WO2014139562A1

WO2014139562A1 - Scalable bandwidth design for ofdm

Info

Publication number: WO2014139562A1
Application number: PCT/EP2013/055152
Authority: WO
Inventors: Kari Pekka Pajukoski; Esa Tapani Tiirola
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2013-03-13
Filing date: 2013-03-13
Publication date: 2014-09-18

Abstract

An apparatus comprises a baseband processing arrangement for block based signals, said arrangement configured to use a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

Description

Title SCALABLE BANDWIDTH DESIGN FOR OFDM

This disclosure relates to methods and apparatus and in particular but not exclusively to apparatus and methods for use with OFDMA (orthogonal frequency division multiple access) or other block based processing based methods.

Communication of control information and data can be provided between two or more devices such as fixed or mobile communication devices, base stations, servers, machine type devices, and/or other communication nodes. A communication system and compatible communicating devices typically operate in accordance with a given standard and/or specification setting out how various entities of the system shall operate. Communications may take be provided on fixed or wireless connections. In a wireless system at least a part of the communication between at least two devices, or stations occurs over a wireless interface. Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access). A more particular example of wireless communication systems is an architecture standardized by the 3rd Generation Partnership Project (3GPP). This system is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. A further development of the LTE is often referred to as LTE-Advanced. Further developments are being contemplated.

In a wireless system a communication device can provide a transceiver station that can communicate with another communication device such as e.g. base stations of access networks and/or other user equipment. A communication device of a user is often referred to as user equipment (UE) or terminal. A communication device is provided with an appropriate signal receiving and transmitting arrangement for enabling communication of data and signalling with other parties. For example, access to a communication network or communications directly with other users can be provided. The communication device may access a wider communication system via an access point such as a base station, for example a base station providing at least one cell. Orthogonal frequency division multiplexing (OFDM) is a possible modulation scheme for wireless communications. OFDM is a technique where a number of spaced subcarriers are modulated instead of a single carrier being modulated. In OFDM systems, OFDM subcarrier spacing should be as small as possible to minimize the relative cyclic prefix overhead in the system. On the other hand, too small subcarrier spacing can increase the sensitivity of the OFDM transmission to Doppler spread and different kinds of frequency inaccuracies.

Orthogonal frequency division multiple access (OFDMA) provides a multi-user OFDM that allows multiple access on the same channel comprising a group of spaced subcarriers. OFDMA distributes subcarriers among users so that they can transmit and receive at the same time within a single channel. Different types or formats of OFDMA can be provided. For example, cyclic prefix OFDMA (CP-OFDMA) and zero padding OFDMA (ZP-OFDMA) are possible. In CP-OFDMA, a cyclic prefix (CP) is added at the transmitter before symbols. The cyclic prefix is then discarded at the receiver end to avoid interblock interference. In ZP-OFDMA a zero signal is transmitted between OFDMA symbols instead of a cyclic prefix.

According to an aspect, there is provided an apparatus comprising: a baseband processing arrangement configured to process block based signals, said arrangement configured to use a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

The said first carrier frequency range and said at least one other different carrier frequency range may be in a range in which a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range

According to another aspect, there is provided an apparatus comprising a base band processing arrangement configured to process block based signals over a range of carrier frequencies, wherein a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

The range of carrier frequencies may comprise a first carrier frequency range and at least one different carrier frequency range, wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range. The arrangement may be configured to use a first baseband processing block size for said first carrier frequency range and said at least one different carrier frequency range.

It should be appreciated that one or more of the following may be used with one or other or both of the above aspects.

The range of frequencies can be any suitable range. In some embodiments, the range of frequencies may be of the order of GHz. In some embodiments, the first frequency range may comprise LTE frequencies. The first frequency range may be of the order of 2GHz. In some embodiments, at least one different frequency range may be at at least an order of magnitude different.

The first frequency range and at least one different frequency range may be such that a carrier spacing and/or bandwidth usable with the first frequency range would not give acceptable performance if used with

The baseband processing block size may be a fast Fourier transform block size. The fast Fourier transform block size may be 2048 or 4096.

The first frequency range may have a first subcarrier spacing and a first carrier bandwidth and the or each different frequency range may have a respective different subcarrier spacing and a different carrier bandwidth.

The first subcarrier spacing may be lower than the or each different subcarrier spacing and the first carrier bandwidth may be lower than the or each different bandwidth.

A cyclic prefix length in time may decrease as a carrier bandwidth and/or carrier frequency increases.

A cyclic prefix length in samples may be the same for said first frequency range and said at least one different carrier frequency range.

A subcarrier length in time may decrease as at least one of a carrier bandwidth and/or carrier frequency increases.

The first carrier frequency range may be adjacent to the or one of said at least one different frequency range.

The first frequency range and said at least one different frequency range may be associated with a same number of effective subcarriers.

A sub frame length of the first carrier frequency range may be the same as a sub frame length of said at least one different frequency range.

A number of symbols in a sub frame of the first carrier frequency range may be the same as a number of symbols in a sub frame of said at least one different frequency range. The baseband processing arrangement may comprise a plurality of baseband processing blocks usable both for said first carrier frequency range and at least one of said at least one different carrier frequency range.

The block based signals may comprise at least one of OFDMA, SC -OFDMA (single carrier OFDMA) and DFT-S-OFDMA (discrete Fourier transform spread OFDM).

According to an aspect, there is provided an apparatus comprising: a baseband processing means for processing block based signals, said processing means using a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

According to another aspect, there is provided an apparatus comprising baseband processing means for processing block based signals over a range of carrier frequencies, wherein a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

The range of carrier frequencies may comprise a first carrier frequency range and at least one different carrier frequency range, wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

The processing means may use a first baseband processing block size for said first carrier frequency range and said at least one different carrier frequency range.

It should be appreciated that one of the following may be used with one or other or both of the above aspects.

A cyclic prefix length in time may decrease as a carrier bandwidth and/or carrier frequency increases. A cyclic prefix length in samples may be the same for said first frequency range and said at least one different carrier frequency range.

A number of symbols in a sub frame of the first carrier frequency range may be the same as a number of symbols in a sub frame of said at least one different frequency range.

The baseband processing means may comprise a plurality of baseband processing blocks usable both for said first carrier frequency range and at least one of said at least one different carrier frequency range.

The block based signals may comprise at least one of OFDMA, SC-OFDMA (single carrier OFDMA) and DFT-S-OFDMA (discrete Fourier transform spread OFDM).

A base station or user equipment may comprise an apparatus such as previously described.

According to another aspect, there is provided a method comprising: processing baseband block based signals, said processing using a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

According to another aspect, there is provided method comprising: processing baseband block based signals over a range of carrier frequencies, wherein a sub- carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

The range of carrier frequencies may comprise a first carrier frequency range and at least one different carrier frequency range, wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range. The processing may comprise using a first baseband processing block size for said first carrier frequency range and said at least one different carrier frequency range.

It should be appreciate that one of the following may be used with one or other or both of the above aspects.

The baseband processing block size may be a fast Fourier transform block size.

The fast Fourier transform block size may be 2048 or 4096.

The baseband processing may comprise using a plurality of baseband processing blocks both for said first carrier frequency range and at least one of said at least one different carrier frequency range.

A base station or user equipment may perform any of the methods such as previously described.

A computer program comprising program code means adapted to perform the herein described methods may also be provided. In accordance with further embodiments apparatus and/or computer program product that can be embodied on a computer readable medium for providing at least one of the above methods is provided.

Various aspects and further embodiments are also described in the following detailed description of examples embodying the invention and in the attached claims.

Embodiments will now be described in further detail, by way of example only, with reference to the following examples and accompanying drawings, in which:

Figure 1 shows an example of a communication system wherein below described examples of the invention may be implemented;

Figure 2 shows an example of a communication device;

Figure 3 shows an example of control apparatus for a base station;

Figure 4 shows one example of a three different options supported in some embodiments;

Figure 5 shows a graph of carrier bandwidth against carrier frequency;

Figure 6 shows schematically a baseband receiver; and

Figure 7 shows schematically a baseband transmitter.

In the following certain exemplifying embodiments are explained with reference to a wireless or mobile communication system serving mobile communication devices. Therefore, before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, components thereof, and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described examples.

In a mobile system a mobile communication device is can be provided wireless access via at least one access node such as a base station, a remote radio head or another wireless transceiver node. In Figure 1 base station 20 and a remote radio head 40 are shown to provide wireless access for devices 21 and 36. It is noted that the number of devices can be greater than two. Nodes 20 and 40 are connected for signalling purposes, as indicated by the connection 39. The communications can be provided based on a Multiple Input / Multiple Output (MIMO) antenna arrangement. It is noted that such an arrangement can be provided in various manners, and that Figure 1 is only one example of a multi-antenna system.

A transceiver node such as a base station or a mobile station is typically controlled by at least one appropriate controller so as to enable operation thereof and management of mobile communication devices in communication with the station. The control apparatus can be interconnected with other control entities. In Figure 1 a control apparatus of an access node such as a base station 20 is shown schematically as being provided by block 30. The control apparatus and functions may be distributed between a plurality of control units. In Figure 1 example controller 30 is connected to a wider communications network 35. In some embodiments the controller can be considered to be part of the access node and in other embodiments separate from the access node. In other embodiments, the function of the controller can be divided between two or more different nodes.

Figure 2 shows a schematic, partially sectioned view of a mobile communication device 21 that a user can use for communication. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) such as a mobile phone or what is known as a 'smart phone', a portable computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia, positioning data, other data, and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet.

A wireless communication device is typically provided with at least one data processing entity 23, at least one memory 24 and other possible components 29 for use in software and hardware aided execution of tasks it is designed to perform, including control of communications of information in radio frames with other stations. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 26. Data processing and memory functions provided by the control apparatus of the mobile device to cause control and signalling operations in accordance with certain embodiments of the present invention will be described later in this description.

The user may control the operation of the mobile device by means of a suitable user interface such as key pad 22, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 25, a speaker and a microphone are also typically provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto. The mobile device 21 may receive and transmit signals 28 via appropriate apparatus for receiving and transmitting signals. In Figure 2 transceiver apparatus is designated schematically by block 27. The transceiver may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device. The transceiver apparatus 27 of the device may be configured to provide a Multiple Input / Multiple Output (MIMO) antenna system.

Figure 3 shows an example of a control apparatus 30, for example to be coupled to and/or for controlling a station of a radio service area, for example the station 20 of Figure 1. The control apparatus 30 can be arranged to process and/or control signalling and other communications by mobile communication devices in a service area of a station. The control apparatus can control operation of mobile devices within its service area based on information communicated in accordance with certain embodiments described below, for example for controlling use of ODFMA.

To provide the herein described functions the control apparatus 30 can comprise at least one memory 31 , at least one data processing unit 32, 33 and an input/output interface 34. Via the interface the control apparatus can be coupled to receiver and transmitter apparatus of a base station. The control apparatus 30 can be configured to execute an appropriate software code to provide the control functions.

Some embodiments may be used with one or more so-called next generations of radio systems. These next generation(s) of radio systems are sometimes referred to as beyond 4G (B4G). However, it should be appreciated that embodiments can of course be used with any one or more current standards or any other proposed standard.

It may be an aim of some beyond 4G radio systems to have scalable OFDMA.

Some embodiments provide a scalable OFDMA baseband design which supports a variety of frequency bands and/or related deployment scenarios.

It is considered that a relatively large amount of spectrum may be required in order to meet the high demands of future traffic. Spectrum at frequencies higher than those currently used for mobile broadband may be used alternatively or additionally. These frequencies include frequencies, such as 4 GHz-10GHz (G, H, I bands) and 10GHz-100GHz (J, K, L, M bands). A transmitter operating at relatively high frequencies, for example of the order of tens of Gigahertz may only support a very limited coverage area due to a relatively high penetration loss. Accordingly, a user equipment which is supporting one or more of the higher frequencies may also need to support at least one lower frequency band. The lower frequency band may be used to ensure that the user equipment has a reasonable coverage area. In order to support different frequencies, a user equipment may be required to support multiband radio. In other words, a user equipment may be required to support different frequencies having differing characteristics.

An oscillator's phase noise may need to be taken into consideration as that phase noise may destroy the orthogonality of sub carriers. The phase noise may increase approximately quadratically with carrier frequency. Accordingly, phase noise may be a particular issue with higher carrier frequencies. One way of addressing this problem is by a proper system design with an increased subcarrier spacing for high carrier frequencies. However, this approach of increasing the subcarrier spacing may increase the cyclic prefix overhead. It has been proposed for the implementation of OFDMA to have multiple designs and numerologies in order to support a wide range of carrier frequencies, for example from 2GHz to 100GHz. As previously discussed, in some scenarios, a single user equipment may be required to support at least part of this wide range of frequencies. In some embodiments, it is proposed to re-use the existing numerology and design principles as much as possible for OFDMA at higher frequencies in order to apply a same baseband design for a set of carrier frequencies. Preferably, that set of carrier frequencies is very large and may for example be across the 2GHz-200GHz range.

It should be appreciated that it is not possible to deploy the existing LTE/LTE-A scenarios at higher carrier frequencies, such as from 4-200GHz. One of the reasons is that the current OFDM sub-carrier spacing used by LTE and LTE-A is optimised for use at 2GHz. This means that that the same numerology is not usable at higher frequencies, in some embodiments. The subcarrier spacing of 15 kHz of the LTE and LTE-A may be one limiting factor.

Some embodiments may maximise the commonality with future standards, such as the beyond 4G standards with LTE/LTE-A in order to reuse the same baseband design for a relatively large set of carrier frequencies. Beyond 4G may be part of future releases of LTE-A. By way of example, that set may be from 2 GHz to 100 GHz. It should be appreciated that other embodiments may be used outside this range. For example some embodiments may be used with frequencies lower than 2GHz. Alternatively or additionally some embodiments may be used with frequencies greater than 100GHz. In some embodiments, the range may defined with other start values than 2GHz (greater or less than this value) and/or the range may be defined with other end values other than 100GHz (greater or less than this value). Some embodiments may allow the entire 3GPP ecosystem with a common baseband design to maximise a commonality of different radios designed for different bands.

In some embodiments, an approach to designing a multiple frequency band capable radio modem is provided. Some embodiments allow the use of a same FFT block size for wide range of carrier frequencies and so can be utilized for multiple frequency band capable radio modems. This radio modem may be used in a user equipment and/or an access point such as the base station. Some embodiments may be based on the approach of the single baseband chip. In other words, one base band chip or chipset is able to deal with a range of carrier frequencies. In some embodiments, the OFDM parameters are defined according to a fixed baseband processing block size common to all frequency bands. In some embodiments, this can be achieved such that the subcarrier spacing and carrier bandwidth may be increased with carrier frequency such that the same sized FFT block is used, regardless of the frequency band. In other words the number of FFT samples stays constant. In some embodiments, alternatively or additionally the cyclic prefix overhead (i.e. number of cyclic prefix samples divided by the number payload samples) may be kept constant for the different frequencies.

In one embodiment, a subcarrier spacing and carrier bandwidth is defined as a function of carrier frequency. In some embodiments, a step function may be used. The step function may have a predefined set of subcarrier spacing values. These subcarrier spacing values may be "legal" values. The legal values may be considered to be a predefined set of supported values which are available. The sampling rate is based on the system clock. Reference is made to figure 5 which schematically shows a graph of carrier bandwidth against carrier frequency. As can be seen from this graph, the carrier bandwidth increases stepwise as the carrier frequency increases. The step size may be determined such that a processing system can be operated at the highest carrier frequency. The phase noise may be an issue with higher carrier frequencies and may be compensated by increasing sub-carrier spacing. On the other hand, in some embodiments, to minimize an overall complexity of a system, there are not too many steps. The number of steps may alternatively or additionally be dependent on the device category.

In some embodiments, 15 kHz (sub carrier spacing) /20MHz (bandwidth) is used for up to 3GHz (or 4GHz), 75 kHz 100MHz is used for 3-13 GHz and then 375 kHz/500MHz is used for 13-50GHz. It should be appreciated that these values are by way of example only and different values may be used. The size and/or number of steps may be different in different embodiments. The step size may be dependent on one or more of oscillator phase noise and sub carrier spacing considering the highest carrier frequency of the step.

As can be seen from Figure 5, the carrier bandwidth is increased as a function of carrier frequency. The block size of FFT remains constant following that sub-carrier spacing increasing with carrier frequency (and carrier bandwidth). The increment of carrier bandwith (and sub-carrier spacing) as function carrier frequency is made on step wise manner denoted by stepped line of Figure 5. The step sizes may be defined in dependence on a phase noise effect.

In another embodiment, the base band processing block size is set according an FFT block size of 2048. In other embodiments, a different FFT block size may be used.

In a third embodiment, the carrier bandwidth is fine-tuned by allocating a predefined number of zeros as the inverse FFT (IFFT) input e.g. for both edges of the carrier. The number of zeros is determined by increasing a number of zero-carriers in the input of IFFT if the effective bandwidth is decreasing. If there are multiple carriers on the same frequency band (i.e. carrier aggregation is in use), then an adjustment of the centre frequency of adjacent carriers can be used to control the bandwidth usage.

In another embodiment, the cyclic prefix CP length may be decreased with carrier frequency such that the relationship between the cyclic prefix and the OFDMA symbol length remain the same for multiple frequency bands. The size of CP in samples remains constant (resulting in that CP length in time decreases as a function of bandwidth/carrier frequency).

In another embodiment, the transmission time interval TTI or subframe length may be decreased with carrier bandwidth in such a way that the number of OFDMA symbols per subframe or TTI remains the same for multiple frequencies.

In some embodiments, two or more configuration options may be supported. Reference is made to figure 4 which shows an example where three different options are supported. In a first option, which is the current LTE/LTE-A option, the carrier frequency is around 2GHz. The carrier bandwidth is 20 MHz (x N). N is the number of carriers. For example LTE-A can support 100MHz with N =5. The value of N can be any suitable value.

In a second option, the carrier frequency is around 10 GHz. The carrier bandwidth may be around 100 MHz (xN).

In a third option, the carrier frequency may be around 50GHz. The carrier bandwidth may be around 500 MHz. As described previously, Figure 5 shows one example of a quantization of carrier bandwidths as the function of carrier frequency. The respective example numerologies according are shown Table 1 .

The first column shows the LTE numerology and the second column shows numerology according to one embodiment to increase an LTE carrier bandwidth from 20 MHz to 100 MHz. All numbers related to the baseband operation such as FFT size and the number of symbols per sub-frame remains unchanged compared to LTE.

There may be one or more of the following advantages associated with this approach:

it allows the use of the same baseband design for both carrier bandwidth options (20 MHz and 100MHz);

it allows for the updating of LTE for higher carrier bandwidths and higher carrier frequencies, without any or much modifications to the standardized solutions and related procedures such as Physical channels and modulation (TS 36.21 1 ), Multiplexing and channel coding (TS 36.212) and Physical layer procedures (TS 36.213);

the sub-carrier spacing of 100 MHz carrier may be increased (from 15 kHz to 75 kHz according to this example) such that LTE can be operated at higher carrier frequencies (and use the 100 MHz bandwidth without carrier aggregation). In some embodiments, 100 MHz bandwidth can be obtained by a single FFT. In LTE, 5x20 MHz carrier need to be aggregated which needs 5 FFT.

The third and fourth column of Table 1 shows further examples for extending LTE -based design to support even higher carrier frequencies and bandwidths while keeping FFT/IFFT size unchanged compared to LTE. In those examples, the number of symbols per sub-frame is increased as function of carrier bandwidths.

Table 2 shows another embodiment. This assumes that numerology is first optimized for a 5 GHz carrier frequency and then extended to support higher carrier frequencies and carrier bandwidths. In this example the FFT block size is 4096.

In this specification terms frame and subframe can be used interchangeably and are understood to refer to a frame or a subframe for carrying information, as appropriate in the context.

A frame can be used to carry at least two types of information, typically at least control information and data. Control information in commonly understood to refer to information communicated on the control plane and required for signalling purposes to control the operation of at least one of the nodes involved in the communications. Data, or data plane (or user plane) information, is commonly understood refer to the user data, or content, communicated between the parties. The planes can be for example Layer 1/ Layer 2 (L1/L2) control and data planes.

The various embodiments above can be provided as alternatives or as complementary solutions.

Figure 6 schematically shows a baseband receiver which may be provided in a user equipment or a base station. The baseband receiver has a guard interval removal block 100 which removes the guard period from a received base band signal. The signal output from the guard interval removal block is provided to an FFT block 102 which converts the received time domain signals to the frequency domain. The received signal contains both reference symbols and data symbols. Channel estimation is performed by the channel estimation block 1 10 on the reference signals output by the FFT block 102. Likewise noise estimation is performed by the noise estimation block 1 12 on the reference signals output by the FFT. An equalizer 104 equalizes the output of the FFT block 102 using channel estimation from the channel estimation block 1 10 and the noise estimation block 1 12. Log likelihood values are determined at block 106 from the equalized output of the equalizer 104. These log likelihood values are provided to a forward error correction block 108 for forward error correction to provide decoded bits.

It should be appreciated that other architectures for the base band receiver can be used.

Reference is made to Figure 7 which shows a baseband transceiver with which embodiments can be used. Data which is to be transmitted is in input to an encoder 120 which encodes the data. The encoded data is input to a mapper 122 which maps the data onto the subcarriers. The I FFT 124 transforms the data representation provided by the mapper 122 into the time domain. The CP block 124 adds the cyclic prefix. It should be appreciated that the I FFT function may be performed by an FFT processor.

It should be appreciated that other architectures for the base band transmitter can be used.

It should be appreciated that the baseband receiver and transmitters of Figures 6 and 7 can be used with a wide range of frequencies. The FFT will have the same FFT size for a wide range of frequencies.

It should be appreciated that the above embodiments have been described in relation to OFDMA. It should be appreciated that other embodiments may be used with any other suitable block processing based method. For example, some embodiments may be used with DFT-S-OFDM (discrete Fourier transform-spread-OFDM), which is a single carrier method or SC-OFDMA (single carrier OFDMA)

In some embodiments, the baseband transmitter and/or receiver may be for different frequencies. The selection of the currently used carrier and frequency range may be achieved using computer program code. The supported frequency ranges may be dependent on the device in which the apparatus is provided. For example if the apparatus is in a UE, then a greater range of frequencies may be supported as compared to if the apparatus is provided in a base station.

Alternatively or addtionally, a baseband transmitter and/or receiver design may be reused so that a different apparatus is provided for each frequency band. For example in a UE point, the same baseband modem apparatus may support e.g. 100 MHz bandwidth at 10 GHz and 20 MHz bandwidth at 2.6 GHz. For example in a base station, it may be that there is one frequency range implemented in one baseband modem apparatus. This may be because different frequency ranges may have different coverage areas.

In some embodiment one or more frequencies may fall into different ranges where the different ranges have different bandwidth/subcarrier spacing. In other embodiments, each frequency may fall only into one range.

In some embodiment, the available frequencies may not be continuous. In other words the available frequency ranges may be separated by one or more unavaible frequency ranges.

The required data processing apparatus and functions of a base station apparatus, an access node, a controller, a communication device and any other appropriate station or element may be provided by means of one or more data processors. The described functions at each end may be provided by separate processors or by an integrated processor. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non- limiting examples. The data processing may be distributed across several data processing modules. A data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity can also be provided in the relevant devices. The memory or memories may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

An appropriately adapted computer program code product or products may be used for implementing the embodiments, when loaded or otherwise provided on an appropriate data processing apparatus, for example for causing determinations when, what and where to communicate and communications of information between the various nodes. The program code product for providing the operation may be stored on, provided and embodied by means of an appropriate carrier medium. An appropriate computer program can be embodied on a computer readable record medium. A possibility is to download the program code product via a data network. In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Embodiments of the inventions may thus be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

It is noted that whilst embodiments have been described using terminology of communications system such as those based on the LTE and 3GPP standards, similar principles can be applied to other communication systems. For example, similar principles are applicable to systems where no fixed station equipment is provided but a communication system is provided e.g. by means of a plurality of user equipment, for example in adhoc networks. Also, the above principles can also be used in networks where relay nodes are employed for relaying transmissions between stations. Therefore, although certain embodiments were described above by way of example with reference to certain exemplifying architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. It is also noted that different combinations of different embodiments are possible. It is also noted herein that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution without departing from the spirit and scope of the present invention.

Claims

1. An apparatus comprising:

a baseband processing arrangement for block based signals, said arrangement configured to use a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

2. An apparatus as claimed in claim 1 , wherein said first carrier frequency range and said at least one other different carrier frequency range are in a range in which a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range

3. An apparatus comprising a base band processing arrangement configured to be used with block based signals over a range of carrier frequencies, wherein a sub- carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

4. An apparatus as claimed in claim 3, wherein said range of carrier frequencies comprise a first carrier frequency range and at least one different carrier frequency range, wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

5. An apparatus as claimed in claim 3 or 4, wherein said arrangement is configured to use a first baseband processing block size for said first carrier frequency range and said at least one different carrier frequency range.

6. An apparatus as claimed in claim 1 or 5, wherein the baseband processing block size is a fast Fourier transform block size.

7. An apparatus as claimed in claim 6, wherein said fast Fourier transform block size is 2048 or 4096.

8. An apparatus as claimed in claim 1 or 4 or any claim appended thereto, wherein said first frequency range has a first subcarrier spacing and a first carrier bandwidth and the or each different frequency range has a respective different subcarrier spacing and a different carrier bandwidth.

9. An apparatus as claimed in claim 8, wherein said first subcarrier spacing is lower than the or each different subcarrier spacing and the first carrier bandwidth is lower than the or each different bandwidth.

10. An apparatus as claimed in claim 8 or 9 wherein a cyclic prefix length in time decreases as a carrier bandwidth and/or carrier frequency increases.

1 1. An apparatus as claimed in claim 8 or 9, wherein a cyclic prefix length in samples is the same for said first frequency range and said at least one different carrier frequency range.

12. An apparatus as claimed in any of claims 8 to 1 1 , wherein a subcarrier length in time decreases as at least one of a carrier bandwidth and/or carrier frequency increases.

13. An apparatus as claimed in claim 1 or 4 or any claim appended thereto, wherein said first carrier frequency range is adjacent to the or one of said at least one different frequency range.

14. An apparatus as claimed claim 1 or 4 or any claim appended thereto, wherein said first frequency range and said at least one different frequency range are associated with a same number of effective subcarriers.

15. An apparatus as claimed in claim 1 or 4 or any claim appended thereto, wherein a sub frame length of the first carrier frequency range is the same as a sub frame length of said at least one different frequency range.

16. An apparatus as claimed in any preceding claim wherein a number of symbols in a sub frame of the first carrier frequency range is the same as a number of symbols in a sub frame of said at least one different frequency range.

17. An apparatus as claimed in claim 1 or 4 or any claim appended thereto wherein said baseband processing arrangement comprises a plurality of baseband processing blocks used both for said first carrier frequency range and at least one of said at least one different carrier frequency range.

18. An apparatus as claimed in any preceding claim wherein said block base signals comprise at least one of OFDMA, SC-OFDMA and DFT-S-OFDMA

19. A method comprising: processing baseband block based signals, said processing using a first baseband processing block size for a first carrier frequency range and for at least one other different carrier frequency range wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range.

20. A method as claimed in claim 19, wherein the said first carrier frequency range and said at least one other different carrier frequency range are in a range in which a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

21. A method comprising: processing baseband block based signals over a range of carrier frequencies, wherein a sub-carrier spacing and a corresponding carrier bandwidth is an increasing function of carrier frequency in a stepwise manner over said range.

22. A method as claimed in claim 21 , wherein the range of carrier frequencies comprises a first carrier frequency range and at least one different carrier frequency range, wherein at least one of said at least one different carrier frequency range is higher than said first carrier frequency range and said processing comprises using a first baseband processing block size for said first carrier frequency range and said at least one different carrier frequency range.

23. A method as claimed in claim 19 or 22, wherein the first frequency range has a first subcarrier spacing and a first carrier bandwidth and the or each different frequency range has a respective different subcarrier spacing and a different carrier bandwidth.

24. A method as claimed in claim 23, wherein the first subcarrier spacing is lower than the or each different subcarrier spacing and the first carrier bandwidth is lower than the or each different bandwidth.

25. A computer program comprising program code means adapted to perform the steps of any of claims 19 to 24 when the program is run on a data processing apparatus.