1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to management of power savings on a wireless communication device.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN 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). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
The fast evolving mobile communication technologies and their intent to meet the high data centric demands of the customers have invariantly paid the price of battery drain on the mobile terminal, otherwise referred to as user equipment (UE). Accessibility to wide-ranged data centric applications for modern mobile terminals contributes equally to the power hungry nature of smartphones. All these factors have chipped in and have motivated standard bodies to also work on new features that would help conserve the mobile battery power. In some cases, the triggering of these features has been granted to the applications that drive the need of data resources.
For example, varied applications and their bursty data requests can generate requests from the mobile terminal to move the mobile terminal to a power saving state, and the underlying radio access technology communicates the requirements to the core network. To have a check on increasing the amount of such back to back requests from a particular mobile terminal, which may increase the signaling overhead, the protocol may place a constraint to limit or time the requests. These types of features provide an opportunity for optimization in terms of choosing when exactly to make such requests.
A method of method of managing a power saving request is offered. The method includes receiving a power saving request from an application on a wireless device and determining whether the wireless device has data waiting for transmission in response to the received power saving request. The method also includes starting a buffer timer when the data waiting for transmission is determined to exist, buffering the power saving request until expiration of the buffer timer, and triggering transmission of a dormancy request to a network component based on whether the data waiting for transmission is determined to exist.
An apparatus of managing a power saving request is offered. The apparatus includes receiving a power saving request from an application on a wireless device and determining whether the wireless device has data waiting for transmission in response to the received power saving request. The apparatus also includes starting a buffer timer when the data waiting for transmission is determined to exist, buffering the power saving request until expiration of the buffer timer, and triggering transmission of a dormancy request to a network component based on whether the data waiting for transmission is determined to exist.
Note, a component in any figure represented within dashed lines may be an optional component.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
Referring to
In the present aspects, however, in response to receiving dormancy request 20, power saving state manager 12 checks UE 10 to determine if any data for transmission 18 is available and waiting to be transmitted. For example, in an aspect, power saving state manager 12 may execute a transmit data manager 40 to check, for example, transmit buffers of UE 10 in order to determine whether any UE 10 data for transmission 18 exists on UE 10. In some aspects, for instance, transmit data determiner 24 may reside at one protocol layer and check other protocol layers for existence of data for transmission 18. In another aspect, for instance, data for transmission may correspond to a single packet data protocol (PDP) context, or to more than one PDP context of UE 10. Note, a PDP context is the connection or link between a mobile device and a network server that allows them to communicate with each other, in other words a session. Therefore, if data for transmission 18 exists, then power saving state manager 12 buffers dormancy request 20 for a time period in order to allow for all or a portion of data for transmission 18 to be transmitted. If data for transmission 18 does not exist, then power saving state manager 12 may initiate generation and transmission of power saving request 14 to network entity 16. In some cases, however, power saving state manager 12 may not trigger transmission of power saving request 14 until after a dormancy request timer has expired. In an aspect, for example in UMTS Release 8 Fast Dormancy, power saving request 14 may be a signaling connection release indication (SCRI) message with a special case ‘UE Requested PS Data session end’ transmitted to request a better power saving state.
For instance, instead of just releasing the signaling connection when it desires the UE 10 has to wait for the expiration of a network configured timer (T323). Once the timer expires, the UE 10 can send a signaling connection release indication message with a new parameter that indicates “UE requested PS data session end”. At this point the network entity 16 can then decide to do nothing, to release the mobile to Idle or to put the connection into Cell-/URA-PCH state.
In any case, network entity 16 may receive power saving request 14 and generate a power saving state message 26 that defines a new power saving state 30 for UE 10. For example, in an aspect, network entity 16 may execute a power saving state determiner 28, which includes a power saving state algorithm that selects a predefined power saving state, or that determines a power saving state, e.g. based on UE and/or network characteristics, to use as new power saving state 30 in response to power saving request 14. In some aspects, for example in UMTS Release 8, new power saving state 30 may be one of IDLE, CELL_PCH, URA_PCH, or CELL_FACH. UE 10 may then receive power saving state message 26, execute power saving state manager 12 to identify new power saving state 30 defined in message 26, and update current power saving state 32 to correspond to new power saving state 30.
The described aspects of power saving state manager 12 may be used to optimize management of dormancy request 20 to improve the efficiency of UE 10 by reducing unnecessary communications with network entity 16, such as when data for transmission 18 exists. Additionally, the described aspects of power saving state manager 12 may be used to optimize management of dormancy request 20 to improve the efficiency of UE 10 transitioning into a reduced power state by eliminating unnecessary ping-ponging between states caused in the prior art by transmission of power saving request 14 when data for transmission 18 exists in the transmit buffers of UE 10.
Thus, the apparatus of
Note, the components/modules/means may be hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof will be discussed in more detail with regards to
Referring to
For instance, after power saving state manager 12 receives a dormancy request 20, the transmit data manager 40 may then execute the transmit data determiner 24 to determine if there is data for transmission on the UE 10. In other words, the transmit data determiner 24 checks the checks is there data on data for transmission 18 of UE 10.
When the transmit data determiner 24 determines that there is data on data for transmission 18, the transmit data manager 40 executes a buffering algorithm 25 such that the dormancy request 20 is moved to a buffer.
Alternatively, when the transmit data determiner 24 determines that there is no data on data for transmission 18, the transmit data manager 40 may notify the dormancy request frequency manager 42 to control the frequency of transmitting power saving requests 14 to network entity 16 (
Power saving sate manager 12 may additionally include a state change manager 56 configured to change the current power saving state 32 of UE 10. For instance, the state change manager 56 may be capable of receiving a power saving message and change the power saving state of UE 10 via changing the current power saving state 32 of the UE 10. The state change manager 56 may change the power saving state of the UE 10 to a active mode, idle mode, a standby mode, or even a periodic active mode based on the need of the UE 10 relative to the network 16.
Thus, in an aspect, UE 10 may be configured to manage a dormancy request 20 from application 22 in order to buffer the request when data for transmission 18 is determined to exist, thereby saving communication resources and more efficiently manage the power saving states of UE 10.
Thus, the apparatus of
Note, the components/modules/means may be hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof will be discussed in more detail with regards to
Referring to
For example, in an aspect, power saving state manager 12 may receive dormancy request 20 and execute a transmit data manager 40 to control handling of the received dormancy request 20. In particular, data transmit manager 40 may execute transmit data determiner 24 to check for data for transmission 18 on UE 10. Specifically, transmit data determiner 24 may perform an inter-protocol layer check, which may be a higher layer (e.g. RRC layer) querying a lower layer (e.g. layer 2, include RLC layer) or vice versa, for data for transmission 18 associated with one or more PDP contexts 44, e.g. with a same PDP context and/or with any or all PDP contexts on UE 10. In others words, the transmit data determiner 24 may be configured to determine whether the data waiting for transmission 18 has a corresponding PDP context.
When transmit data determiner 24 discovers data for transmission 18, then transmit data manager 40 executes a buffering algorithm wherein the received dormancy request 20 is moved to a dormancy request buffer 46 and a transmit data buffer timer 48 is activated. Transmit data timer 48 may have a fixed or dynamic expiration period, e.g. based on an operator setting, an amount of data for transmission 18, an expected time to transmit data for transmission 18, or any other variables associated with transmitting data from UE 10. Upon expiration of transmit buffer timer 48, transmit data manager 40 again may execute transmit data determiner 24 to check UE 10 for existence of data for transmission 18, and repeat the buffering process again if data is available.
Alternatively, when transmit data manager 40 determines that data for transmission 18 does not exist, either initially in response to dormancy request 20 or after buffering of dormancy request 29, then transmit data manager 40 may notify dormancy request frequency manager 42 to control the frequency of transmitting power saving requests 14 (
When dormancy request buffer timer 50 is not active, then dormancy request frequency manager 42 notifies and/or executes request generator 54 to generate power saving request 14 and initiate transmission to network entity 16 (
Power saving state manager 12 may further include a state change manager 56 configured to change settings corresponding to current power saving state 32 of UE 10. For example, state change manager 56 may receive power saving state message 26 and detect or otherwise extract new power saving state 30 determined by network entity 16 in response to power saving request 14. For instance, state change manager 56 may change current power saving state 32 from an active mode, where communication channels are established and maintained, to an idle mode, where UE 10 terminates communication channels and only periodically monitors for pages in order to save power, e.g., to increase a time period that UE 10 can function on a given level of charge in a battery that powers UE 10. In other aspects, for example in UMTS Release 8, state change manager 56 may changes current power saving state 32 to one of IDLE, CELL_PCH, URA_PCH, or CELL_FACH.
Thus, in an aspect, UE 10 manages multiple dormancy requests 20 from multiple applications 22 in order to buffer requests when data for transmission 18 is determined to exist, and to maintain a minimum time period between power saving requests 14, thereby saving communication resources and more efficiently managing the power saving states of UE 10.
Thus, the apparatus of
Note, the components/modules/means may be hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof will be discussed in more detail with regards to
Referring to
Further, method 60 includes determining, in response to the received power saving request, whether the wireless device has data waiting for transmission (Block 63). For example, power saving state manager 12 (
Moreover, in some aspects, method 60 may include starting a buffer timer when the data waiting for transmission is determined to exist (Block 64) and buffering the power saving request until expiration of the buffer timer (Block 65). For example, when transmit data determiner 24 discovers existence of data for transmission 18, such as in a reply to a query to a protocol layer, transmit data manager 40 (
Additionally, method 60 includes triggering transmission of a dormancy request to a network component based on whether the data waiting for transmission is determined to exist (Block 66). For example, in an aspect, power saving state manager 12 (
Additionally, in an optional aspect, method 60 may further include changing current power saving state to new power saving state based on power saving state message received in response to dormancy request (Block 67). For example, power saving state manager 12 (
Referring to
For instance, method 70 may additionally include determining, in response to the expiration of the buffer timer, whether the wireless device has any remaining data waiting for transmission (Block 76). For example, when a transmit data buffer timer 48 (
In addition, method 70 optionally includes triggering transmission of a dormancy request to a network component based on whether the remaining data waiting for transmission is determined to exist (Block 78). For example, in an aspect, power saving state manager 12 (
It should be noted that, prior to the described aspects, multiple features aimed at saving both UE battery power and also signaling overhead from a network perspective were proposed by 3GPP and other standards organization. These features have tried at their best to provide a bilateral communication between the core network and the UE to negotiate a better power saving state. These power saving features should be carefully designed, however, to make sure that they do not add to the signaling overhead and defeat the overall objective. In this case, various applications that utilize the radio resources assigned for communication can trigger requests for a power saving state without prior knowledge about the requests from other peer applications. Prior to the described aspects, such requests could, at times, flood the network with back-to-back requests and thus there arose a need to optimize such requests from the mobile terminal source.
In the 3GPP community, Release 8 Fast Dormancy (FD) is one feature that gave the mobile devices a capability to signal the network a signaling connection release indication (SCRI) message with a special cause ‘UE Requested PS Data session end’ in all RRC states and request for a better power saving state. The core network, by signaling a timer T323 in the broadcast system information, indirectly notifies a UE that it supports this FD feature with a special cause, and puts a check on flooding of SCRI requests from various applications. UTRAN on reception of a SCRI with special cause for Fast Dormancy may initiate a state transition to an efficient battery consumption RRC state that include IDLE, CELL_PCH, URA_PCH, or CELL_FACH.
In other words, instead of just releasing the signaling connection when it desires, the UE 10 has to wait for the expiration of a network configured timer (T323). Once the timer expires, the UE 10 can send a signaling connection release indication message with a new parameter that indicates “UE requested PS data session end”. At this point the network entity 16 can then decide to do nothing, to release the mobile to Idle or to put the connection into Cell-/URA-PCH state.
There might be a case where in an application A sharing the same PDP profile as that of another application B, triggers a power saving request due to unavailability of data in its buffers. When this request reaches the access stratum RRC layer, the request ensures that the T323 timer is inactive, and triggers a SCRI message with special cause ‘UE Requested PS Data session end’ to the network. The core network shall move the UE to a different RRC state that might help enhance the battery saving capability of the user equipment. Now while the T323 timer is actively running, the application B can trigger another request for dormancy due to lack of data activity and this reaches the RRC layer. The request may be buffered until the active T323 timer expires and RRC can subsequently acknowledge the buffered request by sending SCRI message with special cause to the network. The above sent SCRI message for dormancy request might not have considered the current state of data activity after T323 expiry as the RRC layer may not have an idea of the data availability across the RLC buffers.
Accordingly, such back-to-back requests that are triggered based on requests from varied applications fail to consider the current availability of data in UE buffers as, for example, the higher layers may not have insight into this information directly. This incorrect trigger would essentially defeat the whole purpose of the Fast Dormancy power saving feature and may result in unprecedented additional signaling between the user equipment and the network.
The presently discussed embodiments, disclose methods and systems for improving the 3GPP proposed Fast Dormancy power saving feature by helping avoid the above explained additional signaling overhead by carefully designing and handling power saving requests that are buffered due to an active T323 timer.
Referring to
At 84, if a new power saving request 14 (
At 87, in one example, if at the expiry of the T_BUFFER period of time the RLC layer entity indicates that there is no data available in its buffers for transmission, then the RRC layer entity can trigger the buffered dormancy request. At 88, network entity 16 (
In some aspects, the above algorithm may be applied to applications that share a PDP context. In some aspects, the above algorithm may apply for power saving requests that arrive from applications that utilize different PDP contexts. For example, this may be desired to overcome the problem in the prior art where the power saving request perceived by one application might ignore the data available for transmission for applications using a different PDP context but a same uplink radio resource.
Referring to
If no data for transmission 18 (
The processor 104, as will be described further below, is responsible for managing the bus 102 and general processing, including the execution of software stored on the computer-readable medium 106. The software, when executed by the processor 104, causes the processing system 114 to perform the various functions described infra for any particular apparatus. The computer-readable medium 106, as will be described further below may comprise volatile and/or non-volatile storage and may also be used for storing data that is manipulated by the processor 104 when executing software. Note, each and every element/component/module/means of
The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards.
Referring to
Communication between a UE 210 and a Node B 208 may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE 210 and an RNC 206 by way of a respective Node B 208 may be considered as including a radio resource control (RRC) layer. In the instant specification, the PHY layer may be considered layer 1; the MAC layer may be considered layer 2; and the RRC layer may be considered layer 3. Information hereinbelow utilizes terminology introduced in the RRC Protocol Specification, 3GPP TS 25.331 v9.1.0, incorporated herein by reference.
The geographic region covered by the RNS 207 may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, three Node Bs 208 are shown in each RNS 207; however, the RNSs 207 may include any number of wireless Node Bs. The Node Bs 208 provides wireless access points to a CN 204 for any number of mobile apparatuses 221. Examples of a mobile apparatus 221 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus 221 is commonly referred to as a UE in UMTS applications, but may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. In a UMTS system, the UE 210 may further include a universal subscriber identity module (USIM) 211, which contains a user's subscription information to a network. For illustrative purposes, one UE 210 is shown in communication with a number of the Node Bs 208. The DL, also called the forward link, refers to the communication link from a Node B 208 to a UE 210, and the UL, also called the reverse link, refers to the communication link from a UE 210 to a Node B 208.
The CN 204 interfaces with one or more access networks, such as the UTRAN 202. As shown, the CN 204 is a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of CNs other than GSM networks.
The CN 204 includes a circuit-switched (CS) domain and a packet-switched (PS) domain. Some of the circuit-switched elements are a Mobile services Switching Centre (MSC), a Visitor location register (VLR) and a Gateway MSC. Packet-switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit-switched and packet-switched domains. In the illustrated example, the CN 204 supports circuit-switched services with a MSC 212 and a GMSC 214. In some applications, the GMSC 214 may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC 206, may be connected to the MSC 212. The MSC 212 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 212 also includes a VLR that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 212. The GMSC 214 provides a gateway through the MSC 212 for the UE to access a circuit-switched network 216. The GMSC 214 includes a home location register (HLR) 215 containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC 214 queries the HLR 215 to determine the UE's location and forwards the call to the particular MSC serving that location.
The CN 204 also supports packet-data services with a serving GPRS support node (SGSN) 218 and a gateway GPRS support node (GGSN) 220. GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN 220 provides a connection for the UTRAN 202 to a packet-based network 222. The packet-based network 222 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 220 is to provide the UEs 210 with packet-based network connectivity. Data packets may be transferred between the GGSN 220 and the UEs 210 through the SGSN 218, which performs primarily the same functions in the packet-based domain as the MSC 212 performs in the circuit-switched domain.
An air interface for UMTS may utilize a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The “wideband” W-CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the UL and DL between a Node B 208 and a UE 210. Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing (TDD), is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a W-CDMA air interface, the underlying principles may be equally applicable to a TD-SCDMA air interface.
An HSPA air interface includes a series of enhancements to the 3G/W-CDMA air interface, facilitating greater throughput and reduced latency. Among other modifications over prior releases, HSPA utilizes hybrid automatic repeat request (HARQ), shared channel transmission, and adaptive modulation and coding. The standards that define HSPA include HSDPA (high speed downlink packet access) and HSUPA (high speed uplink packet access, also referred to as enhanced uplink, or EUL).
HSDPA utilizes as its transport channel the high-speed downlink shared channel (HS-DSCH). The HS-DSCH is implemented by three physical channels: the high-speed physical downlink shared channel (HS-PDSCH), the high-speed shared control channel (HS-SCCH), and the high-speed dedicated physical control channel (HS-DPCCH).
Among these physical channels, the HS-DPCCH carries the HARQ ACK/NACK signaling on the uplink to indicate whether a corresponding packet transmission was decoded successfully. That is, with respect to the downlink, the UE 210 provides feedback to the node B 208 over the HS-DPCCH to indicate whether it correctly decoded a packet on the downlink.
HS-DPCCH further includes feedback signaling from the UE 210 to assist the node B 208 in taking the right decision in terms of modulation and coding scheme and precoding weight selection, this feedback signaling including the CQI and PCI.
“HSPA Evolved” or HSPA+ is an evolution of the HSPA standard that includes MIMO and 64-QAM, enabling increased throughput and higher performance. That is, in an aspect of the disclosure, the node B 208 and/or the UE 210 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the node B 208 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity.
Multiple Input Multiple Output (MIMO) is a term generally used to refer to multi-antenna technology, that is, multiple transmit antennas (multiple inputs to the channel) and multiple receive antennas (multiple outputs from the channel). MIMO systems generally enhance data transmission performance, enabling diversity gains to reduce multipath fading and increase transmission quality, and spatial multiplexing gains to increase data throughput.
Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data steams may be transmitted to a single UE 210 to increase the data rate or to multiple UEs 210 to increase the overall system capacity. This is achieved by spatially precoding each data stream and then transmitting each spatially precoded stream through a different transmit antenna on the downlink. The spatially precoded data streams arrive at the UE(s) 210 with different spatial signatures, which enables each of the UE(s) 210 to recover the one or more the data streams destined for that UE 210. On the uplink, each UE 210 may transmit one or more spatially precoded data streams, which enables the node B 208 to identify the source of each spatially precoded data stream.
Spatial multiplexing may be used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions, or to improve transmission based on characteristics of the channel. This may be achieved by spatially precoding a data stream for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.
Generally, for MIMO systems utilizing n transmit antennas, n transport blocks may be transmitted simultaneously over the same carrier utilizing the same channelization code. Note that the different transport blocks sent over the n transmit antennas may have the same or different modulation and coding schemes from one another.
On the other hand, Single Input Multiple Output (SIMO) generally refers to a system utilizing a single transmit antenna (a single input to the channel) and multiple receive antennas (multiple outputs from the channel). Thus, in a SIMO system, a single transport block is sent over the respective carrier.
Referring to
As the UE 334 moves from the illustrated location in cell 304 into cell 306, a serving cell change (SCC) or handover may occur in which communication with the UE 334 transitions from the cell 304, which may be referred to as the source cell, to cell 306, which may be referred to as the target cell. Management of the handover procedure may take place at the UE 334, at the Node Bs corresponding to the respective cells, at a radio network controller 206 (see
The modulation and multiple access scheme employed by the access network 300 may vary depending on the particular telecommunications standard being deployed. By way of example, the standard may include Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. The standard may alternately be Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.
The radio protocol architecture may take on various forms depending on the particular application. An example for an HSPA system will now be presented.
Referring to
In the user plane, the L2 layer 408 includes a media access control (MAC) sublayer 409, a radio link control (RLC) sublayer 411, and a packet data convergence protocol (PDCP) 413 sublayer, which are terminated at the node B on the network side. Although not shown, the UE may have several upper layers above the L2 layer 408 including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).
The PDCP sublayer 413 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 413 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between node Bs. The RLC sublayer 411 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 409 provides multiplexing between logical and transport channels. The MAC sublayer 409 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 409 is also responsible for HARQ operations.
At the UE 550, a receiver 554 receives the downlink transmission through an antenna 552 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 554 is provided to a receive frame processor 560, which parses each frame, and provides information from the frames to a channel processor 594 and the data, control, and reference signals to a receive processor 570. The receive processor 570 then performs the inverse of the processing performed by the transmit processor 520 in the Node B 510. More specifically, the receive processor 570 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 510 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 594. The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink 572, which represents applications running in the UE 550 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 590. When frames are unsuccessfully decoded by the receiver processor 570, the controller/processor 590 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
In the uplink, data from a data source 578 and control signals from the controller/processor 590 are provided to a transmit processor 580. The data source 578 may represent applications running in the UE 550 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 510, the transmit processor 580 provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor 594 from a reference signal transmitted by the Node B 510 or from feedback contained in the midamble transmitted by the Node B 510, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 580 will be provided to a transmit frame processor 582 to create a frame structure. The transmit frame processor 582 creates this frame structure by multiplexing the symbols with information from the controller/processor 590, resulting in a series of frames. The frames are then provided to a transmitter 556, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 552.
The uplink transmission is processed at the Node B 510 in a manner similar to that described in connection with the receiver function at the UE 550. A receiver 535 receives the uplink transmission through the antenna 534 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 535 is provided to a receive frame processor 536, which parses each frame, and provides information from the frames to the channel processor 544 and the data, control, and reference signals to a receive processor 538. The receive processor 538 performs the inverse of the processing performed by the transmit processor 580 in the UE 550. The data and control signals carried by the successfully decoded frames may then be provided to a data sink 539 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 540 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
The controller/processors 540 and 590 may be used to direct the operation at the Node B 510 and the UE 550, respectively. For example, the controller/processors 540 and 590 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories 542 and 592 may store data and software for the Node B 510 and the UE 550, respectively. A scheduler/processor 546 at the Node B 510 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs. Note, controller/processors 540 and 590 may be implemented in processing system 114 of
Several aspects of a telecommunications system have been presented with reference to a W-CDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.
By way of example, various aspects may be extended to other UMTS systems such as TD-SCDMA, High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and TD-CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” or processor 104 (
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
This application claims the benefit of U.S. Provisional Application No. 61/621,860 filed Apr. 9, 2012.
Number | Date | Country | |
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61621860 | Apr 2012 | US |