阅读说明：本技术 用于处置无线通信网络中的通信的无线电网络节点、无线装置以及在其中执行的方法 (Radio network node, wireless device and method performed therein for handling communication in a wireless communication network ) 是由 R.巴尔德梅尔 Y-P.E.王 E.达尔曼 S.帕克维尔 J.贝格曼 O.利贝格 于 2018-03-23 设计创作，主要内容包括：本文中的实施例公开了例如一种由无线装置(10)执行以便处置针对无线装置在第二无线通信网络中的通信的方法。第二无线通信网络在频率上的相同带宽上与第一无线通信网络共存,其中第一无线通信网络在上行链路传输中应用频率上的第一偏移。无线装置从无线电网络节点(12、13)接收指示在第二无线通信网络使用频分双工(FDD)的情况下对上行链路传输应用频率上的第二偏移的指示。无线装置进一步对上行链路传输应用频率上的第二偏移,其中第二偏移定义对于子载波相对于第二无线通信网络的子载波栅格的频率上的偏移或定义对于第二无线通信网络的子载波栅格的频率上的偏移。(Embodiments herein disclose, for example, a method performed by a wireless device (10) for handling communications for the wireless device in a second wireless communication network. The second wireless communication network coexists with the first wireless communication network on the same bandwidth on a frequency, wherein the first wireless communication network applies the first offset on the frequency in the uplink transmission. The wireless device receives an indication from the radio network node (12, 13) indicating that a second offset in frequency is applied for uplink transmissions if the second wireless communication network uses Frequency Division Duplexing (FDD). The wireless device further applies a second offset in frequency to the uplink transmission, wherein the second offset defines an offset in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines an offset in frequency for the subcarrier grid of the second wireless communication network.)

1. A method performed by a wireless device for handling communication for the wireless device in a second wireless communication network, wherein the second wireless communication network coexists with a first wireless communication network on a same bandwidth on a frequency, wherein the first wireless communication network applies a first offset on a frequency in an uplink transmission, wherein the method comprises:

-receiving (501), from a radio network node (12, 13), an indication indicating that a second offset in frequency is applied for uplink transmissions if the second wireless communication network uses frequency division duplex, FDD; and

-applying (502) the second offset in frequency for uplink transmissions, wherein the second offset defines an offset in frequency for a subcarrier with respect to a subcarrier grid of the second wireless communication network or defines an offset in frequency for the subcarrier grid of the second wireless communication network.

2. The method according to claim 1, wherein applying (502) the second offset in frequency to uplink transmissions is omitted in case the second wireless communication network uses time division duplex, TDD.

3. The method of any of claims 1-2, wherein the second offset corresponds to the first offset used by the first wireless communication network.

4. The method of any of claims 1-2, wherein the indication indicates omitting the application of the second offset to uplink transmissions.

5. A method performed by a radio network node (13) for enabling communication for a wireless device (10) in a second wireless communication network, wherein the second wireless communication network coexists with a first wireless communication network on a same bandwidth on a frequency, wherein the first wireless communication network applies a first offset on the frequency to uplink transmissions, wherein the method comprises:

-transmitting (513) an indication to the wireless device (10) indicating that a second offset in frequency is applied for uplink transmissions if the second wireless communication network uses frequency division duplex, FDD, wherein the second offset defines an offset in frequency for a subcarrier relative to a subcarrier grid of the second wireless communication network or defines an offset in frequency for the subcarrier grid of the second wireless communication network.

6. The method of claim 5, wherein the indication indicates omitting the application of the second offset to uplink transmissions.

7. The method of claim 5, wherein the second offset corresponds to the first offset used by the first wireless communication network.

8. The method of any of claims 5-7, further comprising:

-determining (511) whether the second wireless communication network uses frequency division duplex, FDD, or time division duplex, TDD.

9. The method of claim 8, wherein the indication is transmitted when FDD is determined to be used and no indication is transmitted when TDD is determined to be used.

10. The method of any of claims 5-9, further comprising:

-determining (512) the second offset.

11. The method of claim 10, wherein the second offset is determined to align the subcarrier grids for the first wireless communication network and the second wireless communication network or to align subcarriers of the first wireless communication network and the second wireless communication network.

12. A wireless device (10) for handling communication for the wireless device (10) in a second wireless communication network, wherein the second wireless communication network is configured to co-exist with a first wireless communication network on a same bandwidth on a frequency, wherein the first wireless communication network is configured to apply a first offset on a frequency in an uplink transmission, and wherein the wireless device (10) is configured to:

receiving an indication from a radio network node (12, 13) indicating that a second offset in frequency is applied for uplink transmissions if the second wireless communication network uses frequency division duplex, FDD; and is configured to

Applying the second offset in frequency to uplink transmissions, wherein the second offset defines an offset in frequency for a subcarrier relative to a subcarrier grid of the second wireless communication network or defines an offset in frequency for the subcarrier grid of the second wireless communication network.

13. The wireless device (10) of claim 12 wherein the wireless device is configured to omit applying the second offset in frequency to uplink transmissions if the second wireless communication network uses time division duplex, TDD.

14. The wireless device (10) of any of claims 12-13, wherein the second offset corresponds to the first offset used by the first wireless communication network.

15. The wireless device (10) of any of claims 12-13, wherein the indication indicates omitting the application of the second offset to uplink transmissions.

16. A radio network node (13) for enabling communication for a wireless device (10) in a second wireless communication network, wherein the second wireless communication network is configured to co-exist with a first wireless communication network on a same bandwidth on a frequency, wherein the first wireless communication network is configured to apply a first offset on a frequency to uplink transmissions, and wherein the radio network node is configured to:

transmitting an indication to the wireless device (10) indicating that a second offset in frequency is applied for uplink transmissions if the second wireless communication network uses frequency division duplex, FDD, wherein the second offset defines an offset in frequency for a subcarrier relative to a subcarrier grid of the second wireless communication network or defines an offset in frequency for the subcarrier grid of the second wireless communication network.

17. The radio network node (13) according to claim 16, wherein the indication indicates omitting applying the second offset to uplink transmissions.

18. The radio network node (13) according to claim 16, wherein the second offset corresponds to the first offset used by the first wireless communication network.

19. The radio network node (13) according to any of claims 16-18, wherein the radio network node (13) is further configured to determine whether the second wireless communication network uses frequency division duplex, FDD, or time division duplex, TDD.

20. The radio network node (13) according to claim 19, wherein the radio network node (13) is configured to: transmitting the indication when FDD is determined to be used; and configured to not transmit an indication when it is determined to use TDD.

21. The radio network node (13) according to any of claims 16-20, wherein the radio network node is configured to determine the second offset.

22. The radio network node (13) according to claim 21, wherein the second offset is determined to align the subcarrier grids for the first and second wireless communication networks or to align subcarriers of the second and first wireless communication networks.

23. A computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of claims 1-11 as performed by the wireless device or the radio network node.

24. A computer-readable storage medium, on which a computer program containing instructions is stored, which when executed on at least one processor causes the at least one processor to carry out the method according to any one of claims 1-11 as performed by the wireless device or the radio network node.

Technical Field

Embodiments herein relate to a radio network node, a wireless device and a method performed therein relating to wireless communication. Further, a computer program and a computer-readable storage medium are provided herein. In particular, embodiments herein relate to handling communication of a wireless device in a wireless communication network.

Background

In a typical wireless communication network, wireless devices (also referred to as wireless communication devices), mobile stations, Stations (STAs), and/or User Equipment (UE) communicate via a Radio Access Network (RAN) with one or more Core Networks (CNs). The RAN covers a geographical area which is divided into service areas or cell areas, with each service area or cell area being served by a radio network node, such as an access node (e.g., a Wi-Fi access point or a Radio Base Station (RBS)), which in some networks may also be referred to as, for example, a "NodeB" or "eNodeB". A service area or cell area is a geographical area in which radio coverage is provided by radio network nodes. The radio network node operates on radio frequencies for communicating over an air interface with wireless devices within range of the radio network node. The radio network node communicates with the wireless device on a Downlink (DL) and the wireless device communicates with the radio network node on an Uplink (UL).

Universal Mobile Telecommunications System (UMTS) is a third generation telecommunications network evolved from the second generation (2G) global system for mobile communications (GSM). UMTS Terrestrial Radio Access Network (UTRAN) is essentially a RAN that uses Wideband Code Division Multiple Access (WCDMA) and/or High Speed Packet Access (HSPA) to communicate with user equipment. In a forum known as the third generation partnership project (3 GPP), telecommunications providers propose and agree upon standards for current and future generations of networks, and research into enhanced data rates and radio capacity. In some RANs, e.g. as in UMTS, several radio network nodes may be connected, e.g. by landlines or microwave, to a controller node, such as a Radio Network Controller (RNC) or a Base Station Controller (BSC), which supervises and coordinates various activities of the plurality of radio network nodes connected to it. The RNCs are typically connected to one or more core networks.

The specification of the Evolved Packet System (EPS) has been completed in 3GPP and the work continues in upcoming 3GPP releases, such as 4G and 5G networks, e.g. new air interfaces (NR). The EPS includes an evolved universal terrestrial radio access network (E-UTRAN), also known as a Long Term Evolution (LTE) radio access network, and an Evolved Packet Core (EPC), also known as a System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a 3GPP radio access technology, where radio network nodes are directly connected to the EPC core network. Thus, the Radio Access Network (RAN) of an EPS has an essentially "flat" architecture comprising radio network nodes directly connected to one or more core networks.

The LTE Uplink (UL) is based on discrete fourier transform spread orthogonal frequency division multiplexing (DFTS-OFDM). The DFTS-OFDM waveform has a lower peak-to-average power ratio (PAPR) than the OFDM waveform, and has been employed for LTE to reduce the required power back-off of the power amplifier and increase power amplifier efficiency.

In direct conversion receivers (most commonly used in wireless devices), Direct Current (DC), local oscillator self-mixing and self-mixing of interference due to transistor mismatch in the signal path result in high unwanted signal components (non-wanted signal components) at the local oscillator frequency, which are converted to DC in baseband. In the LTE Downlink (DL), a null subcarrier (also called DC subcarrier) is introduced that overlaps with DC in order to avoid modulating this subcarrier (due to its low modulation quality). However, for the uplink, this solution is not applicable, since it would compromise the low PAPR of the DFTS-OFDM waveform. In contrast, LTE uplink applicationsSubcarrier shift (shift) (7.5 kHz), theThe subcarrier shift places DC between two subcarriers.

The uplink in the NR supports both OFDM and DFTS-OFDM. Because of the lower PAPR of DFTS-OFDM compared to OFDM waveforms, it has been introduced to support wireless devices with limited coverage and is limited to single layer transmission, while OFDM, which also supports multi-layer transmission, is used in better signal-to-interference-plus-noise ratio (SINR) conditions.

One scenario considered for NR is to enable NR and LTE to coexist on the same bandwidth on frequency, e.g. on overlapping parts of the system bandwidth of NR and LTE systems, or on at least one same frequency band of the system bandwidth. If NR and LTE using a 15kHz parameter set would share the same subcarrier grid, NR and LTE may be deployed on the same frequency and may use unused LTE resource elements for NR (assuming all required signaling is appropriate). In case there is a difference of 7.5kHz in the UL (since LTE applies a shift and NR does not), this is not possible and NR and LTE will have to be separated in time or frequency. NR and LTE can still share the same carrier bandwidth on frequency at the same time, except that a guard band (guard band) is required between the two Radio Access Technologies (RATs); or multiplexing NR and LTE transmissions in the time domain, but this solution is not resource efficient.

Disclosure of Invention

It is an object of embodiments herein to provide a mechanism implemented in a second wireless communication network to enable or to handle communication in a resource efficient manner. For example, a second wireless communication network may be deployed in an efficient manner co-existing with a first wireless communication network.

According to an aspect, the object is achieved by providing a method performed by a wireless device for handling communication for the wireless device in a second wireless communication network. The second wireless communication network coexists with the first wireless communication network on the same bandwidth on a frequency, wherein the first wireless communication network applies a first shift on the frequency in an uplink transmission. The wireless device receives an indication from the radio network node indicating that a second shift in frequency is applied for uplink transmissions if the second wireless communication network uses Frequency Division Duplexing (FDD). The wireless device further applies a second shift in frequency to the uplink transmission, wherein the second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

According to another aspect, the object is achieved by providing a method performed by a radio network node for enabling communication for a wireless device in a second wireless communication network. The second wireless communication network coexists with the first wireless communication network on the same bandwidth on a frequency, wherein the first wireless communication network applies a first shift on the frequency to uplink transmissions. The radio network node transmits an indication to the wireless device indicating that a second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD, wherein the second shift defines a shift in frequency for a subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

Also provided herein is a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method herein as performed by a wireless device or a radio network node. Furthermore, a computer-readable storage medium is provided herein, on which a computer program comprising instructions is stored, which instructions, when executed on at least one processor, cause the at least one processor to carry out the method herein as performed by a wireless device or a radio network node.

According to yet another aspect, the object is achieved by providing a wireless device for handling communication for the wireless device in a second wireless communication network. The second wireless communication network is configured to co-exist with the first wireless communication network over the same bandwidth on a frequency, wherein the first wireless communication network is configured to apply a first shift on the frequency in an uplink transmission. The wireless device is configured to receive an indication from the radio network node indicating that a second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD. The wireless device is also configured to apply a second shift in frequency to the uplink transmission, wherein the second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

According to yet another aspect, the object is achieved by providing a radio network node for enabling communication for a wireless device in a second wireless communication network, wherein the second wireless communication network is configured to co-exist with a first wireless communication network over a same bandwidth over a frequency. The first wireless communication network is configured to apply a first shift in frequency to uplink transmissions. The radio network node is configured to transmit an indication to the wireless device indicating that a second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD, wherein the second shift defines a shift in frequency for a subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

For FDD, cross-link interference does not matter, since the uplink and downlink have their own spectrum, i.e. transmissions in UL and DL are performed on different frequencies. Therefore, it is proposed to shift the UL transmission such that the subcarriers or subcarrier grids of the different wireless communication networks are aligned. This shift can be done in baseband, which is not preferred, since in this case the low modulation quality of the DC frequency will be spread over several sub-carriers; or the shift may be adjusted, e.g., by adjusting the duplex distance between the NR downlink and uplink relative to the LTE duplex distance used in the operating bandSub-carriers (such as 7.5 kHz).

Embodiments herein enable good coexistence in terms of resource-elements over the same bandwidth in frequency (which may be the same carrier bandwidth in some examples) between a second wireless communication network, such as NR using 15kHz wide subcarriers, and a first wireless communication network, such as LTE, without impacting UL performance, particularly if uplink shifting is achieved by adjusting the duplex distance for FDD. Accordingly, embodiments herein provide a resource efficient solution.

For TDD, there are, for exampleSeveral disadvantages of the individual subcarrier shifts, such as difficulty in cancelling cross-link interference, and the low modulation quality of the DC subcarrier may spread over several tones (tones). Thus, for TDD, UL shifting would complicate cross-link interference cancellation and would result in low modulation quality of the DC frequency spread over multiple subcarriers or spread over the need to use two local oscillators, both of which are serious drawbacks. Thus, some embodiments herein propose not to shift the uplink transmission in frequency relative to the downlink, which means that in such embodiments the downlink and uplink share the same carrier frequency, and that the second shift is also not implemented in the baseband. In other words, some embodiments herein avoid these drawbacks by omitting to apply the second shift when TDD is used, at the expense of achieving UL coexistence of different networks such as NR and LTE via guardband or time domain multiplexing.

Embodiments herein show that a second wireless communication network can be deployed in an efficient manner co-existing with a first wireless communication network.

Drawings

Embodiments will now be described in more detail with respect to the disclosed drawings, in which:

fig. 1 shows a schematic overview depicting a wireless communication network according to embodiments herein;

FIG. 2: the NR and LTE UL subcarrier grids are not aligned. The NR subcarrier grid is shown at 15 kHz;

fig. 3 is a flow diagram and signaling scheme (signaling scheme) of an exemplary combination according to embodiments herein;

4a-4b illustrate shifted and unshifted grids of subcarriers;

fig. 5a is a schematic flow diagram according to embodiments herein;

fig. 5b is a schematic flow chart diagram depicting a method performed by a wireless device, according to an embodiment herein;

fig. 5c is a schematic flow chart diagram depicting a method performed by a radio network node according to embodiments herein;

fig. 6 is a block diagram depicting a radio network node according to embodiments herein; and

fig. 7 is a block diagram depicting a wireless device according to embodiments herein.

Detailed Description

Embodiments herein relate generally to wireless communication networks. Fig. 1 is a schematic overview depicting a wireless communication network 1. The wireless communication network 1 includes one or more RANs and one or more CNs. The wireless communication network 1 may use one or more different technologies such as new air interface (NR), Wi-Fi, LTE-Advanced, fifth generation (5G), Wideband Code Division Multiple Access (WCDMA), global system for mobile communications/enhanced data rates for GSM evolution (GSM/EDGE), worldwide interoperability for microwave access (WiMax), or Ultra Mobile Broadband (UMB), to name just a few possible implementations. Embodiments herein relate to recent technological trends of particular interest in the 5G context. However, the embodiments are also applicable to further developments of existing wireless communication systems such as e.g. WCDMA and LTE.

In a wireless communication network 1, wireless devices (e.g., wireless devices 10), such as mobile stations, non-access point (non-AP) STAs, user equipment and/or wireless terminals, communicate with one or more Core Networks (CNs) via one or more Access Networks (ANs) (e.g., RANs). Those skilled in the art will appreciate that "wireless device" is a non-limiting term meaning any terminal, wireless communication terminal, user equipment, Machine Type Communication (MTC) device, device-to-device (D2D) terminal or node, such as a smartphone, laptop computer, mobile phone, sensor, relay, mobile tablet or even a small base station, capable of communicating with a radio network node within an area served by the radio network node using radio communication.

The wireless communication network 1 comprises a first radio network node 12 providing radio coverage over a first Radio Access Technology (RAT), such as LTE, Wi-Fi, WiMAX, or a geographical area (first service area 11) or a first beam of the first wireless communication network. The first wireless communication network may be a broadband network. Depending on e.g. the first radio access technology and terminology used, the first radio network node 12 may be a transmission and reception point, e.g. a radio network node such as a Wireless Local Area Network (WLAN) access point or access point station (AP STA), an access node, an access controller, a base station (e.g. a radio base station such as a NodeB, an evolved node B (eNB, eNodeB), a gnnodeb), a base transceiver station, a radio remote unit, an access point base station, a base station router, a transmission arrangement of radio base stations, a stand-alone access point or any other network unit or node capable of communicating with wireless devices within a service area served by the first radio network node 12. The first radio network node 12 may be referred to as a serving network node, wherein the first serving area may be referred to as a serving beam, and the serving network node serves the wireless device 10 and communicates with the wireless device 10 in the form of DL transmissions to and UL transmissions from the wireless device 10.

The second radio network node 13 may further provide radio coverage over a second Radio Access Technology (RAT), such as NR, LTE, Wi-Fi, WiMAX or a second service area 14 or a second beam of a second wireless communication network. The second wireless communication network may be a narrowband network. The first RAT and the second RAT may be the same or different RATs. Depending on e.g. the second radio access technology and terminology used, the second radio network node 13 may be a transmission and reception point, e.g. a radio network node such as a Wireless Local Area Network (WLAN) access point or access point station (AP STA), an access node, an access controller, a base station (e.g. a radio base station such as a NodeB, an evolved node B (eNB, eNodeB), a gnnodeb), a base transceiver station, a radio remote unit, an access point base station, a base station router, a transmission arrangement of radio base stations, a stand-alone access point or any other network unit or node capable of communicating with wireless devices within an area served by the second radio network node 13.

According to embodiments herein, a first wireless communication network, such as an LTE network, is configured to apply a first shift in frequency for subcarriers of an uplink transmission from one or more wireless devices relative to, for example, a grid of subcarriers used for DL transmissions (also referred to as a subcarrier grid). To enable co-existence in terms of resource-elements with a first wireless communication network, uplink transmissions in a second wireless communication network, such as an NR network using a 15kHz subcarrier bandwidth, are shifted in frequency. Coexistence in terms of resource-elements of the first and second wireless communication networks may occur over the same bandwidth on frequency. The same bandwidth on a frequency may be, for example, an overlapping portion of the system bandwidths of the first and second wireless communication networks, or the first and second wireless communication networks may coexist on at least one same frequency band of the system bandwidth. In some embodiments, the same bandwidth on a frequency may be the same carrier bandwidth of the first and second wireless communication networks.

Thus, embodiments herein disclose that the wireless device 10 transmits by shifting the subcarrier pair of its uplink transmission relative to the subcarrier grid of the second wireless communication network, e.g., byThe subcarriers, or the second shift in frequency is applied by grid shifting the subcarriers of a second wireless communication network, such as an NR network, such that the subcarriers of the different wireless communication networks are aligned. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

This is performed for UL transmission by the wireless device when the second wireless communication network is configured for or uses Frequency Division Duplex (FDD) for UL communication. The second shift in frequency may correspond to the first shift in frequency for the first wireless communication network, i.e. it may be the same shift in frequency as the first shift. This application of the second shift can be done in baseband, which is less preferred, since in this case the low modulation quality of the DC frequency will spread over several sub-carriers; or by correlating the duplex distance between the downlink and uplink grids of the second wireless communication network with respect to the operating frequency bandUsed duplex distance adjustsSub-carriers.

Applications in a second wireless communication network, e.g. an NR networkShifts like subcarrier shifts are acceptable for DFTS-OFDM but may be disadvantageous for OFDM because the low modulation quality of the DC frequency will not be limited to a single subcarrier but spread across multiple subcarriers due to the sine-transfer function of each OFDM tone. Thus, according to some embodiments, the second shift may be selectively applied depending on whether DFTS-OFDM is used for uplink transmission in the second wireless communication network. In some embodiments, to enable a second wireless communication network, such as NR using 15kHz wide subcarriers, to co-exist on the same carrier bandwidth as the first wireless communication network at a per resource element granularity, the second wireless communication network (exemplified by the NR network) and the first wireless communication network (exemplified by LTE) may share the same subcarrier grid. For NR and LTE this may be met for the downlink, but LTE applies e.g. 7.5kHz or LTE in the uplinkSubcarrier shifting, which results in a misaligned subcarrier grid if NR does not apply such shifting, see fig. 2.

Fig. 3 is a flow chart and signaling scheme depicting a schematic combination of some embodiments herein. A first wireless communication network, such as an LTE network, is configured to apply a first shift in frequency to subcarriers of an uplink transmission from one or more wireless devices. It should be noted that embodiments herein encompass the following: when a first wireless communication network is present; and also in the absence of the first wireless communication network. Therefore, even if there is no other wireless communication network for coexistence, the second shift may always be applied for FDD, and may not be applied for TDD.

Act 301 the second radio network node 13 may determine that the second wireless communication network, such as an NR network, uses FDD for transmission to and/or for reception from the wireless device. For example, the second radio network node 13 may determine whether the second wireless communication network (e.g. NR) uses FDD or TDD, e.g. for transmission to and reception from the wireless device.

Action 302 when it is determined that the second wireless communication network uses FDD, the second radio network node 13 determines a second shift in frequency of uplink transmissions from the wireless device. The second shift in frequency is a shift in frequency of the subcarrier relative to the subcarrier grid for the uplink transmission to the second wireless communication network, or the second shift is a shift in frequency of the subcarrier grid for the uplink transmission to the second wireless communication network. The second shift may correspond to the first shift for the first wireless communication network. For example, the second shift may beThe subcarriers are shifted such that the subcarrier grids (also referred to as grids of subcarriers) for the first wireless communication network and the second wireless communication network are aligned. In case the second wireless communication network is the only wireless communication network present, the second radio network node 13 may implement the second shift (via the shifted duplex distance or shift in baseband) based on the FDD decision only. A shift to the subcarrier grid means a duplex distance shift, i.e. a shift to the subcarrier grid obtained by adjusting the duplex distance, and a shift to the subcarrier with respect to the subcarrier grid means a shift in the baseband.

Act 303. the second radio network node 13 may configure the wireless device 10 with the second shift determined for the UL transmission. The second radio network node 13 may for example transmit an indication instructing the wireless device 10 to apply or not apply the second shift to the uplink transmission. The indication may be an index in a table or a value of the second shift in frequency.

Act 304 the wireless device 10 applies a second shift, for example, to the subcarrier grid, for example, as a shift with respect to a duplex distance, or as a shift to the subcarrier grid with respect to the subcarrier grid, for example, as a shift in baseband, for communication in the second wireless communication network using FDD (i.e., using different frequencies in DL and UL transmissions).

Action 305 the second radio network node 13 may then receive and read or decode transmissions from the wireless device 10 in relation to or applying the shifted subcarrier grid or subcarriers shifted with respect to the subcarrier grid. That is, the second radio network node 13 may use the second shift to read or decode the UL transmission from the wireless device 10 and/or may read or decode the UL transmission based on the second shift.

For FDD, taking coexistence between LTE and NR as an example, the second shift may be implemented in two ways: as in LTE, the UL is shifted in basebandA subcarrier; or adjust the duplex distance of NR with respect to that of LTE deployed in the operating band, e.g., by 7.5kHz (kHz)Sub-carriers).

Subcarrier baseband shifting

The second shift may be described as the shift in LTE specification 36.211v.14.0.0 is described by:

wherein:

: number of PRBs in uplink

: subcarriers per PRB

: complex valued modulation symbols

: subcarrier spacing

: length of cyclic prefix in samples

: duration of one sample (chip rate)

Expression formula（Part) is implemented in basebandThe subcarriers are shifted. This may be done for a second wireless communication network such as an NR. In an OFDM system, each subcarrier has a sine-type subcarrier transfer function. Fig. 4a shows an example in which no shift is applied and the DC frequency (0) coincides with subcarrier 0 of the subcarrier grid. FIG. 4b shows a circuit with an implementation in basebandEmbodiments where the sub-carriers are shifted such that the DC frequency (0) is between two sub-carriers. The sine class function indicates the subcarrier transfer function. If the DC frequency coincides with the subcarrier (i.e. no shift is applied, see fig. 4 a), the low modulation quality of the DC frequency (0) is mainly limited to a single tone (subcarrier 0) (since the DC frequency falls on top of the zero of the sine-like function of the adjacent subcarriers). In case of a shift, the DC frequency (0) falls in the middle of two subcarriers (see fig. 4 b), and a low modulation quality compromises multiple subcarriers. Especially for OFDM, it is preferred that the low modulation quality of the DC frequency is limited to a single subcarrier, rather than spread over multiple subcarriers. Therefore, implementing the second shift as a DC subcarrier shift in baseband is not a preferred solution, but is indeed a possibility.

Adjusting duplex distance

In a first wireless communication network, such as LTE, the duplex distance between uplink and downlink may have a default band-specific value or may be signaled as part of system information. In both cases, the duplex distance is always a multiple of 100kHz (i.e., the separation of the uplink and downlink center frequencies).

To achieve alignment between downlink and uplink subcarrier grids, one possibility is to adjust the duplex distance of the second wireless communication network with a second shift, e.g. the NR duplex distance would beOr。

This second shift may be fixed, i.e. the duplex distance for the second wireless communication network may always follow the above formula at least for the frequency band defined for the first wireless communication network. Alternatively, the duplex distance may be configured for the second wireless communication network and the at least one possible configuration value for NR may beOr。

An alternative equation is to have an offset (offset) for the duplex distance for the second wireless communication network. The duplex distance in a given frequency band will for example follow LTE values. At the top of the duplex value, the NR will have an offset of 7.5kHz or-7.5 kHz. The offset may be fixed (e.g., in a specification) or configurable as an example of the second shift.

The shift value of 7.5kHz for NR is 15kHz based on the NR parameter set. If the NR carrier is not operating at 15kHz, there is no need to adjust the duplex distance by 7.5 kHz. However, if the NR carrier operates at 15kHz and another parameter set, it may make sense to apply a shift of 7.5kHz even for the other parameter set. Parameter sets herein cover, for example, the width of the subcarriers and the like.

For TDD, UL shifting may be achieved using a baseband shifting method or using two local oscillators (one in each direction, offset by 7.5 kHz). As outlined in the previous section (see fig. 4 b), for OFDM, baseband shifting has a disadvantage because the low modulation quality of the DC frequency extends across multiple subcarriers. An alternative solution would be to use two local oscillators, however, this would increase the wireless device power consumption and is also not preferred.

NR supports TDD and also dynamic TDD, where the link direction can be dynamically selected. Especially in dynamic TDD, cross-link interference, i.e. downlink-to-uplink interference or vice versa, may occur and cancellation of the cross-link interference may be beneficial. Such cancellation is greatly simplified if the uplink and downlink share a common subcarrier grid. This also applies not to NR TDDYet another reason for subcarrier shifting.

Thus, for NR uplink applications, for exampleSubcarrier shifting is not straightforward. In the absence ofIn case of subcarrier shifting, coexistence in terms of resource-elements between NR and LTE using 15kHz is not possible in UL; using guard bands, NR and LTE may still share the same bandwidth on a frequency, e.g., the same carrier bandwidth on a frequency; or NR and LTE may be multiplexed in the time domain, but such a solution is not resource efficient.

For TDD, none of the technical solutions provide sufficient benefits and therefore are not proposed to enable shifting for TDD. Accordingly, embodiments herein relate to adjusting duplex distance (e.g., including duplex distance) for a second wireless communication network using FDD, e.g., by an offset of 7.5kHz that is fixed or configurableEquation (c)) to realize (e.g.A second shift of subcarriers. Alternatively, the second shift may be implemented in baseband as disclosed herein.

A flow chart describing some embodiments herein is shown in fig. 5 a.

Act 5001. determine whether the second wireless communication network uses FDD or TDD, e.g., at the second radio network node 13 and/or the wireless device 10.

Act 5002. in the case where FDD is used, a second shift is applied to the UL transmission. For TDD, the second shift is not implemented.

In case TDD is used, no shift is used and a guard band is used to separate the first and second wireless communication networks. Thus, the wireless device 10 applies a second shift in frequency to uplink transmissions if the second wireless communication network uses FDD. The wireless device may omit applying the second shift in frequency for uplink transmissions if the second wireless communication network uses TDD.

Whether the second wireless communication network uses FDD may be a decision criterion. The second radio network node 13 may then not need to signal anything to the wireless device 10, since the wireless device 10 knows from the operating frequency band whether the second wireless communication network uses FDD or not.

Method acts performed by the wireless device 10 in order to handle communication for the wireless device in the second wireless communication network according to some embodiments will now be described with reference to the flowchart depicted in fig. 5 b. These actions need not be performed in the order recited below, but may be performed in any suitable order. Acts performed in some, but not necessarily all, embodiments are labeled with dashed boxes. The second wireless communication network coexists with the first wireless communication network on the same bandwidth on frequency. The first wireless communication network applies a first shift in frequency to uplink transmissions.

Act 501 the wireless device 10 receives an indication from the radio network node indicating that a second shift in frequency is applied or used for uplink transmissions if the second wireless communication network uses FDD.

Act 502. the wireless device 10 further applies a second shift in frequency to the uplink transmission, wherein the second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the second wireless communication network.

The wireless device 10 may further omit applying the second shift in frequency for uplink transmissions if the second wireless communication network uses TDD. The second shift may correspond to the first shift used by the first wireless communication network. The indication may indicate to omit applying the second shift to the uplink transmission, e.g., indicate zero may be indicated as the second shift.

Method actions performed by a radio network node, such as the second radio network node 13, for enabling communication for the wireless device 10 in the second wireless communication network according to some embodiments will now be described with reference to the flowchart depicted in fig. 5 c. The actions need not be performed in the order recited below, but may be performed in any suitable order. Acts performed in some, but not necessarily all, embodiments are labeled with dashed boxes. The second wireless communication network coexists with the first wireless communication network on the same bandwidth on frequency. The first wireless communication network applies a first shift in frequency to uplink transmissions.

Action 511 the radio network node may determine whether the second wireless communication network uses FDD or time division duplex, TDD.

Action 512 the radio network node may determine a second shift. For example, the radio network node may determine the second shift to align a grid of subcarriers for the first wireless communication network and the second wireless communication network or to align subcarriers of the second wireless communication network and the first wireless communication network. In some examples, the subcarrier grid may be an uplink subcarrier grid of the first and second wireless communication networks.

Act 513 the radio network node transmits an indication to the wireless device 10 indicating that the second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD. The second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. The indication may indicate that the second shift is omitted from being applied to the uplink transmission. The second shift may correspond to the first shift used by the first wireless communication network. The indication may be transmitted when FDD is determined to be used, and may not be transmitted when TDD is determined to be used.

Fig. 6 is a block diagram depicting, in two embodiments, a radio network node, such as the second radio network node 13, for enabling communication in a second wireless communication network for the wireless device 10, according to embodiments herein. The second wireless communication network is configured to co-exist with the first wireless communication network over the same bandwidth on a frequency, wherein the first wireless communication network is configured to apply a first shift on the frequency to uplink transmissions.

The second radio network node 13 may comprise processing circuitry 1201, e.g. one or more processors, configured to perform the methods herein.

The second radio network node 13 may comprise a determining module 1202. The second radio network node 13, the processing circuitry 1201 and/or the determining module 1202 may be configured to determine whether the second wireless communication network uses Frequency Division Duplex (FDD) or Time Division Duplex (TDD). The second radio network node 13, the processing circuitry 1201 and/or the determination module 1202 may be configured to determine whether the second wireless communication network uses FDD. The second radio network node 13, the processing circuit 1201 and/or the determining module 1202 may be configured to determine the second shift. A grid of subcarriers used to align for the first wireless communication network and the second wireless communication network or subcarriers used to align the first wireless communication network and the second wireless communication network may be determined.

The second radio network node 13 may comprise a transmitting module 1203, e.g. a transmitter or a transceiver. The second radio network node 13, the processing circuitry 1201 and/or the transmitter and/or transmitting module 1203 are configured to transmit an indication to the wireless device 10 indicating that the second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD. The second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. For example, the second radio network node 13, the processing circuitry 1201 and/or the transmitter and/or transmitting module 1203 may be adapted to configure the wireless device with an indication instructing the wireless device 10 to apply the second shift to the UL transmission. For example, a second shift to the subcarrier grid (this is also denoted as second subcarrier grid) is applied for UL transmission or a second shift to the subcarriers relative to on the second subcarrier grid is applied for UL transmission. The indication may indicate that the second shift is omitted from being applied to the uplink transmission, e.g., the shift is zero. The second shift may correspond to the first shift used by the first wireless communication network. The second radio network node 13, the processing circuit 1201 and/or the transmitter and/or transmitting module 1203 are configured to: transmitting an indication when FDD is determined to be used; and when it is determined to use TDD, no indication is transmitted.

The second radio network node 13 may comprise a receiving module 1204, such as a receiver or a transceiver. The second radio network node 13, the processing circuitry 1201 and/or the receiver and/or receiving module 1204 may be configured to receive the UL transmission on a subcarrier related to or taking into account the second shift.

The second radio network node 13 further comprises a memory 1205. The memory includes one or more units to be used for storing data such as shifted sets, subcarrier grids, scheduling information, duplex information, indices, applications (when executed) for performing the methods disclosed herein. The second radio network node 13 may comprise a communication interface 1208, such as a transmitter, a receiver, a transceiver and/or one or more antennas.

The method according to embodiments described herein for the second radio network node 13 is implemented by means of, for example, a computer program 1206 or a computer program product comprising instructions (i.e. software code portions), respectively, which, when executed on at least one processor, cause the at least one processor to carry out the herein described actions as being performed by the second radio network node 13. The computer program 1206 may be stored on a computer readable storage medium 1207 such as a disk, a Universal Serial Bus (USB) stick, a memory, or the like. The computer-readable storage medium 1207, having a computer program stored on the computer-readable storage medium 1207, may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein as being performed by the second radio network node 13. In some embodiments, the computer-readable storage medium may be a non-transitory computer-readable storage medium or a transitory computer-readable storage medium. Thus, a radio network node may comprise processing circuitry and a memory, the memory comprising instructions executable by the processing circuitry, whereby the radio network node is operable to perform the methods herein.

Fig. 7 is a block diagram depicting a wireless device 10 for handling communications for the wireless device 10 in a second wireless communication network in two embodiments according to embodiments herein. The second wireless communication network is configured to co-exist with the first wireless communication network over the same bandwidth on a frequency, wherein the first wireless communication network is configured to apply a first shift on the frequency in an uplink transmission.

The wireless device 10 may include processing circuitry 1001, such as one or more processors, configured to perform the methods herein.

The wireless device 10 may include a determination module 1002. The wireless device 10, the processing circuitry 1001 and/or the determining module 1002 may be configured to determine whether the second wireless communication network uses FDD (whether FDD or TDD is used).

The wireless device 10 may include a receiving module 1004, such as a receiver or transceiver. The wireless device 10, the processing circuitry 1001 and/or the receiving module 1004 are configured to receive an indication from the radio network node indicating that a second shift in frequency is applied for uplink transmissions if the second wireless communication network uses FDD. For example, wireless device 10, processing circuitry 1001, and/or receiving module 1004 may be configured to receive an indication instructing wireless device 10 to apply a second shift to the UL transmission. For example, a second shift to the subcarrier grid (this is also denoted as second subcarrier grid) is applied for UL transmission, or a second shift of subcarriers relative to the second subcarrier grid is applied for UL transmission. The indication may indicate that the second shift is omitted from being applied to the uplink transmission.

The wireless device 10 may include a transmit module 1003, such as a transmitter or transceiver. The wireless device 10, the processing circuitry 1001 and/or the transmitter and/or the transmitting module 1003 are configured to apply a second shift in frequency to the uplink transmission, wherein the second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for the subcarrier grid of the second wireless communication network. For example, where FDD is used in the second wireless communication network, the wireless device 10, the processing circuitry 1001 and/or the transmitter and/or the transmitting module 1003 is configured to apply a second shift to the subcarriers relative to the subcarrier grid for UL transmissions or to apply a second shift to the subcarrier grid for UL transmissions in the second wireless communication network. In some embodiments, the wireless device 10, the processing circuit 1001 and/or the transmitting module 1003 may be configured to omit applying the second shift if TDD is used in the second wireless communication network. The second shift may correspond to the first shift used by the first wireless communication network.

The wireless device 10 further includes memory 1005. The memory includes one or more units to be used for storing data such as shifts, subcarrier grids, scheduling information, duplex information, indices, applications (when executed) for performing the methods disclosed herein. The wireless device 10 may include a communication interface 1008 such as a transmitter, receiver, transceiver, and/or one or more antennas.

The methods according to embodiments described herein for the wireless device 10 are implemented by means of, for example, a computer program 1006 or a computer program product comprising instructions (i.e. software code portions), which when executed on at least one processor, cause the at least one processor to carry out the actions described herein as being performed by the wireless device 10, respectively. The computer program 1006 may be stored on a computer readable storage medium 1007, such as a disk, USB stick, memory, or the like. The computer-readable storage medium 1007 having a computer program stored thereon may comprise instructions that, when executed on at least one processor, cause the at least one processor to perform the actions described herein as being performed by the wireless device 10. In some embodiments, the computer-readable storage medium may be a non-transitory computer-readable storage medium or a transitory computer-readable storage medium. Thus, the wireless device 10 may comprise processing circuitry and memory, the memory comprising instructions executable by the processing circuitry, whereby the wireless device is operable to perform the methods herein.

It should be noted that in a general scenario, the term "radio network node" may be replaced by "transmission and reception point". The distinction between Transmission Reception Points (TRPs) can be made generally based on the RS or different synchronization signals transmitted and the BRS. Several TRPs may be logically connected to the same radio network node, but if they are geographically separated or point to different propagation directions, the TRPs will suffer from the same problems as different radio network nodes. In the sections herein, the terms "radio network node" and "TPR" may be considered interchangeable.

It should further be noted that the wireless communication network may be a network virtually sliced into multiple network/RAN slices, each supporting one or more types of wireless devices and/or one or more types of services, i.e., each supporting a different set of functionality. Network segmentation introduces the possibility of: the network/RAN slices are used for different services and usage scenarios, and these services and usage scenarios may introduce differences in the functionality supported in the different network slices. Each network/RAN slice may include one or more network nodes or elements of network nodes that provide services/functionality for the respective network slice. Each network/RAN slice may include network nodes such as RAN nodes and/or core network nodes.

In LTE uplink, there is a half tone shift of the subcarriers. The current agreement is that such half tone shifts will not be used in the NR uplink. In case LTE and NR coexist on the same carrier frequency, the uplink subcarriers of the two RATs will therefore not be aligned with respect to each other, resulting in inter-subcarrier interference.

There are different alternatives as to how to handle this problem.

Alternative # 1: do nothing

One alternative is to preserve the current agreement that there is no half tone shift in the NR uplink. Inter-subcarrier interference between NR and LTE uplink transmissions on the same carrier may be reduced to an acceptable level by means of a joint scheduler that provides sufficient (intra-carrier) guard band between the two RATs. Note that in case of LTE/NR coexistence (where NR operates with a non-15 kHz parameter set), the guard band provided by such a scheduler is needed anyway.

Alternative # 2: introducing half tone shifting for NR uplink

The second alternative changes the current agreement, i.e. half tone shift is also introduced for the NR uplink. There are different ways by which this can be done

In general, half tone shifting is used for the NR uplink

Having the general possibility of configuring the half tone shift for the NR uplink, as a complement to the "normal" non-half tone shifted uplink transmission

-using or having the following possibilities: configuring half tone shifts for NR uplink only for frequency bands for which coexistence with LTE may be relevant or even possible

We believe that the general half tone shifting for the NR uplink is not attractive as this may negatively impact link performance. It should also be noted that a half tone shift for a parameter set other than 15kHz would not provide any benefit.

At the same time, although potentially providing some benefits in NR/LTE coexistence scenarios, supplemental half tone shifting will increase device complexity.

Alternative 3: adjusting uplink carrier frequency by 7.5kHz offset

A third alternative is to introduce the possibility to shift the entire uplink carrier by 7.5kHz instead of the general half tone shift. This can be viewed simply as a flex duplex separation where there is no impact on the RAN1 specification. Such flexible duplexing is a specification aspect that is supported today by specifications that support the uplink carrier frequency configuration offset. For LTE, the granularity of this configuration is in steps of 100kHz, i.e., significantly larger than the required 7.5 kHz. However, for NB-IoT, the granularity is 2.5kHz, i.e., meeting the desired 7.5 kHz.

Of the above 3 alternatives discussed above, alternative #1 is obviously the simplest and straightforward, meaning that the agreement that has been reached is not changed. If found to be insufficient, alternative #3, i.e. the possibility of introducing a 7.5kHz shift of the uplink carrier, should be considered as a supplement. This alternative would have no impact on the RAN #1 specification (where the carrier frequency is not visible). It will have an impact on the RAN4 specifications and, to some extent, on the RAN2 RRC specifications (signaling of uplink carrier offset).

Examples herein disclose:

a method performed by a wireless device for handling communications for the wireless device in a second wireless communication network. The second wireless communication network may coexist with the first wireless communication network within or on the same bandwidth. The wireless device applies a second shift in frequency to the uplink transmission if the second wireless communication network uses Frequency Division Duplexing (FDD). The wireless device may omit applying a second shift in frequency for uplink transmissions if the second wireless communication network uses Time Division Duplexing (TDD). The second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. The second shift may correspond to the first shift used by the first wireless communication network.

A method performed by a second radio network node or a radio network node for enabling communication for a wireless device in a second wireless communication network. The second communication network may coexist with the first wireless communication network within or on the same bandwidth. The second radio network node configures the wireless device with an indication indicating or instructing the wireless device to apply a second shift in frequency to uplink transmissions if the second wireless communication network uses FDD. The indication may further indicate or instruct the wireless device to omit applying a second shift in frequency for uplink transmissions if the second wireless communication network uses TDD. The second shift defines a shift in frequency for the subcarrier relative to a subcarrier grid of the second wireless communication network or defines a shift in frequency for a subcarrier grid of the second wireless communication network. The second shift may correspond to the first shift used by the first wireless communication network. The second radio network node may further determine that the second wireless communication network uses FDD (whether FDD or TDD is used).

Furthermore, a wireless device and a second radio network node configured to perform the method herein are also disclosed.

In some embodiments, the more general term "radio network node" is used and may correspond to any type of radio network node or any network node that communicates with a wireless device and/or with another network node. Examples of network nodes are NodeB, primary eNB, secondary eNB, network nodes belonging to a primary cell group (MCG) or a Secondary Cell Group (SCG), Base Station (BS), multi-standard radio (MSR) radio node such as MSR BS, eNodeB, network controller, Radio Network Controller (RNC), Base Station Controller (BSC), relay, donor node controlling relay, Base Transceiver Station (BTS), Access Point (AP), transmission point, transmission node, Radio Remote Unit (RRU), Radio Remote Head (RRH), node in a Distributed Antenna System (DAS), core network node (e.g., Mobility Switching Center (MSC), Mobile Management Entity (MME), etc.), operation and maintenance (O & M), Operation Support System (OSS), self-organizing network (SON), positioning node (e.g., evolved serving mobile positioning center (E-SMLC))), Minimization of Drive Tests (MDT), etc.

In some embodiments, the non-limiting term wireless device or User Equipment (UE) is used and it refers to any type of wireless device that communicates with a network node and/or with another wireless device in a cellular or mobile communication system. Examples of wireless devices are target devices, device-to-device (D2D) UEs, proximity-enabled wireless devices (also known as proseues), machine type wireless devices or machine-to-machine (M2M) communication enabled wireless devices, PDAs, PADs, tablets, mobile terminals, smart phones, Laptop Embedded Equipment (LEEs), Laptop Mounted Equipment (LMEs), USB dongles, and the like.

These embodiments are described with respect to 5G. However, these embodiments may be applicable to any RAT or multi-RAT system in which a wireless device receives and/or transmits signals (e.g., data), such as LTE, LTE FDD/TDD, WCDMA/HSPA, GSM/GERAN, WiFi, WLAN, CDMA2000, and so forth.

An antenna node is a unit capable of generating one or more beams covering a particular service area or direction. The antenna node may be a base station or a part of a base station.

As will be readily apparent to those familiar with communication design, the functional components or modules may be implemented using digital logic and/or one or more microcontrollers, microprocessors, or other digital hardware. In some embodiments, some or all of the various functions may be implemented together, such as in a single Application Specific Integrated Circuit (ASIC) or in two or more separate devices with appropriate hardware and/or software interfaces therebetween. For example, several functions may be implemented on a processor shared with other functional components of the wireless device or network node.

Alternatively, several of the functional elements of the processing means discussed may be provided through the use of dedicated hardware, while other functional elements are provided with hardware for executing software in association with appropriate software or firmware. Thus, the term "processor" or "controller" as used herein does not refer exclusively to hardware capable of executing software, but may implicitly include, without limitation, Digital Signal Processor (DSP) hardware, Read Only Memory (ROM) for storing software, random access memory for storing software and/or program or application data, and non-volatile storage. Other hardware, conventional and/or custom, may also be included. The designer of a communication device will appreciate the cost, performance, and maintenance tradeoffs inherent in these design choices.

It will be appreciated that the foregoing description and drawings represent non-limiting examples of the methods and apparatus taught herein. Accordingly, the apparatus and techniques taught herein are not limited by the foregoing description and accompanying drawings. Rather, the embodiments herein are limited only by the following claims and their legal equivalents.