BR112016003172B1 - DOWNLINK PROCEDURES FOR LTE-A COMMUNICATION SYSTEMS WITH UNLICENSED SPECTRUM - Google Patents

Abstract

DOWNLINK PROCEDURES FOR LTE A COMMUNICATION SYSTEMS WITH UNLICENSED SPECTRUM. Long Term Evolution (LTE)/LTE-Advanced (LTE-A) deployments with unlicensed spectrum leverage aspects of more effective LTE communication over unlicensed spectrum, such as over WiFi radio access technology. To accommodate such communications , several downlink procedures can be modified to handle communications between licensed and unlicensed spectrum with LTE/LTE-A deployments with unlicensed spectrum.

Description

CROSS-REFERENCE TO RELATED ORDERS

[0001] This application claims the benefit of US provisional patent application No. 61/866 905, entitled “DOWNLINK PROCEDURES FOR LTE-U COMMUNICATION SYSTEMS”, filed on August 16, 2013, and the utility application US No. 14/459 651, entitled “DOWNLINK PROCEDURES FOR LTE/LTE-A COMMUNICATION SYSTEMS WITH UNLICENSED SPECTRUM”, filed on August 14, 2014, which are hereby expressly incorporated in their entirety by way of reference.

BACKGROUND Field

[0002] The aspects of the present disclosure relate generally to wireless communication systems and, more specifically, to downlink procedures for long-term evolution (LTE)/LTE-Advanced (LTE-A) communication systems with unlicensed spectrum.

Background

[0003] Wireless communication networks are widely implemented to provide various communication services, such as voice, video, packet data, messaging, broadcasting and the like. These wireless networks can be multiple access networks capable of supporting multiple users by sharing available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing available network resources. An example of such a network is the Universal Terrestrial Radio Access Network (UTRAM). UTRAM is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). Examples of multiple access network formats include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal OFDMA networks ( OFDMA) and Single Carrier FDMA (SC-FDMA) networks.

[0004] A wireless communications network may include multiple base stations or B-nodes and may support communication to multiple user equipment (UEs). A UE can communicate with a base station via downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

[0005] A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a base station transmission may encounter interference due to transmissions from neighboring base stations or other wireless radio frequency (RF) transmitters. At the UL, a UE's transmission may encounter interference from uplink transmissions from other UEs communicating with neighboring base stations or from other wireless RF transmitters. This interference can deteriorate performance on both the downlink and the uplink.

[0006] As the demand for mobile broadband access continues to increase, the possibilities for interference and congested networks grow with more UEs accessing long-range wireless communication networks and more short-range wireless systems being deployed in communities . Research and development continues to advance UMTS technologies to not only meet the growing demand for mobile broadband access, but to advance and improve the user experience with mobile communications.

SUMMARY

[0007] Under one aspect of the disclosure, a method of wireless communication includes generating, at a base station configured to transmit Orthogonal Frequency Division Multiple Access (OFDMA) communication signals over at least one unlicensed spectrum, at least one of: one or more synchronizing signals, or a system broadcast signal for transmission, determine by the base station a non-channel release (non-CCA) evaluation subframe for transmission of at least one of: o sync signal or signals, the system broadcast signal, and transmitting, by the base station, the at least one of: the sync signal or signals or the system broadcast signal in the non-CCA subframe.

[0008] Under a further aspect of the disclosure, a method of wireless communication includes receiving, in user equipment configured to receive OFDMA communication signals over at least one unlicensed spectrum, at least one of: one or more signals from synchronization or a system broadcast signal in a non-CCA subframe from a base station, and communicate, by user equipment, with the base station based on at least one received from: one or more synchronization signals or a system broadcast signal.

[0009] Under a further aspect of the disclosure, equipment configured for wireless communication includes a device for generating, at a base station configured to transmit OFDMA communication signals over at least one unlicensed spectrum, at least one of: one or plus synchronizing signals or a system broadcast signal for transmission. The equipment further includes a device for determining, by the base station, a non-CCA subframe for transmission of the at least one of: the synchronization signal or signals or the system broadcast signal. The equipment also includes a device for transmitting, by the base station, the at least one of: the synchronization signal or signals or the system broadcast signal in the non-CCA subframe.

[0010] Under a further aspect of the disclosure, an equipment configured for wireless communication includes a device for receiving, in a user equipment configured to receive OFDMA communication signals over at least one unlicensed spectrum, at least one of: a or more synchronizing signals or a system broadcast signal in a non-CCA subframe of a base station. The equipment further includes a device for communicating, by the user equipment, with the base station, based on at least one received from: one or more synchronization signals or a system broadcast signal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 shows a diagram that shows an example of wireless communication system according to different modalities.

[0012] Figure 2A shows a diagram showing examples of deployment scenarios for using LTE in an unlicensed spectrum according to various modalities.

[0013] Figure 2B shows a diagram that shows another example of deployment scenarios for utilizing LTE in unlicensed spectrum under various arrangements.

[0014] Figure 3 shows a diagram showing an example of carrier aggregation when using LTE concomitantly in licensed and unlicensed spectrum, according to different modalities.

[0015] Figure 4 is a block diagram conceptually showing a base station/eNB design and a UE configured in accordance with an aspect of the present disclosure.

[0016] Figures 5A and 5B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

[0017] Figures 6A and 6B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

[0018] Figure 7 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure.

[0019] Figure 8 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure.

[0020] Figure 9 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure.

[0021] Figures 10A and 10B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

[0022] Figure 11 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure.

[0023] Figure 12 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure.

[0024] Figures 13A and 14B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

[0025] Figure 14 is a block diagram showing a transmission timeline in an LTE/LTE-A deployment with unlicensed spectrum configured in accordance with an aspect of the present disclosure.

[0026] Figure 14 is a functional block diagram showing a transmission timeline in an LTE/LTE-A deployment with unlicensed spectrum configured in accordance with an aspect of the present disclosure.

[0027] Figures 16A and 16B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

[0028] Figure 17 is a block diagram showing blocks an assured transmission configured in accordance with an aspect of the present disclosure.

[0029] Figures 16A and 16B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure.

DETAILED DESCRIPTION

[0030] The detailed description presented below, in connection with the accompanying drawings, is intended to be a description of various configurations and is not intended to limit the scope of the disclosure. Rather, the detailed description includes specific details for the purpose of providing a complete understanding of the inventive object. It will be apparent to those skilled in the art that these specific details are required in every case and that, in some instances, well known structures and components are shown in block diagram form for clarity of presentation.

[0031] Operators have so far looked to WiFi as the primary mechanism when utilizing unlicensed spectrum to alleviate the ever-increasing levels of congestion on cellular networks. However, a new carrier type (NCT) based on LTE/LTE-A on an unlicensed spectrum may be WiFi compatible with the carrier type, making LTE/LTE-A with unlicensed spectrum an alternative for WiFi. LTE/LTE-A with unlicensed spectrum can leverage LTE concepts and can introduce modifications in physical layer (PHY) and Medium Access Control (MAC) aspects of network appliances in order to achieve efficient operation in the unlicensed spectrum and in order to satisfy regulatory requirements. Unlicensed spectrum can range from 600 Megahertz (MHz) to 6 Gigaherz (GHz), for example. In some scenarios LTE/LTE-A with unlicensed spectrum can perform significantly better than WiFi. For example, a full LTE/LTE-A deployment with unlicensed spectrum (single-operator or multi-operator) compared to a In an all-WiFi deployment, or where there are dense small cell deployments, LTE/LTE-A with unlicensed spectrum can perform significantly better than WiFi. LTE/LTE-A with unlicensed spectrum can perform better than WiFi. of WiFi in other scenarios, such as when LTE/LTE-A with unlicensed spectrum is mixed with WiFi (single carrier or multiple carriers).

[0032] For a service provider (SP) with each other, an LTE/LTE-A network with unlicensed spectrum can be configured to be synchronous with an LTE network in licensed spectrum. However, LTE/LTE-A networks with unlicensed spectrum deployed on a given channel by multiple SPs can be configured to be synchronous across multiple SPs. One approach to incorporating both of the above features could involve using a constant timing offset between LTE/LTE-A with and without unlicensed spectrum for a given SP. An LTE/LTE-A network with unlicensed spectrum can provide unicast and/or multicast services according to the needs of the SP. Furthermore, an LTE/LTE-A with unlicensed spectrum can operate in an initialization mode, in which the LTE cells act as an anchor and provide relevant cellular unlicensed spectrum information (such as radio frame timing , common channel configuration, number of system or SFN frames, etc.). In this mode, there can be intimate interworking between LTE/LTE-A with and without unlicensed spectrum. For example, the initialization mode can support the supplemental downlink and carrier aggregation modes described above. The PHY-MAC layers of LTE/LTE-A network with unlicensed spectrum can work in an independent mode, in which LTE/LTE-A with unlicensed spectrum works independently of an LTE network. In this case, there may be loose interworking between LTE/LTE-A with and without unlicensed spectrum based on aggregation at the RLC level with co-located licensed and unlicensed cells, or multiple flow across multiple cells and/or or base stations, for example.

[0033] The techniques described here are not limited to LTE and various wireless communication systems can also be used, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) etc. CDMA200 covers IS-2000, IS-95, and IS-856 standards. IS-2000 versions 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856(TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Broadband CDMA (WCDM) and other variants of CDMA. A TDMA system can implement a radio technology such as the Global System for Mobile Communications (GSM). An OFDMA system can implement a radio technology such as Ultra-Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (WiFi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-Advanced (LTE-A) are new versions of UMTS that use E-UTRA, UTRA, UMTS, LTE, LTE-A and GSM are described in documents of the organization called “Project of 3rd Generation Partnerships” ( 3GPP). CDMA2000 and UMB are described in documents from an organization called “3rd Generation Partnership Project 2” (3GPP2). The techniques described here can be used in systems and radio technologies mentioned above as well as in other systems and radio technologies. The description below, however, describes an LTE system for exemplary purposes, and LTE terminology is used in much of the description that follows, although the techniques apply beyond LTE applications.

[0034] Thus, the following description presents examples and does not limit the scope, applicability or configuration presented in the claims. Changes can be made to the function and arrangement of the elements discussed without departing from the spirit and scope of the revelation. Various modalities may omit, replace, or add various procedures or components as appropriate. For example, the described methods can be performed in a different order than described and several steps can be added, omitted or combined. In addition, features described with respect to certain modalities may be combined in other modalities.

[0035] Referring first to Figure 1, a diagram shows an example wireless communication system or network 100. The system 100 includes base stations (or cells) 105, communication devices 115 and a core network 130. The base stations 105 can communicate with communication apparatus 115 under control of a base station controller (not shown), which can be part of the core network 130 or base stations 105 in various ways. The base stations 105 may communicate control information and/or user data with the core network 130 via backhaul links 132. In embodiments, the base stations may communicate either directly or indirectly with each other via links backhaul 134 that can be wired or wireless communication links. System 100 can support operation on multiple carriers (waveform signals of different frequencies), multi-carrier transmitters can transmit modulated signals simultaneously on multiple carriers. For example, each communication link 125 may be a multi-carrier signal modulated according to various radio technologies. each modulated signal can be sent on a different carrier and can carry control information (such as reference signals, control channels, etc.), overhead information, data, etc.

[0036] The base stations 105 can communicate wirelessly with the handsets 115 via one or more base station antennas. Each of the base station locations 105 may provide communication coverage for a respective geographic area 110. In some embodiments, the base stations 105 may be referred to as a base transceiver station, a radio base station, an access point, a radio -transceiver, a basic service set (DSS), an expanded service set (ESS), a NodeB, eNodeB (eNB), a Native NodeB, a Native eNodeB, or some other suitable terminology. The coverage area 110 for a base station can be divided into sectors that make up only a portion of the coverage area (not shown). System 100 may include base stations 105 of different types (macro, micro and/or pico base stations, for example). There may be overlapping coverage areas for different technologies.

[0037] In some embodiments, system 100 is an LTE-A network that supports one or more communication operating modes or deployment scenarios over unlicensed spectrum. In other embodiments, system 100 can support wireless communications using unlicensed spectrum and access technology other than LTE/LTE-A with unlicensed spectrum or licensed spectrum and access technology other than LTE-A. The terms Evolved Node B (eNB) and User Equipment (UE) may generally be used to describe base stations 105 and handsets 115, respectively. System 100 may be a Heterogeneous LTE/LTE-A network with or without licensed spectrum in which different types of eNB provide coverage for different geographic regions. For example, each eNB 105 can provide communication coverage for a macro cell, a pico cell, a femto cell, or other cell types. Small cells such as pico cells, femto cells and/or other cell types may include low power nodes or LPMs. A macrocell generally covers a relatively large geographical area (within a radius of several kilometers, for example) and can allow unrestricted access by UEs with service subscriptions from the network provider. A pico-cell would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions to the network provider. A femto cell would usually also cover a relatively small geographic area (a household, for example) and in addition to unrestricted access it may also provide restricted access by UEs that are associated with the femto cell (UEs in a closed subscriber group, CSG) , UEs for home users and the like, for example. An eNB for a macrocell can be referred to as a macro-eNB. An eNB for a pico-cell may be referred to as a pico-eNB. And an eNB for a femto-cell can be referred to as femto-eNB or Native eNB. An eNB can support one or several (two, three, four and the like, for example) cells.

[0038] The core network 130 can communicate with the eNBs 105 via a backhaul channel 132 (such as S1, etc.). The eNBs 105 can also communicate with each other directly or indirectly, for example, via backhaul transport links 134 (such as X2, etc.) and/or via backhaul transport links 134 return 132 (through the basic network 130, for example). System 100 can support synchronous or asynchronous operation. For synchronous operation, the eNBs can have frame and/or gated timing and similar transmissions from different eNBs can be approximately time-aligned. For asynchronous operation, the eNBs may have different frame timing and/or gate connection, and transmissions from different eNBs may not be time-aligned. The techniques described here can be used for either synchronous or asynchronous operation.

[0039] The UEs 115 are dispersed throughout the system 100, and each UE can be stationary or mobile. A UE 115 may also be referred to by those skilled in the art as a mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, station mobile subscriber, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client or some other suitable terminology. A UE 115 can be a cell phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handset, a tablet computer, a laptop computer, a cordless phone, a dock wireless local loop (WLL) or similar. A UE is capable of communicating with macro-eNBs, pico-eNBs, femto-eNBs, relays and the like.

[0040] The communication links 125 shown in the system 100 may include uplink transmissions (UL) from a mobile device 115 to a base station 105 and/or downlink transmissions (DL) from a base station 105 to a device 115. downlink transmissions can also be called forward link transmissions while uplink transmissions can also be called reverse link transmissions. Downlink transmissions can be made using licensed spectrum, unlicensed spectrum, or both. Likewise, uplink transmissions can be made using licensed spectrum, unlicensed spectrum, or both.

[0041] In some embodiments of the system 100, several deployment scenarios for LTE/LTE-A with unlicensed spectrum can be supported, including a supplemental downlink mode (SDL), in which the LTE downlink capacity in a licensed spectrum can be be offloaded to unlicensed spectrum, a carrier aggregation mode in which both downlink and uplink LTE capacity can be offloaded from licensed spectrum to unlicensed spectrum, and a standalone mode in which communications LTE downlink and uplink between a base station (eNB, for example) and a UE can occur in unlicensed spectrum. Base stations 105 as well as UEs 115 may support one or more of these operating modes or similar operating modes. OFDMA communication signals may be used on communication links 125 for LTE downlink transmissions in an unlicensed spectrum, while SC-FDMA communication signals may be used on communication links 125 for LTE uplink transmissions on an unlicensed spectrum. Additional details regarding the implementation of deployment scenarios or LTE/LTE-A operating modes with unlicensed spectrum in a system such as System 100, as well as other features and functions related to the operation of LTE/LTE-A with unlicensed spectrum , are set forth below with reference to Figures 2A-18B.

[0042] Referring next to Figure 2A, a diagram 200 shows examples of a supplemental downlink mode and a carrier aggregation mode for an LTE network supporting LTE/LTE-A with unlicensed spectrum. Diagram 200 may be an example of parts of the system 100 of Figure 1. Furthermore, base station 105-a may be an example of base stations 105 of Figure 1, while UEs 115-a may be examples of UEs 115 from Figure 1.

[0043] In the example of the supplemental downlink mode in diagram 200, the base station 105-a can transmit OFDMA communication signals to a UE 115-a using a downlink 205. The downlink 205 is associated with a frequency F1 to a spectrum not licensed. The base station 105-a can transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 210 and can receive SC-FDMA communication signals from that UE 115-a using the bidirectional link 210. The bidirectional link 210 is associated at an F4 frequency in a licensed spectrum. The downlink 205 in the unlicensed spectrum and the bidirectional link 210 in the licensed spectrum can function concurrently. Downlink 205 may provide an offload of downlink capacity to base station 105-a. In some embodiments, downlink 205 may be used for unicast services (addressed to one UE, for example) or for multicast services (addressed to multiple UEs, for example). This scenario can occur with any service provider (traditional mobile network operator or MNO, for example) that uses licensed spectrum and needs to alleviate some of the traffic or signaling congestion.

[0044] In an example of the carrier aggregation mode in diagram 200, the base station 105-a can transmit OFDMA communication signals to a UE 115-a using a bidirectional link 215 and can receive SC-FDMA communication signals from the same UE 115-a using bidirectional link 215. Bidirectional link 215 is associated with frequency F1 in the unlicensed spectrum. The base station 105-a can also transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 220 and can receive SC-FDMA communication signals from the same UE 115-a using the bidirectional link 220. The bidirectional link 220 is associated with an F2 frequency in a licensed spectrum. The bidirectional link can provide an offload of downlink and uplink capacity to base station 105-a. Similar to the supplemental downlink described above, this scenario can occur with any service provider (MNO, for example) that uses licensed spectrum and needs to alleviate traffic and/or signaling congestion.

[0045] In another example of the carrier aggregation mode in diagram 200, the base station 105-a can transmit OFDMA communication signals to a UE 115-a using a bidirectional link 225 and can receive SC-FDMA communication signals from the same UE 115-a using bidirectional link 225. Bidirectional link 225 is associated with frequency F3 in unlicensed spectrum. The base station 105-a can also transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 230 and can receive SC-FDMA communication signals from the same UE 115-a using the bidirectional link 230. The bidirectional link 230 is associated with the F2 frequency in the licensed spectrum. Bidirectional link 225 may provide an offload of downlink and uplink capacity to base station 105-a. This example and those above are provided for illustration purposes and there may be other similar operating modes or deployment scenarios that combine LTE-A with and without unlicensed spectrum for capacity offload.

[0046] As described above, the typical service provider that can benefit from the capacity offload offered by utilizing LTE/LTE-A with unlicensed spectrum and a traditional MNO with LTE spectrum. For these service providers, an operational configuration may include an initialization mode (supplemental downlink, carrier aggregation, for example) that uses the primary component carrier (PCC) LTE in the licensed spectrum and the secondary component carrier (SCC) in the unlicensed spectrum. licensed.

[0047] In supplemental downlink mode, control for LTE/LTE-A with unlicensed spectrum can be supported via the LTE uplink (the uplink portion of the bidirectional link 210, for example). One of the reasons for providing downlink capacity offload is because demand for data is considerably driven by downlink consumption. Furthermore, in this mode, there may not be a regulatory impact since the UE is not transmitting in the unlicensed spectrum. There is no need to implement Listen Before Talk (LBT) or Carrier Sense Multiple Access (SCMAQ) requirements in the UE. However, LBT can be implemented at the base station (eNB, for example) by, for example, using a periodic channel release evaluation (CCA) (every 10 milliseconds, for example) and/or the hold and release mechanism. aligned with a boundary between radio frames.

[0048] In the carrier aggregation mode, data and control can be communicated on LTE (the bidirectional links 210, 220 and 230, for example) while secondly they can be communicated on LTE/LTE-A with unlicensed spectrum (the bidirectional links 215 and 225, for example). Carrier aggregation mechanisms supported when using LTE/LTE-A with unlicensed spectrum can be subsumed within a hybrid frequency division-time division (FDD-TDD) duplex carrier aggregation or a carrier aggregation TDD-TDD with different symmetry across component carriers.

[0049] Figure 2B shows a diagram 200-a showing an example of standalone mode for LTE/LTE-A with unlicensed spectrum. Diagram 200-a may be an example of parts of the system 100 of Figure 1. Furthermore, base station 105-b may be an example of base stations 105 of Figure 1 and base station 105-a of Figure 2A. While the UE 115-b may be an example of the UEs 115 of Figure 1 and the UEs 115-a of Figure 2A.

[0050] In the example of the independent mode in diagram 200-a, base station 105-b can transmit OFDMA communication signals to UE 115-b using a bidirectional link 240 and can receive SC-FDMA communication signals from UE 115- b using bidirectional link 240. Bidirectional link 240 is associated with frequency F3 in an unlicensed spectrum described above with reference to Figure 2A. Standalone mode can be used in non-traditional wireless access scenarios such as stadium access (unicast, multicast, for example). The typical service provider for this mode of operation could be a stadium owner, a telegraph company, event hosts, hotels, corporations and large companies that do not have licensed spectrum. For these service providers, an operational configuration for standalone mode can utilize PCC LTE/LTE-A with unlicensed spectrum. Furthermore, LBT can be implemented at both the base station and the UE.

[0051] Referring next to Figure 3, a diagram 300 shows an example of carrier aggregation when using LTE concurrently in licensed and unlicensed spectrum according to various embodiments. The carrier aggregation scheme in diagram 300 may correspond to the hybrid FDD-TDD carrier aggregation described above with reference to Figure 2A. This type of carrier aggregation can be used in at least parts of the system 100 of Figure 1. Furthermore, this type of carrier aggregation can be used in base stations 105 and 105-a of Figure 1 and Figure 2A, respectively , and/or in UEs 115 and 115-a of Figure 1 and Figure 2A, respectively.

[0052] In this example, an FDD (FDD-LTE) can be performed in connection with LTE on the downlink, a first TDD (TDD1) can be performed in connection with LTE/LTE-A with unlicensed spectrum, a second TDD (TDD2) can be performed in connection with LTE, and another FDD (FDD-LTE) can be performed in connection with LTE on the uplink. TDD1 results in a DL-UL ratio of 6:4 while the ratio for TDD2 is 7:3. On the timescale, the different effective DL:UL ratios are 3:1, 1:3, 2:2, 3:1, 2:2, and 3:1. This example is provided for illustration purposes and there may be other carrier aggregation schemes that combine LTE/LTE-A operation with unlicensed spectrum.

[0053] Figure 4 shows a block diagram of a design of a base station/eNB 105 and a UE 105, which can be one of the base stations/eNBs and one of the UEs of Figure 1. The eNB 105 can be equipped with antennas 434a to 434t, and UE 115 may be equipped with antennas 452a to 452r. In the eNB 105, a transmission processor 42o may receive data from a data source 412 and control information from a controller/processor 440. The control information may be for the physical broadcast channel (PBCH) the format indicator channel. physical control channel (PCFICH), the physical hybrid autorepeat request indicator channel (PHICH), the physical downlink control channel (PDCCH), etc. The data can be for physical downlink shared channel (PDSCH), etc. Stream processor 420 may process (encode and symbol map, for example) the data and control information to obtain data symbols and control symbols, respectively. Stream processor 420 may also generate reference symbols for the primary signaling signal (PSS), the secondary signaling signal (SSS), and the cell-specific reference signal, for example. A multi-input, multi-output (MIMO) transmission (TX) processor 430 can perform spatial processing (precoding, for example) on the data symbols, control symbols, and/or reference symbols, if applicable, and may send output symbol streams to modulators (MODs) 432a to 432p. Each modulator 432 can process a respective output symbol stream (such as for OFDM, etc.) to obtain an output sample stream. Each modulator 432 can also process (convert to analogue, amplify, filter and upconvert, for example) the output sample stream in order to obtain a downlink signal. Downlink signals from modulators 432a to 432t may be transmitted through antennas 434a to 434t, respectively.

[0054] At UE 114, antennas 52a to 452r can receive downlink signals from eNB 105 and can send received signals to demodulators (DEMODs) 454a to 454r, respectively. Each demodulator 452 can condition (filter, amplify, effect, downconvert and digitize, for example). A respective signal received in order to obtain input samples. Each demodulator 554 can also process the input samples (such as for OFDM, etc.) in order to obtain received symbols. A MIMO detector 456 may obtain received symbols from all demodulators 454a to 454r, perform MIMO detection on received symbols if applicable, and obtain detected symbols. A receive processor 458 may process (demodulate, deinterleave, and decode, for example) the detected symbols, send decoded data to UE 115 to a data dump 460, and send decoded control information to a controller/processor 480.

[0055] On the uplink, at UE 115, a transmission processor 464 can receive and process data (for the shared physical uplink channel (PUSCH), for example) from a data source 462 and control information (for the channel of physical uplink control (PUCCH), for example) from controller/processor 480. Transmission processor 464 may also generate reference symbols for a reference signal. Symbols from transmission processor 464 may be pre-encoded by a MIMO TX processor 466 if applicable, further processed by demodulators 454a to 454r (such as for SC-FDM, etc.) and transmitted to eNB 105. eNB 105, the uplink signals from the UE 115 can be received by the antennas 434, processed by the demodulators 432, detected by a MIMO detector 436 if applicable and also processed by a reception processor 438 in order to obtain decoded data and control information sent by UE 115. Processor 438 may send the decoded data to a data store 439 and the decoded control information to controller/processor 440.

[0056] Controllers/processors 440 and 480 may direct operation in eNB 105 and UE 115, respectively. The controller/processor 440 and/or other processors and modules in the eNB 105 can perform or direct the execution of various processes for the techniques described herein. Controller/processor 480 and/or other processors and modules in UE 115 may also execute or direct the execution of the functional blocks shown in Figures 5-13 and 16 and/or other processes for the techniques described herein. Memories 442 and 482 can store data and program codes for eNB 105 and/or UE 115, respectively. A scheduler 444 can schedule UEs for data transmission on the downlink and/or the uplink.

[0057] With the implementation of wireless technologies for communication using LTE/LTE-A with unlicensed spectrum, several adaptations may be desirable in order to accommodate LTE operations through an unlicensed band effectively and with a small change in the current LTE standards as possible. For example, several downlink procedures can be adapted for LTE operations with unlicensed spectrum in LTE/LTE-A deployments with unlicensed spectrum.

[0058] One aspect of LTE downlink operations for consideration in adapting for LTE/LTE-A applications with unlicensed spectrum is cyclic prefix (CP) operation. In LTE two CP durations are supported (Normal CP (NCP)) and Extended CP (ECP)). The NCP duration is approximately 5 μs, while the ECP and storage device duration is 17 μs. NCP makes more efficient use of overhead than ECP configurations. Therefore, it may be desirable to provide NCP in LTE/LTE-A deployments with unlicensed spectrum. CP for DL and UL can be configured separately, which would therefore result in four combinations for CP DL and UL durations between NCP and ECP.

[0059] As indicated, NCP may be sufficient for LTE/LTE-A deployments with unlicensed spectrum at least for unicast transmissions. Due to the limited transmit power and coverage range there may also be motivation to consider an even shorter CP for more efficient operations. Figure 5A is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 500, a base station configured to transmit OFDMA communication signals over unlicensed spectrum generates a communication for transmission. At block 501, the base station adds an unlicensed band cyclic prefix to the communication, wherein the duration of the unlicensed band cyclic prefix is less than or equal to a normal cyclic prefix associated with communications over the licensed spectrum. At block 502, the base station transmits the communication to one or more UEs over an unlicensed band. The communication can be a unicast communication specifically addressed to each of the UE or UEs or it can be a broadcast communication to the UE or UEs within the coverage area of the base station.

[0060] Figure 5B is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 503, a UE configured to receive OFDMA communication signals from a base station over licensed and unlicensed spectrum receives a communication from a serving base station over an unlicensed band. In response to receiving the communication over the unlicensed band, at block 504, the UE processes the communication using a cyclic unlicensed band prefix, wherein the duration of the cyclic unlicensed band prefix is less than or equal to a normal cyclic prefix associated with communications over a licensed band. In such OFDMA communications received by the UE over an unlicensed band, the UE uses the unlicensed band cyclic prefix, which, under selected aspects, may be of a shorter duration than a normal cyclic prefix in licensed band communications . As such, communications can be received and processed more efficiently and potentially with an increase in data transmission capacity.

[0061] In LTE, eMBMS transmissions can be performed as single-cell transmissions or multi-cell transmissions. In the case of multi-cell transmission, the cells and content are synchronized to allow the terminal to tentatively combine the energy of multiple transmissions. The superimposed sign appears to multipath to the terminal. This concept is also known as Single Frequency Network (SFN). The LTE network can configure which cells are part of an SFN for transmitting an eMBMS service. In single-frequency multicast, broadcast (MBSFN) networking, transmission takes place from a time-synchronized set of eNBs using the same block of resources. The CP typically used for MBSFN is an ECP, and this allows the UE to combine transmissions from different eNBs located far away from each other, thus somewhat negating some of the operating advantages of SFN.

[0062] Communications using eMBMS can also be implemented in LTE/LTE-A deployments with unlicensed spectrum. For such eMBMS communication over unlicensed spectrum, NCP may be sufficient because of the limited coverage range of LTE/LTE-A deployments with unlicensed spectrum. As noted above, however, current MBSFN reference signals are projected based on the ECP. Therefore, when performing eMBMS communications over MBSFN channels, the NCP is used for the eMBMS communication in addition to a new MBSFN reference signal standard (Reuse Port 5 DM-RS standard and the like, for example). Figure 6A is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 600, a base station configured to transmit OFDMA communication signals over unlicensed spectrum generates a broadcast communication, such as an eMBMS communication. At block 601, the base station adds a cyclic unlicensed band prefix to the broadcast communication, wherein the duration of the cyclic unlicensed band prefix is the same as a normal cyclic prefix associated with licensed spectrum communications. At block 602, the base station generates a broadcast reference signal, such as the MBSFN reference signal, according to a pattern associated with the unlicensed band cyclic prefix. At block 603, the base station broadcasts the broadcast reference signal and broadcasts communication over an unlicensed band.

[0063] Figure 6B is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 604, a UE configured to receive OFDMA communication signals from a base station over licensed and unlicensed spectrum receives a broadcast signal over an unlicensed band. At block 605, in response to receiving the broadcast signal over the unlicensed band, the UE detects a broadcast reference signal, such as an MBSFN reference signal in a pattern configured according to a cyclic unlicensed band prefix, where the duration of the unlicensed band cyclic prefix is equal to that of a normal cyclic prefix associated with communications over a licensed band. At block 606, the UE detects a broadcast communication, such as an eMBMS transmission of the broadcast signal that uses the unlicensed band cyclic prefix.

[0064] Under additional aspects of the present disclosure, LTE/LTE-A with unlicensed spectrum can simplify the frame structure by selecting the cyclic prefix type based on the specific sub-frame. For example, evaluation subframes for channel release (CCA), or modified special (S') subframes in which CCA is done, will use NCP. While other subframes may use either NCP or ECP depending on the deployment, such as supplemental downlink (SDL) and carrier aggregation (CA) LTE/LTE-A deployments with unlicensed spectrum. Figure 7 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 700, a base station configured to transmit OFDMA communication signals over unlicensed spectrum generates a communication for transmission to one or more UEs. At block 701, the base station detects a subframe in which the communication will be transmitted. At block 702 the base station selects an unlicensed band cyclic prefix based on the detected subframe. At block 703, the base station adds the selected unlicensed band cyclic prefix to the communication. At block 704, the base station transmits the communication over an unlicensed band.

[0065] In LTE/LTE-A SDU and CA deployments with unlicensed spectrum where the unlicensed band deployment is the secondary component carrier (SCC), the unlicensed band can have the same cyclic prefix or different cyclic prefix as CC of anchor. Therefore, there would be no need to enforce the same cyclic prefix, under those aspects where the unlicensed band SCC may use a different cyclic prefix, the unlicensed band base station may transmit the cyclic prefix to the UE via direct signaling. Alternatively, the cyclic prefix information of a secondary unlicensed band CC may be discovered by the UE using blind detection. For example, the cyclic downlink prefix can be blindly detected through some physical signals/channels, eg PSS/SSS, by the UE.

[0066] Under certain aspects of the disclosure, unicast transmissions may be configured with a single type of cyclic prefix.

[0067] Additional downlink aspects that can be accommodated for LTE/LTE-A deployments with unlicensed spectrum includes frame structure. In LTE, both frequency division duplex (FDD) and time division duplex (TDD) structures are supported. In order to allow for initial differentiation of these two frame structures, the PSS/SS are generally placed differently. For example, FDD structures put PSS/SSS in subframes 0/5 in the last two symbols of partition 0 - SSS followed by PSS. TDD structures place PSS/SSS in subframes 0/1/5/6, with SSS placed in the last symbol of subframes 0/5 and TSS in the third symbol of subframes 1/6. For LTE/LTE-A deployments with unlicensed spectrum, however, there are no paired downlink/uplink carriers. LTE/LTE-A with unlicensed spectrum uses two types of frame: downlink-only subframes and mixed downlink/uplink subframes, such as downlink plus at least one uplink subframe. Downlink-only subframe configurations on LTE/LTE-A with unlicensed spectrum can be similar to LTE downlink-only Band 29 support at least in SDL and CA deployment scenarios. So, for example, some UEs can only be configured to receive in the unlicensed carrier band, instead of receiving and transmitting in the unlicensed carrier band.

[0068] For LTE/LTE-A SDL/CA deployments with unlicensed spectrum, the two structures, or the actual configurations can be indicated by means of the anchor CC UEs can still fetch these carriers, before being added to the serving cells, without any assistance from anchor CC. However, the same frequency can belong to a licensed band in one region or country and an unlicensed band in a different region or country. The UE may not be aware of such a difference and can perform cell lookup transparently. Thus, both structures for downlink exclusively and for mixed downlink/uplink can be supported. The distinction between the two structures may, in some respects, be indicated by different PSS/SSS collocations, or, in other respects conveyed in system messages such as master information blocks (MIBs) or system information blocks (SIBs).

[0069] Figure 8 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. At block 800, a UE obtains indication of a frame structure for communicating with a serving base station in which the UE is configured to receive Orthogonal Frequency Division Multiple Access (OFDMA) communication signals from the serving base station over licensed spectrum and not licensed. To get the frame structure indication, the UE can receive the frame indication by accessing the anchor CC. Signaling can be contained in various system messages, such as MIBs or SIBs. Additional aspects make the UE able to perform cell lookup for the frame structure. By performing such a cell search transparently, the UE can obtain the frame irrespective of whether the carrier frequency belongs to a licensed or unlicensed band. In addition, the UE can obtain frame structure indication through the further device of PSS/SSS settings. In block 801, the UE configures its communication with the base station according to the indicated frame structure. The indicated frame structures can support at least exclusive downlink and mixed downlink/uplink structures.

[0070] It should be noted that in many alternative deployments of LTE/LTE-A with unlicensed spectrum, an uplink-only subframe configuration may be defined. In these respects, three configurations are available, downlink only, uplink only and mixed downlink/uplink.

[0071] Additional downlink aspects that can be accommodated for LTE/LTE-A deployments with unlicensed spectrum include synchronization signals. In LTE PSS/SSS can be used for UE to acquire time and frequency synchronization and to facilitate cell search. PSS/SSS is typically only broadcast on the 6 central RBs. In LTE/LTE-A with unlicensed spectrum, similar signals must be generated at least for independent (SA) deployments.

[0072] Considering time domain, LTE/LTE-A deployments with unlicensed spectrum should consider transmitting synchronization signals less frequently than the 5 msec period defined in LTE. The reduced frequency of the synchronization signals represents a consideration between overhead, acquisition delay compensation and dynamic resource availability. LTE/LTE-A Deployments with Unlicensed Spectrum with Unlicensed Spectrum using WiFi nodes work within a flexible 5% transmission budget. The flexible 5% transmission budget prevents a WiFi node from autonomously transmitting more than 5% within any 50 msec period for guaranteed PSS/SSS transmission. Similar to cell standby operation. In such respects, the buffer size for PSS/SSS samples would be increased by a certain proportion, such as the period value of 80 msec, for example.

[0073] The LTE/LTE-A node with unlicensed spectrum can provide guaranteed transmission (such as CCA-free) of non-CCA sub-frame synchronization signals according to a fixed period, such as from 80 msec and still satisfy the flexible 5% transmission budget. Figure 9 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. In block 900, an LTE/LTE-A base station with unlicensed spectrum generates one or more synchronization signals, such as PSS/SSS, for transmission. At block 901, the LTE/LTE-A base station with unlicensed spectrum determines a non-CCA subframe for transmitting the synchronization signals. Using non-CCA sub-frame, LTE/LTE-A base station with unlicensed spectrum can establish guaranteed transmission of synchronization signals. At block 902, the LTE/LTE-A base station with unlicensed spectrum transmits the sync signals in the non-CCA subframe subject to the fixed period.

[0074] It should be noted that, under further aspects of the present disclosure, the fixed period for guaranteed transmission may be fixed at a time other than 80 msec. For example, since the flexible 5% transmission budget requirements are measured over a period of 50 msec, the fixed period for guaranteed transmissions could also be fixed at 50 msec. While 80 msec offers the benefit of being evenly divisible or comparable across many different system parameters, a shorter period such as 50 msec would provide more opportunity for guaranteed trades. Other times can be considered as well, such as 60 msec, 70 msec and similar.

[0075] In order for connected and/or idle UEs to reduce the measurement intervals to a minimum, the UEs can assume synchronization between neighboring cells/neighbouring frequencies, or the LTE/LTE-A base station with unlicensed spectrum with unlicensed spectrum can signal the UEs to look for guaranteed PSS/SSS transmissions. For connected UEs, additional information can be displayed for improved time/frequency tracking (more PSS/SSS subframes, for example).

[0076] The guaranteed transmission of synchronization signals can be located at a fixed subframe index (subframe 9, for example), subject to a certain periodicity, or it can be staggered across different cells/different carriers. Scaling can allow multiple carriers to have non-overlapping synchronization signals transmitted across LTE/LTE-A deployment with unlicensed spectrum.

[0077] The fixed frequency of guaranteed transmissions from PSS/SSS to SDL/CA may differ from the fixed period for LTE/LTE-A AS deployments with unlicensed spectrum. This difference is bearable given that coarse timing can be obtained from an anchor CC for SDL/CA deployments. Assuming the anchor CC and an unlicensed band CC are in sync with each other or the timing offset is fixed (which may be supported by or indicated to the UE). For example, unlicensed band CCs can be time-aligned with each other, and licensed band CCs can also be time-aligned with each other. However, there may be some fixed timing offset between licensed and unlicensed band CCs.

[0078] In addition to guaranteed transmission of synchronization signals, LTE/LTE-A with unlicensed spectrum can also provide additional opportunistic transmission of synchronization signals. The additional PSS/SSS that are opportunistically transmitted in subframes based on the CCA can provide additional help for cell search and synchronization. In such CCA-based subframes, if the base station detects a release CCA, then it may transmit synchronization signals at some point before the expiration of the release period. Upon detection of a release CCA, the stream is guaranteed to be available for a predetermined duration, such as 5-10 msec. In addition to searching for synchronization signals at guaranteed locations, UEs can also perform cell searches for synchronization signals more frequently. For example, idle UEs can also try to look for PSS/SSS every 5 msec. However, the inter-frequency condition must be based on guaranteed transmission subframes.

[0079] The number of synchronization symbols may also be considered for various aspects of the present disclosure. In one respect, both PSS and SSS can have separate symbols. Separation of PSS/SSS symbols can be fixed (similar to current FDD placement) or placed differently for different frame structures (only DL structure versus mixed DL/UL subframe structure, for example). Under additional aspects of the present disclosure, 1-symbol synchronization signals can be transmitted as well. For example, a 1-symbol sync signal can include a 1-symbol combination of both PSS/SSS and a 1-symbol transmission with only SSS (no PSS transmission since SSS carries all the information needed to the cell ID).

[0080] Under various aspects of the present disclosure, the LTE/LTE-A base station with unlicensed spectrum with unlicensed spectrum can multiplex the synchronization signals with other reference signals, such as CRS, in a block of resources of the same symbol . At least for SSS where feature elements for other reference signals can be derived based on PSS. For example, if multiplexed with CRS, the PSS can provide the frequency offset for the CRS.

[0081] Regulations make PSS/SSS symbols transmitted using WiFi over LTE/LTE-A systems with unlicensed spectrum to be broadband symbols. Thus, the set of system bandwidths for LTE/LTE-A with unlicensed spectrum may be different from LTE (>1.4 MHz). Due to large bandwidths, the trace size can be increased as well. Figures 10A and 10B are functional block diagrams showing exemplary blocks executed to implement aspects of the present disclosure. In block 1000, an LTE/LTE-A base station with unlicensed spectrum generates one or more synchronization signals for transmission. In block 1001, the LTE/LTE-A base station with unlicensed spectrum transmits the synchronization signal or signals in a wideband symbol. In block 1002, the UE receives the wideband sync symbol over the unlicensed band, and in block 1003 performs synchronization based on the wideband sync symbol. Under the various aspects of the disclosure shown in Figures 10A and 10B, the sync signals themselves can be generated with wideband sync signals (such as wideband PSS/SSS signals). In such respects, PSS/SSS can simply include repeating PSS/SSS sequences from 1.8 MHz up to larger bandwidths. Alternatively, a new sync sequence includes the narrowband sync signals plus information, such as CUPS/CUDS. The new sequence may help provide an initial indication of LTE/LTE-A systems with unlicensed spectrum versus unlicensed spectrum. Since guaranteed transmissions of PSS/SSS signals are less frequent, better sequence design can significantly improve performance. A trade-off for increased bandwidth for PSS/SSS at an increase in power consumption and UE buffer size (80 msec x 20 MHz versus 80 msec x 1.4 MHz, for example).

[0082] Under an alternative aspect of the present disclosure, the wideband synchronization symbol may be a combination of the wideband PSS/SSS signals (6 RBs as in LTE, for example) plus other signals. The other signals can be CUPS/CUBS. In certain aspects, the wideband sync symbol can include PSS/SSS but CUPS/CUBS regardless of the base station schedule. Additional aspects of the present disclosure may also dictate what additional information is added to the wideband PSS/SSS to make up the wideband symbols. For example, when there is no traffic at the base station, then the wideband sync symbols include PSS/SSS and wideband CUBS. However, if there is traffic at the base station for transmission, then the wideband sync symbol includes the narrowband PSS/SSS plus data signals. Thus, under such aspects, the data transmission capacity can be improved.

[0083] For LTE/LTE-A SDL/CA deployments with unlicensed spectrum, it is possible to omit the transmission of synchronization signals entirely on secondary DCs. Figure 11 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. In block 1100, the base station LTE/LTE-A SDL/CA with unlicensed spectrum detects synchronization between a secondary CCA and a primary CC associated with the secondary CC. This would not apply to CCs that are not co-located (multistream, for example) or if the measurement relies on PSS/SSS knowledge. At block 1101, the LTE/LTE-A SDL/CA base station with unlicensed spectrum omits transmission of sync signals on the secondary CC in response to the sync detection.

[0084] Additional downlink aspects that can be accommodated for LTE/LTE-A deployments with unlicensed spectrum include the broadcast channel that carries system information used for cell scanning by the UE. In LTE, the broadcast channel, the physical broadcast channel (PBCH), provides critical system information and is transmitted every 10 msec with a transmission time interval (TTI) of 40 msec. Thus, the information contained within the PBCH changes every 40 msec. Typically, the PBCH includes an 8-bit SFM, 4-bit system wideband information, and 3-bit PHICH information. In LTE/LTE-A with unlicensed spectrum, the possibility is considered that either EPBCH or SIB-lite (SIB-0) is transmitted.

[0085] The transmission of the EPBCH in LTE/LTE-A deployments with unlicensed spectrum is similar to the transmission of synchronization signals, as disclosed above. In the time domain, EPBCH will be similar to PSS/SSS and can have the same or different periodicity. Since LTE/LTE-A deployments with unlicensed spectrum may have higher system bandwidth available, the EPBCH may occupy less than 4 symbols if the system bandwidth is large (20 MHz or higher, for example). At 20 MHz at approximately 800 tones/symbols for 20 MHz [1200-4 (CRS tones (RB) x 100 tones (RBs)], versus 240 tones for EPBCH on LTE without unlicensed spectrum. EPBCH transmission is also subject to the 5% flexible transmission budget, the EPBCH TTI can be more than twice as long as the existing 40 msec. With a flow period of 80 msec, for example, the EPBCH TTI can be of 320 msec so that the contents of the EPBCH do not change through 320 msec. The flexible 5% transmission budget or 5% duty cycle through 50 msec is a combined measurement. Therefore the combination of PSS/SSS, EPBCH and measurement RS transmission must not exceed the duty cycle of 5% in 50 msec.

[0086] Figure 12 is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. In block 1200, an LTE/LTE-A base station with unlicensed spectrum generates one or more system broadcast signals for transmission. System broadcast signals may include EPBCH, PBCH and the like which carry important system information used by the UE for cell search, synchronization and the like. At block 1801, the base station determines a non-CCA subframe for transmitting at least one of the system broadcast signals. Similar to the guaranteed transmission of the sync signals as disclosed above, the guaranteed transmission of the system broadcast signals can be configured according to similar procedures. Non-CCA subframes have no transmission restrictions associated with them. In block 1202, the LTE/LTE-A base station with unlicensed spectrum with unlicensed spectrum transmits the system broadcast signals in the non-CCA subframe at a fixed period that allows duty cycle restrictions of 5% through 50 mseg are satisfied.

[0087] As with the sync signals, the symbol location or subframe location for the EPBCH may be fixed or a function of cell ID and/or carrier index. The bandwidth of system broadcast signals may or may not be similar to that of sync signals. Arrangements provide for the transmission of wideband EPBCH symbols, which can either be implemented using a wideband EPBCH or the combination of a narrowband EPBCH and additional symbols such as CUPS/CUBS, data transmissions or the like. Figures 13A and 13D are functional block diagrams showing exemplary blocks executed to implement various aspects of the present disclosure. In the block an LTE/LTE-A base station with unlicensed spectrum generates one or more system broadcast signals, such as an EPBCH for transmission. In block 1301, the LTE/LTE-A base station with unlicensed spectrum transmits the system broadcast signals in a wideband symbol. In block 1302, a UE, configured to receive LTE/LTE-A base station communication with unlicensed spectrum, receives a wideband system broadcast symbol over an unlicensed band and, in block 1303, is able to recover system information about LTE/LTE-A base station with unlicensed spectrum of broadband system broadcast service.

[0088] Furthermore, the location/frequency tones for the EPBCH may be at a fixed location or be a function of cell ID and/or carrier index. For example, within a 20 MHz bandwidth, a reuse factor of 3 can be achieved if each cell occupies every 3 tones. Generally, some reuse of the EPBCH across different cells/frequencies can be achieved through frequency, time (different symbols within a subframe and/or different subframes), or a combination thereof. Figure 14 is a block diagram showing a transmission timeline 1400 in an LTE/LTE-A deployment with unlicensed spectrum configured in accordance with an aspect of the present disclosure. Four LTE Unlicensed Spectrum (LUT-US) transmissions 1401-1404 represent guaranteed EPBCH transmissions at fixed intervals. LTE-US1 1401 and LTE-US2 1402 transmit the EPBCH at the same time and in the same slot. In order to increase frequency reuse for EPBCH signals, the EPBCH transmission of LTE-US1 1401 and LTE-US2 is frequency division multiplexed (FDM) into FDM transmission 1405. The EPBCH transmissions of LTE-US3 1403 and LTE-US4 1404 are also made at the same time and at the same interval and can also be FDM in another FDM transmission. Also increasing the reuse of the EPBCH transmissions, the FDM transmission 1405 and the FDM transmission of LTE-US3 1406 and LTE-US4 1404 can each be time division multiplexed 1406.

[0089] An additional aspect of the EPBCH that can be modified to accommodate LTE/LTE-A deployments with unlicensed spectrum is the information fields added to the EPBCH in the unlicensed band. For example, the information fields of EPBCH and LTE/LTE-A deployments with unlicensed spectrum may include network identifiers such as the 24-bit public land mobile number (PLMN), cell identifiers such as the global 28-bit cell (CGI) and other such information. The information fields may also include some of the physical random access channel (PRACH) parameters to enable fast random access procedure with the LTE/LTE-A base station with unlicensed spectrum.

[0090] In addition, Single Frequency Network (SFMN) bits may be used in the EPBCH for eMBMS services, paging and the like. Furthermore, depending on how the PSS/SSS/PBCH are transmitted, the SFN bits in the EPBCH may not be the same as the eight-bit SFN in LTE. For example, in LTE/LTE-A with unlicensed spectrum with an EPBCH ITTI of 320 msec, an SFN of just 5 bits may be sufficient.

[0091] The system bandwidths of LTE/LTE-A deployments with unlicensed spectrum can either be fixed (20 MHz, for example) or variable with two or more bandwidths (20 MHz/40 MHz/80 MHz/ 160 MHz). When bandwidths are fixed, there would be no reason to include a bandwidth indicator in the EPBCH information fields. However, when variable system bandwidths are available, the EPBCH may also include a system bandwidth identifier that signals the UE what the system bandwidth is for the base station. Each component carrier can have the same bandwidth and its own EPBCH that includes a separate bandwidth indicator. In addition, or separately, the EPBCH on a first component carrier may indicate a set of component carriers of the same bandwidth as the first component carrier available to the UE. This would help the UE to detect the set of component carriers associated with an LTE/LTE-A eNB with unlicensed spectrum.

[0092] The information fields in the EPBCH in LTE/LTE-A with unlicensed spectrum may also contain information related to the control channel (EPDCCH), size and location instead of fixed location based on a physical cell identifier (PCI) and also information on frame structures related to LTE/LTE-A base station transmissions using unlicensed spectrum.

[0093] LTE/LTE-A with EPBCH with unlicensed spectrum would not necessarily include PHICH-related information. Nor would it be necessary to transmit the number of RS ports (such as CRS, CSI-RS, etc.) through the EPBCH. It should be noted that there is generally no strong motivation to support bandwidths of less than 20 MHz in LTE/LTE-A deployments with unlicensed spectrum essentially referring to smaller bandwidths such as 1.4 MHz , 3 MHz and 15 MHz. In addition, there has not been a strong motivation to support different downlink and uplink bandwidths in LTE/LTE-A deployments with unlicensed spectrum.

[0094] Additional downlink procedures that can be accommodated for LTE/LTE-A deployments with unlicensed spectrum include multiple measurement reference signals. Such measurement reference signals can be similar to cell specific reference signal (CRS) or channel state feedback reference signal (CSI-RS) in LTE. For example, the reference signal for decoding the EPBCH can be used for measurements. Channel utilization indicator signals (CUPS) which may also be referred to as channel utilization indication signals (CUBS), may also be used for measurements. The CUPS/CUBS in subframe 9 can additionally be used for measurements.

[0095] Similar to PSS/SSS/EPBCH, some reuse must be provided for measurement reference signals in order to facilitate the coexistence of different implementations (from different operators, for example). Reuse can be achieved through TDM within a subframe (different symbols in a subframe or different partitions in a subframe), TDM across subframes (different subframes for different deployments) FDM within of a symbol or a combination of them. Figure 15 is a block diagram showing a transmission timeline 1500 in an LTE/LTE-A deployment with unlicensed spectrum configured in accordance with an aspect of the present disclosure. The exemplary PSS/SSS/EPBCH arrangement in Figure 15 shows the guaranteed signal transmissions 1505-1508 of LTE-US1 1501 - LTE-US7 1504 at a periodicity of 80 msec, with a reuse factor of 1/7 in two sub- frames (28 symbols), where each node uses 28/7 = 4 symbols. A 2-port reference signal, which can be a CRS, RS to EPBCH or CUPS/CUBS or similar, is present in all symbols. The PSS/SSS is present in the first 2 symbols in the central 6 RBs 1509, and the EPBCH is present in the first symbol in the remaining bandwidth (assuming 20 MHz, which results in 94 RPs x 8 tones/RB = 752 tones for the EPBCH. Alternatively, the PSS/SSS can be repeated for the first 2 symbols. Yet another alternative is to just repeat the SSS on one of the remaining second symbols. The remaining resource elements can be for other purposes (eMBMS, paging or similar , for example.) Group power control can be ported in the region (not shown). Other broadcast/group or cast signaling can be ported in the region (paging, for example). can be provided in a few later symbols, so that the first several symbols can be used as a preamble to stabilize automatic gain control (AGC) Other system information blocks (SIBs) can be transmitted in unsecured CCA subframes .

[0096] In the foregoing examples described in connection with various aspects of the present disclosure, it is assumed that the length of autonomous transmission duration for a node is fixed, such as 4 symbols every 80 msec. However, such a fixed extension can be restrictive. Various aspects of the present disclosure can provide a variable length autonomous region for guaranteed or autonomous transmissions in LTE/LTE-A deployments with unlicensed spectrum. Figures 16A and 16B are functional block diagrams showing exemplary blocks executed to implement an aspect of the present disclosure. In block 1600, a length is determined at an LTE/LTE-A base station with unlicensed spectrum for an autonomous region of a guaranteed transmission in a non-CCA subframe. An LTE/LTE-A base station with unlicensed spectrum can select a length from a number of lengths that provide adequate bandwidth for the desired transmit payload. For example, an LTE/LTE-A base station with unlicensed spectrum with unlicensed spectrum can be a selection from four possible values (4 symbols, 7 symbols (one partition), 14 symbols (1 subframe) and 28 symbols (2 sub-frames). In block 1601, the base station generates a transmission signal for the autonomous region according to the length. In block 1612, it transmits the guaranteed transmission with the autonomous region to one or more UEs through a band not licensed.

[0097] In block 1603, the UE determines a variable length indicator for an autonomous region of a guaranteed transmission from the base station over an unlicensed band. The UEs can blindly detect the length of the region or be told the length of the region. As an example, the length of the region can be indicated by means of a 2-bit indicator in the EPBCH. In block 1604 the UE receives the guaranteed transmission from the base station over the unlicensed band. At block 1605 the UE detects the transmission signal in the autonomous region using a variable length indicator.

[0098] In the previous examples described with respect to various aspects of the present disclosure, the autonomous region for guaranteed transmission is specific to a node. However, several aspects of the present disclosure provide for construction of two subregions. Figure 17 is a block diagram showing guaranteed transmission 1700 configured in accordance with an aspect of the present disclosure. Group region 1701 provides SFN operation for two or more nodes. This region can provide information such as group and beam discovery signals to two or more nodes. The length of the region can be fixed, but in many aspects of the development it can be variable or selected. Individual region 1702 exhibits node-specific functioning. The length of individual region 1702 can be either fixed or variable. For variable lengths, the group region 1701 may generate a signal to indicate the length of the individual region 1702.

[0099] Figure 18A is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. 9, 10A, 10B, 12 and the like, at block 1800, a base station generates one or more synchronization signals or a system broadcast signal for transmission to a coverage area served by the base station. In block 1801 the base station lays out a non-CCA subframe for transmissions. In block 1802, the base station transmits either the sync signals or the system broadcast signals in the non-CCA subframe.

[0100] Figure 18B is a functional block diagram showing exemplary blocks executed to implement an aspect of the present disclosure. The blocks shown in Fig. 18B are directed to a UE that can be served by the base station as depicted in Fig. 18A. 9, 10A, 10B and 12 and the like, at block 1803 the UE receives the signals transmitted by the base station, such as, for example, either the sync signal or the system broadcast signal in a non-CCA subframe. In block 1804 the UE communicates with the base station based on the received signals, be it the received synchronization signals or the received system broadcast signal. The UE uses the received signal to establish interleave with the base station.

[0101] Those skilled in the art would understand that information and signals can be represented using any of a number of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols and chips that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles or any other combination of them.

[0102] The functional blocks and modules of Figures 5-13, 16 and 18 may comprise processors, electronic devices, hardware devices, electronic components, logic circuits, memories, software codes, firmware codes, etc., or any combination from them.

[0103] Those skilled in the art would also understand that the various blocks, modules, circuits, and algorithm steps described in connection with the present disclosure may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, several 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 on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art may implement the described functionality in varying ways for each specific application, but such implementation decisions should not be construed as causing a departure from the scope of the present disclosure. Those skilled in the art will also readily recognize that the order or combination of components, methods or interactions that are described herein are merely exemplary and that the components, methods or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those shown and described here.

[0104] The various blocks, modules and illustrative logic circuits described in connection with the present disclosure can be implemented or executed 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 alternatively the processor may be any conventional processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, such as a DSP microprocessor combination, multiple microprocessors, one or more microprocessors together with a DSP core, or any other such configuration.

[0105] The method or algorithm steps described in connection with the present disclosure may be embodied directly, in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of media. known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral with the processor. The processor and/or storage medium may reside in an ASIC. The ASIC can reside on a user terminal. Alternatively, the processor and storage medium can reside as discrete components in a user terminal.

[0106] In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware or any combination thereof. If implemented in software, functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Computer readable media include both computer storage media and communication media which include any medium that facilitates the transfer of a computer program from one place to another. The computer-readable storage media may be any available media that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired computer-readable program code in the form of instructions or data structure and that can be accessed by a general purpose or special purpose computer or a general purpose or special purpose processor. Furthermore, any connection is properly called a computer-readable medium. For example, if the software is transmitted from a remote website, server, or other source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio and microwave, so coaxial cable, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. Disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disc and Blu-ray disc, where discs usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above elements are also included within the range of computer readable media.

[0107] As used herein, including in the claims, the term "and/or" when used in a list of two or more items means that any of the items listed can be used by itself, or any combination of two or more of the enumerated items can be used. For example, if a construct is described as containing components A, B and/or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A and B and C in combination. Furthermore, as used herein, including in the claims, "or" as used in a list of items prefaced by "at least one of" indicates a disjunctive list so that, for example, a list of "at least one of A, B or C” means A or B or C or AB or AC or BC or ABC (ie A and B and C).

[0108] The foregoing description of the disclosure is presented to enable anyone skilled in the art to manufacture or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and those described herein, but is to be given the broadest scope compatible with the unpublished principles and features disclosed herein.

Claims (15)

1. A wireless communication method, comprising: generating (1800), at a base station configured to transmit Orthogonal Frequency Division Multiple Access, OFDMA, communication signals over at least one unlicensed spectrum, a system broadcast signal for transmission, wherein the system broadcast signal comprises an indication of a frame structure for at least one unlicensed carrier of the base station, and wherein the frame structure is at least one of: a downlink-only frame structure, a mixed downlink/uplink frame structure, or an uplink-only frame structure; determining (1801), by the base station, a non-evaluation subframe for non-CCA channel release for transmission of the system broadcast signal; transmitting (1802), by the base station, the system broadcast signal in the non-CCA subframe, wherein the non-CCA subframe in which the system broadcast signal is transmitted is staggered across different carriers. 2. Method, according to claim 1, characterized by the fact that the transmission in the non-CCA sub-frame is associated with a duration and a periodicity, and the ratio between the duration and the periodicity is not more than 5%. 3. Method, according to claim 1, characterized in that it additionally includes: detecting, by the base station, a release CCA in a CCA sub-frame; and transmitting, by the base station, another system broadcast signal in the CCA subframe in response to the release CCA detection. 4. Method according to claim 1, characterized in that the system broadcast signal comprises at least one of: a network identifier, a bandwidth identifier that identifies one of a plurality of available bandwidths associated with the base station, an indication of the number of carriers in the unlicensed spectrum, a plurality of reference signal ports, one or more parameters associated with a random access procedure, a system frame number, or, channel-related information control channel, in which the information comprises at least one of the size or location of the control channels. 5. Method, according to claim 1, characterized in that the base station includes at least one licensed carrier and is in communication with at least one user equipment configured with one of: a supplementary downlink, SDL, or operation with carrier aggregation, CA, which uses carrier in unlicensed spectrum. 6. Method according to claim 1, characterized in that the at least one of: the synchronization signal or signals or the system broadcast signal is a broadband signal spanning more than 1.4 MHz. 7. Method according to claim 1, characterized in that the transmission of the non-CCA subframe associated with an offset and the offset is a function of a network identifier. 8. Method, according to claim 1, characterized in that it additionally includes, in the non-CCA sub-frame, at least one of: cell-specific reference signals, CRS; channel state information reference signals, CSI-RS; reference signals for enhanced physical broadcast channel, EPBCH; or channel user pilot tones, CUPS/channel user indication signals, CUBS. 9. Method, according to claim 1, characterized by the fact that the duration of a cyclic prefix of the unlicensed band is less than or equal to that of a normal cyclic prefix associated with communications through the licensed spectrum. 10. A wireless communication method, comprising: receiving (1803), on user equipment configured to receive Orthogonal Frequency Division Multiple Access, OFDMA, communication signals over at least one unlicensed spectrum , a system broadcast signal in a non-evaluation subframe for non-CCA channel release from a base station, wherein the non-CCA subframe in which the system broadcast signal is received is staggered through different carriers; wherein the system broadcast signal comprises an indication of a frame structure for at least one unlicensed carrier of the base station, and wherein the frame structure is at least one of: a downlink-only frame structure, a mixed downlink/uplink frame or an uplink-only frame structure; and communicating (1804), by the user equipment, with the base station based on the received system broadcast signal. 11. Method, according to claim 10, characterized in that the receipt in the non-CCA sub-frame is associated with a duration and a periodicity and the ratio between the duration and the periodicity is not greater than 5%. 12. Method, according to claim 10, characterized in that it additionally includes: detecting, by the user equipment, a release CCA in a CCA sub-frame; and receiving, by the user equipment, another system broadcast signal in the CCA subframe in response to the release CCA detection. 13. Equipment configured for wireless communication, characterized in that it comprises: a device for generating (1801) at a base station configured to transmit Orthogonal Frequency Division Multiple Access, OFDMA, communication signals over at least one unlicensed spectrum, a system broadcast signal for transmission, wherein the system broadcast signal comprises an indication of a frame structure for at least one unlicensed carrier of the base station, and wherein the frame structure is at least one of: a downlink-only frame structure, a mixed downlink/uplink frame structure, or an uplink-only frame structure; means for determining (1802), by the base station, a non-evaluation sub-frame for channel release, not CCA, for transmitting the system broadcast signal; and an arrangement for transmitting (1803), by the base station, the system broadcast signal in the non-CCA subframe, wherein the non-CCA subframe in which the system broadcast signal is transmitted is staggered across different carriers . 14. Equipment configured for wireless communication, comprising: a receiving device (1804), in a user equipment configured to receive Orthogonal Frequency Division Multiple Access, OFDMA, communication signals via at least an unlicensed spectrum, a system broadcast signal in a non-evaluation subframe for channel release, non-CCA, from a base station, in which the non-CCA subframe in which the system broadcast signal is received is staggered across different carriers; wherein the system broadcast signal comprises an indication of a frame structure for at least one unlicensed carrier of the base station, and wherein the frame structure is at least one of: a downlink-only frame structure, a mixed downlink/uplink frame or an uplink-only frame structure; an arrangement for communicating (1805), by the user equipment, with the base station based on the received system broadcast signal. 15. Computer-readable memory characterized by the fact that it comprises instructions stored therein that, when executed, cause a computer to perform the method as defined in any one of claims 1 to 9 or 10 to 12.