Patent Application
20060160533
The field of invention relates generally to wireless communication networks and, more specifically but not exclusively relates to a method and system for fast hand-over of mobile subscriber stations in broadband wireless networks.
IEEE (Institute of Electrical and Electronic Engineers) 802.16 is an emerging suite of air interface standards for combined fixed, portable and Mobile Broadband Wireless Access (MBWA). Initially conceived as a radio standard to enable cost-effective last-mile broadband connectivity to those not served by wired broadband such as cable or DSL, the specifications are evolving to target a broader market opportunity for mobile, high-speed broadband applications. The IEEE 802.16 architecture not only addresses the traditional “last mile” problem, but also supports nomadic and mobile clients on the go. The MBWA architecture is being standardized by the Worldwide Interoperability for Microwave Access (WiMAX) forum Network Working Group (NWG). For convenience, the terms 802.16 and WiMAX are used interchangeably throughout this specification to refer to the IEEE 802.16 suite of air interface standards.
Transmission of data bursts from network 100 to an SS 108 proceeds in the following manner. The data bursts such as IP packets or Ethernet frames forwarded from an appropriate RAN to an appropriate BS within a given cell. The BS encapsulates the data into IEEE 802.16-2004 data frame format, and then transmits non-line-of-sight (NLOS) data to each SS 108 using a unidirectional wireless link 110, which is referred to as a “downlink.” Transmission of data from an SS 108 to network 100 proceeds in the reverse direction. In this case, the encapsulated data is transmitted from an SS to an appropriate BS using a unidirectional wireless link referred to as an “uplink.” The data packets are then forwarded to an appropriate RAN, converted to IP Packets or Ethernet frames, and transmitted henceforth to a destination node in network 100. Data bursts can be transmitted using either Frequency-Division-Duplexing (FDD), half-duplex FDD, or Time-Division-Duplexing (TDD) schemes. In the TDD scheme, both the uplink and downlink share the same RF channel, but do not transmit simultaneously, and in the FDD scheme, the uplink and downlink operate on different RF channels, but the channels are transmitted simultaneously.
Multiple BSs are configured to form a cellular-like wireless network. A network that utilizes a shared medium requires a mechanism to efficiently share it. Within each cell, the wireless network architecture is a two-way PMP, which is a good example of a shared medium; here the medium is the space (air) through which the radio waves propagate. The downlink, from the base station (BS) to an SS, operates on a PMP basis. Provisions within the IEEE 802.16-2004 standard and IEEE 802.16e/D5a draft specification (December, 2004) include a central BS with AAS within each cell. Such an AAS includes a sectorized antenna that is capable of handling multiple independent sectors simultaneously. Under this type of configuration, the operations of base stations described below may be implemented for each of the independent sectors, such that multiple co-located base stations with multiple sector antennas sharing a common controller may be employed in the network. Within a given frequency channel and antenna sector, all stations receive the same transmission, or parts thereof.
In the other direction, the subscriber stations share the uplink to the BS on a demand basis. Depending on the class of service utilized, the SS may be issued continuing rights to transmit, or the right to transmit may be granted by the BS after receipt of a request from an SS. In addition to individually-addressed messages, messages may also be sent on multicast connections (control messages and video distribution are examples of multicast applications) as well as broadcast to all stations. Within each sector, users adhere to a transmission protocol that controls contention between users and enables the service to be tailored to the delay and bandwidth requirements of each user application.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified:
a-e are schematic representations of a Management Information (data)Base (MIB) structure employed in the management reference model of
a shows an exemplary configuration for a wireless MAN (metropolitan area network) base station (BS) provisioned service flow table corresponding to the wmanIfBsProvisionedSfTable object of
b shows an exemplary configuration for a wireless MAN BS service class table corresponding to the wmanIfBsServiceClassTable object of
c shows an exemplary configuration for a wireless MAN BS classifier rule table corresponding to the wmanIfBsClassifierRuleTable object of
d shows an exemplary configuration for a wireless MAN BS registered subscriber station table corresponding to the wmanIfBsRegisteredSsTable object of
e shows an exemplary configuration for a wireless MAN common service flow table corresponding to the wmanIfCmnCpsServiceFlowTable object of
Embodiments of a method and systems of network management and service provisioning for mobile broadband wireless networks are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
One of the more important aspects designed into 802.16-based broadband wireless networks is the ability to support mobile subscribers. Notably, this is one of the weak links with present cellular-based networks. While modern “2½ G” and “3 G” cellular services enable subscribers to receive and send data from mobile platforms, the transmission rates are relatively poor. A significant reason for this is that the underlying delivery mechanisms (the cellular networks) were originally intended for voice communication, which requires relatively low transmission rates.
The MBWA architecture being standardized by the WiMAX forum Network Working Group (NWG) is targeted to provide support for high transmission rates for mobile subscribers. At the same time, the MBWA architecture has also been designed to support the rich service capabilities such as high-speed data, streaming videos, and voice-over-IP (VoIP) services that were originally targeted for fixed subscriber stations to fulfill the “last mile” service requirements.
Another important aspect of WiMAX networks is service provisioning. To enable end-user access to a WiMAX network, the user's SS and service flows (i.e., unidirectional flow of MAC service data units on a connection with a particular quality of service (QoS)) must be provisioned. Unlike the limited QoS support provided by the more simplistic Wi-Fi (i.e., IEEE 802.11) networks commonly used to provide wireless network access in today's environments, the IEEE 802.16 architecture supports a rich set of QoS features. Furthermore, WiMAX employs a more sophisticated wireless air interface than does Wi-Fi, thus requiring more complex service provisioning considerations.
More specifically, WiMAX is based on a centralized control architecture, where the scheduler in the BS has complete control of the wireless media access among all SS's within its cell. WiMAX can simultaneously support multiple wireless connections that are characterized with a complete set of QoS parameters. Moreover, WiMAX provides the packet classifier to map these connections with various user applications and interfaces, ranging from Ethernet, TDM (Time-Division Multiplexing), ATM (Asynchronous Transfer Mode), IP (Internet Protocol), VLAN (Virtual Local Area Network), etc. However, the rich feature set and flexibility in WiMAX also increases the complexity in the service deployment and provisioning for fixed and mobile broadband wireless access networks.
Each of base stations 206 and 208 provide a respective coverage area. The “footprint” (i.e., shape) of each coverage area will general depend on the type of antenna provided (e.g., single sector, multiple sector or omni-directional) by the base station in combination with geographical and/or infrastructure considerations and the power of the radio signal. For example, although referred to as non-line-of-sight (NLOS), geographical terrain such as mountains and trees, and public infrastructure such as large buildings may affect the wireless signal propagation, resulting in a reduced coverage area. The radio signal strength for WiMAX transmissions are also limited by the available RF spectrum for licensed and/or licensed-free operations. For simplicity, the respective coverage areas 222 and 224 for base stations 206 and 208 are depicted as ovals.
A given base station is able to support communication with both MSSs and fixed SSs within its coverage area. In order to support complete mobility, the coverage area of proximate “neighbor” base stations must have some degree of overlap, as depicted by an overlap coverage area 226 in
As used herein, an MSS generally refers to an electronic system that enables two-way communication at Radio Frequencies (RFs) with base stations in a broadband wireless network. An MSS can be, for example, a IEEE 802.16e chipset inside an express card or network interface card, which plugs-in a mobile client platform, such as a notebook computer (e.g., notebook computer 230 depicted in
The Service Flow Database 210 contains the service flow and the associated QoS information that directs the BS and SS/MSS in the creation of transport connections when a service is provisioned, an SS enters the WiMAX network, or a mobile SS roams into a BS coverage area. In general, SSs/MSSs can be managed directly from an NMS, or indirectly through a BS that functions as an SNMP proxy. In one embodiment, the management information between as SS/MSS and a BS is carried over a Second Management CID (Connection Identifier) for a managed SS/MSS. If the Second Management CID does not exist, the SNMP message may go through another interface provided by the customer premise equipment.
There are three types of service flows defined by the IEEE 802.16-2004 standard, including provisioned service flows, admitted service flows, and active service flows. A provisioned service flow is a service flow that is provisioned but not immediately activated. External triggers are use to transition a provisioned service flow to an admitted service flow. This service flow is initiated when an SS enters the network through a network entry procedure, with provision commands being managed by the NMS.
Under an admitted serve flow, a network resource is reserved through admission control. External triggers are used to transition an admitted service flow to an active service flow. Events similar to “off-hook” in a telephony model are employed to activate an unsolicited grant service (UGS) service flow. Application triggers may also be employed to effect the transition to an active service flow.
An active service flow is a service flow that is active. That is, it is a service flow that is granted uplink and downlink bandwidth for data transport usage. It employs an active QoS parameter set that is a subset of the Admitted QoS parameter set.
SNMP is based on the manager/agent model consisting of a manager, an agent, a database of management information, managed objects and the network protocol. The manager executes management applications that monitors and control managed network. The agent is a management software module that resides in a managed device to execute the commands from the manager.
The manager and agent use a Management Information Base (MIB) and a relatively small set of commands to exchange information. The MIB is organized in a tree structure with individual variables, such as point status or description, being represented as leaves on the branches.
a-e show various levels of detail for a wmanIfMib (wireless MAN interface) MIB data structure 300, according to one embodiment. The MIB data structure includes multiple MIB objects nested at various levels (groups) in an object hierarchy. At the top of the hierarchy is the wmanifMib object shown in
a shows an exemplary configuration of a BS provisioned service flow table (wmanIfBsProvisionedSfTable 400), according to one embodiment of the MIB data structure 300. This table contains the pre-provisioned dynamic service flow information to be used to create connections when a user enters the network. In includes an sfIndex field 402, an SS(/MSS) MAC address field 404, a QoS Index field 406, and a Direction field 408, among other fields (not shown). (For simplicity, only “SS”-related fields are shown in
b shows an exemplary configuration for a BS service class table (wmanIfBsServiceClassTable 420), according to one embodiment of the MIB data structure 300. This table contains the QoS parameters that are associated with service flows. The illustrated fields include a QoS Index field 422, a Service Class field 424, a Traffic Priority field 426, a Maximum Sustained Data Rate field 428, a Maximum Traffic Burst field 430, a Minimum Reserved Rate field 532, a Tolerated Jitter field 434, and a Maximum Latency field 436. The QoS Index field 422 is analogous to QoS Index field 406, and stores a pointer (index) to the QoS parameter set for the corresponding dynamic service flow. The Service Class field 424 stores a service class name. In one embodiment, the level of service class names are linked to respective sets of QoS parameters, such that a particular set of commonly used QoS parameters may be identified by simply entering a corresponding service class name.
The Traffic Priority field 426 contains a value (e.g., 0, . . . , 7) that specifies the priority assigned to an active service flow. When two service flows have identical QoS parameters besides priority, the higher priority service flow should be given lower delay and higher buffering preference. The Maximum Sustained Data Rate field 428 specifies the peak data rate of the dynamic service flow in bits per second. The Maximum Traffic Burst field 430 specifies the maximum burst size that can be transported. The Minimum Reserved Rate field 432 is used to specify a rate in bits per second that specifies the minimum amount of data to be transported on the service flow when averaged over time. The Tolerated Jitter field 434 is used to specify the maximum frequency delay variation (jitter) for the service flow. The Maximum Latency field 436 specifies the maximum latency between the reception of a packet by the BS or SS on its network interface and the forwarding of the packet to its radio frequency (RF) interface.
c shows an exemplary configuration for a BS classifier rule table (wmanIfBsClassifierRuleTable 440), according to one embodiment of the MIB data structure 300. This table contains rules for the packet classifier to map downlink and uplink packets to the dynamic service flow. The table's fields include an sfIndex field 442 (analogous to sfIndex field 402), a Source IP Address field 444 in which the IP address for a source endpoint is stored, a Destination IP Address field 446, in which the IP address for a destination endpoint is stored, and a Type of Service (TOS)/Differentiated Service Code Point (DSCP) field 448, in which a TOS or DSCP parameter is stored. In the downlink direction, when a packet is received from the network, the classifier in the BS may use the MAC address or IP address to determine which SS the packet shall be forwarded to, and may use TOS or DSCP parameters to select the dynamic service flow with a suitable QoS. In the uplink direction, when a packet is received from the customer premise, the classifier in the SS may use the source/destination MAC address or IP address and port number, TOS/DSCP, Virtual Local Area Network (VLAN) ID to forward the packet to a service flow with the appropriate QoS support.
d shows an exemplary configuration of a BS registered SS table (wmanIfBsRegisteredSsTable 460), according to one embodiment of the MIB data structure 300. This table includes information corresponding to registered SSs. The illustrated fields include an ssIndex field 462, which contains an index to a subscriber station identifier, and an ifIndex field 464, which contains in interface index into an MIB instance. An SS MAC address field 466 is used to store the MAC address for a subscriber station.
e shows an exemplary configuration of a common dynamic service flow table (wmanIfCmnCpsServiceFlowTable 480), according to one embodiment of the MIB data structure 300. This table includes a service flow index (sfIndex) field 482, a service flow connection identifier (sfCid) field 484, a Direction Field 485, a QoS Index field 486, and a service flow state field 487. The remaining fields shown are analogous to like-named field in the smanIfBsServiceClassTable 420, and include a Service Class Name field 488, a Traffic Priority field 489, a Maximum Sustained Data Rate field 490, a Maximum Traffic Burst field 491, a Minimum Reserved Rate field 492, a Tolerated Jitter field 493, and a Maximum Latency field 494. These fields are populated with the same QoS parameters stored in wmanIfBsServiceClassTable 420 corresponding to their associated service class name. In addition to the illustrated fields, the smanIfCmnCpsServiceFlowTable may contain other fields that are not shown.
To facilitate the NMS task of provisioning dynamic service flow attributes for hundreds or even thousands of subscriber stations supported by each BS, the concept of Provisioned Service Classes has been devised.
In response to an MSS entering a BS coverage area, the BS downloads dynamic service flow parameters that are provisioned for the MSS from service flow database in a block 604. Details of one embodiment of these operations are shown in
The process begins in a block 700, wherein an MSS performs a scanning operation and synchronizes with BS. Generally, scanning is performed to identify base stations within the range of the MSS and select the best BS to provide service for the MSS. During scanning, an MSS scans neighboring BS to measure radio signal reception strength. In further detail, a carrier-to-interference plus noise ratio (CINR) and/or relative-signal strength indicator (RSSI) are measured to a resolution of 0.5 decibels (dB) using a pre-defined process and message exchange sequence. Prior to performing a scan, an MSS and its serving BS exchange MOB_SCN_REQ (mobile scan request) and MOB_SCN_RSP (mobile scan response) message to set up a timeframe for performing the scan. Once a BS is selected to serve the MSS, the MSS and BS perform a synchronization operation to establish uplink and downlink communication channels.
In a block 702, the MSS obtains uplink and downlink parameters from corresponding uplink channel descriptor (UDC) and downlink channel descriptor (DCD) messages. The MSS then performs initial ranging using RNG messages. Under this operation, the MSS sends a RNG_REQ ranging request message to a BS, which returns an RNG_RSP ranging response message containing current ranging information. After successful ranging, the BS obtains the MSS's MAC (Media Access Channel) address.
In a block 706, the BS uses the MSS's MAC address as a lookup parameter to download the service flow information corresponding to the MSS (entered above in block 602) from service flow database 210 (via server 212, network 214 and RAN 102) to pre-provision service for the MSS at the BS. In conjunction with the operations of block 706, the wmanIfBsProvisionedSfTable is populated with the corresponding service flow information, while corresponding QoS parameters are entered in the wmanIfBsServiceClassTable and corresponding classifier rules are entered in the wmanBsClassifierRuleTable.
After the appropriate BS MIB tables are updated with the pre-provisioned service flow data, the MSS and BS exchange subscriber basic capability (SBC) messages to negotiate basic capabilities that both the BS and MSS agree to operate, as depicted in a block 708. Next, in a block 710, the MSS and BS use public key management (PKM) messages for MSS authentication and authorization according to IEEE 802.16e/D5a draft specification (December, 2004). As depicted in a block 712, the MSS then sends a REG message to register the MSS into the BS and receives a secondary management CID. The BS then enters the MSS into its wmanIfBsRegisteredSsTable 460 using its MAC address to identify the MSS. In the present example, a MAC address 0x123ab54 is entered, as shown in the first row of wmanifBsRegisteredSsTable 460 in
A management IP connection is then established on the secondary management CID in a return block 714. In one embodiment, the management IP connection is extended to the host device for the MSS (e.g. notebook, PDA (personal digital assistant, hand-held personal computer, etc.), which runs an IP application.
Returning to a block 606 in
The process starts in a block 900, wherein the BS packs the operational parameters and dynamic service flow parameters for the MSS into a configuration file and encrypts the file. In a block 902, the BS uses the trivial file transfer protocol (TFTP) to download the configuration file to a TFTP client running on the host device for the management IP connection. The TFTP client then passes the configuration file to the WiMAX NIC for the MSS via an appropriate API (application program interface), such as Network Driver Interface Specification (NDIS). The MSS WiMAX NIC then decrypts the configuration file an updates its operating parameters in a return block 806.
Continuing at a block 608 in
As discussed above, wmanIfCmnCpsServiceFlowTable 480 contains both service flow information and QoS parameters. Depending on the network condition, the QoS parameters in wmanIfCmnCpsServiceFlowTable 480 may correspond to a lower service level than what have been pre-provisioned for a given MSS in wmanIfBsProvisionedSfTable 400. In one embodiment, the classifier rules will be created in the classifier rules table (not shown) in the BS. The dynamic service flows will then be available for the subscriber to send data traffic, as depicted by an end block 610. In response to appropriate conditions that invoke corresponding triggers, the pre-provisioned service flows will be advanced to admitted and then active service flows.
As an MSS moves throughout a network coverage area, its signal-strength will vary such that a hand-over process is warranted. More particularly, the HO process is the process under which an MSS migrates from the air-interface provided by a (currently) serving BS to the air-interface provided by a target (for future service) BS. Upon HO completion, the target BS becomes the new serving BS. Under a conventional HO process, the MSS needs to synchronize with the target BS downlink channel, obtain the uplink parameters and perform its network re-entry process, including re-authorization, re-registration, and re-establish its IP connectivity in a manner similar to that employed for new MSS entering the network according to the IEEE 802.16e/D5a draft specification (December, 2004). This conventional HO process requires a large amount of message traffic, resulting in a significant time-delay as well as significant workload levels at the BSs.
Operations and logic corresponding to one embodiment of a hand-over process are shown in
Cell selection refers to the process of an MSS scanning and/or ranging one or more BSs in order to determine suitability, along with other performance considerations, for network connection or hand-over. The MSS may incorporate information acquired from a MOB_NBR-ADV (mobile neighbor advertisement) message to give insight into the available neighboring BSs for cell selection consideration. If currently connected to a serving BS, an MSS shall schedule periodic scanning intervals or sleep-intervals to conduct cell selection for the purpose of evaluating MSS interest in hand-over to potential target BSs. This procedure does not involve termination of existing connections to a serving BS and their re-opening in a target BS. If ranging a target BS for hand-over, any newly assigned basic and primary CIDs (connection identifiers) are specific to the target BS and do not replace or supplant the basic and primary CIDs the MSS employs in its communication with its serving BS.
In view of these cell selection operations, an MSS periodically scans neighboring BS to measure radio signal reception strength. As discussed above, a CINR and/or RSSI value is measured using a pre-defined process and message exchange sequence, which is proceeded by the aforementioned MOB_SCN_REQ and MOB_SCN_RSP message exchange to set up a timeframe for performing the scan. As another option, a serving BS may initiate scanning activities by sending a NBR_ADV (Neighbor Advertisement) message to the MSS. The message informs the MSS of a number of local neighbors from which it might obtain better service. In response to the message, the MSS and serving BS exchange MOB_SCN_REQ and MOB_SCN_RSP messages and then the MSS scans the neighbor BSs identified in the MOB-NBR-ADV message. In one embodiment, the determination of block 1000 is made by an MSS in view of the foregoing scanning operations.
In one embodiment, an MSS employs a MSS Channel Measurement Table with the following structure to store channel measurement data:
In one embodiment; an BS employs a BS Channel Measurement Table with the following structure to store channel measurement data:
In one embodiment, the serving BS transfers a copy of entries for the MSS contained in its wmanIfBsProvisionedSfTable 400, wmanIfBsServiceClassTable 420, and wmanBsClassifierRuleTable 440 to the target BS prior to the handoff, using an out-of-band channel, as depicted in a block 1002. For instance, a management channel hosted by an Ethernet link or the like may be maintained between the various base stations for a broadband wireless network. Optionally, or wireless-based management channel may be employed for similar purposes. The operation of block 1002 produces a result similar to the BS service pre-provisioning operation of 604 discussed above, except in the case the service information is forwarded from a serving BS to the target BS rather than being sent from service flow database 210.
In one embodiment, the serving BS builds an MIB sub-tree export containing current MSS service data stored in appropriate tables, including wmanIfBsProvisionedSfTable 400, wmanIfBsServiceClassTable 420, and wmanBsClassifierRuleTable 440. The serving BS then sends an SNMP encapsulated message containing the MIB sub-tree export. The sub-tree is then extracted by the target BS and parsed. The wmanIfBsProvisionedSfTable 400, wmanIfBsServiceClassTable 420, and wmanBsClassifierRuleTable 440 in the local MIB instance at the target BS are then populated with the parsed sub-tree data.
In a block 1004 the serving BS informs the target BS of the dynamic service flow parameters that are currently provisioned for the MSS. The serving BS then sends an MOB_MSSHO_RSP (mobile MSS hand-over response) message to the MSS to inform the MSS that the transfer of dynamic service flow parameters to the target BS has been completed, as depicted in a block 1006.
At this point, the MSS is ready to perform the hand-over of its air interface from the serving BS to the target BS, the operations of which are generally depicted by a block 1008, while details of one embodiment of this process are shown in
The process begins in a block 1100, wherein the MSS scans and synchronizes with the target BS in a manner similar to that described above for block 700 of
In a block 1110, the target BS locates the pre-provisioned service flow information that was received above in block 1002. The MSS then sends a REG message to register the MSS into the target BS and receives a secondary management CID in a block 1112, and enters the MSS into is wmanIfBsRegisteredSsTable. The processing of
Upon return, the logic proceeds to a decision block 1010, wherein a determination is made to whether the MSS is already using the same dynamic service flow parameters as those being provisioned by the target BS—in other words, the dynamic service flow parameters for the serving and target BS are the same. In one embodiment, this is identified by using a configuration tag. Under this approach, each configuration file has an associated tag indicating the version of the set of operational parameters and dynamic service flow parameters. In one embodiment, a standard set of configuration files is defined that can be reused across multiple base stations to simply the hand-over procedure. If the answer to decision block 1010 is YES, the logic proceeds directly to a block 1014, skipping a block 1012.
If the answer to decision block 1010 is NO, there is a need to obtain new operational and/or dynamic service flow parameters or the changes from the currently used parameters. Accordingly, the target BS downloads such dynamic service flow parameters in a block 1012. Details of this process are shown in
First, in a block 1200, the target BS packs the operational parameters for the MSS into a configuration file and encrypts the file. The target BS then sends the configuration file to a TFTP client running on the host for the management IP connection in a block 1202. The TFTP client then passes the configuration file to the WiMAX NIC via an appropriate MAC API in a block 1204, whereupon the WiMAX NIC decrypts the configuration file and updates the operating parameters in the WiMAX NIC in view of corresponding dynamic service flow parameters in a return block 1206, thus returning the logic to block 1012.
Continuing at block 1014, the target BS uses DSA messages to create service flows based on service flow information obtained in block 1002 (if the parameters are the same) or 1012 (if the parameters are different) and creates corresponding entries in its smanIfCmnCpsServiceFlowTable. As depicted by an end block 1016, this completes the hand-over process, and thus the service flows for the MSS are now provided by the target BS.
There are various building blocks and components employed by digital board 1300 to facilitate its process operations. These include an optional Joint Test Action Group (JTAG) component 1304, a convergence sub-layer 1306, an IEEE P802.16-2004 MAC hardware block 1308, an IEEE P802.16-2004 physical layer transceiver 1310, a TDM component 1312, a memory controller 1314, an IEEE P802.16-2004 MAC layer 1316, an Ethernet MAC block 1318, synchronous dynamic random access memory (SDRAM) 1320, an Ethernet physical interface 1322, flash memory 1324, and a processor 1326.
Since digital board process digital signals, while IEEE P802.16-2004 transmissions comprise analog signals, means are provided for interfacing between the two signal types. Furthermore, circuitry is needed to produce RF signals having appropriate baseband characteristics. These functions are facilitated by an IF/ (intermediate frequency) Baseband transmitter (Tx) signal chip 1329, which includes a digital-to-analog converter (DAC) 1330 and an IF/Baseband receiver (Rx) signal chip 1331 that includes an analog-to-digital converter (ADC) 1332. DAC 1330 chip converts digital signals generated by IEEE P802.16-2004 physical layer transceiver 1310 into a corresponding analog signal. This signal is fed into an RF up-converter 1336 on RF board 1302, which up-converts the baseband signal frequency to the carrier frequency. The up-converted signal is then amplified via a programmable gain amplifier (PGA) 1338, which outputs an amplified up-converted signal to a transmitter antenna 1340.
Incoming IEEE P802.16-2004 transmission signals are received at a receiver antenna 1342. The received signal is then amplified (as needed) via a PGA 1343 and provided as an input to an RF down-converter 1344, which down converts the received signal to the selected IF/Baseband frequency. The down-converted signal is then converted to a digital signal via ADC chip 1332.
In general, processor 1326 is representative of various types of processor architectures, including, but not limited to general-purpose processors, network processors, and microcontrollers. In addition, processor 1326 is representative of one or more processing elements. The operations performed by the various digital board layers and components are facilitated by execution of instructions on one or more processing elements, including processor 1326. Generally, the instructions may comprise firmware, software, or a combination of the two. In one embodiment, firmware instructions are stored in flash memory 1324. In one embodiment, software instructions are stored in a storage device, such as a disk drive (not shown), that is connected to processor 1326 via a disk controller (not shown). In one embodiment, all or a portion of the software instructions may be loaded as a carrier wave over a network, which interfaces to digital board 1300 via Ethernet physical interface 1322.
Thus, embodiments of this invention may be used as or to support a firmware and/or software modules executed upon some form of processing core or otherwise implemented or realized upon or within a machine-readable medium. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium can include such as a read only memory (ROM); a random access memory (RAM); a magnetic disk storage media; an optical storage media; and a flash memory device, etc. In addition, a machine-readable medium can include propagated signals such as electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.).
In addition to the configuration depicted in
In general, the size of the MIB data stored at a base station will be much larger than the corresponding operational and dynamic service flow parameters maintained at an MSS. In general, the MIB data at the BS will comprise a small subset of the data stored in service flow database 214 (depending on the number of BSs for a given network). Typically, the SNMP agent operations may be implemented as a separate application running on an BS, or may be included as part of an 802.16 interface application used to access the network. The operational and dynamic service flow parameters may be stored in a memory store or a disk drive or the like. For larger MIB data requirements, it may be advantageous to employ a dedicated database server at a BS to serve the MIB data.
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the drawings. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
