# Patent

## Title
Multi-radio coexistence

## Abstract

A method of wireless communication includes monitoring coexistence issues among supported radios in a User Equipment (UE). The method includes configuring a UE with first and second filter configurations. The first filter configuration covers a first frequency band, for example a portion of the ISM band. The first filter configuration may be wider than the second filter configuration, which excludes a portion of the first frequency band that is adjacent to a proximate second frequency band, for example LTE Band 7 or LTE Band 40. The UE selects between the first and second filter configurations based on the frequency of a first UE event. If the UE event is in a frequency in the adjacent portion excluded by the second filter configuration, the UE arbitrates depending on event priority. The second filter configuration may be chosen to reduce or minimize arbitration.

## Background
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. provisional patent application No. 61/392,831 filed Oct. 13, 2010, entitled “MULTI-RADIO COEXISTENCE,” the disclosure of which is expressly incorporated herein by reference in its entirety.


TECHNICAL FIELD
The present description is related, generally, to multi-radio techniques and, more specifically, to coexistence techniques for multi-radio devices.
BACKGROUND
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-single-out or a multiple-in-multiple out (MIMO) system.
Some conventional advanced devices include multiple radios for transmitting/receiving using different Radio Access Technologies (RATs). Examples of RATs include, e.g., Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications (GSM), cdma2000, WiMAX, WLAN (e.g., WiFi), Bluetooth, LTE, and the like.
An example mobile device includes an LTE User Equipment (UE), such as a fourth generation (4G) mobile phone. Such 4G phone may include various radios to provide a variety of functions for the user. For purposes of this example, the 4G phone includes an LTE radio for voice and data, an IEEE 802.11 (WiFi) radio, a Global Positioning System (GPS) radio, and a Bluetooth radio, where two of the above or all four may operate simultaneously. While the different radios provide useful functionalities for the phone, their inclusion in a single device gives rise to coexistence issues. Specifically, operation of one radio may in some cases interfere with operation of another radio through radiative, conductive, resource collision, and/or other interference mechanisms. Coexistence issues include such interference.
This is especially true for the LTE uplink channel, which is adjacent to the Industrial Scientific and Medical (ISM) band and may cause interference therewith It is noted that Bluetooth and some Wireless LAN (WLAN) channels fall within the ISM band. In some instances, a Bluetooth error rate can become unacceptable when LTE is active in some channels of Band 7 or even Band 40 for some Bluetooth channel conditions. Even though there is no significant degradation to LTE, simultaneous operation with Bluetooth can result in disruption in voice services terminating in a Bluetooth headset. Such disruption may be unacceptable to the consumer. A similar issue exists when LTE transmissions interfere with GPS. Currently, there is no mechanism that can solve this issue since LTE by itself does not experience any degradation
With reference specifically to LTE, it is noted that a UE communicates with an evolved NodeB (eNB; e.g., a base station for a wireless communications network) to inform the eNB of interference seen by the UE on the downlink. Furthermore, the eNB may be able to estimate interference at the UE using a downlink error rate. In some instances, the eNB and the UE can cooperate to find a solution that reduces interference at the UE, even interference due to radios within the UE itself. However, in conventional LTE, the interference estimates regarding the downlink may not be adequate to comprehensively address interference.
In one instance, an LTE uplink signal interferes with a Bluetooth signal or WLAN signal. However, such interference is not reflected in the downlink measurement reports at the eNB. As a result, unilateral action on the part of the UE (e.g., moving the uplink signal to a different channel) may be thwarted by the eNB, which is not aware of the uplink coexistence issue and seeks to undo the unilateral action. For instance, even if the UE re-establishes the connection on a different frequency channel, the network can still handover the UE back to the original frequency channel that was corrupted by the in-device interference. This is a likely scenario because the desired signal strength on the corrupted channel may sometimes be higher be reflected in the measurement reports of the new channel based on Reference Signal Received Power (RSRP) to the eNB. Hence, a ping-pong effect of being transferred back and forth between the corrupted channel and the desired channel can happen if the eNB uses RSRP reports to make handover decisions.
Other unilateral action on the part of the UE, such as simply stopping uplink communications without coordination of the eNB may cause power loop malfunctions at the eNB. Additional issues that exist in conventional LTE include a general lack of ability on the part of the UE to suggest desired configurations as an alternative to configurations that have coexistence issues. For at least these reasons, uplink coexistence issues at the UE may remain unresolved for a long time period, degrading performance and efficiency for other radios of the UE.
SUMMARY
Offered is a method for wireless communication. The method includes configuring a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band. The first filter configuration has a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration. The method also includes selecting between the first filter configuration and second filter configuration to reduce interference with a second frequency band. The second frequency band is proximate to the first frequency band.
Offered is an apparatus for wireless communication. The apparatus includes means for configuring a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band. The first filter configuration has a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration. The apparatus also includes means for selecting between the first filter configuration and second filter configuration to reduce interference with a second frequency band. The second frequency band is proximate to the first frequency band.
Offered is a computer program product for wireless communications. The computer program product includes a non-transitory computer-readable medium having program code recorded thereon. The program code includes program code to configure a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band. The first filter configuration has a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration. The program code also includes program code to select between the first filter configuration and second filter configuration to reduce interference with a second frequency band. The second frequency band is proximate to the first frequency band.
Offered is an apparatus for wireless communication. The apparatus includes a memory and at least one processor coupled to the memory. The processor(s) is configured to configure a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band. The first filter configuration has a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration. The processor(s) is also configured to select between the first filter configuration and second filter configuration to reduce interference with a second frequency band. The second frequency band is proximate to the first frequency band.
Additional features and advantages of the disclosure will be described below. It should be appreciated by those skilled in the art that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the teachings of the disclosure as set forth in the appended claims. The novel features, which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages, will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.



BRIEF DESCRIPTION OF THE DRAWINGS
The features, nature, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout.
FIG. 1 illustrates a multiple access wireless communication system according to one aspect.
FIG. 2 is a block diagram of a communication system according to one aspect.
FIG. 3 illustrates an exemplary frame structure in downlink Long Term Evolution (LTE) communications.
FIG. 4 is a block diagram conceptually illustrating an exemplary frame structure in uplink Long Term Evolution (LTE) communications.
FIG. 5 illustrates an example wireless communication environment.
FIG. 6 is a block diagram of an example design for a multi-radio wireless device.
FIG. 7 is graph showing respective potential collisions between seven example radios in a given decision period.
FIG. 8 is a diagram showing operation of an example Coexistence Manager (CxM) over time.
FIG. 9 is a block diagram of a system for providing support within a wireless communication environment for multi-radio coexistence management according to one aspect of the present disclosure.
FIG. 10 is a block diagram illustrating adjacent frequency bands.
FIG. 11 is a block diagram illustrating customizable ISM band filters according to aspects of the present disclosure.
FIG. 12 is a block diagram illustrating tuner control hardware according to one aspect of the present disclosure.
FIG. 13 is a flow diagram for determining a coexistence policy for communication resource operation according to one aspect of the present disclosure.



DETAILED DESCRIPTION
Various aspects of the disclosure provide techniques to mitigate coexistence issues in multi-radio devices, where significant in-device coexistence problems can exist between, e.g., the LTE and Industrial Scientific and Medical (ISM) bands (e.g., for BT/WLAN). As explained above, some coexistence issues persist because an eNB is not aware of interference on the UE side that is experienced by other radios. According to one aspect, the UE declares a Radio Link Failure (RLF) and autonomously accesses a new channel or Radio Access Technology (RAT) if there is a coexistence issue on the present channel. The UE can declare a RLF in some examples for the following reasons: 1) UE reception is affected by interference due to coexistence, and 2) the UE transmitter is causing disruptive interference to another radio. The UE then sends a message indicating the coexistence issue to the eNB while reestablishing connection in the new channel or RAT. The eNB becomes aware of the coexistence issue by virtue of having received the message.
The techniques described herein can be used for various wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are often used interchangeably. A CDMA network can implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network can implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network can implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known in the art. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in portions of the description below.
Single carrier frequency division multiple access (SC-FDMA), which utilizes single carrier modulation and frequency domain equalization is a technique that can be utilized with various aspects described herein. SC-FDMA has similar performance and essentially the same overall complexity as those of an OFDMA system. SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. SC-FDMA has drawn great attention, especially in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. It is currently a working assumption for an uplink multiple access scheme in 3GPP Long Term Evolution (LTE), or Evolved UTRA.
Referring to FIG. 1, a multiple access wireless communication system according to one aspect is illustrated. An evolved Node B 100 (eNB) includes a computer 115 that has processing resources and memory resources to manage the LTE communications by allocating resources and parameters, granting/denying requests from user equipment, and/or the like. The eNB 100 also has multiple antenna groups, one group including antenna 104 and antenna 106, another group including antenna 108 and antenna 110, and an additional group including antenna 112 and antenna 114. In FIG. 1, only two antennas are shown for each antenna group, however, more or fewer antennas can be utilized for each antenna group. A User Equipment (UE) 116 (also referred to as an Access Terminal (AT)) is in communication with antennas 112 and 114, while antennas 112 and 114 transmit information to the UE 116 over a downlink (DL) 120 and receive information from the UE 116 over an uplink (UL) 118. The UE 122 is in communication with antennas 106 and 108, while antennas 106 and 108 transmit information to the UE 122 over a downlink (DL) 126 and receive information from the UE 122 over an uplink 124. In a frequency division duplex (FDD) system, communication links 118, 120, 124 and 126 can use different frequencies for communication. For example, the downlink 120 can use a different frequency than used by the uplink 118.
Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the eNB. In this aspect, respective antenna groups are designed to communicate to UEs in a sector of the areas covered by the eNB 100.
In communication over the downlinks 120 and 126, the transmitting antennas of the eNB 100 utilize beamforming to improve the signal-to-noise ratio of the uplinks for the different UEs 116 and 122. Also, an eNB using beamforming to transmit to UEs scattered randomly through its coverage causes less interference to UEs in neighboring cells than a UE transmitting through a single antenna to all its UEs.
An eNB can be a fixed station used for communicating with the terminals and can also be referred to as an access point, base station, or some other terminology. A UE can also be called an access terminal, a wireless communication device, terminal, or some other terminology.
FIG. 2 is a block diagram of an aspect of a transmitter system 210 (also known as an eNB) and a receiver system 250 (also known as a UE) in a MIMO system 200. In some instances, both a UE and an eNB each have a transceiver that includes a transmitter system and a receiver system. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to a transmit (TX) data processor 214.
A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, wherein NS≦min{NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
A MIMO system supports time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, the uplink and downlink transmissions are on the same frequency region so that the reciprocity principle allows the estimation of the downlink channel from the uplink channel. This enables the eNB to extract transmit beamforming gain on the downlink when multiple antennas are available at the eNB.
In an aspect, each data stream is transmitted over a respective transmit antenna. The TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.
The coded data for each data stream can be multiplexed with pilot data using OFDM techniques. The pilot data is a known data pattern processed in a known manner and can be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream can be determined by instructions performed by a processor 230 operating with a memory 232.
The modulation symbols for respective data streams are then provided to a TX MIMO processor 220, which can further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 220 then provides NT modulation symbol streams to NT transmitters (TMTR) 222a through 222t. In certain aspects, the TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.
Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from the transmitters 222a through 222t are then transmitted from NT antennas 224a through 224t, respectively.
At a receiver system 250, the transmitted modulated signals are received by NR antennas 252a through 252r and the received signal from each antenna 252 is provided to a respective receiver (RCVR) 254a through 254r. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.
An RX data processor 260 then receives and processes the NR received symbol streams from NR receivers 254 based on a particular receiver processing technique to provide NR “detected” symbol streams. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by the RX data processor 260 is complementary to the processing performed by the TX MIMO processor 220 and the TX data processor 214 at the transmitter system 210.
A processor 270 (operating with a memory 272) periodically determines which pre-coding matrix to use (discussed below). The processor 270 formulates an uplink message having a matrix index portion and a rank value portion.
The uplink message can include various types of information regarding the communication link and/or the received data stream. The uplink message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by a modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to the transmitter system 210.
At the transmitter system 210, the modulated signals from the receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by an RX data processor 242 to extract the uplink message transmitted by the receiver system 250. The processor 230 then determines which pre-coding matrix to use for determining the beamforming weights, then processes the extracted message.
FIG. 3 is a block diagram conceptually illustrating an exemplary frame structure in downlink Long Term Evolution (LTE) communications. The transmission timeline for the downlink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes with indices of 0 through 9. Each subframe may include two slots. Each radio frame may thus include 20 slots with indices of 0 through 19. Each slot may include L symbol periods, e.g., 7 symbol periods for a normal cyclic prefix (as shown in FIG. 3) or 6 symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices of 0 through 2L−1. The available time frequency resources may be partitioned into resource blocks. Each resource block may cover N subcarriers (e.g., 12 subcarriers) in one slot.
In LTE, an eNB may send a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) for each cell in the eNB. The PSS and SSS may be sent in symbol periods 6 and 5, respectively, in each of subframes 0 and 5 of each radio frame with the normal cyclic prefix, as shown in FIG. 3. The synchronization signals may be used by UEs for cell detection and acquisition. The eNB may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH may carry certain system information.
The eNB may send a Cell-specific Reference Signal (CRS) for each cell in the eNB. The CRS may be sent in symbols 0, 1, and 4 of each slot in case of the normal cyclic prefix, and in symbols 0, 1, and 3 of each slot in case of the extended cyclic prefix. The CRS may be used by UEs for coherent demodulation of physical channels, timing and frequency tracking, Radio Link Monitoring (RLM), Reference Signal Received Power (RSRP), and Reference Signal Received Quality (RSRQ) measurements, etc.
The eNB may send a Physical Control Format Indicator Channel (PCFICH) in the first symbol period of each subframe, as seen in FIG. 3. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to 1, 2 or 3 and may change from subframe to subframe. M may also be equal to 4 for a small system bandwidth, e.g., with less than 10 resource blocks. In the example shown in FIG. 3, M=3. The eNB may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each subframe. The PDCCH and PHICH are also included in the first three symbol periods in the example shown in FIG. 3. The PHICH may carry information to support Hybrid Automatic Repeat Request (HARQ). The PDCCH may carry information on resource allocation for UEs and control information for downlink channels. The eNB may send a Physical Downlink Shared Channel (PDSCH) in the remaining symbol periods of each subframe. The PDSCH may carry data for UEs scheduled for data transmission on the downlink. The various signals and channels in LTE are described in 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation,” which is publicly available.
The eNB may send the PSS, SSS and PBCH in the center 1.08 MHz of the system bandwidth used by the eNB. The eNB may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The eNB may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The eNB may send the PDSCH to specific UEs in specific portions of the system bandwidth. The eNB may send the PSS, SSS, PBCH, PCFICH and PHICH in a broadcast manner to all UEs, may send the PDCCH in a unicast manner to specific UEs, and may also send the PDSCH in a unicast manner to specific UEs.
A number of resource elements may be available in each symbol period. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource elements not used for a reference signal in each symbol period may be arranged into resource element groups (REGs). Each REG may include four resource elements in one symbol period. The PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period 0. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may all belong in symbol period 0 or may be spread in symbol periods 0, 1 and 2. The PDCCH may occupy 9, 18, 32 or 64 REGs, which may be selected from the available REGs, in the first M symbol periods. Only certain combinations of REGs may be allowed for the PDCCH.
A UE may know the specific REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. An eNB may send the PDCCH to the UE in any of the combinations that the UE will search.
FIG. 4 is a block diagram conceptually illustrating an exemplary frame structure 300 in uplink Long Term Evolution (LTE) communications. The available Resource Blocks (RBs) for the uplink may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The design in FIG. 4 results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.
A UE may be assigned resource blocks in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks in the data section to transmit data to the eNodeB. The UE may transmit control information in a Physical Uplink Control Channel (PUCCH) 310a, 310b on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a Physical Uplink Shared Channel (PUSCH) 320a, 320b on the assigned resource blocks in the data section. An uplink transmission may span both slots of a subframe and may hop across frequency as shown in FIG. 4.
The PSS, SSS, CRS, PBCH, PUCCH and PUSCH in LTE are described in 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation,” which is publicly available.
In an aspect, described herein are systems and methods for providing support within a wireless communication environment, such as a 3GPP LTE environment or the like, to facilitate multi-radio coexistence solutions.
Referring now to FIG. 5, illustrated is an example wireless communication environment 500 in which various aspects described herein can function. The wireless communication environment 500 can include a wireless device 510, which can be capable of communicating with multiple communication systems. These systems can include, for example, one or more cellular systems 520 and/or 530, one or more WLAN systems 540 and/or 550, one or more wireless personal area network (WPAN) systems 560, one or more broadcast systems 570, one or more satellite positioning systems 580, other systems not shown in FIG. 5, or any combination thereof. It should be appreciated that in the following description the terms “network” and “system” are often used interchangeably.
The cellular systems 520 and 530 can each be a CDMA, TDMA, FDMA, OFDMA, Single Carrier FDMA (SC-FDMA), or other suitable system. A CDMA system can implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. Moreover, cdma2000 covers IS-2000 (CDMA2000 1X), IS-95 and IS-856 (HRPD) standards. A TDMA system can implement a radio technology such as Global System for Mobile Communications (GSM), Digital Advanced Mobile Phone System (D-AMPS), etc. An OFDMA system can implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). In an aspect, the cellular system 520 can include a number of base stations 522, which can support bi-directional communication for wireless devices within their coverage. Similarly, the cellular system 530 can include a number of base stations 532 that can support bi-directional communication for wireless devices within their coverage.
WLAN systems 540 and 550 can respectively implement radio technologies such as IEEE 802.11 (WiFi), Hiperlan, etc. The WLAN system 540 can include one or more access points 542 that can support bi-directional communication. Similarly, the WLAN system 550 can include one or more access points 552 that can support bi-directional communication. The WPAN system 560 can implement a radio technology such as Bluetooth (BT), IEEE 802.15, etc. Further, the WPAN system 560 can support bi-directional communication for various devices such as wireless device 510, a headset 562, a computer 564, a mouse 566, or the like.
The broadcast system 570 can be a television (TV) broadcast system, a frequency modulation (FM) broadcast system, a digital broadcast system, etc. A digital broadcast system can implement a radio technology such as MediaFLOTM, Digital Video Broadcasting for Handhelds (DVB-H), Integrated Services Digital Broadcasting for Terrestrial Television Broadcasting (ISDB-T), or the like. Further, the broadcast system 570 can include one or more broadcast stations 572 that can support one-way communication.
The satellite positioning system 580 can be the United States Global Positioning System (GPS), the European Galileo system, the Russian GLONASS system, the Quasi-Zenith Satellite System (QZSS) over Japan, the Indian Regional Navigational Satellite System (IRNSS) over India, the Beidou system over China, and/or any other suitable system. Further, the satellite positioning system 580 can include a number of satellites 582 that transmit signals for position determination.
In an aspect, the wireless device 510 can be stationary or mobile and can also be referred to as a user equipment (UE), a mobile station, a mobile equipment, a terminal, an access terminal, a subscriber unit, a station, etc. The wireless device 510 can be cellular phone, a personal digital assistance (PDA), a wireless modem, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, etc. In addition, a wireless device 510 can engage in two-way communication with the cellular system 520 and/or 530, the WLAN system 540 and/or 550, devices with the WPAN system 560, and/or any other suitable systems(s) and/or devices(s). The wireless device 510 can additionally or alternatively receive signals from the broadcast system 570 and/or satellite positioning system 580. In general, it can be appreciated that the wireless device 510 can communicate with any number of systems at any given moment. Also, the wireless device 510 may experience coexistence issues among various ones of its constituent radio devices that operate at the same time. Accordingly, device 510 includes a coexistence manager (CxM, not shown) that has a functional module to detect and mitigate coexistence issues, as explained further below.
Turning next to FIG. 6, a block diagram is provided that illustrates an example design for a multi-radio wireless device 600 and may be used as an implementation of the radio 510 of FIG. 5. As FIG. 6 illustrates, the wireless device 600 can include N radios 620a through 620n, which can be coupled to N antennas 610a through 610n, respectively, where N can be any integer value. It should be appreciated, however, that respective radios 620 can be coupled to any number of antennas 610 and that multiple radios 620 can also share a given antenna 610.
In general, a radio 620 can be a unit that radiates or emits energy in an electromagnetic spectrum, receives energy in an electromagnetic spectrum, or generates energy that propagates via conductive means. By way of example, a radio 620 can be a unit that transmits a signal to a system or a device or a unit that receives signals from a system or device. Accordingly, it can be appreciated that a radio 620 can be utilized to support wireless communication. In another example, a radio 620 can also be a unit (e.g., a screen on a computer, a circuit board, etc.) that emits noise, which can impact the performance of other radios. Accordingly, it can be further appreciated that a radio 620 can also be a unit that emits noise and interference without supporting wireless communication.
In an aspect, respective radios 620 can support communication with one or more systems. Multiple radios 620 can additionally or alternatively be used for a given system, e.g., to transmit or receive on different frequency bands (e.g., cellular and PCS bands).
In another aspect, a digital processor 630 can be coupled to radios 620a through 620n and can perform various functions, such as processing for data being transmitted or received via the radios 620. The processing for each radio 620 can be dependent on the radio technology supported by that radio and can include encryption, encoding, modulation, etc., for a transmitter; demodulation, decoding, decryption, etc., for a receiver, or the like. In one example, the digital processor 630 can include a CxM 640 that can control operation of the radios 620 in order to improve the performance of the wireless device 600 as generally described herein. The CxM 640 can have access to a database 644, which can store information used to control the operation of the radios 620. As explained further below, the CxM 640 can be adapted for a variety of techniques to decrease interference between the radios. In one example, the CxM 640 requests a measurement gap pattern or DRX cycle that allows an ISM radio to communicate during periods of LTE inactivity.
For simplicity, digital processor 630 is shown in FIG. 6 as a single processor. However, it should be appreciated that the digital processor 630 can include any number of processors, controllers, memories, etc. In one example, a controller/processor 650 can direct the operation of various units within the wireless device 600. Additionally or alternatively, a memory 652 can store program codes and data for the wireless device 600. The digital processor 630, controller/processor 650, and memory 652 can be implemented on one or more integrated circuits (ICs), application specific integrated circuits (ASICs), etc. By way of specific, non-limiting example, the digital processor 630 can be implemented on a Mobile Station Modem (MSM) ASIC.
In an aspect, the CxM 640 can manage operation of respective radios 620 utilized by wireless device 600 in order to avoid interference and/or other performance degradation associated with collisions between respective radios 620. CxM 640 may perform one or more processes, such as those illustrated in FIGS. 11 and 13. By way of further illustration, a graph 700 in FIG. 7 represents respective potential collisions between seven example radios in a given decision period. In the example shown in graph 700, the seven radios include a WLAN transmitter (Tw), an LTE transmitter (Tl), an FM transmitter (Tf), a GSM/WCDMA transmitter (Tc/Tw), an LTE receiver (Rl), a Bluetooth receiver (Rb), and a GPS receiver (Rg). The four transmitters are represented by four nodes on the left side of the graph 700. The four receivers are represented by three nodes on the right side of the graph 700.
A potential collision between a transmitter and a receiver is represented on the graph 700 by a branch connecting the node for the transmitter and the node for the receiver. Accordingly, in the example shown in the graph 700, collisions may exist between (1) the WLAN transmitter (Tw) and the Bluetooth receiver (Rb); (2) the LTE transmitter (Tl) and the Bluetooth receiver (Rb); (3) the WLAN transmitter (Tw) and the LTE receiver (Rl); (4) the FM transmitter (Tf) and the GPS receiver (Rg); (5) a WLAN transmitter (Tw), a GSM/WCDMA transmitter (Tc/Tw), and a GPS receiver (Rg).
In one aspect, an example CxM 640 can operate in time in a manner such as that shown by diagram 800 in FIG. 8. As diagram 800 illustrates, a timeline for CxM operation can be divided into Decision Units (DUs), which can be any suitable uniform or non-uniform length (e.g., 100 μs) where notifications are processed, and a response phase (e.g., 20 μs) where commands are provided to various radios 620 and/or other operations are performed based on actions taken in the evaluation phase. In one example, the timeline shown in the diagram 800 can have a latency parameter defined by a worst case operation of the timeline, e.g., the timing of a response in the case that a notification is obtained from a given radio immediately following termination of the notification phase in a given DU.
In-device coexistence problems can exist with respect to a UE between resources such as, for example, LTE and ISM bands (e.g., for Bluetooth/WLAN). In current LTE implementations, any interference issues to LTE are reflected in the DL measurements (e.g., Reference Signal Received Quality (RSRQ) metrics, etc.) reported by a UE and/or the DL error rate which the eNB can use to make inter-frequency or inter-RAT handoff decisions to, e.g., move LTE to a channel or RAT with no coexistence issues. However, it can be appreciated that these existing techniques will not work if, for example, the LTE UL is causing interference to Bluetooth/WLAN but the LTE DL does not see any interference from Bluetooth/WLAN. More particularly, even if the UE autonomously moves itself to another channel on the UL, the eNB can in some cases handover the UE back to the problematic channel for load balancing purposes. In any case, it can be appreciated that existing techniques do not facilitate use of the bandwidth of the problematic channel in the most efficient way.
A UE may utilize multiple filter configurations to reduce or minimize interference between events on the ISM band and events on adjacent LTE Band 7 or LTE Band 40. In certain embodiments the UE may structure the filter configurations to reduce or minimize interference and reduce or minimize resource intensive arbitration.
Turning now to FIG. 9, a block diagram of a system 900 for providing support within a wireless communication environment for multi-radio coexistence management is illustrated. In an aspect, the system 900 can include one or more UEs 910 and/or eNBs 940, which can engage in UL, DL communications, and/or any other suitable communication with each other and/or any other entities in the system 900. In one example, the UE 910 and/or eNB 940 can be operable to communicate using a variety resources, including frequency channels and sub-bands, some of which can potentially be colliding with other radio resources (e.g., a broadband radio such as an LTE modem). Thus, the UE 910 can utilize various techniques for managing coexistence between multiple radios utilized by the UE 910, as generally described herein.
To mitigate at least the above shortcomings, the UE 910 can utilize respective features described herein and illustrated by the system 900 to facilitate support for multi-radio coexistence within the UE 910. For example, a channel monitoring module 912, a frequency filter configuration analyzer 914, an event arbitration analyzer 916, and a frequency filter configuration module 918 can be provided. The various modules 912-918 may, in some examples, be implemented as part of a coexistence manager such as the CxM 640 of FIG. 6. The various modules 912-918 and others may be configured to implement the embodiments discussed herein.
As shown in FIG. 10, Long Term Evolution (LTE) in band (B) 7 (used for frequency division duplex (FDD) uplink), band 40 (used for time division duplex (TDD) communication), and band 38 (used for FDD downlink) are adjacent to the 2.4 GHz Industrial Scientific and Medical (ISM) band used by Bluetooth (BT) and Wireless Local Area Network (WLAN) technologies. Frequency planning for these bands is such that there is limited or no guard band permitting traditional filtering solutions to avoid interference at adjacent frequencies. For example, a 20 MHz guard band exists between ISM and band 7, but no guard band exists between ISM and band 40.
To be compliant with appropriate standards, communication devices operating over a particular band must be operable over the entire specified frequency range. For example, in order to be LTE compliant, a mobile station/user equipment needs to be able to use the entirety of both band 40 (2300-2400 MHz) and band 7 (2500-2570 MHz) as defined by the 3rd Generation Partnership Project (3GPP). Without a sufficient guard band, devices employ filters which overlap into other bands causing band interference. Because band 40 filters are 100 MHz wide to cover the entire band, the rollover from those filters cross over into the ISM band causing interference. Similarly, ISM devices which use the entirety of the ISM band (e.g. from 2401 through  ̃2480 MHz) will employ filters which rollover into the neighboring band 40 and band 7 and may cause interference. A particular UE may only be assigned to one of band 40 or band 7 at a time, therefore interference may only be a problem for one of those bands at a time.
Many solutions to these coexistence issues rely on time division techniques. If true simultaneous operation were available, performance (particularly for Bluetooth) can be improved. Conventionally, a radio frequency (RF) solution to the coexistence problem has been treated as “impossible.” This is not so. Most filters are designed to protect the entire wanted band and provide rejection from adjacent bands. With this constraint, there isn't enough of a guard band between the Industrial Scientific and Medical (ISM) band and the LTE bands (especially B40). If, however, a solution is willing to remove some of the ISM band from the use of a Bluetooth radio (thereby creating an artificial guard band), an RF filtering solution becomes possible.
Offered is such an RF solution to the coexistence problem. An ISM band filter with a 60 MHz wide pass band and 50 dB attenuation is possible and practical. Such a filter would work well for Bluetooth. Further, such a filter would cut off frequencies on the opposite side of the ISM band from the interfering device. Another approach is a filter approximately 100 MHz wide that may be tuned to the center of the ISM band when LTE is disabled, tuned high when LTE B40 is in use, and tuned low when LTE B7 is in use.
Different configurations of a customizable ISM band filter solution are shown in FIG. 11. In one aspect a filter is chosen to be larger than the desired total width of the 2.4 GHz ISM band. The center frequency of the band may be moved such that it is centered on the ISM band (as shown with filter 1110), centered low on the ISM band cutting off upper end of the band (as shown with filter 1112), or centered high on the ISM band cutting off lower end of the band (as shown with filter 1114).
The choice of which filter/tuning to use may be based on use priorities. When LTE is disabled, the filter may be set to state 1 (centered), as shown with filter 1110. When LTE is enabled using band (B) 7, the filter is nominally in state 2 (high), as shown with filter 1114. When LTE is enabled in B40, the filter is nominally in state 3 (low), as shown with filter 1112. When the filter is in state 2 (high) or 3 (low), and Bluetooth may desire to use frequency regions made unusable by the filter state, Bluetooth may request (via a coexistence bus or similar communication configuration) for LTE to center the filter into state 1. If the relative priority of Bluetooth is higher than that of LTE, the request may be granted. If an LTE event in the contended frequency range has a higher relative priority than the Bluetooth event, the request may be denied.
In another aspect, a 60 MHz filter ISM band filter may be used, as shown with filter 1108 in FIG. 11. A 60 MHz filter creates separation between band 7 and band 40, thereby artificially creating high and low gap bands. In another aspect, a moveable/adaptive filter cutoff frequency may be used. For example, a 80-100 MHz filter that moves based on the priority of a UE event and/or other interference circumstances. In another aspect, multiple filters may be used, where the choice of a particular filter may depend on priority of a UE event, a desired frequency of the UE event, and/or other interference circumstances. In another aspect, a standard filter may be used if the potentially interfering LTE band is not being used during the UE event at issue (due to circumstances such as LTE not being enabled at that time, geographic restrictions, etc.).
In another aspect multiple filters may be available to the UE, which may select a particular filter to provide an artificial guard band to improve performance. Once adaptive frequency hopping (AFH) is enabled for the Bluetooth radio, the UE may select the filter that gives the most band available. Filter configurations may include multiple filters, tunable filters, or other hardware/software configurations.
In another aspect a UE may employ a priority based mechanism for selecting the center frequency of the ISM band filter. When the center frequency is non-optimal for one technology, and that technology is unable to re-map frequencies into a used band (for example, before AFH is enabled), a TDD priority/arbitration mechanism may be used in the frequency ranges close to adjacent bands. This mechanism may use a coexistence bus/manager or other communication configuration.
If use of the border frequencies of the ISM band (where interference is most likely) is desired, the UE may perform arbitration in those regions (based on priority, or any other arbitration technique) to determine whether the ISM event or the LTE event should be executed. Use of the filter configurations in conjunction with arbitration reduces the need to perform arbitration for each UE event (such as transmission, reception, discovery, or other tasks), as may be necessary if only a single filter/filter configuration is employed. Reducing arbitration may lead to improved performance. Filter configurations may take into account certain situations (such as temperature, etc.) that may cause varying interference. In response to those situations, a filter cutoff might shift left, right, or expand/contract. Filter configuration choices may be made on an event by event basis. Filter configurations are not limited to the ISM band. Filters may be employed in band 7, band 40, or other bands.
A 100 MHz tunable ISM band filter offers several advantages. It is backwards compatible with existing Bluetooth devices. It allows simultaneous operation for LTE and Bluetooth with no restrictions in throughput, use cases or topology. It also allows simultaneous operation for LTE and WLAN in ad-hoc mode if WLAN can avoid operating on a channel adjacent to LTE. A 100 MHz tunable ISM band filter may also be made to work with existing Bluetooth silicon. Though improved performance may be achieved with updated firmware and a coexistence bus. These benefits are primarily in the states before AFH is enabled (scanning, scan response, paging/inquiry, initial connection setup).
A centered 100 MHz ISM band filter may be preferable for use when LTE is disabled or asleep, when LTE B38 is in use, or during paging, inquiry, and other high priority events (if priority signaling is available). The centered 100 MHz ISM band filter allows full operation by Bluetooth or WLAN.
A low tuned 100 MHz ISM band filter may be preferable when LTE B7 is in use. The low filter may limit WLAN use of upper channels in the ISM band (for example, channels 10 and higher) for infrastructure mode, though is less limiting in ad-hoc mode. Priority signaling may be used to reduce the impact to Bluetooth performance.
A high tuned 100 MHz ISM band filter may be preferable when LTE B40 is in use. The high filter may limit WLAN use of lower channels in the ISM band (for example, channels 3 and lower) for infrastructure mode, though is less limiting in ad-hoc mode. Priority signaling may be used to reduce the impact to Bluetooth performance.
In addition to the hardware configurations disclosed above, the configuration shown in FIG. 12 may be used to control the filter tuning and to coordinate between LTE, Bluetooth and/or WLAN. As shown, the filter tuning control may be controlled by an LTE sub-system or a different sub-system. The switch operates to control which unit, Bluetooth or WLAN, is in operation at any particular time.
As shown in FIG. 13 a UE may be configured with a first and second filter configuration, where the first and second filters cover different frequency ranges of a first frequency band, as shown in block 1302. A selection is made between the first and second filter configurations based on potential interference with a second frequency band proximate to the first frequency band, as shown in block 1304.
A UE may comprise means for configuring a user equipment with a first filter configuration and a second filter configuration for use communicating in a first frequency band, the first filter configuration having a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration. The UE may also comprise means for selecting between the first filter configuration and second filter configuration to reduce interference with a second frequency band, the second frequency band proximate to the first frequency band. In one aspect, the aforementioned means may be the processor 270, the receive data processor 260, the CxM 640, the controller/processor 650, the frequency filter configuration analyzer 914, the event arbitration analyzer 916, and/or the frequency filter configuration module 918 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
The examples above describe aspects implemented in an LTE system. However, the scope of the disclosure is not so limited. Various aspects may be adapted for use with other communication systems, such as those that employ any of a variety of communication protocols including, but not limited to, CDMA systems, TDMA systems, FDMA systems, and OFDMA systems.
It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

## Claims

1. A method for wireless communications, comprising:
configuring a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band, the first filter configuration having a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration; and
selecting between the first filter configuration and second filter configuration to reduce interference with a second frequency band, the second frequency band being proximate to the first frequency band,
in which the first filter configuration and the second filter configuration are radio frequency (RF) filter configurations.

2. The method of claim 1 in which the first filter configuration and the second filter configuration include at least one tunable filter.

3. The method of claim 1 in which the first filter configuration and second filter configuration include a plurality of filters.

4. The method of claim 1 in which the frequency pass band of the second filter configuration excludes a portion of the first frequency band adjacent to the second frequency band.

5. The method of claim 1 in which the first filter configuration overlaps with at least one channel of the second filter configuration, the at least one channel being within the first frequency band.

6. The method of claim 1 in which the frequency pass band of the first filter configuration or the frequency pass band of the second filter configuration is chosen to reduce interference with the second frequency band.

7. The method of claim 1 in which the selecting is based on at least one of a relative priority of an event of a first radio access technology and a frequency of the event of the first radio access technology.

8. The method of claim 1 in which the selecting comprises arbitrating between a first radio access technology and a second radio access technology when a frequency of an event of the first radio access technology falls within the frequency pass band of the first filter configuration, but not the frequency pass band of the second filter configuration.

9. The method of claim 1 in which the selecting comprises engaging the second filter configuration when a frequency of an event of a first radio access technology falls within the frequency pass band of the second filter configuration.

10. The method of claim 1 in which the frequency pass band of the first filter configuration and the frequency pass band of the second filter configuration comprise at least the first frequency band.

11. An apparatus for wireless communications, comprising:
means for configuring a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band, the first filter configuration having a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration; and
means for selecting between the first filter configuration and second filter configuration to reduce interference with a second frequency band, the second frequency band being proximate to the first frequency band,
in which the first filter configuration and the second filter configuration are radio frequency (RF) filter configurations.

12. A computer program product for wireless communications, the computer program product comprising:
a non-transitory computer-readable medium having program code recorded thereon, the program code comprising:
program code to configure a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band, the first filter configuration having a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration; and
program code to select between the first filter configuration and second filter configuration to reduce interference with a second frequency band, the second frequency band being proximate to the first frequency band,
in which the first filter configuration and the second filter configuration are radio frequency (RF) filter configurations.

13. An apparatus for wireless communications, comprising:
a memory; and
at least one processor coupled to the memory, the at least one processor being configured:
to configure a user equipment with a first filter configuration and a second filter configuration for use when communicating in a first frequency band, the first filter configuration having a frequency pass band covering different frequencies than a frequency pass band of the second filter configuration; and
to select between the first filter configuration and second filter configuration to reduce interference with a second frequency band, the second frequency band being proximate to the first frequency band,
in which the first filter configuration and the second filter configuration are radio frequency (RF) filter configurations.

14. The apparatus of claim 13 in which the first filter configuration and the second filter configuration include at least one tunable filter.

15. The apparatus of claim 13 in which the frequency pass band of the second filter configuration excludes a portion of the first frequency band adjacent to the second frequency band.

16. The apparatus of claim 13 in which the first filter configuration overlaps with at least one channel of the second filter configuration, the at least one channel being within the first frequency band.

17. The apparatus of claim 13 in which the frequency pass band of the first filter configuration or the frequency pass band of the second filter configuration is chosen to reduce interference with the second frequency band.

18. The apparatus of claim 13 in which the selecting is based on at least one of a relative priority of an event of a first radio access technology and a frequency of the event of the first radio access technology.

19. The apparatus of claim 13 in which the selecting comprises arbitrating between a first radio access technology and a second radio access technology when a frequency of an event of the first radio access technology falls within the frequency pass band of the first filter configuration, but not the frequency pass band of the second filter configuration.

20. The apparatus of claim 13 in which the selecting comprises engaging the second filter configuration when a frequency of an event of a first radio access technology falls within the frequency pass band of the second filter configuration.