HK1186622B - Expedited handoff - Google Patents

Description

Accelerated handover

The application is a divisional application of Chinese patent application with application date of 2007, 7-month and 14-day, application number of 200780026756.1 and name of 'accelerated switching'.

Technical Field

The following description relates generally to wireless communications, and more particularly to handover between access points or base stations in wireless communications.

Background

Wireless communication systems are widely deployed to provide various types of communication; for example, voice and/or data may be provided via such wireless communication systems. A typical wireless communication system or network may provide multi-user access to one or more shared resources. For example, the system may use various multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and the like.

Common wireless communication systems utilize one or more base stations that provide a coverage area. A typical base station can transmit multiple data streams for broadcast, multicast, and/or unicast services, wherein a data stream may be a stream of data that can be of independent reception interest to a wireless terminal. A wireless terminal within the coverage area of such base station can be configured to receive one, more than one, or all of the data streams carried by the composite stream. Similarly, a wireless terminal may transmit data to a base station or another wireless terminal.

Handoffs between base stations and/or base station sectors commonly occur within wireless communication systems. For example, the handoff can be mobile-directed such that when a signal having a signal quality (e.g., signal-to-noise ratio (SNR)) above a threshold is detected from a disparate sector other than the sector to which the wireless terminal is currently connected, the wireless terminal can attempt to access the disparate sector. It is often possible to utilize a handover before disconnection so that the link to the current sector can be disconnected before accessing the disparate detected sector. Additionally, access to a sector may be contention-based, wherein two or more wireless terminals may transmit access requests to the sector at substantially similar times over a shared resource (e.g., channel); thus, by utilizing contention-based techniques, handover in a typical wireless communication system may experience significant time delays. In addition, a wireless terminal performing a conventional handoff within a multi-carrier setting where different sectors may be associated with different carriers may probe other sectors and/or carriers for handoff by reporting back, which may cause the current connection to be lost.

Disclosure of Invention

The following presents a summary of one or more embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

In accordance with one or more embodiments and corresponding disclosure thereof, various aspects are described in connection with facilitating a handoff from a first sector to a second sector. The established link to the first sector may be used to communicate with the second sector. A handoff request from a wireless terminal to the second sector and an associated handoff response from the second sector to the wireless terminal may traverse the first sector.

According to related aspects, a method of handing off from a first sector to a second sector is described herein. The method may include detecting a signal emanating from the second sector. The method may also include sending a handoff request to the second sector via the first link with the first sector. Additionally, the method can include receiving a handoff response from the second sector over the first link and the first sector, wherein the handoff response includes the identified information. Additionally, the method can include establishing a second link with a second sector utilizing the identified information.

Another aspect relates to a wireless communications apparatus that can comprise a memory that retains instructions for switching from a first sector to a second sector. Additionally, the processor may detect a signal associated with the second sector, send a handoff request to the second sector via the first link with the first sector, receive a handoff response from the second sector via the first link and the first sector, and create a second link with the second sector based on the identified information included in the handoff response.

Yet another aspect relates to a wireless communications apparatus that facilitates mitigating delay associated with a handoff from a first sector to a second sector. The wireless device may include: means for detecting a signal emanating from a second sector; means for sending a handoff request to a second sector via a first link with a first sector; means for receiving a handoff response from a second sector over a first link and the first sector; and means for establishing a second link with a second sector.

Further aspects relate to a machine-readable medium having stored thereon machine-executable instructions for receiving a beacon associated with a second sector and sending a handoff request to the second sector, the handoff request routed over a first link with a first sector. Additionally, the machine-readable medium may have stored thereon machine-executable instructions for obtaining a handoff response from the second sector routed over the first link and the first sector, wherein the handoff response includes the identified information. Additionally, the machine-readable medium may have stored thereon machine-executable instructions for creating a second link with a second sector by utilizing the identified information.

According to another aspect, a processor is described herein, wherein the processor is capable of executing instructions for detecting a signal associated with a second sector. Additionally, the processor may execute instructions for sending an expedited handoff request to a second sector via a first link with a first sector. The processor may also execute instructions for receiving a handoff response including the identified information from the second sector via the first link and the first sector. Additionally, the processor can execute instructions for utilizing the identified information to establish a second link with a second sector.

According to other aspects, a method that facilitates allocating resources to a wireless terminal to mitigate handoff delay is described herein. The method can receive a handoff request from a wireless terminal via a disparate sector. The method may also include allocating resources to the wireless terminal. The method may also include transmitting a handover response including the identified information related to the allocated resources. Additionally, the method can include establishing a link with the wireless terminal by utilizing the allocated resources.

Yet another aspect relates to a wireless communications apparatus that can include a memory that can retain an identifier associated with a wireless terminal. In addition, the processor can receive a handoff request from a wireless terminal, incorporate an identifier associated with the wireless terminal in the handoff request, route the handoff request to a disparate sector, receive a handoff response from the disparate sector, and forward the handoff response to the wireless terminal.

Another aspect relates to a wireless communications apparatus that facilitates allocating resources to a wireless terminal for utilization in connection with a handover. The wireless communication apparatus may include: means for obtaining a handoff request from a wireless terminal over a disparate sector; means for allocating resources to a wireless terminal; means for transmitting, via the disparate sector, information of an identity associated with the allocated resource to the wireless terminal in a handover response; and means for establishing a link with the wireless terminal using the allocated resources.

Further aspects relate to a machine-readable medium having stored thereon machine-executable instructions for: receiving a handoff request from a wireless terminal via a disparate sector in response to a beacon; allocating resources to a wireless terminal; transmitting information of the identifier associated with the resource to the wireless terminal through the distinct sector in a handover response; and creating a link with the wireless terminal using the resource.

According to another aspect, described herein is a processor that may execute instructions for: receiving a handoff request from a wireless terminal for a disparate sector; routing the handoff request to a disparate sector; receiving a handoff response for the wireless terminal from the disparate sector; and sending a handover response to the wireless terminal.

To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more embodiments. These aspects are indicative, however, of but a few of the various ways in which the principles of various embodiments may be employed and the described embodiments are intended to include all such aspects and their equivalents.

Drawings

Fig. 1 is an illustration of a wireless communication system in accordance with various aspects set forth herein.

Fig. 2 is an exemplary schematic illustration of a method for performing an accelerated handoff from a first sector to a second sector.

Fig. 3 is an exemplary schematic illustration of a method for enabling physical layer access to a sector that can be utilized in connection with an expedited handoff.

Fig. 4 is an exemplary schematic illustration of optimized physical layer access for association with an expedited handoff.

Fig. 5 is an illustration of a communication device that can be used to mitigate handoff delay by utilizing an established connection.

Fig. 6 is a flow diagram including various operations associated with an ACCESS (ACCESS) state.

Fig. 7 is an exemplary diagram relating to random access that may be implemented when a Wireless Terminal (WT) in a SLEEP or NULL state intends to transition to an ON or HOLD state with a Base Station Sector (BSS).

Fig. 8 is an exemplary depiction of various channel segments.

Fig. 9 is an exemplary timing diagram associated with physical layer access.

Fig. 10 is an illustration of a methodology that facilitates handing off from a first sector to a second sector.

Fig. 11 is an illustration of a methodology that facilitates routing handover signals related to an operation associated with expedited handover.

Fig. 12 is an illustration of an implementation of a method of allocating resources to a wireless terminal prior to physical layer access to mitigate handoff delay.

Fig. 13 is an illustration of an example communication system (e.g., a cellular communication network) implemented in accordance with various aspects.

Fig. 14 is an illustration of an example end node (e.g., mobile node) associated with various aspects.

Fig. 15 is an illustration of an example access node implemented in accordance with various aspects described herein.

Fig. 16 is an illustration of a system that mitigates delay associated with handing off from a first sector to a second sector.

Fig. 17 is an illustration of a system for allocating resources to wireless terminals utilized in connection with a handover.

Detailed Description

Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Additionally, various embodiments are described herein in connection with a wireless terminal. A wireless terminal may refer to a device that provides voice and/or data connectivity to a user. The wireless terminal may be connected to a computing device such as a laptop computer or desktop computer, or it may be a self-contained device such as a Personal Digital Assistant (PDA). A wireless terminal can also be called a system, a subscriber unit, a subscriber station, mobile, remote station, access point, remote terminal, access terminal, user agent, user device, or user equipment. A wireless terminal may be a subscriber station, wireless device, cellular telephone, PCS telephone, cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having wireless connection capability, or other processing device connected to a wireless modem.

A base station (e.g., access point) can refer to a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminals. The base station may act as a router between the wireless terminal and the rest of the access network, which may include an IP network, by converting received air-interface frames to IP packets. The base station also coordinates management of attributes for the air interface.

Moreover, various aspects or features described herein may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term "article of manufacture" as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., Compact Disk (CD), Digital Versatile Disk (DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). In addition, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media capable of storing, containing, and/or carrying one or more instructions and/or data.

Referring now to fig. 1, a wireless communication system 100 is illustrated in accordance with various embodiments presented herein. System 100 can comprise a number of base station sectors (e.g., base station sector 1102, base station sector 2104, etc.) that receive, transmit, repeat, and otherwise process wireless communication signals for wireless terminal 106. Base station sector 1102 and base station sector 2104 may be associated with the same base station or disparate base stations. It is further contemplated that system 100 may include multiple wireless terminals similar to wireless terminal 106. Base station sector 102 can comprise a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art. Base station sectors 102 and 104 may be located at fixed locations and/or may be mobile. The wireless terminal 106 may be, for example, a cellular telephone, a smart phone, a laptop computer, a handheld communication device, a handheld computing device, a satellite radio, a global positioning system, a PDA, and/or any other suitable device for communicating over the wireless communication system 100. The wireless terminal 106 may also be fixed or mobile.

Wireless terminal 106 may communicate with base station sector 102 and/or one or more disparate base station sectors 104 on downlink and/or uplink channels at any given moment. The downlink refers to the communication link from base station sector 102-104 to wireless terminal 106, and the uplink channel refers to the communication link from wireless terminal 106 to base station sector 102-104. Base station sector 102 can also communicate with one or more other base station sectors and/or any disparate devices (e.g., servers) (not shown) that can perform functions such as authentication and authorization, accounting, etc. for wireless terminal 106. Note that the term "sector" may refer to a geographic sector as is commonly understood or it may refer to a specific carrier frequency (or pair of carrier frequencies) carrying uplink and downlink transmissions. Thus, a "base station sector" may refer to two geographic sectors covered by the same base station or two carrier frequencies in the same geographic area.

System 100 enables mitigating delay associated with a handoff from a first base station sector (e.g., base station sector 1102) to a second base station sector (e.g., base station sector 2104); such a delay may be the time that the wireless terminal 106 is connected to neither the first base station sector nor the second base station sector. A current link may exist between wireless terminal 106 and base station sector 1102, e.g., such that wireless terminal 106 may be physically connected to base station sector 1102. The link between wireless terminal 106 and base station sector 1102 has been established in any manner. Wireless terminal 106 may detect a signal (e.g., a beacon) emanating from base station sector 2104 and decide to initiate a handoff from base station sector 1102 to base station sector 2104. Wireless terminal 106 may determine to switch to base station sector 2104 based on an estimate of the signal received at wireless terminal 106 (e.g., signal strength, SNR, signal quality, etc.).

Wireless terminal 106 may effect a handoff to base station sector 2104 by utilizing the current link to base station sector 1102. Various signals can pass through base station sector 1102 (e.g., transmitted by wireless terminal 106, base station sector 2104, etc.) to enable a new link to be established between wireless terminal 106 and base station sector 2104. Accordingly, at least a portion of the initialization can be performed prior to a physical handoff to base station sector 2104 (e.g., prior to a physical connection existing between wireless terminal 106 and base station sector 2104).

Upon detecting a signal (e.g., a beacon) emanating from base station sector 2104 and deciding to effectuate a handoff, wireless terminal 106 can derive a Connection Identifier (CID) associated with base station sector 2104. Wireless terminal 106 may send a handoff request (e.g., an expedited handoff request) to base station sector 1102 over the current link; base station sector 1102 can then route the handoff request to base station sector 2104. Pursuant to an illustration, the handoff request can include the derived CID associated with base station sector 2104. According to yet another example, the handover request can be a layer 2 message indicating that the handover is associated with a base station sector associated with the derived CID.

Based on the handoff request, base station sector 2104 can send a handoff response to base station sector 1102, which can then be sent to wireless terminal 106. The handoff response may include identified information provided by base station sector 2104 that may be used in conjunction to establish a link between wireless terminal 106 and base station sector 2104. The identified information may include, for example, a session ON (ON) ID, an active ID, an assigned access slot (e.g., reserved for the wireless terminal 106), timing information, an identification of a destination Medium Access Control (MAC) state (e.g., ON state, HOLD state, SPLIT tone ON (SPLIT-tone) state, etc.), a period of time during which an assigned ID (e.g., MACID, session ON ID, active ID, etc.) is valid, and so forth.

Wireless terminal 106 can utilize the identified information obtained via the handoff response and establish a link with base station sector 2104. For example, wireless terminal 106 can disconnect the link with base station sector 1102 prior to establishing the link with base station sector 2105 (e.g., when base station sector 1102 and base station sector 2104 are associated with disparate carriers). According to another example, wireless terminal 106 can be simultaneously connected to base station sector 102-104 (without the link between wireless terminal 106 and base station sector 1102 needing to be disconnected) if base station sector 1102 and base station sector 2104 utilize the same carrier.

Conventional Physical (PHY) access operations to obtain a physical connection between wireless terminal 106 and base station sector 2104 may be modified by utilizing the identified information associated with the handoff response. In one example access scheme, wireless terminal 106 and base station sector 2104 may communicate information associated with an access request, an access grant, and an access exchange. For some expedited handoffs (e.g., corresponding to the same logical link controller) implemented by system 100, access request/access grant signaling transfer timing and power connection and/or access exchange signaling may be ignored. According to an example, N bits (where N can be any integer (e.g., 2 bits)) in the handover response from base station sector 2104 can explicitly indicate which one or more portions of physical access layer operations to perform or ignore (e.g., ignore access switch signaling, ignore the entire access procedure, etc.).

Resources in an access time interval of an uplink channel structure may be shared between a paging acknowledgement channel and a dedicated access request channel. Resources may typically be dedicated to paging acknowledgement segmentation; however, resources can sometimes be dynamically reallocated for use as dedicated (contention-free) access request segments as part of expedited handoff. When resources are to be used as dedicated access request segments, the base station sector can ignore the corresponding downlink page, which may need to be acknowledged with the same access request segment resources. It should be noted that if the base station sector sends a corresponding downlink page, the paging wireless terminals send page response signals in the same resources, causing collisions. By sharing air link resources and performing dynamic reallocation from paging acknowledgement usage to dedicated uplink access segment usage, efficient resource usage can be achieved with minimal disruption to ongoing paging operations.

Referring to fig. 2, an illustrative example 200 for performing an expedited handoff from a first sector (e.g., sector 1, base station sector 1102 of fig. 1) to a second sector (e.g., sector 2, base station sector 2104 of fig. 1) is illustrated. A wireless terminal, such as wireless terminal 106 of fig. 1, may have a previously established link 202 (e.g., a physical connection) associated with sector 1. A wireless terminal may detect a signal 204 (e.g., a beacon) from sector 2. For example, a wireless terminal may continuously obtain and estimate received signals transmitted from one or more sectors other than sector 1 (e.g., sector 2). Based on an analysis of the signal 204 (e.g., strength, signal-to-noise ratio, etc.), the wireless terminal may decide to effect the handover. For example, when sector 1 and sector 2 utilize the same carrier, the wireless terminal may still choose to perform a handoff because the wireless terminal may be connected to both sectors in parallel, even though the signal quality of signal 204 is inferior to the signal quality associated with sector 1. When sector 1 and sector 2 utilize different carriers, the wireless terminal can effect a handoff if the signal quality associated with detected signal 204 associated with sector 2 is greater than the signal quality associated with sector 1, as link 202 can be dropped (e.g., if the wireless terminal is a narrowband mobile device). In addition, based on the detected signal 204, the wireless terminal can derive a Connection Identifier (CID) corresponding to sector 2.

The wireless terminal may generate an expedited handoff message. For example, the expedited handoff message can include a CID associated with the sector (e.g., sector 2) and/or carrier to which the link is to be established. Additional parameters (e.g., a CID associated with one or more distinct, current connections in addition to link 202, etc.) may also be included in the expedited handoff message. The message may be sent to sector 1 via the existing link as a handoff request 206. In addition, the CID may identify to sector 1 a disparate sector (e.g., sector 2) to which the handoff request is to be routed. For example, sector 1 may interpret the CID associated with sector 2 to generate a routable address and/or may encapsulate the handoff request 206 based on IP protocols. In addition, sector 1 can incorporate a mobile identifier associated with the wireless terminal with the handoff request. Additionally or alternatively, the wireless terminal can include its associated mobile identifier in the handoff request 206 sent to sector 1.

Sector 1 then forwards the handoff request 208 to sector 2. Sector 2 can recognize that handoff request 208 was sent by sector 1 rather than over the air. Sector 2 can determine whether to grant the request. Pursuant to an example, sector 2 can initiate an exchange of an encryption key (not shown) with a wireless terminal via sector 1. According to this example, downlink and uplink communications between sector 2 and wireless terminals associated with encryption key exchange may be routed through sector 1.

Sector 2 may allocate resources to wireless terminals; these allocated resources may be included as identified information in a handoff response 210 that may be sent to sector 1. The identified information may be, for example, an assigned access slot, timing information, one or more MAC layer identifiers (e.g., a session on ID utilized in a session on state, an active ID utilized in an active state), information identifying the destination MAC state, a time period during which the assigned ID is valid, and so forth. Sector 1 can also include communicating with wireless terminals to provide handoff response 212.

For example, the wireless terminal may obtain a contention-free access slot in the received handover response 212. The contention-free access slot may be in a dedicated portion of the access channel. The contention-free access slot may be statically reserved for expedited handoff and may be used for other purposes (e.g., acknowledgment for paging). However, once a given contention-free access slot is allocated for expedited handoff, that slot may not be used for any distinct purpose. Also by way of example, there may be 7 access slots available for access in a time interval of 11.4 ms. Six of the seven access slots may be used by any access wireless terminal and thus be subject to contention, while the seventh access slot may be used for contention-free access in the sense that only the allocated wireless terminal is allowed to use the seventh access slot. However, claimed subject matter is not so limited. The contention-free access slot may allow a wireless terminal to remain connected to sector 1 until immediately before the assigned time and then use the assigned contention-free access slot to access sector 2. Regardless of the collision, the wireless terminal may be granted access to sector 2 with high certainty. Therefore, handover delay can be mitigated. In contrast, conventional physical layer access sometimes utilizes a contention-based model associated with access channels on which requests from many wireless terminals may collide, interfere, etc. due to parallel transmissions over a shared channel; thus, the general technique may be associated with a delay based on one or more access requests transmitted by wireless terminals that are not approved due to collisions, interference, etc., associated with access requests associated with disparate wireless terminals.

In addition, a link can be established between the wireless terminal and sector 2 via physical layer access 214. For example, conventional physical layer access (e.g., using contention-based random access) may be utilized. Alternatively, the wireless terminal may use the allocated contention-free access slot to establish the link. According to another example, various signaling associated with physical layer access may be omitted as described below. Although not depicted, it is to be understood that the link between the wireless terminal and sector 1 can be broken prior to physical layer access 214. Thus, if sector 1 and sector 2 utilize different carriers, the link between the wireless terminal and sector 1 can be severed prior to physical layer access 214.

Referring to fig. 3, illustrated is an exemplary illustration 300 that can be utilized in connection with expedited handoff to enable physical layer access to a sector (e.g., base station sector 2104 of fig. 1, sector 2 of fig. 2). A wireless terminal (e.g., wireless terminal 106 of fig. 1, wireless terminal of fig. 2) may initiate physical layer access after severing a currently established link to another sector (e.g., base station sector 1102 of fig. 1, sector 1 of fig. 2). According to another example, physical layer access may also be achieved without breaking the established link when performing an intra-carrier handover; thus, a wireless terminal may be connected to multiple sectors in parallel in such a case.

The wireless terminal begins physical layer access by sending an access request 302 to the sector. The access request 302 may be a lightweight request. In addition, the wireless terminal may transmit an access request 302 during a dedicated contention-free access slot. For example, a sector may have allocated a dedicated access slot, and a wireless terminal may have utilized a handoff response via a previous sector with which the wireless terminal had a link to obtain an indication associated with the dedicated access slot. By utilizing contention-free access techniques, wireless terminals can initiate the creation of a new physical connection by breaking an established link at a known time and with a reduced likelihood of collision with a disparate wireless terminal. Pursuant to another example, the wireless terminal may transmit the access request 302 over a contention-based access channel.

Based on access request 302, the sector can send access grant 304 to the wireless terminal. In a contention-based model, access request 302 may collide with one or more disparate access requests, which may result in a delay associated with the sector sending access grant 304. However, this delay can be mitigated via utilizing contention-free access slots for access requests 302, and thus handover optimization can be improved.

The uplink access exchange 306 and the downlink access exchange 308 may then be utilized. For example, the wireless terminal may transmit a small amount of data (e.g., a random number) to the sector via the uplink access exchange 306, and the sector may send the data back in the downlink access exchange 308 to resolve one or more potentially undetected collisions associated with the access request 302. In addition, the sector may include information such as a session on id (sonid) and/or an activity id (actid) (e.g., related to the allocated resources) in the downlink access exchange 308. Pursuant to an illustration, the wireless terminal may have obtained the SONID and/or the actiid with a handover response from the sector as discussed above; thus, uplink access exchange 306 can include information indicating that the sector previously approved the handoff response and allocated these resources to the wireless terminal, and the sector need not provide such information in downlink access exchange 308. In addition, the wireless terminal and sector can use encryption parameters that have been established between the wireless terminal and sector via the previous sector with which the wireless terminal has a past link.

Referring to fig. 4, illustrated is an exemplary schematic 400 for optimizing physical layer access in association with expedited handoff. For example, a wireless terminal may transmit an access request 402 to a sector in connection with contention-free access. By utilizing dedicated resources, the probability of a collision between access request 402 and a disparate access request associated with another wireless terminal can be reduced. Based on access request 402, the sector can send access grant 404 to the wireless terminal. The access request 402 and the access grant may be used for time synchronization. According to one example, base stations are often not synchronized; thus, when a wireless terminal effectuates a handoff from a first sector to a second sector, time synchronization can be utilized during physical layer access (e.g., access request 402, access grant 404) associated with the second sector. In addition, by transmitting access signals using the assigned contention-free access slots, the wireless terminal effectively identifies itself to the sector so that the wireless terminal and sector can begin using identification information (e.g., one or more MAC layer IDs) that has been established between the wireless terminal and sector via the previous sector with which the wireless terminal had a link

The illustrative example 400 may omit the uplink and downlink access exchanges as described in fig. 3 and commonly utilized in the conventional art. Such access exchanges may often be used to mitigate collisions and/or provide identification information (e.g., one or more MAC layer IDs). However, by utilizing contention-free access and obtaining such identification information via the handover response described above, access switching signaling may be ignored and handover may be further optimized. It is to be appreciated that the sector can provide an indication to the wireless terminal that access exchange signaling can be omitted (e.g., as part of a handoff response, access grant, etc.).

Pursuant to another illustration, two sectors of the same base station can be synchronized in terms of Orthogonal Frequency Division Multiplexing (OFDM) time. The OFDM time associated with a base station sector can be the timing to which a wireless terminal is synchronized when accessing the base station sector to be able to support providing a common understanding of time between the base station sector and one or more wireless terminals. Thus, if a wireless terminal hands off from one sector to another sector of the same base station, the wireless terminal may ignore the access request 402 and access grant 404 associated with physical layer access. In such a case, the wireless terminal may transition directly (e.g., at a predetermined time) from one on state in the first base station sector to another on state in the second base station sector without performing physical layer access upon receiving a handoff response. The two sectors may be in the same base station and thus synchronized in timing. Thus, if the wireless terminal is already timing synchronized with the first sector, the wireless terminal is also timing synchronized with the second sector.

Referring now to fig. 5, illustrated is a communications apparatus 500 that can mitigate handoff delay via utilization of an established connection. The communication device 500 may be a wireless communication device, such as a wireless terminal. Additionally or alternatively, the communications apparatus 500 may reside within a wired network. The communications apparatus 500 can include a memory 502, the memory 502 can retain information associated with parameters relating to handoff requests and/or instructions for effecting a handoff from a first sector to a second sector. Further, the communications apparatus 500 can include a processor 504, the processor 504 can execute instructions within the memory 502 and/or instructions received from another network device.

In one example, communications apparatus 500 can be a base station sector. In such an example, memory 502 can retain instructions for determining whether to approve or reject the handoff request, identifying resources allocated pursuant to the handoff request, incorporating identifying information in the handoff request, and/or routing information between the wireless terminal and disparate base station sectors. The processor 504 may be utilized in connection with executing such instructions.

In yet another example, the communications apparatus 500 may be a terminal such as a wireless terminal. In this example, memory 502 may include instructions for detecting a signal from a second sector. The processor 504 may be configured to perform such signal detection and analysis. The processor 504 may also be used to send an expedited handoff request to a second sector via the first sector, receive a handoff response from the second sector through the first sector, and/or establish a link with the second sector.

Fig. 6-9 relate to ACCESS (ACCESS) states that may be utilized in connection with various aspects of the claimed subject matter. A Wireless Terminal (WT) in an access state may attempt to establish a connection to a Base Station Sector (BSS). The access state is a transient state in which the WT and BSS go through a series of operations and if successful, transition to an on, hold, or sleep state.

The following channels may be utilized in conjunction with the access state.

Dl.bch.bn, dl.bch.ts, dl.bch.bst channels: segments of these channels are broadcast. The WT may receive segments of these channels. The BSS may transmit all of these channel segments.

PICH channel: segments of the pich channel are broadcast. The WT may receive dl. The BSS may transmit all dl.pch segments.

Ul.ach.ar channel: segmentation of the ul.ach.ar channel is contention-based. The WT may use any of the ul.ach.ar segments. The BSS may receive all ul.ach.ar segments.

Gxch channel: segmentation of the dl.gxch channel can be used in one of two scenarios. In a first scenario, dl.gxch segments are broadcast. After the WT has transmitted the ul.ach.ar segment of the access request, the WT may receive the corresponding dl.gxch segment to determine whether the segment has been detected by the BSS. If the BSS has detected any ul.ach.ar segment of the access request, it may send an access grant message in the corresponding dl.gxch segment. In a second scenario, dl.gxch segments are shared. After the WT has transmitted the ul.axch segment of the access exchange, the WT may receive a corresponding dl.gxch segment to receive the access exchange message from the BSS. In this case, the assignment of dl.gxch segments is implicitly given in the respective ul.axch segment. The WT may receive the dl.gxch segment if the WT transmits a corresponding ul.axch segment. The BSS may transmit a dl.gxch segment if it has received the corresponding ul.axch segment.

Axch channel: segments of the ul. The assignment of the ul.axch segment is given implicitly in the respective dl.gxch segment. In an operation not to ignore the access exchange procedure, the WT may transmit the ul.axch segment if the WT receives the access grant message in the corresponding dl.gxch, and the BSS may receive the ul.axch segment if the BSS transmits the access grant message to the WT in the corresponding dl.gxch.

Referring to fig. 6, a flow diagram 600 including various operations associated with an access state is illustrated. At 602, a system determination may be implemented. The WT may use dl.bch.bn, dl.bch.ts, dl.bch.bst and dl.pich channels to identify and select the appropriate BSS and tone block to which it may connect. The tone block may be a set of frequencies that the WT and BSS may use to form a connection. Open loop synchronization may be performed at 604. The WT may synchronize its receiver with the Downlink (DL) signal of the selected BSS in the selected tone block and may set its own transmission parameters based on the acquired receiver synchronization. Operations associated with the access request and approval may be performed at 606. The WT may transmit an Uplink (UL) access request message to the BSS using an ul.ach.ar channel and receive a DL access grant message from a dl.gxch channel. An access exchange may be performed at 608. The WT sends an access switch request message in the ul. The BSS responds via the dl.gxch channel with an access exchange response message. The access switching procedure may be omitted in some operations as specified below.

After the WT enters the access state, the WT may traverse at least one access cycle. Each access cycle may begin with the operation of system determination 602, possibly followed by open loop synchronization 604, access request and grant 606, and final access exchange 608. The set of operations to be performed in each access cycle depends on the particular protocol used by the WT and is described below.

If all operations in the access cycle are successful, the access cycle is successful and may terminate when the BSS and WT migrate to an ON, Hold, or sleep state. If any operation fails, an access failure occurs and the WT may immediately terminate the current access cycle. In general, after an access failure, the WT may wait for a certain period of time before attempting a new access cycle. However, a new access cycle may start immediately. After a predetermined number of unsuccessful access cycles have been performed, the WT may abort the access attempt and generate an error message to the upper layer.

Referring to fig. 7, illustrated is a schematic example 700 relating to random access that may be implemented when a WT in a dormant or inactive state intends to migrate to an on or hold state with a BSS. The operations associated with the illustrative example 700 may be used by a WT that does not have a valid wtacitive id assigned by the BSS. The WT may have or still have a connection with another BSS at one time.

System determination and synchronization 702. The WT may receive dl.bch.bn, dl.bch.ts, dl.bch.bst and dl.pich channels to identify and select an appropriate BSS for connection. The WT may obtain system parameters such as bsssslope, bssSectorID, bssSectorType, wtOpenLoopPowerOffset, and dlultraslot superstoretindex from these DL channels. The BSS and WT may also operate in open loop synchronization according to open loop frequency, timing and power control procedures.

An access request 704. When the WT intends to send an access request in the superslot, the WT may randomly select and send one of the ul.ach.ar segments to the BSS in the superslot. The BSS may receive all ul.ach.ar segments of each superslot and attempt to detect ul.ach.ar segments transmitted by any WT.

Access approval 706. After the WT transmits the ul.ach.ar segment, the WT may receive the corresponding dl.gxch segment to determine whether the ul.ach.ar segment has been approved by the BSS. After the BSS detects the presence of the ul.ach.ar segment transmitted by the WT, the BSS may transmit an access grant message in the corresponding dl.gxch segment to grant the ul.ach.ar segment.

UL access switching 708. Upon granting the WT access via a dl.gxch segment, the WT may transmit a corresponding ul.axch segment of the dl.gxch segment. The WT may indicate in the ul.axch segment that it intends to migrate to the on or hold state of the BSS and provide the relevant configuration information. After the BSS transmits the access grant message in the dl.gxch segment, the BSS may receive a corresponding ul.axch segment of the dl.gxch segment.

DL access switching 710. After the BSS receives the ul.axch segment, the BSS may transmit a dl.gxch segment of the ul.axch segment. The BSS may specify assignment and configuration information in the dl.gxch segment. The BSS may assign a MAC state (on or hold) to which the WT may migrate after the access state. After the WT transmits the ul.axch segment, the WT may receive dl.gxch.

MAC state transition 712. The BSS and WT may migrate to the MAC state assigned in the DL access exchange step and use the parameters assigned in the DL access exchange message, such as wtActiveID, wtononid and wtOnMask in the destination MAC state.

The following relates to access approval 706. The corresponding dl.gxch segment of the ul.ach.ar segment in the UL superslot is the dl.gxch segment [1] of the parallel DL superslot. To grant the access request, the BSS may use an "access grant" format in the dl.gxch segment. In the access approval message, an "index of approved ul.ach.ar segments" may be set as an index of ul.ach.ar segments to which the access approval message is transmitted. The access grant may also contain closed loop timing control and power control commands in the "timing correction" and "power correction" fields, respectively. The BSS may measure the received power and timing of the approved ul.ach.ar segment to calculate timing control and power control commands. Timing and power adjustments ensure that the WT's UL signal arrives at the BSS at the proper power and is properly time aligned in order to compensate for round-trip propagation delay. By accurately adjusting the WT's transmitter timing/power, the UL signals from the WT do not interfere with UL signals from other existing WT and BS connections in the tone block.

To disallow any access request, the BSS may discontinue transmission of the corresponding dl.gxch segments of all ul.ach.ar segments of the UL superslot. Alternatively, the BSS may transmit the dl.gxch segment using an "access grant" format, wherein the "index of granted ul.ach.ar segment" field is set to 7. Access requests in the ul.ach.ar segment (if any) are not approved if the BSS does not approve any access requests. The BSS may discard memory of any ul.ach.ar segments detected in the UL superslot, but not approved in the corresponding dl.gxch segment.

The WT may use timing control and power control commands to adjust its transmitter timing and power if the WT's access request is granted. The WT may consider the access to fail if the ul.ach.ar segmentation is not approved.

The following relates to UL access switching 708. The corresponding ul.axch segment for dl.gxch period [1] in DL super slot k is the ul.axch segment for UL super slot k + 1. The WT may use the "access initialization" format in the ul. In the UL access exchange message, the "destination MAC state" field may be set to on or hold state depending on whether the WT intends to migrate to on or hold state with the BSS after the access state. The WT may also specify in the "ONMASK" field the particular format the WT requests to use in the ul.dcch channel if the WT intends to transition to the on state. The "active ID" field may be set to 0x00 because the WT has no valid wtActiveID. The WT may generate and include a random number in the "RAND number" field.

The following relates to DL access switching 710. The corresponding dl.gxch segment of the ul.axch segment in UL superslot k +1 is dl.gxch segment [0] in DL superslot k + 2. If the BSS does not detect a valid UL access exchange message in the ul.axch segment, the BSS may transmit the dl.gxch segment using the "access exchange for initialization response" format with the "active ID" field set to 0x 00. Otherwise, the BSS may send a DL access exchange based on the received UL access exchange message as described below.

To migrate the WT to the on or hold state, the BSS may send a DL access exchange message in the dl.gxch segment using an "access exchange for initialization response" format. The "active ID", "turn-on ID", and "turn-on mask" (ONMASK) fields may be set to wtActiveID, wtOnID, and wtOnMask assigned by the BSS to the WT. If the BSS assigns the WT to the on state, the BSS may assign a significand to all three of the above parameters. If the BSS assigns the WT to the hold state, the BSS may set the "on ID" field to 0x 00. The MAC state assigned by the BSS in the DL access exchange message may be different from the MAC state requested by the WT in the UL access exchange message.

The BSS may also set the "number of RAND" field in the DL access exchange message to be equal to the "number of RAND" field in the received UL access exchange message.

The WT may consider the access to be successful if one of the following access failure conditions does not occur. First, the "access switch type" field of the DL and UL access switch messages is different. Second, the "RAND number" field in the DL and UL access exchange messages is different. Third, the "active ID" field is set to 0x 00.

The following relates to MAC state transition 712. The WT may migrate to the assigned MAC state immediately after it has successfully received the access exchange message and considers the access successful, and may explicitly do so in a subsequent superslot after receiving the DL access exchange message. The BS may migrate to the assigned MAC state immediately after transmitting the DL access exchange message.

Referring to fig. 8, a schematic example 800 of various channel segments is illustrated. Fig. 8 shows the relationship between the respective ul.ach, ul.axch and dl.gxch channel segments. The figure shows DL and UL signals and the timing is measured at the BSS antenna connector. The ul.ach.ar segment in the UL superslot k has a corresponding dl.gxch segment, dl.gxch segment [1] in the DL superslot k. Dl.gxch segments have a corresponding ul.axch segment in UL superslot k + 1. The ul.axch segment has a corresponding dl.gxch segment, dl.gxch [0] in DL superslot k + 2. If the final access switch is sent in DL superslot k +2, the BSS may transition to the assigned MAC state in the middle of DL superslot k +2, and after the WT has successfully received the access switch message, the WT may transition to the MAC state in UL superslot k + 2. The WT may migrate to the MAC state in UL superslot k + 3.

In the scenario where the WT transitions to the on state, UL superslot k +2 is considered the first UL superslot of the WT to be in the on state.

Active connection-random access is requested using the pre-assigned MAC identifier. This section details the random access operation that can be performed when the WT has a valid wtActiveID assigned by the BSS in the upper layer handover request and response protocol. The current BSS may assign wtActiveID to the WT in one of the following two scenarios. In a first scenario, the BSS and WT already have a connection on a different tone block than the current tone block. The current BSS has already assigned wtActiveID to the WT for establishing the connection in the current tone block. In a second scenario, the WT already has a connection with a different BSS, referred to as a second BSS. The current BSS has assigned wtActiveID to the WT via the second BSS for establishing a connection with the current BSS in the current tone block. This operation may be similar to the above-described operation except for the following changes (see fig. 7). In the UL access exchange step, the "active ID" field may be set to a valid wtActiveID assigned by the BSS. In the step of DL access switching, the "active ID" field in the DL access switching message may not necessarily be the same as the "active ID" field in the UL access switching message.

Active connection-reservation access is requested using the pre-assigned MAC identifier. This section particularly illustrates the access operations that can be performed when a WT has a valid wtActiveID and reserved ul. The current BSS may assign wtActiveID and ul. Further, the current BSS may have assigned a destination MAC state (on or hold) to the WT. If the destination MAC state is on state, the current BSS may have assigned to the WT a valid pair of wtOnID and wtOnMask that will be used after the WT successfully transitions to on state. When the ul.ach.pa segment has been pre-assigned to the WT, no paging message may be transmitted in the corresponding dl.pch. This operation may be similar to the above-described operation (e.g., fig. 7) except for the following changes. In the access request step, the WT may transmit the reserved ul. In the access approval step, if the national BSS intends to approve the access request transmitted by the ul.ach.pa segment, the BSS may set "index of approved ul.ach.pa segment" to 6. The access switching step may be omitted according to upper layer handover request and response protocol exchanges between the WT and the BSS. When the BSS allocates the reserved ul.ach.pa field to the WT, the BSS may inform the WT whether to omit the access switching step. If the access exchange step cannot be omitted, the WT and BSS may follow the steps associated with requesting active connection-random access with the pre-assigned MAC identifier described above to complete the access exchange. If the access exchange step can be omitted, the WT may migrate to the pre-assigned MAC state with the pre-assigned MAC identifier when it successfully receives the access grant message and is deemed to be successful in access, and do so in a subsequent superslot upon receiving the DL access annotation message. The BS may migrate to the assigned MAC state immediately after transmitting the DL access grant message. In the scenario where the WT transitions to the on state, the UL superslot k shown in fig. 8 is considered to be the first UL superslot that the WT will be in the destination on state, since transmission of UL.

Referring now to fig. 9, an example timing diagram 900 relating to physical layer access is illustrated. For example, the wireless terminal may perform an expedited handoff (e.g., send a handoff request and obtain a handoff response). The wireless terminal may obtain the identified information included in the handover response. The identified information may also include an assigned access slot, timing related information, a session on ID, an active ID, a destination MAC state, and/or a time period for which the assigned ID is valid.

By way of example, a wireless terminal may be at time t₀A handover response is obtained. The identified information associated with the handover response may indicate a time period (e.g., from time t) for which an assigned ID (e.g., MACID, session on ID, active ID, etc.) is valid_aTo time t_bThe active period of time). The validity period may be at time t_aAt the beginning of the time t_aMay be related to time t₀Are substantially the same. Alternatively, time t_aCan be later than the timet₀。

The handover response may also include identified information associated with the allocated access slot 902. The assigned access slot 902 may be a time within the active period. In addition, the allocated access slots 902 may enable wireless terminals to implement physical layer access in a contention-free manner, as resources associated with the allocated access slots 902 may be reserved for wireless terminals obtaining a handover response.

Wireless terminals may implement physical layer access at disparate times. For example, the wireless terminal may initiate physical layer access at a904 corresponding to the assigned access slot 902. Thus, the wireless terminal may be enabled by being in a dedicated time (e.g., t)_c) An access request is sent and an access grant is obtained to establish a link using the reserved resources. In addition, uplink and downlink access exchange signaling may be ignored by implementing physical layer access at a 904. Additionally, encryption and/or authentication associated with time a904 may be omitted.

Physical layer access may also be performed during the validity period at either B906 or B908. Time B906 may be before the time associated with the associated access slot 902 and time B908 may be after the time associated with the assigned access slot 902. The wireless terminal may perform random access at B906-908. Such random access may be contention based and may utilize uplink and downlink access exchange signaling. However, encryption and/or authentication may be omitted.

In addition, physical layer access may be achieved at times other than the validity period (e.g., at time C910). At C910, random access may be implemented. In addition, uplink and downlink access exchange signaling may be utilized. In addition, encryption and authentication may be performed (e.g., because the MACID provided in the handover response is no longer valid).

Referring to fig. 10-12, methodologies relating to efficiently handing off from a first sector to a second sector to mitigate handoff delays are illustrated. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or times, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more embodiments.

Referring to fig. 10, a methodology 1000 that facilitates handing off from a first sector to a second sector is illustrated. At 1002, a signal emanating from a second sector can be detected. For example, the signal may be a beacon. Additionally, analysis of the detected signal may be performed to identify whether to switch to a sector (e.g., a second sector) associated with the signal; the analysis may be based on signal quality, signal strength, inter-carrier handoff versus intra-carrier handoff, and the like. According to another illustration, a Connection Identifier (CID) may be derived based on the detected signal. At 1004, a handoff request can be sent to a second sector via a first link with a first sector. The handoff request may include, for example, a CID to identify the second sector, the particular carrier, and/or the like. The handover request may include a Wireless Terminal Identifier (WTID) and/or may be inserted after the transmission.

At 1006, a handoff response may be received from the second sector over the first link and the first sector. For example, the handover response may include the identified information. The identified information may relate to an assigned access slot, timing related information, a session on ID, an active ID, a destination MAC state, a time period for which an assigned ID (e.g., MACID, session on ID, active ID, etc.) is valid, and so forth. Pursuant to an illustration, the identified information can include an access slot associated with contention-free access by providing a dedicated access channel. At 1008, a second link may be established with a second sector. The link may be established using the identified information. For example, the link with the first sector may be broken before the link with the second sector is established. Alternatively, the link with the first sector may remain normal while the link with the second sector is established. The link may be obtained by utilizing physical layer access. The identified information may enable omitting a portion of the physical layer access or ignoring the physical layer access entirely. For example, to establish a link with the second sector, an access request may be sent to the second sector (e.g., in an assigned access slot) and an access grant may be received (e.g., to achieve timing synchronization). For example, the access grant message may include a timing correction command. In addition, a transmitter symbol timing can be adjusted based at least in part on the timing correction command and can be used to transmit signals to the second sector. According to another example, an access request may be sent, an access grant may be received, and uplink and downlink access exchange signaling may be performed. According to this example, the uplink access exchange and/or the downlink access exchange may communicate an identifier, wherein the identifier may be utilized in connection with the second link once the second link is established. Pursuant to yet another example, a random access slot can be selected and an access signal can be transmitted to the second sector in the random access slot. In response, an access grant message may be received from the second sector, which includes at least the timing correction command. The transmitter symbol timing can be adjusted according to the timing correction command and can be used to transmit the uplink access exchange to the second sector. For example, the uplink access exchange may convey at least a portion of the identified information received in conjunction with the handover response. A downlink access exchange may also be received from the second sector.

Referring to fig. 11, illustrated is a methodology 1100 that facilitates routing handover-related signals for utilization in connection with expedited handovers. At 1102, a handover request can be received from a wireless terminal. For example, the handoff request may include a CID associated with the disparate sector. Further, upon receiving the handover request, information related to the wireless terminal (e.g., a Wireless Terminal Identifier (WTID)) may be included in the handover request. In addition, the handover request may be encapsulated according to an IP protocol. At 1104, the handoff request can be routed to the disparate sector. For example, routing may be based on CID. According to one example, after routing the handoff request, information related to the encryption key can be obtained from the disparate sector and forwarded to the wireless terminal. According to this example, a response relating to encryption key related information may be received from the wireless terminal and may be routed to the disparate sector. At 1106, a handoff response can be received from the disparate sector. At 1108, the handover response may be forwarded to the wireless terminal. The link to the wireless terminal may then be broken; however, claimed subject matter is not so limited.

Referring to fig. 12, illustrated is a methodology 1200 employed by a base station sector that enables allocating resources to wireless terminals prior to physical layer access to mitigate handoff delays. At 1202, a handoff request can be received from a wireless terminal via a disparate sector. For example, the handover request may be distinguished from a handover request obtained over the air. In addition, the handover request may include an identifier (e.g., WTID) specific to the wireless terminal. A decision may also be made as to whether to approve or reject the handover request. According to another illustration, encryption key signaling information can be transmitted to a wireless terminal over disparate sectors and can be received from the wireless terminal via the disparate sectors.

At 1204, resources can be allocated to the wireless terminal. For example, the resources may be associated with dedicated access slots, timing related information, session on ID, active ID, destination MAC state, and the like. At 1206, a handoff response including information related to the resource can be transmitted to the wireless terminal over the disparate sector.

At 1208, a link can be established with the wireless terminal utilizing the allocated resources. For example, contention-free physical layer access may be used to establish a link. Thus, an access request may be obtained and an access grant may be sent. In addition, the access request and access grant may enable the wireless terminal to synchronize to a particular time. The base station sector may expect the wireless terminal to transmit the assigned contention-free access signal. Once an access signal arrives from a wireless terminal according to the allocated resources, the base station sector can immediately identify the wireless terminal and start using the established parameters (encryption parameters or MAC identifier) for the new link. However, if the wireless terminal utilizes a contention-based access signal, the wireless terminal may have to identify itself (e.g., via an access exchange) so that the base station sector can identify the wireless terminal and begin using the established parameters (e.g., encryption parameters or MAC identifiers) for the new link.

It is to be appreciated that in accordance with one or more aspects described herein, inferences can be made regarding identification of signaling to utilize with physical layer access, determination of a time to break an established link with a first sector to effect a handoff to a second sector, and the like. As used herein, the terms "inference" and "infer" refer generally to the process of reasoning about or inferring states of the system, environment, and/or user from a set of observations as captured via events and/or data. Speculation may be used to identify a specific context or action or may generate a probability distribution over states, for example. The inference can be probabilistic-that is, the computation of a probability distribution over states of interest based on a consideration of data and events. Inference can also refer to techniques employed for composing higher-level events from a set of events and/or data. Such inference results in the construction of new events or actions from a set of observed events and/or a set of stored event data, whether or not the events are associated with close temporal proximity, and whether the events and data come from one or several event and data sources.

According to an example, one or more methods presented above can include making inferences pertaining to determining signaling to perform in association with physical layer access. According to one example, inferences can be made regarding whether various signaling utilized in connection with conventional techniques should be utilized to facilitate establishing a new link between a wireless terminal and a sector. Additionally, speculation may be made as to the time to disconnect an established link with a sector to begin physical layer access to create a new link. It will be appreciated that the foregoing examples are illustrative in nature and are not intended to limit the number of inferences that can be made or the manner in which such inferences are made in conjunction with the various embodiments and/or methods described herein.

Referring to fig. 13, illustrated is an example communication system 1300 (e.g., a cellular communication network) implemented in accordance with various aspects that includes a plurality of nodes interconnected by communication links. The nodes in the example communication system 1300 exchange information using signals (e.g., messages) based on a communication protocol (e.g., the Internet Protocol (IP)). For example, the communication links of system 1300 may be implemented using wire, fiber optic cable, and/or wireless communication techniques. The exemplary communication system 1300 includes a plurality of end nodes 1344, 1346, 1344 ', 1346 ', 1344 ", 1346" that access the communication system 1300 via a plurality of access nodes 1340, 1340 ' and 1340 ". End nodes 1344, 1346, 1344 ', 1346 ', 1344 ", 1346" may be, for example, wireless communication devices or terminals, and access nodes 1340, 1340 ' and 1340 "may be, for example, wireless access routers or base stations. The example communication system 1300 also includes a plurality of other nodes 1304, 1306, 1309, 1310, and 1312 to provide intercommunication or to provide specific services or functions. In particular, the example communication system 1300 includes a server 1304 that is employed to support the transfer and storage of state associated with end nodes. The server node 1304 may be an AAA server, a text transfer server (contexttransfer server), a server including an AAA server function and a text transfer server function.

The example communication system 1300 depicts a network 1302, the network 1302 including a server 1304, a node 1036, and a home agent node 1309 connected to an intermediate network node 1310 by respective network links 1305, 1307, and 1308. Intermediate network node 1310 in network 1302 also provides intercommunication with network nodes that are external from the perspective of network 1302 via network link 1311. Network link 1311 connects to another intermediate network node 1312, which intermediate network node 1312 further provides communication with a plurality of access nodes 1340, 1340 ', 1340 "via network links 1341, 1341', 1341", respectively.

Each access node 1340, 1340 ', 1340 "is depicted as providing communication with a plurality of sets of N end nodes (1344, 1346), (1344 ', 1346 '), (1344", 1346 "), respectively, via respective access links (1345, 1347), (1345 ', 1347 '), (1345", 1347 "). In the example communication system 1300, each access node 1340, 1340', 1340 "is depicted as using wireless technology (e.g., a wireless access link) to provide access. The radio coverage area (e.g., communication cell 1348, 1348 ', 1348 ") of each access node 1340, 1340', 1340" is illustrated as a circle around the respective access node.

An example communication system 1300 is presented as a basis for describing various aspects set forth herein. Additionally, various disparate network technologies are intended to fall within the scope of the claimed subject matter, wherein the number and type of network nodes, the number and type of access nodes, the number and type of end nodes, the number and type of servers and other agents, the number and type of links, and the connectivity between nodes may differ from the corresponding content of the example communication system 1300 shown in fig. 13. Moreover, functional entities depicted in the example communication system 100 may be omitted or combined. The location or arrangement of the functional entities in the network may also vary.

Fig. 14 illustrates an example end node 1400 (e.g., mobile node, wireless terminal, etc.) associated with various aspects. Example end node 1400 may be a device that may be used as any of end nodes 1344, 1346, 1344 ', 1346', 1344 ", 1346" shown in fig. 13. As shown, end node 1400 includes a processor 1404, a wireless communication interface 1430, a user input/output interface 1440, and memory 1410 coupled together by a bus 1406. Thus, various components of end node 1400 can exchange information, signals and data via bus 1406. Components 1404, 1406, 1410, 1430, 1440 of end node 1400 may be located within housing 1402.

Wireless communication interface 1430 provides a mechanism by which internal components of end node 1400 can send and receive signals to/from external devices and network nodes, e.g., access nodes. Wireless communication interface 1430 includes, for example, a receiver module 1431 with a corresponding receive antenna 1436 and a transmitter module 1434 with a corresponding transmit antenna 1438 for coupling end node 1400 to other network nodes (e.g., via wireless communication channels).

The example end node 1400 also includes a user input device 1442 (e.g., a keyboard) and a user output device 1444 (e.g., a display) coupled to bus 1406 via a user input/output interface 1440. Thus, user input device 1442 and user output device 1444 can exchange information, signals and data with other components of end node 1400 via input/output interface 1440 and bus 1406. User input/output interface 1440 and associated devices (e.g., user input device 1442, user output device 1444) provide a mechanism by which a user can operate end node 1400 to perform various tasks. In particular, user input device 1442 and user output device 144 provide functionality that allows a user to control the end node 1400 and applications (e.g., modules, programs, routines, functions, etc.) executing in memory 1410 of the end node 1400.

Processor 1404 may be controlled by various modules (e.g., routines) contained in memory 1410 and may control the operation of end node 1400 to perform various signaling and processing as described herein. The modules contained in memory 1410 are executed at startup or when called by other modules. Modules may exchange data, information, and signals when executed. Modules may also share data and information when executed. Memory 1410 of end node 1400 may include a signaling/control module 1412 and signaling/control data 1414.

Signaling/control module 1412 controls processing related to receiving and sending signals (e.g., messages) for managing state information storage, retrieval, and processing. Signaling/control data 1414 includes state information such as parameters, state, and/or other information related to the operation of the end node. In particular, signaling/control data 1414 may include configuration information 1416 (e.g., end node identification information) and operational information 1418 (e.g., information relating to current processing state, state of pending responses, etc.). Signaling/control module 1412 may access and/or modify signaling/control data 1414 (e.g., update configuration information 1416 and/or operational information 1418).

Memory 1410 of end node 1400 may also include a detector module 1446, a requester module 1448, and/or a link establisher module 1450. Further, although not depicted, it is to be appreciated that detector module 1446, requester module 1448, and/or link establisher module 1450 can store and/or retrieve associated data that can be stored in memory 1410. Detector module 1446 can be utilized to detect one or more signals transmitted from a base station sector. Additionally, requester module 1448 can enable sending a handover request to a base station sector via a link associated with a disparate base station sector. Link establisher module 1450 can also enable establishment of a link with one or more base station sectors based on information received in response to the handover request sent by transmitter module 1448.

Fig. 15 provides an illustration of an example access node 1500 implemented in accordance with various aspects described herein. Example access node 1500 may be an apparatus utilized as any one of access nodes 1340, 1340', 1340 ″ shown in fig. 13. Access node 1500 includes a processor 1504, memory 1510, network/internet interface 1520 and wireless communication interface 1530 coupled together by a bus 1560. Thus, the various components of access node 1500 can exchange information, signals and data via bus 1506. Components 1504, 1506, 1510, 1520, 1530 of access node 1500 may be located within a housing 1502.

Network/internetwork interface 1520 provides a mechanism by which the internal components of access node 1500 can send and receive signals to/from external devices and network nodes. Network/internetwork interface 1520 includes a receiver module 1522 and a transmitter module 1524 used for coupling access node 1500 to other network nodes (e.g., via copper or fiber optic lines). Wireless communication interface 1530 also provides a mechanism by which the internal components of access node 1500 can send and receive signals to/from external devices and network nodes (e.g., end nodes). Wireless communication interface 1530 includes, for example, a receiver module 1532 with a corresponding receive antenna 1536 and a transmitter module 1534 with a corresponding transmit antenna 1538. Wireless communication interface 1530 may be used to couple access node 1500 to other network nodes (e.g., via wireless communication channels).

Processor 1504, under control of various modules (e.g., routines) contained in memory 1510, controls operation of access node 1500 to perform various signaling and processing. The modules contained in memory 1510 may be executed at startup or upon invocation by other modules that may be present in memory 1510. Modules may exchange data, information, and signals when executed. Modules may also share data and information when executed. For example, the memory 1510 of the access node 1500 may include a state management module 1512 and a signaling/control module 1514. Corresponding to each of these modules, memory 1510 also includes state management data 1513 and signaling/control data 1515.

The state management module 1512 controls the processing of received signals from end nodes or other network nodes in connection with state storage and retrieval. State management data 1513 includes, for example, information relating to the end node, such as state or partial state or the location of the current end node state if stored in some other network node. The state management module 1512 can access and/or modify state management data 1513.

A signaling/control module 1514 controls the processing of signals to/from end nodes over a wireless communication interface 1530 and to and/or from other network nodes over a network/internet interface 1520 as required by other operations, such as basic wireless functions, network management, etc. Signaling/control data 1515 includes, for example, end node-related data regarding the assignment of wireless channels for basic operations, as well as other network-related data such as addresses of support/management servers and configuration information for basic network communications. Signaling/control module 1514 can access and/or modify signaling/control data 1515.

Additionally or alternatively, memory 1510 may include a resource allocation module 1540, a handoff response module 1542, a link establishment module 1544, and/or a routing module 1546. Although not depicted, it is to be appreciated that resource allocation module 1540, handoff response module 1542, link establishment module 1544, and/or routing module may store and/or retrieve data that may be stored in memory 1510. The resource allocation module 1540 can enable allocation of resources to the wireless terminal (e.g., in response to a received handoff request) as described above. Handover response module 1542 may facilitate sending a handover response that includes identified information related to allocated resources. Link establishment module 1544 may enable establishing a link with a wireless terminal. Additionally, routing module 1546 may allow data to be received from wireless terminals and routed to appropriate base station sectors and/or received from base station sectors and routed to appropriate wireless terminals.

Referring to fig. 16, illustrated is a system 1600 that mitigates a delay associated with handing off from a first sector to a second sector. It is to be appreciated that system 1600 is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System 1600 can be implemented in a wireless terminal and can include a logic module for detecting a signal emanating from second sector 1602. For example, the signal may be a beacon from which signal quality measurements may be obtained. Additionally, system 1600 can include a logical module for sending a handoff request to a second sector via a first link with a first sector 1604. System 1600 can also include a logical module for receiving a handoff response from a second sector over a first link and a first sector 1606. According to an example, the handover response may include the identified information. The identified information can relate to resources allocated by the second sector and can include, for example, an allocated access slot, timing related information, a session on ID, an active ID, a destination MAC state, a time period during which an assigned ID (e.g., MAC ID, session on ID, active ID, etc.) is valid, and the like. System 1600 can also include a logical module for establishing a second link with a second sector 1608. For example, the identified information associated with the handover response may be utilized in connection with establishing such a link.

Referring now to fig. 17, illustrated is a system 1700 that allocates resources to a wireless terminal for utilization in connection with a handover. System 1700 is represented as including functional blocks, which can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System 1700 can be implemented in a base station and can include a logical module for obtaining a handoff request from a wireless terminal over disparate sector 1702. System 1700 may also include a logical module for allocating resources to wireless terminals 1704. Such allocation may be based on the obtained handover request, for example. Additionally, system 1700 can comprise a logical module for transmitting identified information associated with the allocated resources to the wireless terminal in a handoff response via disparate sector 1706. The identified information may include the assigned access slot, timing related information, session on ID, active ID, destination MAC state, and/or a time period for which the assigned ID is valid. Additionally, system 1700 can include a logical module for establishing a link with a wireless terminal utilizing allocated resources 1708. For example, the assigned access slot may be utilized in conjunction with physical layer access to establish a link. According to yet another example, the link may be established during a time period in which the assigned ID is valid; thus, authentication and/or encryption may be omitted.

For a software implementation, the techniques described herein may be implemented with modules (procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.

Examples that include one or more aspects are described above. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art may recognize that many further combinations and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

Claims (30)

1. A method of handing off from a first sector to a second sector, the method being performed by a wireless terminal, the method comprising:

detecting a signal emanating from said second sector;

sending a handoff notification to the second sector via a first link with the first sector;

receiving a handoff response from the second sector over the first link and the first sector, wherein the handoff response received over the first sector includes identified information provided by the second sector, wherein the identified information includes information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

establishing a second link with the second sector using the identified information;

transmitting an access signal to the second sector in the access resource;

receiving an access grant message from the second sector, the access grant message including at least a timing correction command;

adjusting transmitter symbol timing in accordance with the timing correction command; and

transmitting signals to the second sector using the transmitter symbol timing.

2. The method of claim 1, wherein the identified information further comprises at least one of timing related information, a session on ID, an active ID, a destination MAC state, or a time period during which an assigned ID is valid.

3. The method of claim 1, further comprising:

transmitting an uplink access exchange to the second sector;

receiving a downlink access exchange from the second sector, wherein at least one of the uplink access exchange and the downlink access exchange communicates an identifier; and

using the identifier in the second link.

4. The method of claim 1, wherein the identified information further comprises an identifier, and the method further comprises using the identifier in the second link.

5. The method of claim 1, further comprising disconnecting the first link with the first sector before establishing the second link with the second sector.

6. The method of claim 1, further comprising:

recording transmitter symbol timing associated with the first link; and

using the transmitter symbol timing in the second link.

7. The method of claim 1, further comprising:

deriving a Connection Identifier (CID) associated with the second sector based on the detected signal; and

sending the CID as part of a handover request.

8. A method of handing off from a first sector to a second sector, the method being performed by a wireless terminal, the method comprising:

detecting a signal emanating from said second sector;

sending a handoff notification to the second sector via a first link with the first sector;

receiving a handoff response from the second sector over the first link and the first sector, wherein the handoff response received over the first sector includes identified information provided by the second sector, wherein the identified information includes information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

establishing a second link with the second sector using the identified information;

selecting a random access resource;

transmitting an access signal to the second sector in the random access resource;

receiving an access grant message from the second sector, the access grant message including at least a timing correction command;

adjusting transmitter symbol timing in accordance with the timing correction command;

transmitting an uplink access exchange to the second sector using the transmitter symbol timing, wherein the uplink access exchange conveys at least part of the identified information; and

a downlink access exchange is received from the second sector.

9. The method of claim 8, wherein the identified information includes a time period during which an assigned ID is valid, the random access resource being associated with a time before an end of the time period during which the assigned ID is valid.

10. A wireless communications apparatus that facilitates handing off from a first sector to a second sector, comprising:

means for detecting a signal emanating from said second sector;

means for transmitting a handoff notification to the second sector via a first link with the first sector;

means for receiving a handoff response from the second sector over the first link and the first sector, wherein the handoff response received over the first sector includes identified information provided by the second sector, wherein the identified information includes information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless communication device;

means for establishing a second link with the second sector using the identified information;

means for selecting a random access resource;

means for transmitting an access signal to the second sector in the random access resource;

means for receiving an access grant message from the second sector, the access grant message including at least a timing correction command;

means for adjusting transmitter symbol timing in accordance with the timing correction command;

means for transmitting an uplink access exchange to the second sector using the transmitter symbol timing, wherein the uplink access exchange conveys at least a portion of the identified information; and

means for receiving a downlink access exchange from the second sector.

11. The wireless communications apparatus of claim 10, wherein the identified information further includes a time period during which an assigned ID is valid, the random access resource associated with a time prior to an end of the time period during which the assigned ID is valid.

12. A wireless communications apparatus for mitigating delay associated with handing off from a first sector to a second sector, comprising:

means for detecting a signal emanating from said second sector;

means for transmitting a handoff request to the second sector via a first link with the first sector;

means for receiving a handoff response from the second sector over the first link and the first sector, wherein the handoff response received over the first sector includes identified information provided by the second sector, wherein the identified information includes information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless communication device;

means for establishing a second link with the second sector;

means for transmitting an access signal to the second sector in a dedicated access resource;

means for obtaining an access grant message from the second sector, the access grant message including at least a timing correction command;

means for adjusting transmitter symbol timing in accordance with the timing correction command; and

means for transmitting a signal to the second sector using the transmitter symbol timing.

13. The wireless communications apparatus of claim 12, further comprising:

means for establishing the second link with the second sector with contention-free access.

14. The wireless communications apparatus of claim 12, wherein the identified information further includes at least one of timing related information, a session on ID, an active ID, a destination MAC state, or a time period during which an assigned ID is valid.

15. A method that facilitates allocating resources to a wireless terminal to mitigate handoff delay, comprising:

receiving a handoff request from a wireless terminal via a first sector;

allocating resources of a second sector to the wireless terminal;

transmitting a handover response to the wireless terminal via the first sector, wherein the handover response comprises identified information provided by the second sector relating to the allocated resources, wherein the identified information comprises information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

establishing a link with the wireless terminal by utilizing the allocated resources, wherein establishing the link with the wireless terminal further comprises:

receiving an access request message from the wireless terminal in the allocated access resource;

transmitting an access grant message including at least a timing correction command to the wireless terminal; and

receiving a signal from the wireless terminal that is adjusted based on the timing correction command.

16. The method of claim 15, wherein the identified information further comprises at least one of timing related information, a session on ID, an active ID, a destination MAC state, or a time period during which an assigned ID is valid.

17. The method of claim 15, further comprising:

receiving an uplink access exchange from the wireless terminal; and

transmitting a downlink access exchange to the wireless terminal, wherein at least one of the uplink access exchange and the downlink access exchange includes an identifier.

18. The method of claim 15, further comprising synchronizing the wireless terminal when establishing the link.

19. A method that facilitates allocating resources to a wireless terminal to mitigate handoff delay, comprising:

receiving a handoff request from a wireless terminal via a first sector;

allocating resources of a second sector to the wireless terminal;

transmitting a handover response to the wireless terminal via the first sector, wherein the handover response comprises identified information provided by the second sector relating to the allocated resources, wherein the identified information comprises information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

establishing a link with the wireless terminal by utilizing the allocated resources;

receiving an access signal in a random access resource;

transmitting an access approval message to the wireless terminal, the access approval message including at least a timing correction command;

receiving an uplink access exchange from the wireless terminal, the uplink access exchange synchronized based on the timing correction command and including at least part of the identified information; and

transmitting a downlink access exchange to the wireless terminal.

20. The method of claim 19, wherein the identified information includes an index of the allocated access resource and the random access resource is earlier than the allocated access resource.

21. A wireless communications apparatus that facilitates allocating resources to wireless terminals to mitigate handoff delays, comprising:

means for receiving a handoff request from a wireless terminal via a first sector;

means for allocating resources of a second sector to the wireless terminal;

means for transmitting a handover response to the wireless terminal via the first sector, wherein the handover response comprises identified information provided by the second sector related to the allocated resources, wherein the identified information comprises information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

means for establishing a link with the wireless terminal by utilizing the allocated resources;

means for receiving an access signal in a random access resource;

means for transmitting an access grant message to the wireless terminal, the access grant message including at least a timing correction command;

means for receiving an uplink access exchange from the wireless terminal, the uplink access exchange synchronized based on the timing correction command and including at least a portion of the identified information; and

means for transmitting a downlink access exchange to the wireless terminal.

22. The wireless communications apparatus of claim 21, wherein the identified information further includes an index of the allocated access resource, and the random access resource is earlier than the allocated access resource.

23. A wireless communications apparatus that facilitates allocating resources to a wireless terminal for utilization in connection with a handover, comprising:

means for obtaining a handoff request from a wireless terminal through a first sector;

means for allocating resources of a second sector to the wireless terminal;

means for transmitting, via the first sector, identified information provided by the second sector and associated with the allocated resources to the wireless terminal in a handover response, wherein the identified information includes information about allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal;

means for establishing a link with the wireless terminal using the allocated resources;

means for receiving an access signal from the wireless terminal in the allocated access resource;

means for transmitting an access grant message to the wireless terminal, the access grant message including at least a timing correction command; and

means for receiving a signal from the wireless terminal, the signal modified based on the timing correction command.

24. The wireless communications apparatus of claim 23, wherein the identified information further includes at least one of timing related information, a session on ID, an active ID, a destination MAC state, or a time period during which an assigned ID is valid.

25. A method for wireless communication, comprising:

receiving a handoff request from a wireless terminal for a disparate sector;

routing the handoff request to the disparate sector;

receiving a handoff response for the wireless terminal from the disparate sector, wherein the handoff response comprises identified information provided by the disparate sector, wherein the identified information comprises information regarding allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal; and

sending the handover response to the wireless terminal,

wherein the identified information is used to establish a link between the wireless terminal and the disparate sector, and wherein establishing the link comprises:

receiving, by the disparate sector, an access request message from the wireless terminal in the allocated access resource;

transmitting, by the disparate sector, an access grant message including at least a timing correction command to the wireless terminal; and

receiving, by the disparate sector, a signal from the wireless terminal that is adjusted based on the timing correction command.

26. The method of claim 25, further comprising:

receiving a Connection Identifier (CID) as part of the handover request;

identifying the distinct sector based at least in part on the CID; and

routing the handoff request to the disparate sector based on the CID.

27. The method of claim 25, further comprising:

determining an identifier associated with the wireless terminal; and

incorporating the identifier into the handoff request routed to the disparate sector.

28. An apparatus for wireless communication, comprising:

means for receiving a handoff request from a wireless terminal for a disparate sector;

means for routing the handoff request to the disparate sector;

means for receiving a handoff response for the wireless terminal from the disparate sector, wherein the handoff response comprises identified information provided by the disparate sector, wherein the identified information comprises information regarding allocated access resources, and wherein the allocated access resources are dedicated to the wireless terminal; and

means for sending the handover response to the wireless terminal,

wherein the identified information is used to establish a link between the wireless terminal and the disparate sector, and wherein establishing the link comprises:

receiving, by the disparate sector, an access request message from the wireless terminal in the allocated access resource;

transmitting, by the disparate sector, an access grant message including at least a timing correction command to the wireless terminal; and

receiving, by the disparate sector, a signal from the wireless terminal that is adjusted based on the timing correction command.

29. The apparatus of claim 28, further comprising:

means for receiving a Connection Identifier (CID) as part of the handover request;

means for identifying the distinct sector based at least in part on the CID; and

means for routing the handoff request to the disparate sector based on the CID.

30. The apparatus of claim 28, further comprising:

means for determining an identifier associated with the wireless terminal; and

means for incorporating the identifier into the handoff request routed to the disparate sector.