation by any base band unit is o lncrease=r^*(Maximum available - Currently utilized), where r is a parameter 1 >r >1/N (N is the number of base band units) based on an acceptable risk of causing overuse. Figure 8 shows an alternative realization where a centralized function executes the control functionality. This could be the preferred implementation in a SDN based network.

The method suggested provides multiple advantages:

• Overuse of the fronthaul link is avoided by avoiding allocation of resources. This means eschewing complicated exception handling due to dropped packets.

• Usability of microwave as a fronthaul solution is improved. The user experience is greatly improved during congestion during periods when the capacity is reduced due to e.g. rain and synchronization and control signaling over the fronthaul link is maintained.

• The method is suitable both for local control and centralized software defined networking (SDN) type of implementations. In Figure 9 the fronthaul link may have a variable throughput or variable transport capacity in terms of, e.g., bits/sec. This means that overuse of the link can be caused by a capacity reduction due to e.g. rain. This means that an additional step must be executed to reduce resource utilization in that case. According to an example;

- If (Maximum available - Currently utilized) < 0 then reduce capacity utilization according to the following:

Calculate own percentage of total utilization p=(Own utilization)/(Currently utilized) Reduce=p^*(Maximum available - Currently utilized) where“Maximum available” is now the reduced link speed.

Figure 10 is a schematic diagram showing a control unit, such as a control unit arranged to control a base band unit like those discussed above, or a control unit arranged to control a shared communication link transceiver like those discussed above. The control unit 1000 comprises processing circuitry 1010, and optional communications interface 102 and storage medium 1030.

Figure 11 shows one example of a computer program product 1110 comprising a computer program 1120, and a computer readable storage medium 1130 on which the computer program is stored. The computer program 1120 is configured for providing fronthaul communication between one or more baseband units 130a, 130b, 130c and at least one radio unit 170a, 170b, 170c in a wireless communication system 100, over a shared communication link 150 arranged between a first shared communication link transceiver 140 connected to the one or more baseband units 130a, 130b, 130c and a second shared communication link transceiver 160 connected to the at least one radio unit 170a, 170b, 170c, wherein the wireless communication system 100 is arranged for wireless communication 180 between the radio units 170a, 170b, 170c and one or more wireless devices 185 using radio transmission resources, the computer program comprising computer code which, when run on processing circuitry 1010 of a control unit 1000, causes the control unit 1000 to:

obtain information associated with a current data transmission capacity of the shared communication link 150,

allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link 150 below the current data transmission capacity of the shared communication link 150, and

generate data for transmission over the shared communication link based on the allocated radio transmission resources.

In the example of Fig. 11 , the computer program product 1010 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu- Ray disc. The computer program product 1010 could also be embodied as a memory, such as a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1020, is here schematically shown as a track on the depicted optical disk, the computer program 1020, can be stored in any way which is suitable for the computer program product 1010.

Fig. 32 schematically illustrates a telecommunication network connected via an intermediate network to a host computer. The wireless devices shown in Fig. 32 as 3291 and 3292 correspond to wireless devices 185 discussed above. The radio transmitters 3212a, 3212b, 3212c correspond to radio heads and baseband units. The fronthaul link, i.e., the shared communication link 150 is integrated in the schematically illustrated radio transmitters 3212a, 3212b, 3212c. Thus, an information stream comprising data passing between a host node 3230, such as a data server, and wireless device 3291 , 3292, will traverse the fronthaul system discussed above.

Fig. 33 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection. The fronthaul system discussed above is, according to aspects, part of the base station 3320.

Claims

1. A method for providing fronthaul communication between one or more baseband units (130a, 130b, 130c) and at least one radio unit (170a, 170b, 170c) in a wireless communication system (100), over a shared communication link (150) arranged between a first shared communication link transceiver (140) connected to the one or more baseband units (130a, 130b, 130c) and a second shared communication link transceiver (160) connected to the at least one radio unit (170a, 170b, 170c), wherein the wireless communication system (100) is arranged for wireless communication (180) between the radio units (170a, 170b, 170c) and one or more wireless devices (185) using radio transmission resources, the method comprising;

obtaining (S1 ) information associated with a current data transmission capacity of the shared communication link (150),

allocating (S2) an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link (150) at or below the current data transmission capacity of the shared communication link (150), and

generating (S3) data for transmission over the shared communication link based on the allocated radio transmission resources.

2. The method according to claim 1 , wherein the allocating (S2) comprises de-allocating (S21 ) a sub-set of radio transmission resources in case a current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link (150) in excess of the current data transmission capacity of the shared communication link (150).

3. The method according to any previous claim, wherein the allocating (S2) comprises de-allocating (S22) at least part of radio transmission resources not used for wireless communication (180) between the at least one radio unit (170a, 170b, 170c) and the one or more wireless devices (185).

4. The method according to any previous claim, wherein the allocating (S2) comprises de-allocating (S23) radio transmission resources used by a first baseband unit by an amount determined based on a fraction of the current data transmission capacity of the shared communication link (150) occupied by transmissions associated with the first baseband unit.

5. The method according to any previous claim, wherein the allocating (S2) comprises allocating (S24) additional radio transmission resources only if the current radio transmission resource allocation corresponds to a data transmission utilization of the shared communication link (150) below the current data transmission capacity of the shared communication link (150).

6. The method according to claim 5, wherein the allocating (S24) of additional radio transmission resources comprises allocating resources corresponding to a pre-determined fraction of the difference between the current data transmission capacity and a currently utilized data transmission capacity of the shared communication link.

7. The method according to any previous claim, wherein the radio transmission resources used for communication with the one or more wireless devices (185) comprises any of a time resource, a frequency resource, a code resource, and a power resource.

8. The method according to any previous claim, wherein the radio transmission resources used for communication with the one or more wireless devices (185) comprises any of a spatial communication resource, an antenna beam resource, and an antenna array element resource.

9. The method according to any previous claim, wherein the radio transmission resources used for communication with the one or more wireless devices (185) comprises a quantization resolution resource in terms of number of bits per data sample communicated over the shared communication link (150).

10. The method according to any previous claim, wherein the shared communication link comprises one or more wireless radio links.

11. The method according to any previous claim, wherein the shared communication link comprises one or more wireline links.

12. The method according to any previous claim, wherein the information from a shared communication link transceiver (140, 160) associated with a current data transmission capacity of the shared communication link (150) comprises any of; a current data throughput in terms of bits/second, an error rate associated with data transport via the shared communication link (150), an error condition associated with one or more components of the shared communication link (150), and a fading condition associated with the shared communication link (150).

13. The method according to any previous claim, wherein the obtaining

(S11 ) and/or the allocating (S25) is performed by the one or more baseband units (130a, 130b, 130c).

14. The method according to any of claims 1 -12, wherein the communication system comprises one or more centralized control units (190a, 190b), wherein the obtaining (S12) and/or the allocating (S26) is performed by the one or more centralized control units (190a, 190b).

15. A computer program (1120) for providing fronthaul communication between one or more baseband units (130a, 130b, 130c) and at least one radio unit

(170a, 170b, 170c) in a wireless communication system (100), over a shared communication link (150) arranged between a first shared communication link transceiver (140) connected to the one or more baseband units (130a, 130b, 130c) and a second shared communication link transceiver (160) connected to the at least one radio unit (170a, 170b, 170c), wherein the wireless communication system (100) is arranged for wireless communication (180) between the radio units (170a, 170b, 170c) and one or more wireless devices (185) using radio transmission resources, the computer program comprising computer code which, when run on processing circuitry (1010) of a control unit (1000), causes the control unit (1000) to:

obtain information associated with a current data transmission capacity of the shared communication link (150),

allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link (150) below the current data transmission capacity of the shared communication link (150), and

16. A computer program product (1110) comprising a computer program (1120) according to claim 15, and a computer readable storage medium (1130) on which the computer program is stored.

17. A control unit (190a, 190b, 310) arranged to configure fronthaul communication between one or more baseband units (130a, 130b, 130c) and at least one radio unit (170a, 170b, 170c) in a wireless communication system (100), over a shared communication link (150) arranged between a first shared communication link transceiver (140) connected to the one or more baseband units (130a, 130b, 130c) and a second shared communication link transceiver (160) connected to the at least one radio unit (170a, 170b, 170c), wherein the wireless communication system (100) is arranged for wireless communication (180) between the radio units (170a, 170b, 170c) and one or more wireless devices (185) using radio transmission resources, the control unit comprising;

an obtaining unit (Sa1 ) configured to obtain information associated with a current data transmission capacity of the shared communication link (150),

a resource allocation unit (Sa2) arranged to allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link (150) below the current data transmission capacity of the shared communication link (150), and a transmission unit (Sa3) arranged to generate data for transmission over the shared communication link based on the allocated radio transmission resources.

18. A baseband unit (130a, 130b, 130c, 320) arranged for fronthaul communication with at least one radio unit (170a, 170b, 170c) in a wireless communication system (100), over a shared communication link (150), the baseband unit comprising;

an obtaining unit (Sb1 ) configured to obtain information associated with a current data transmission capacity of the shared communication link (150),

a resource allocation unit (Sb2) arranged to allocate an amount of radio transmission resources based on the obtained information, wherein the allocated amount corresponds to a data transmission utilization of the shared communication link (150) below the current data transmission capacity of the shared communication link (150), and

a transmission unit (Sb3) arranged to generate data for transmission over the shared communication link based on the allocated radio transmission resources.

19. A communication link transceiver (140, 160, 330) arranged for fronthaul communication with a corresponding shared communication link transceiver in a wireless communication system (100), over a shared communication link (150), the shared communication link transceiver comprising;

a capacity determining unit (Sc1 ) arranged to determine information associated with a current data transmission capacity of the shared communication link (150), a capacity reporting unit (Sc2) arranged to report the determined information to a control unit of the wireless communications system, and

a transceiver (Sc3) arranged to transmit and receive data over the shared communication link at the current data transmission capacity.