Patent Description:
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to supporting energy efficient signaling in a network device and/or a user equipment.

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stations, also referred to as nodeBs or eNodeBs (eNBs), which can support communication for a number of user equipments (UEs). A UE may communicate with a base station via a downlink and an uplink. The downlink (or forward link) refers to a communication link from the base station to the UE, and the uplink (or reverse link) refers to a communication link from the UE to the base station. In an example, a base station can assign a number of downlink and/or uplink resources to a UE. Moreover, the base station can allow the UE to establish multiple carriers for communicating with the base station over the downlink or uplink using multiple physical or virtual antennas or other radio resources to improve communication throughput.

Due to the euer increasing popularity of wireless communications, efficiently utilizing the limited resources of both the base stations and UEs has become a concern.

One manner in which this concern is addressed in 3GPP Long Term Evolution (LTE) Release <NUM> (Rel-<NUM>) through the definition of a new carrier type, also referred to as an extension carrier, which may provide enhanced spectral efficiency by removing unneeded synchronization signals, and which also may provide enhanced energy efficiency.

Moreover, current agreements or operating assumptions include the base station transmitting certain synchronization signals with increased periodicity. The proposed increase in separation of the synchronization signals may not provide sufficient energy savings, however, and further separation of the signals may lead to possible delays in communications as well as possible user congestion.

Accordingly, improved mechanisms or techniques for more energy efficient signaling are desired.

<CIT> relates to methods and arrangements in an ad-hoc network, wherein the ad-hoc devices are configured to enter DRX mode. The basic concept of the embodiments is to let a node initiate and maintain transmission of a specific reference signal pattern during the DRX operation of an adhoc device, referred to as a UE. The transmission of the reference signal pattern enables the UE to maintain synchronization.

3GPP paper R2-<NUM> concerns fixed and flexible DRX/DTX control (e.g. for configuring a DRX period), wherein such control is signalled to the UE at radio bearer set up (both fixed and flexible schemes) and either by means of pre-defined rule or by means of explicit signalling (flexible only).

3GPP paper R2-<NUM> and <CIT> discloses a system to provide DRX/DTX configuration for mixed real time and non-real time transmission scenarios in a mobile telecommunications environment, particularly applicable to 3GPP networks.

The underlying problem of the present invention is solved by the subject matter of the independent claims.

The techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDMA, 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. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

<FIG> shows a wireless communication network <NUM>, which may be an LTE network. The wireless network <NUM> may include a number of evolved Node Bs (eNBs) <NUM> and other network entities. An eNB may be a station that communicates with the user equipments (UEs) and may also be referred to as a base station, a Node B, an access point, etc. Each eNB <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of an eNB and/or an eNB subsystem serving this coverage area, depending an the context in which the term is used.

An eNB may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. An eNB for a pico cell may be referred to as a pico eNB. An eNB for a femto cell may be referred to as a femto eNB or a home eNB. In the example shown in <FIG>, the eNBs 110a, 110b and 110c may be macro eNBs for the macro cells 102a, 102b and 102c, respectively. The eNB 110x may be a pico eNB for a pico cell 102x. The eNBs 110y and 110z may be femto eNBs for the femto cells 102y and 102z, respectively. An eNB may support one or multiple (e.g., three) cells.

A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., an eNB or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or an eNB). In the example shown in <FIG>, a relay station 110r may communicate with the eNB 110a and a UE 120r in order to facilitate communication between the eNB 110a and the UE 120r. A relay station may also be referred to as a relay eNB, a relay, etc..

The wireless network <NUM> may be a heterogeneous network that includes eNBs of different types, e.g., macro eNBs, pico eNBs, femto eNBs, relays, etc. These different types of eNBs may have different transmit power levels, different coverage areas, and different impact an interference in the wireless network <NUM>. For example, macro eNBs may have a high transmit power level (e.g., <NUM> Watts) whereas pico eNBs, femto eNBs and relays may have a lower transmit power level (e.g., <NUM> Watt).

The wireless network <NUM> may support synchronous or asynchronous Operation. For synchronous operation, the eNBs may have similar frame timing, and transmissions from different eNBs may be approximately aligned in time. For asynchronous operation, the eNBs may have different frame timing, and transmissions from different eNBs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous Operation.

A network controller <NUM> may couple to a set of eNBs and provide coordination and control for these eNBs. The network controller <NUM> may communicate with the eNBs <NUM> via a backhaul. The eNBs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

The UEs <NUM> may be dispersed throughout the wireless network <NUM>, and each UE may be stationary or mobile. A UE may also be referred to as a device, a terminal, a mobile station, a subscriber unit, a station, a smart phone, etc. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem (or other tethered device), a wireless communication device, a handheld device, a laptop computer, a tablet or netbook computer, a cordless phone, a wireless local loop (WLL) station, etc. A UE may be able to communicate with macro eNBs, pico eNBs, femto eNBs, relays, etc. For example, UE 120x may communicate with eNB 110x which may be a pico eNB of pico cell 102x, and UE 120y may communicate with eNB 110y or eNB 110z which may be femto eNBs of femto cells 102y and 102z, respectively. In <FIG>, a solid line with double arrows indicates desired transmissions between a UE and a serving eNB, which is an eNB designated to serve the UE on the downlink and/or uplink. A dashed line with double arrows indicates potentially interfering transmissions between a UE and an eNB.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. In general, modulation symbols are sent in the frequency domain with OFDM or a similar multiplexing scheme and in the time domain with SC-FDM or a similar multiplexing scheme. For example, K may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM>, and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

<FIG> shows a down link frame structure <NUM> used in LTE. The transmission timeline for the downlink may be partitioned into units of radio frames, such as radio frame <NUM>. Each radio frame may have a predetermined duration (e.g., <NUM> milliseconds (ms)) and may be partitioned into <NUM> subframes with indices of <NUM> through <NUM>, such as subframe <NUM><NUM>. Each subframe may include two slots, such as slot <NUM><NUM> and slot <NUM><NUM>. Each radio frame may thus include <NUM> slots with indices of <NUM> through <NUM>. Each slot may include L symbol periods, e.g., <NUM> symbol periods for a normal cyclic prefix (as shown in <FIG>) or <FIG> symbol periods for an extended cyclic prefix. The <NUM> symbol periods in each subframe may be assigned indices of <NUM> through <NUM>-<NUM>. Each resource block may cover N subcarriers (e.g., <NUM> 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 primary and secondary synchronization signals may be sent in symbol periods <NUM> and <NUM>, respectively, in each of subframes <NUM> and <NUM> of each radio frame with the normal cyclic prefix, as shown in <FIG>. 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 <NUM> to <NUM> in slot <NUM> of subframe <NUM>. The PBCH may carry certain system information.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) in a portion of the first symbol period of each subframe, although depicted in the entire first symbol period in <FIG>. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to <NUM>, <NUM> or <NUM> and may change from subframe to subframe. M may also be equal to <NUM> for a small system bandwidth, e.g., with less than <NUM> resource blocks. In the example shown in <FIG>, M=<NUM>. The eNB may send a Physical hybrid automatic repeat/request (HARQ) Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each subframe (M=<NUM> in <FIG>). The PHICH may carry information to support hybrid automatic retransmission (HARQ). The PDCCH may carry information on resource allocation for UEs and control information for downlink channels. Although not shown in the first symbol period in <FIG>, it is understood that the PDCCH and PHICH are also included in the first symbol period. Similarly, the PHICH and PDCCH are also both in the second and third symbol periods, although not shown that way in <FIG>. 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 can correspond to an LTE configuration.

The eNB may send the PSS, SSS and PBCH in a center of the system bandwidth used by the eNB (e.g., a center <NUM> megahertz (MHz)). 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 (REG). 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 <NUM>. 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 <NUM> or may be spread in symbol periods <NUM>, <NUM> and <NUM>. The PDCCH may occupy <NUM>, <NUM>, <NUM> or <NUM> REGs, which may be selected from the available REGs, in the first M symbol periods. 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.

A UE may be within the coverage of multiple eNBs. One of these eNBs may be selected to serve the UE. The serving eNB may be selected based on various criteria such as received power, path loss, signal-to-noise ratio (SNR), etc. Moreover, it is to be appreciated that the UE can utilize a similar subframe and slot structure to communicate with the eNB on the uplink. For example, the UE can transmit physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), sounding reference signal (SRS), or other communications over one or more symbol periods in one or more slots of a subframe.

<FIG> shows a block diagram of a design of a base station/eNB <NUM> and a UE <NUM>, which may be one of the base stations/eNBs and one of the UEs in <FIG>. For a restricted association scenario, the base station <NUM> may be the macro eNB 110c in <FIG>, and the UE <NUM> may be the UE 120y. The base station <NUM> may be equipped with antennas 334a through 334t, and the UE <NUM> may be equipped with antennas 352a through 352r.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, etc. The data may be for the PDSCH, etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 332a through 332t. Downlink signals from modulators 332a through 332t may be transmitted via the antennas 334a through 334t, respectively.

At the UE <NUM>, the antennas 352a through 352r may receive the downlink signals from the base station <NUM> and may provide received signals to the demodulators (DEMODs) 354a through 354r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 354a through 354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.

On the uplink, at the UE <NUM>, a transmit processor <NUM> may receive and process data (e.g., for the PUSCH) from a data source <NUM> and control information (e.g., for the PUCCH) from the controller/processor <NUM>. The processor <NUM> may also generate reference symbols for a reference signal. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the modulators 355a through 355r (e.g., for SC-FDM, etc.), and transmitted to the base station <NUM>. At the base station <NUM>, the uplink signals from the UE <NUM> may be received by the antennas <NUM>, processed by the demodulators 333a through 333t, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE <NUM>. The processor <NUM> may provide the decoded data to a data sink <NUM> and the decoded control information to the controller/processor <NUM>.

The controllers/processors <NUM> and <NUM> may direct the Operation at the base station <NUM> and the UE <NUM>, respectively. The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct the execution of various processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. In addition, for example, the processor <NUM> can comprise or at least be operatively coupled to modules illustrated in <FIG> and <FIG> for performing aspects described herein. The memories <NUM> and <NUM> may store data and program codes for the base station <NUM> and the UE <NUM>, respectively, which can include instructions for executing the methods in <FIG>, <FIG>, and <FIG>, the modules in <FIG>, <FIG>, and <FIG>, and/or the like.

LTE-Advanced UEs can use spectrum in <NUM> bandwidths allocated in a carrier aggregation of up to a total of <NUM> (<NUM> component carriers) for transmission in each direction. Generally, less traffic is transmitted on the uplink than the downlink, so the uplink spectrum allocation may be smaller than the downlink allocation. For example, if <NUM> is assigned to the uplink, the downlink may be assigned <NUM>. These asymmetric FDD assignments can conserve spectrum and are a good fit for the typically asymmetric bandwidth utilization by broadband subscribers, though other assignments can be possible.

For the LTE-Advanced mobile systems, two types of carrier aggregation (CA) methods have been proposed, continuous CA and non-continuous CA, examples of which are illustrated in <FIG>. Non-continuous CA occurs when multiple available component carriers <NUM> are separated along the frequency band (<FIG>). On the other hand, continuous CA occurs when multiple available component carriers <NUM> are adjacent to each other (<FIG>). As shown, for example, in continuous CA, carrier <NUM><NUM>, carrier <NUM><NUM>, and carrier <NUM><NUM> are adjacent in frequency. In non-continuous CA, carrier <NUM><NUM>, carrier <NUM><NUM>, and carrier <NUM><NUM> are not adjacent in frequency. Both non-continuous and continuous CA operate to aggregate multiple LTE/component carriers to serve a single unit of LTE Advanced UE.

Multiple RF receiving units and multiple FFTs may be deployed with non-continuous CA in LTE-Advanced UE since the carriers are separated along the frequency band. Because non-continuous CA supports data transmissions over multiple separated carriers across a large frequency range, propagation path loss, Doppler shift and other radio channel characteristics may vary a lot at different frequency bands.

Thus, to support broadband data transmission under the non-continuous CA approach, methods may be used to adaptively adjust coding, modulation and transmission power for different component carriers. For example, in an LTE-Advanced system where the enhanced NodeB (eNB) has fixed transmitting power an each component carrier, the effective coverage or supportable modulation and coding of each component carrier may be different.

<FIG> illustrates performing data aggregation <NUM> to aggregate transmission blocks (TBs) from different component carriers <NUM>, <NUM>, and <NUM> at the medium access control (MAC) layer (<FIG>) for an International Mobile Telecommunications (IMT)-Advanced or similar system. With MAC layer data aggregation, each component carrier has its own independent hybrid automatic repeat request (HARD) entity <NUM>, <NUM>, and <NUM> in the MAC layer and its own transmission configuration parameters (e.g., transmitting power, modulation and coding schemes, and multiple antenna configuration) in the physical layer. Similarly, in the physical layer, one physical layer entity <NUM>, <NUM>, and <NUM> can be provided for each component carrier.

In general, there are three different approaches for deploying control channel signaling for multiple component carriers. The first involves a minor modification of the control structure in LTE systems where each component carrier is given its own coded control channel.

The second method involves jointly coding the control channels of different component carriers and deploying the control channels in a dedicated component carrier. The control information for the multiple component carriers can be integrated as the signaling content in this dedicated control channel. As a result, backward compatibility with the control channel structure in LTE systems is maintained, while signaling overhead in the CA is reduced (e.g., for the dedicated control channel).

Multiple control channels for different component carriers are jointly coded and then transmitted over the entire frequency band formed by a third CA method. This approach offers low signaling overhead and high decoding performance in control channels, at the expense of high power consumption at the UE side. However, this method may not be compatible with LTE systems.

It is preferable to support transmission continuity during the handover procedure across multiple cells when CA is used for an IMT-Advanced UE. However, reserving sufficient system resources (e.g., component carriers with good transmission quality) for the incoming UE with specific CA configurations and quality of service (QoS) requirements may be challenging for the next eNB. The reason is that the channel conditions of two (or more) adjacent cells (eNBs) may be different for the specific UE. In one approach, the UE measures the performance of only one component carrier in each adjacent cell. This offers similar measurement delay, complexity, and energy consumption as that in LTE systems. An estimate of the performance of the other component carriers in the corresponding cell may be based on the measurement result of the one component carrier. Based on this estimate, the handover decision and transmission configuration may be determined.

<FIG> illustrates a methodology <NUM> for controlling radio links in a multiple carrier wireless communication system by grouping physical channels according to one example. As shown, the method includes, at block <NUM>, aggregating control functions from at least two carriers onto one carrier to form a primary carrier and one or more associated secondary carriers. Next at block, <NUM>, communication links are established for the primary carrier and each secondary carrier. Then, communication is controlled based on the primary carrier in block <NUM>.

In LTE Release <NUM> (Rel-<NUM>), a new control channel structure referred to as enhanced Physical Downlink Control Channel (ePDCCH) is introduced. Unlike legacy PDCCH, which occupies the first several control symbols in a subframe, ePDCCH occupies the data region, similar to Physical Downlink Shared Channel (PDSCH).

<FIG> illustrates various example ePDCCH structures <NUM> in an example portion of time over a portion of frequency, which can be a subframe. For example, a portion of initial resources in the subframe can be reserved for a legacy control region <NUM> for communicating control data to legacy devices, which can include PDCCH, PCFICH, PHICH, and/or similar channels. In LTE, the legacy control region <NUM> can be a number of OFDM symbols, n, in the subframe where n can be between one and three. It is to be appreciated that where ePDCCH is defined for a new carrier type, the legacy control region <NUM> may not be present. In any case, the remaining resources can comprise a data region <NUM> of the subframe. Thus, unlike legacy PDCCH, ePDCCH for a new carrier type may occupy only the data region <NUM>.

Five alternatives are depicted for defining an enhanced control channel structure, though it is to be appreciated that other alternatives are possible. For example, an enhanced control channel structure can support increased control channel capacity, support frequency domain inter-cell interference coordination (ICIC), achieve improved spatial reuse of control channel resources, support beamforming and/or diversity, operate on a new carrier type and in Multicast/Broadcast over Single Frequency Network (MB SFN) subframes, coexist on the same carrier as legacy devices, etc..

In alternative <NUM><NUM>, the enhanced control channel structure can be similar to relay-PDCCH (R-PDCCH), such that downlink grants are assigned over the control channel in at least a portion of frequency over a first portion of region <NUM>, and uplink grants are assigned over the control channel in the portion of frequency over a second portion of the region <NUM>. In alternative <NUM><NUM>, the enhanced control channel structure allows downlink and uplink grants to be assigned over a portion of frequency in region <NUM> spanning both the first and the second slots. In alternative <NUM><NUM>, the enhanced control channel structure allows downlink and uplink grants to be assigned over a portion of frequency using TDM in at least a portion of region <NUM>. In alternative <NUM><NUM>, the enhanced control channel structure allows downlink and uplink grants to be assigned over the control channel in at least a portion of frequency over a first portion of region <NUM>, and uplink grants are assigned over the control channel in the portion of frequency over a second portion of the region <NUM>. In alternative <NUM><NUM>, downlink grants can be assigned using TDM over at least a portion of region <NUM>, while uplink grants can be assigned using FDM in a different, and optionally overlapping, portion of frequency over region <NUM>.

Using one or more of the alternatives, it is to be appreciated that an enhanced control channel can allow assignment of resources using various multiplexing schemes for downlink and/or uplink assignments as compared to conventional legacy control channel structures.

Additionally, for ePDCCH, one or more additional conditions or agreements may apply. For example, both localized and distributed transmission of the ePDCCH may be supported. In this case, at least for localized transmission, and for distributed transmission where a Common Reference Signal (CRS) is not used for demodulation of the enhanced control channel, the demodulation of the enhanced control channel is based on a DeModulation-Reference Signal (DM-RS) transmitted in one or more Physical Resource Block(s) (PRB(s)) used for transmission of the enhanced control channel.

Further, for example, in some cases ePDCCH messages may span both the first and second slots (e.g., FDM based ePDCCH) with a restriction on a maximum number of Transport CHannel (TrCH) bits receivable in a Transmission Time Interval (TTI), e.g. to allow a relaxation of the processing requirements for the UE. Also, for example, multiplexing of PDSCH and ePDCCH within a PRB pair may not be permitted.

Moreover, for example, in some cases Rank-<NUM> single-user MIMO (SU-MIMO) is not supported for a single blind decoding attempt. And, the same scrambling sequence generator may be used for ePDCCH DM-RS as for PDSCH DM-RS.

Thus, resource assignment for an enhanced control channel can be defined to accommodate one or more of the enhanced alternative control channel structures.

The following concepts can be applied to a new carrier type (NCT) or an extension carrier, a single carrier, two or more carriers in CA, coordinated multiple point (CoMP), and/or any non-backward compatible carrier, such as an LTE Release <NUM> (Rel-<NUM>) new carrier type, allowing resource granting within resources of various portions of a subframe. In an aspect, the new carrier type or extension carrier may be a carrier that is supported in addition to LTE Release <NUM> (Rel-<NUM>) carriers. In some aspects, the new carrier type or extension carrier may be an extension of another carrier, and as such, may have to be accessed as a part of a carrier aggregation set.

The present apparatus and methods relate to an energy efficient design of a wireless communication system. In particular, in an aspect, the present apparatus and methods may be configured with signal bursts specifically targeted or matched to some discontinuous reception (DRX) periods, either at a user equipment or at a base station, or both. In other optional or additional aspects, the present apparatus and methods may be configured to deal with the resulting uneven distribution of DRX-related traffic. Moreover, in some other alternative or additional aspects, the present apparatus and methods may be configured to make the introduced new time structure of signals backward compatible.

Referring to <FIG>, in one aspect, a wireless communication system <NUM> provides energy efficient signaling by modifying transmission-related and/or reception-related resources of a base station <NUM> and/or a user equipment (UE) <NUM> to reduce energy usage. In system <NUM>, base station <NUM> can provide wireless network access to UE <NUM>. Base station <NUM> may include, but is not limited to, a macro base station or nodeB or eNB, a femto node, a pico node, a mobile base station, a relay, a remote radio head (RRH), a mobile device (e.g., communicating in peer-to-peer or ad-hoc mode with UE <NUM>), a portion thereof, and/or the like. UE <NUM> may include, but is not limited to, an access terminal, a mobile device, a modem (or other tethered device), a portion thereof, and/or the like.

In an aspect, base station <NUM> includes a signal pattern obtainer component <NUM> configured to obtain a signal pattern <NUM> defining resources for use in transmitting or receiving signals, e.g. such as transmitted signal <NUM> or received signal <NUM>. For example, signal pattern obtainer component <NUM> may obtain signal pattern <NUM> from a local memory or via a communication with another device. Further, for example, signal pattern obtainer component <NUM> may be configured to obtain signal pattern <NUM> based on a determination by signal pattern obtainer component <NUM>. For instance, in one case, signal pattern obtainer component <NUM> may determine signal pattern <NUM> by selecting signal pattern <NUM> from a set of available signal patterns based on a given selection algorithm, by receiving signal pattern <NUM> as defined by an Operator or other management or controlling entity relating to wireless communication system <NUM>. Alternatively, or in addition, signal pattern obtainer component <NUM> may determine signal pattern <NUM> by calculating signal pattern <NUM> according to a given pattern-calculating algorithm and/or in conjunction with received characteristics of wireless communication system <NUM>, such as other signal patterns used by other cells and/or other carriers relative to base station <NUM>.

Additionally, signal pattern <NUM> may be configured to define variable density signal transmission or reception over time, where the signals include a plurality of signals defining a signal burst <NUM> aligned with a discontinuous reception (DRX) period. In these aspects, "density" may be defined as a number of resources (for example, resource elements) occupied by the signal across the whole channel bandwidth over a unit time. Further, for example, when the number of such resources varies, the density may be averaged over the given evaluation period. As such, for instance, signal burst <NUM> may be more dense relative to another set of signals when density is evaluated within a given reference period corresponding to a duration of signal burst <NUM>. Further, the alignment of signal burst <NUM> with a DRX period may include providing signal burst <NUM> for transmission in a discontinuous transmission (DTX) period <NUM> of base station <NUM> that corresponds to a discontinuous reception (DRX) period <NUM> of UE <NUM>, or providing signal burst <NUM> for reception in a DRX period <NUM> of base station <NUM> that corresponds to a DTX period of UE <NUM>. The matching of signal burst <NUM> with a respective DRX period provided by the present apparatus and methods may, for example, improve energy efficiency and/or performance within wireless communication system <NUM>. For example, in one aspect, signal pattern <NUM> may be a bit mask, however, it should be understood that other techniques and/or mechanism may be used to define signal pattern <NUM>.

Additionally, it should be noted that to achieve the variable density signal transmission or reception, signal burst <NUM> may be only a portion of the signals defined by signal pattern <NUM>. For instance, in an aspect, signal pattern <NUM> may provide a first, relatively low, signal density to cause generation of signals having relatively low detectability, e.g., for when UE <NUM> is already in communication with base station <NUM> such as for connected mode emergency fast detection. On the other hand, signal pattern <NUM> may provide a second, relatively high, signal density to cause generation of signals having a relatively high detectability, e.g., signal burst <NUM>, for discovery by UE <NUM> when UE <NUM> is not yet in communication with base station <NUM>. In other words, signal pattern <NUM> may concentrate most discontinuous transmission (DTX) and/or discontinuous reception (DRX) related signaling into relatively short bursts, e.g., signal burst <NUM>, as compared to prior techniques, thereby providing a relatively longer maximum duration without signal present.

For example, in an aspect, signal pattern <NUM> may define a signal transmission pattern, such as for base station <NUM> to operate a transmitter to transmit signals, e.g., signals <NUM>, to UE <NUM>. In an aspect, transmitted signals <NUM> may be, for example, reference signals or broadcast signals transmitted by base station <NUM>. For instance, the reference signals may include, but are not limited to, one or more of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a common reference signal (CRS), and a channel state information reference signal (CSI-RS). Other broadcast signals transmitted by base station <NUM> may include, but are not limited to, signals such as a system information signal, or a paging signal.

Further, in an alternative or additional aspect, signal pattern <NUM> may define transmissions of the first set of signals according to a first periodicity and transmission of the second set of signals according to a second periodicity, wherein the first periodicity is substantially greater than the second periodicity. In other words, when combined with the above noted relative density of the first set of signals relative to the signal burst <NUM>, then the first set of signals provides a relatively shorter maximum duration without signal present as compared to signal burst <NUM>. In some cases, for example, signal pattern <NUM> configures transmissions of synchronization signals according to the first periodicity to support connected mode emergency detection by UE <NUM>, and transmitting the same set or a different set of synchronization signals according to the second periodicity, e.g. signal burst <NUM>, to support discovery by the UE <NUM>. Additionally, in some aspects, signal pattern <NUM> configures transmissions of one or more signals with a constant periodicity according to the first periodicity, and transmitting the one or more signals with an irregular periodicity according to the second periodicity. Moreover, in some aspects, signal pattern <NUM> configures transmissions of one or more signals with different durations between at least one signal in different instances of a given set of signals, or between at least one signal in the different sets of signals having the first periodicity and the second periodicity. In some cases, the differing periodicities, differing sets of signals, and/or differing signal durations may be further defined by a muting configuration or a reuse factor or any other filtering mechanism, where certain ones of the signals are muted or not used at certain instances, associated with signal pattern <NUM>. For example, "muting" of signals means that some of a set of signals may or may not be transmitted in a given period, e.g., based an a given bit mask, muting pattern, signal filter, or some other transmission attribute of a signal or set of signals, etc. Further, in the aspects where signal pattern <NUM> defines a signal transmission pattern for base station <NUM>, signal pattern <NUM> may be used to define a discontinuous transmission (DTX) mode of Operation for base station <NUM>, and a corresponding discontinuous reception (DRX) mode of Operation for UE <NUM>.

It should be noted that while this description uses the example of a first periodicity and a second periodicity, it is understood that the present apparatus and methods include signal pattern <NUM> defining two or more different periodicities.

Further, in another aspect where signal pattern <NUM> defines a transmission pattern of base station <NUM>, signal pattern <NUM> may be used as a basis for obtaining, determining or otherwise defining wake up periods for UE <NUM> to listen for transmissions from base station <NUM>. For example, signal pattern <NUM> comprising a base station transmission pattern may define a base station discontinuous transmission (DTX) timing. Accordingly, signal pattern <NUM> may be used to obtain a wake up configuration for UE <NUM> that includes a UE signal reception pattern, e.g. a UE DRX, corresponding to the base station DTX timing.

In another example, signal pattern <NUM> may define a reception pattern, such as a pattern for base station <NUM> to operate a receiver to receive signals, e.g. signals <NUM>, from UE <NUM>. Alternatively, or correspondingly, signal pattern <NUM> may define a transmission pattern, such as a pattern for UE <NUM> to operate a transmitter to transmit signals to base station <NUM>. In an aspect, received signals <NUM> may be, for example, uplink signals transmitted by UE <NUM>. For instance, the uplink signals may include, but are not limited to, one or more of a data signal, a scheduling request (SR) signal, a channel quality indicator (CQI) signal, demodulation reference signal (DM-RS). sounding reference signal (SRS), and a Physical Random Access (PRACH) signal. In any case, these aspects of signal pattern <NUM> may be utilized to define a discontinuous reception (DRX) mode of Operation for base station <NUM>, and/or a corresponding discontinuous transmission (DTX) mode of Operation for UE <NUM>.

As such, in an aspect of this example, signal pattern <NUM> may define a base station signal reception pattern or a UE signal transmission pattern in which one or more signals are received at base station <NUM> or are transmitted from UE <NUM> with different signal densities, and/or with different periodicities. In some cases, for example, signal pattern <NUM> concentrates uplink signals transmitted by UE <NUM> into relative short bursts, as compared to prior UE transmission techniques.

Additionally, in some aspects, signal pattern <NUM> that defines a base station signal reception pattern or a UE signal transmission pattern may be used as a basis for obtaining, determining or otherwise defining one or more random access channel (RACH) configurations for UE <NUM>. For example, signal pattern <NUM> defining different signal densities and/or different signal periodicities for a signal receiving pattern of base station <NUM> may be used to define different random access channel (RACH) configurations corresponding to the signal reception pattern having the first periodicity and the second RACH configuration corresponds to the signal reception pattern. For example, the combination of the first RACH configuration and the second RACH configuration may define sparse RACH opportunities corresponding to dormant time of base station <NUM>, and dense RACH opportunities corresponding to active reception time of base station <NUM>.

Additionally, in some aspects, signal pattern <NUM> may additionally define patterns for control and/or paging signals. For instance, with the variable density DTX and/or DRX configurations described above for base station <NUM>, the paging and/or control signaling load may be relatively high (as compared to prior techniques) during the resulting DTX and/or DRX short burst periods. As such, in one aspect, signal pattern <NUM> defines different sets of control signals during the different signal density and/or periodicities, as described above. For example, in an aspect, signal pattern <NUM> defines a number of control signals in a second set of control signals associated with the second, relatively higher, signal density as being substantially greater than a number of control signals in a first set of control signals associated with the first, relatively lower, signal density. Alternatively, or in addition, in another aspect, signal pattern <NUM> defines transmitting a wake up message, such as but not limited to a quick page on a quick paging channel, wherein the wake up message may include a cross-subframe wake up indicator corresponding to the one or more signals transmitted during the second periodicity. In other words, since certain aspects of the present apparatus and methods may put a large number of UEs in the same DRX wake up period, the base station may have some difficulty, e.g., due to resource constraints, if many UEs need to be woken up at the same time. For instance, the base station typically wakes up a UE by sending a downlink (DL) grant on the PDCCH and an accompanying PDSCH transmission. By providing a wake up message, the present apparatus and methods can skip sending data and just send the grant. As a result, the wake up message of these aspects will wake up the UE, causing the UE to look for retransmissions of the data. Alternatively, or in addition, in some aspects, the present apparatus and methods may not send data in the first subframe, however, the PDCCH can get congested. In either case, the wake up message can relieve the above-noted issued by not sending a full DL grant on the PDCCH and accompanying PDSCH transmission, but just sending a wake up indication to the UE.

Thus, signal pattern <NUM> defining signal burst <NUM> aligned with a DRX period results in different signal densities and/or different periodicities providing variable signal density over time, thereby allowing short periods of bursty signal transmission to be followed by substantially lengthy periods without transmissions, as compared to the relatively distributed transmissions of prior art techniques. For example, the first signal density may be substantially less than the second signal density such that, for example, the combination of the first set of signals and the second set of signals provide sufficient dormant periods for improved energy savings while at the same time providing sufficient signaling so as to avoid communication delays and/or user congestion. In other words, the first signal density provides a shorter maximum duration without signal present as compared to the second signal density. Therefore, according to the present apparatus and methods, signal pattern <NUM> may increase idle time at base station <NUM> and/or UE <NUM>, thereby improving energy efficiency.

Additionally, base station <NUM> includes resource configuring component <NUM> operable to configure base station resources based an signal pattern <NUM>, including aligning a discontinuous reception (DRX) period of UE <NUM> and/or base station <NUM> with signal burst <NUM>. For example, resource configuring component <NUM> may configure a transmitter, receiver, transceiver, transmit chain hardware and/or software, receive chain hardware and/or software, or any other signal-related component to operate to transmit signals <NUM> or receive signals <NUM> according to signal pattern <NUM>. It should be noted that in some aspects, signal pattern <NUM> that defines base station transmissions may be unknown to UE <NUM>. In other optional aspects, however, resource configuring component <NUM> operates base station <NUM> to generate and transmit a message <NUM> to provide UE <NUM> with information to receive the base station transmissions according to signal pattern <NUM>. For example, message <NUM> may be a wake up configuration that defines a wake up mode of Operation of UE <NUM> that corresponds to signal pattern <NUM>. In another example, message <NUM> may include a signal timing indicator that identifies signal pattern <NUM>.

Moreover, base station <NUM> includes resource utilization component <NUM> operable to transmit signals <NUM> or receive signals <NUM>, each optionally including signal burst <NUM>, according to signal pattern <NUM> to achieve variable density signal transmission or reception over time. For example, resource utilization component <NUM> may be a transmitter, receiver, transceiver, transmit chain hardware and/or software, receive chain hardware and/or software, or any other signal-related component.

UE <NUM> of wireless communication system <NUM> may include a receiver component <NUM> configured to receive transmitted signals <NUM>, e.g. reference signals, from base station <NUM>. For example, receiver component <NUM> may be configured to receive signals, including signal burst <NUM>, during DRX period <NUM>, which may be aligned with DTX period <NUM> of base station <NUM>. Further, UE <NUM> may include a transmitter component <NUM> configured to transmit signals <NUM>, e.g. uplink signals, to base station <NUM>. For example, transmitter component <NUM> may be configured to transmit signals, including signal burst <NUM>, during DTX period <NUM>, which may be aligned with DRX period <NUM> of base station <NUM>. Receiver component <NUM> and transmitter component <NUM> may generally be part of a communications component that includes one or more of a transmitter, a receiver, a transceiver, transmit chain hardware and/or software, receive chain hardware and/or software, or any other signal-related components.

Optionally, UE <NUM> may include a signal timing determiner component <NUM> operable to configure receiver component <NUM> and/or transmitter component <NUM> to operate according to, or in correspondence with, signal pattern <NUM>. For example, in an aspect, signal timing determiner component <NUM> may receive message <NUM>, including a wake up configuration or a signal timing indicator, and in response configure receiver component <NUM> and/or transmitter component <NUM>. For example, upon receiving wake up configuration, signal timing determiner component <NUM> may configure receiver component <NUM> to wake up according to periodicities and/or durations corresponding to a base station signal transmission timing. Further, for example, in one aspect of receiving a signal timing indicator that identifies a burstiness, e.g. a signal density, of transmitted signals <NUM> from base station <NUM>, signal timing determiner component <NUM> may configure receiver component <NUM> to wake up according to the burstiness of transmitted signals <NUM>. In other words, signal timing determiner component <NUM> may configure receiver component <NUM> to receive signals, including signal burst <NUM>, during DRX period <NUM>, which may be aligned with DTX period <NUM> of base station <NUM>. In another example, such as an aspect where the signal timing indicator identifies a UE transmission signal timing for signals <NUM> sent to base station <NUM>, signal timing determiner component <NUM> may configure transmitter component <NUM> to transmit according to the signal timing indicator, which can correspond to a DRX mode of Operation of base station <NUM>. In other words, signal timing determiner component <NUM> may configure transmitter component <NUM> to transmit signals, including signal burst <NUM>, during DTX period <NUM>, which may be aligned with DRX period <NUM> of base station <NUM>.

Thus, according to the present apparatus and methods, base station <NUM> and UE <NUM> of wireless communication system <NUM> are configured for energy efficient signaling based an modified transmission-related and/or reception-related resources, thereby reducing energy usage. In an aspect, the present apparatus and methods may be applied to transmitting a new carrier type (NCT) or extension carrier, or to any transmission of any of a base station, a user equipment, a relay, a femto node, a remote radio head (RRH), customer premises equipment (CPE) and a user equipment relay. Moreover, in other aspects, the present apparatus and methods may further include coordinating the transmitting or receiving the signals according to the signal pattern with at least one of another cell and another carrier, thereby increasing the efficiency of the overall network or system.

Referring to <FIG>, in one aspect of the present apparatus and methods, an example transmission pattern <NUM>, e.g. which may result from signal pattern <NUM> (<FIG>), defines a first set <NUM> of one or more signals <NUM> having a first signal density and a second set, e.g. signal burst <NUM>, of one or more signals <NUM> having a second signal density. Further, for example, in an aspect of transmitting reference or broadcast signals, each of first set <NUM> and second set, e.g., signal burst <NUM>, may include any combination of one or more of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a common reference signal (CRS), a channel state information reference signal (CSI-RS), a system information signal, and a paging signal. Also, each type of such signal may have a signal-specific arrangement or configuration that defines membership in a given set or whether the signal is transmitted in a given instance of the set.

It should be noted that, in <FIG>, the one or more signals <NUM> of first set <NUM> have been represented as a single signal, the set of signals transmitted during any given transmission occurrence, which may also be referred to as a density period, may include more than one signal, which may be the same signal or different signals. For example, in an aspect, one or more signals <NUM> of first set <NUM> may be a CSI-RS signal that is transmitted in two consecutive symbols or with one extra symbol in between them. In other aspects, for instance, the one more signals <NUM> of first set <NUM> may be synchronization signals.

Also, it should be noted that the second set, e.g. signal burst <NUM>, of one or more signals <NUM> has been represented as a plurality of different signals. Such a plurality of one or more signals <NUM> may include sets of the same signals or sets of different signals, or variable sets of signals. In one aspect, for instance, the one or more signals <NUM> of signal burst <NUM> may include signals <NUM>, such as paging and/or system information signals, and synchronization signals <NUM>. It should be noted that synchronization signals <NUM> in signal burst <NUM> may be the same signals as synchronization signals used in the one more signals <NUM> of first set <NUM>, however, the density of the synchronization signals, e.g. signals <NUM>, in signal burst <NUM> during the time period or duration of signal burst <NUM> is greater than a density of the corresponding synchronization signals in first set <NUM> of one or more signals <NUM>. For example, in one case that is not to be construed as limiting, during the duration of signal burst <NUM> of <FIG>, first set <NUM> includes three (<NUM>) signals <NUM> that may be synchronization signals, while second set or signal burst <NUM> includes eight (<NUM>) signals <NUM> that may be synchronization signals. As such, the synchronization signals <NUM> of signal burst <NUM> are nearly three (<NUM>) times as dense as the signals <NUM> of first set <NUM> during the duration of signal burst <NUM>.

Moreover, first set <NUM> of one or more signals <NUM> having the first signal density and second set, e.g. signal burst <NUM>, of one or more signals <NUM> having the second signal density may be a same signal or set of signals, or a different signal or set of signals. For example, in one aspect, one or more signals <NUM> of first set <NUM> may be a signal that occupies the center <NUM> resource blocks (RBs) in frequency, while the same <NUM> RB signal within signal burst <NUM> may be transmitted on multiple frequencies at the same time. In another example, signal burst <NUM> may be desired that is denser than the regular 2Tx pattern, but that is understood by legacy UEs so that they can rate match around them. So, in this case, one or more signals <NUM> of first set <NUM> may use a <NUM> transmit (Tx) port CSI-RS pattern, while signal burst <NUM> may use the same CSI-RS signal but with an 8Tx pattern, where on each antenna the same signal is repeated <NUM> times. The result is a configuration where the 8Tx pattern can achieve both a density of signal burst <NUM> greater than a regular 2Tx pattern, and a configuration that can be understood by legacy UEs.

It should be noted that signal burst <NUM>, as illustrated in <FIG>, is merely a representation of an irregular set of signals, and that other sets and patterns of signals may be included in signal burst <NUM>. The reasons for irregular arrangement can be, for example, one or more of: Different cells use a pseudo-random pattern within signal burst <NUM> in order to create some interference diversity; the PSS/SSS are transmitted on multiple symbols in a subframe, skipping over CRS symbols, which themselves are somewhat irregular; when signal burst <NUM> exists in MBSFN subframes, according to certain implemented standards, some subframes may be reserved for other information and thus would not be able to carry signal burst <NUM>, e.g., in some cases signal burst <NUM> may skip subframes #<NUM>, <NUM>, <NUM>, <NUM> in a ten subframe period, or in other cases signal burst <NUM> may skip subframes #<NUM> and #<NUM> because these are used for legacy synchronization signals and system information block (SIBs).

Further, first set <NUM> of one or more signals <NUM> may have a first periodicity <NUM>, while second set, e.g. signal burst <NUM>, of one or more signals <NUM> may have a second periodicity <NUM>. In an aspect, for example, first periodicity <NUM> is substantially different from second periodicity <NUM>. In this figure, for instance, first periodicity <NUM> is substantially less than second periodicity <NUM>.

In some cases, each of first periodicity <NUM> and second periodicity <NUM> may be regular or irregular. For improved energy savings, for example, the transmission of reference signals (e.g., PSS/SSS, CSI-RS, CRS, etc) by base station <NUM> (<FIG>) does not need to be "regular," e.g. does not need to have a constant interval. Rather, the transmission may use at least one of at least two different physical constructions of signals, and/or a same signal but with different configurations (e.g., periodicity, muting configuration, reuse factors, etc.). Further, an "irregular" periodicity, e.g. a periodicity having a variable interval, may not be used for energy savings, but can be used for signal detection purposes. For example, PSS and SSS can be arranged with two different periodicities, wherein one periodicity is every <NUM> second with "infinite" duration (e.g., until another Radio Resource Control (RRC) configuration or broadcast message or signal timing indicator defining a new periodicity), and the other periodicity is every <NUM> for a duration of <NUM> such that PSS and SSS are transmitted in the following subframes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. In this example, the first periodicity serves a "keep-alive" purpose to maintain communications between base station <NUM> (<FIG>) and UE <NUM> (<FIG>), while the second periodicity is may be defined as "performance-driven," e.g. for a connected mode fast detection, especially for an active UE <NUM> (<FIG>).

Additionally, in some aspects, a duration of a given signal transmission period or density period, may vary between first set <NUM> and second set, e.g. signal burst <NUM>, or between different instances of a given set. Thus, the different periodicities and signal densities of first set <NUM> of one or more signals <NUM> and second set, e.g. signal burst <NUM>, of one or more signals <NUM> provide a signal distribution large enough to create energy savings, but sufficiently dose together so as to avoid data communication delays and/or user congestion.

Referring to <FIG>, in one aspect of the present apparatus and methods, another example transmission pattern <NUM>, e.g. which may result from signal pattern <NUM> (<FIG>), defines a first set <NUM> of one or more signals <NUM> having a first signal density and a second set <NUM> of one or more signals <NUM> having a second signal density. Further, first set <NUM> of one or more signals <NUM> may have a first periodicity <NUM>, while second set <NUM> of one or more signals <NUM> may have a second periodicity <NUM>, where first periodicity <NUM> is substantially different from second periodicity <NUM>. In this example, for instance, first periodicity <NUM> may be less or substantially less than second periodicity <NUM>.

Moreover, in some aspects, the one or more signals <NUM> of first set <NUM> and/or the one or more signals <NUM> of second set <NUM>, at different instances, may each comprise different sets of signals. For example, the first instance of first set <NUM> may include signals <NUM> while a later instance of first set <NUM> may include signals <NUM>, wherein signals <NUM> are a different type and/or number of signals relative to signals <NUM>. Similarly, the first instance of second set <NUM> may include signals <NUM> while a later instance of second set <NUM> may include signals <NUM>, wherein signals <NUM> are a different type and/or number of signals relative to signals <NUM>. Further, each type of such signal may have a signal-specific arrangement or configuration that defines membership in a given set or whether the signal is transmitted in a given instance of the set. Alternatively, or in addition, the different signals in each instance of each set may be controlled by a bit map, an attribute or transmission characteristic of each signal or each set of signals, a muting or filtering or reuse pattern, etc..

Additionally, in some aspects, a duration of a given signal may vary between first set <NUM> and second set <NUM>, or between different instances of a given set. Thus, the different periodicities and signal densities of first set <NUM> of one or more signals <NUM> and second set <NUM> of one or more signals <NUM> provide a signal distribution large enough to create energy savings, but sufficiently dose together so as to avoid data communication delays and/or user congestion.

Additionally, the second set <NUM> of one or more signals <NUM> may be aligned with DRX periods of one or more UEs that may at least partially receive the one or more signals <NUM>. For example, in one non-limiting aspect, the second set <NUM> of one or more signals <NUM> may be aligned with a first set <NUM> of one or more DRX periods <NUM> of a first UE and a second set <NUM> of one or more DRX periods <NUM> of a second UE. As such, the one or more DRX periods <NUM> of the first UE and the one or more DRX periods <NUM> of the second UE are aligned with each other and with the second set <NUM> of one or more signals <NUM>. In an aspect, the DRX periods of UEs in a system according to the present aspects may be set to be the same, e.g., where the one or more DRX periods <NUM> of the first UE and the one or more DRX periods <NUM> of the second UE may be identically aligned so that they occur in the same time period.

It should be noted that <FIG> and <FIG> are two examples of transmission patterns, but many other transmission pattern arrangements are contemplated by the present apparatus and methods. For instance, in a simple (but not necessarily the most generic) example, a first set of signals may be a single signal that occurs every <NUM>. Additionally, a second set of signals may occur in every n x <NUM> (e.g., where n could be <NUM>), having a duration of <NUM>, thereby defining a signal burst. For instance, the signal burst may include a dense pattern (which may vary at different instances due to muting, reuse, etc., as discussed above) of duplicates of the same signal as in the first set of signals, where the signal burst may not interrupt the pattern of the first set of signals.

Referring to <FIG>, a method <NUM> of wireless communication system includes, at block <NUM>, obtaining a signal pattern defining resources for use in transmitting or receiving signals, wherein the signals include a plurality of signals defining a signal burst.

Additionally, at block <NUM>, method <NUM> includes configuring the resources based an the signal pattern, including aligning a discontinuous reception (DRX) period with the signal burst.

Further, at block <NUM>, method <NUM> includes transmitting or receiving the signals, including the signal burst aligned with the DRX period, according to the signal pattern to achieve variable density signal transmission or reception over time.

Method <NUM> may provide an enhanced DTX mode of operation of base station <NUM> (<FIG>) and/or an enhanced DRX wake up mode of UE <NUM> (<FIG>), as described above.

Alternatively, or in addition, method <NUM> may also provide an enhanced DRX mode of operation of base station <NUM> (<FIG>), as described above.

Alternatively, or in addition, method <NUM> may also provide concentrated, or non-distributed, UE wake up times, e.g. a UE DRX mode of operation corresponding to the base station DTX mode of operation. In this case, method <NUM> reduces overhead due a reduction in UE DRX maintenance signaling.

Alternatively, or in addition, method <NUM> may also provide enhancements to control signaling and/or page signaling, including increased control overhead during relatively high signal densities and/or transmitting a wake up message with a cross-subframe wake up indication.

Alternatively, or in addition, method <NUM> may also include coordinating the transmitting or receiving the signals according to the signal pattern with at least one of another cell and another carrier, thereby increasing the efficiency of the overall network or system.

Referring to <FIG>, in an aspect, a wireless communication apparatus <NUM> such as a base station or UE, or a portion thereof, includes an electrical component <NUM> for obtaining a signal pattern defining resources for use in transmitting or receiving signals, wherein the signals include a plurality of signals defining a signal burst. Further, apparatus <NUM> may include electrical component <NUM> for configuring the resources based an the signal pattern, including aligning a discontinuous reception (DRX) period with the signal burst. Additionally, the apparatus <NUM> may also include electrical component <NUM> for transmitting or receiving the signals, including the signal burst aligned with the DRX period, according to the signal pattern to achieve variable density signal transmission or reception over time.

The apparatus <NUM> also includes memory <NUM> within which the electrical components <NUM>, <NUM>, and <NUM> can be implemented. Additionally or alternatively, memory <NUM> can include instructions for executing electrical components <NUM>, <NUM>, and <NUM>, parameters related to electrical components <NUM>, <NUM>, and <NUM>, and/or the like.

Alternatively, or in addition, apparatus <NUM> can include a processor <NUM>, which may include one or more processor modules, and which retains instructions for executing functions associated with electrical components <NUM>, <NUM>, and <NUM>, or that executes instructions defined by electrical components <NUM>, <NUM>, and <NUM>. While shown as being external to processor <NUM>, it is to be understood that one or more of electrical components <NUM>, <NUM>, and <NUM> can exist within processor <NUM>.

Thus, the apparatus <NUM> may further implement various techniques described herein. In one example, the apparatus <NUM> can include base station <NUM> (<FIG>) and/or UE <NUM> (<FIG>) to perform the techniques described herein.

Referring to <FIG>, in one aspect, a method <NUM> for energy efficient communication is illustrated. Method <NUM> may provide an enhanced DTX and/or DRX mode of Operation of base station <NUM> and/or UE <NUM> (<FIG>), as described with reference to method <NUM>. It should be understood that in other implementations, other systems and/or UEs, Node Bs, or communication managers comprising different components than those illustrated in <FIG> may be used in implementing method <NUM> of <FIG>.

Method <NUM> includes, at block <NUM>, determining [figure shows obtaining rather than determining] a signal pattern that defines a first set of signals with a first density and a first periodicity and a second set of signals with a second density and a second periodicity.

Additionally, at block <NUM>, method <NUM> includes communicating reference signals among a plurality of communications devices based on the signal pattern.

Method <NUM> may provide any of the methods or functions described herein with respect to method <NUM>.

Alternatively, or in addition, the signal pattern of method <NUM> may define signal bursts that correspond to a plurality of aligned discontinuous reception (DRX) or discontinuous transmission (DTX) periods of the plurality of communications devices.

Alternatively, or in addition, in the signal pattern of method <NUM>, the second density may be greater than the first density and a second period of the second periodicity may be less than a first period of the first periodicity.

Referring to <FIG>, in one aspect, a wireless communication apparatus <NUM> for energy efficient communication is illustrated. Apparatus <NUM> may be base station <NUM> and/or UE <NUM> (<FIG>) or a portion thereof. It should be understood that in other implementations, other systems and/or UEs, Node Bs, or communication managers comprising different components than those illustrated in <FIG> may correspond to apparatus <NUM> of <FIG>.

In an aspect, apparatus <NUM> such as a base station or UE, or a portion thereof, includes an electrical component <NUM> for determining a signal pattern that defines a first set of signals with a first density and a first periodicity and a second set of signals with a second density and a second periodicity. Further, apparatus <NUM> may include electrical component <NUM> for communicating reference signals among a plurality of communications devices based on the signal pattern.

The apparatus <NUM> also includes memory <NUM> within which the electrical components <NUM> and <NUM> can be implemented. Additionally or alternatively, memory <NUM> can include instructions for executing electrical components <NUM> and <NUM>, parameters related to electrical components <NUM> and <NUM>, and/or the like.

Alternatively, or in addition, apparatus <NUM> can include a processor <NUM>, which may include one or more processor modules, and which retains instructions for executing functions associated with electrical components <NUM> and <NUM>, or that executes instructions defined by electrical components <NUM> and <NUM>. While shown as being external to processor <NUM>, it is to be understood that one or more of electrical components <NUM> and <NUM> can exist within processor <NUM>.

<FIG> is a block diagram illustrating an example of a hardware implementation for an apparatus <NUM> employing a processing system <NUM> to operate, for example, base station <NUM>, UE <NUM>, signal pattern obtainer component <NUM>, apparatus <NUM>, apparatus <NUM>, (see <FIG>, <FIG>, and <FIG>), and/or respective components thereof. In this example, the processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> links together various circuits including one or more processors, represented generally by the processor <NUM>, and computer-readable media, represented generally by the computer-readable medium <NUM>. The bus <NUM> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface <NUM> provides an interface between the bus <NUM> and a transceiver <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface <NUM> (e.g., keypad, display, speaker, microphone, joystick) may also be provided.

The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described infra for any particular apparatus, such as for executing signal pattern obtainer component <NUM> which may be signal pattern obtainer component <NUM> (see <FIG>). The computer-readable medium <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software.

Accordingly, in some aspects the present apparatus and methods relate to DRX alignment. For example, in one case, the present apparatus and methods include a base station configured to send and/or receive signals so that the signals align with a UE DRX period, e.g., <NUM>, <NUM>, or periodically changing some attribute of the signal in alignment with a common DRX period. Further, in some cases, the present apparatus and methods may include a base station configuring all UEs with the same DRX subframe offset (e.g., to make them wake up at the same time) or distributing the DRX subframe offset over a substantially limited set of subframe offsets, where the substantially limited set is smaller than all possible subframe offsets. In still other aspects, the present apparatus and methods include changing some other signal attributes or configuration in alignment with the common DRX period. For example, the changed attribute or configuration may increase a control region during the period when DRX is On, or may allow cross-subframe scheduling during the period when DRX is On, etc. Further, in other cases, the present apparatus and methods may include a base station configuring the common DRX for new UEs and using distributed DRX for legacy UEs. As noted above, the common DRX may be a same DRX period and/or subframe offset assigned to each UE or a subframe offset assigned from a substantially limited set of subframe offsets. Thus, the present apparatus and methods include a base station having DTX aligned with UE DRX.

In other alternative or additional aspects, the present apparatus and methods relate to synchronization signal design. For example, in one case, the same synchronization signal may have different periodicities of different densities where either periodicity may be regular or irregular (e.g., the latter may be described by a bit map) or having a fine structure within one period that may be regular or irregular (e.g., the latter may be described by a bit map). In addition to different periodicity, the signal within each density period may have somewhat different attributes. For example, in a high density period, the PSS/SSS frequency location may be changed or it may be duplicated an multiple frequencies. Another example is using more CSI-RS antenna ports to send the same signal from the same antenna.

In further alternate or additional aspects, the present apparatus and methods may include techniques to provide backward compatibility. For example, in MBSFN or non-MBSFN subframes, the present apparatus and methods can configure zero power CSI-RS (muting) for legacy UEs aligned with the signal with new densities. Further, for example, if muting is already used for legacy UEs for other purposes, then the present apparatus and methods can configure MBSFN subframes aligned with the DRX period and send the "new" signal in the MBSFN portion, e.g., in the subframes defined for carrying MBSFN data. In another case, for instance, the present apparatus and methods may limit a CSI-RS frequency span in these subframes in order to be able to more efficiently multiplex with ePDCCH.

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.

Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed an the overall system.

A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

Claim 1:
A method (<NUM>) of energy efficient wireless communication performed by a user equipment, UE, comprising:
obtaining (<NUM>) a signal pattern (<NUM>) defining resources for use in receiving a first set (<NUM>, <NUM>) of reference signals (<NUM>, <NUM>) with a first density and a first periodicity (<NUM>, <NUM>) and a second set (<NUM>, <NUM>) of reference signals (<NUM>, <NUM>, <NUM>) with a second density and a second periodicity (<NUM>, <NUM>), wherein the first density is less than the second density and the first periodicity provides a shorter maximum duration without signal present than the second periodicity and wherein the second set of reference signals comprises a signal burst (<NUM>);
receiving (<NUM>) the reference signals according to the signal pattern; and
receiving a wake up message with a cross-subframe wake up indication corresponding to the second set of reference signals.