Patent Application
20080212692
The present invention relates to communications network. More specifically, the present invention relates wireless communications network.
In recent years, the transfer of information over the wireless communications network based on the IEEE 802.16 standard has been increasing popularity for digital terrestrial television broadcasting, mobile communications and the like. The IEEE 802.16 standard includes the IEEE 802.16-2004 standard, which is mainly directed to fixed applications, and the IEEE 802.16e standard, which is typically directed to mobile applications. The IEEE 802.16-2004 standard is based on an orthogonal frequency-division multiplexing (“OFDM”) PHY (physical layer) and is directed to fixed broadband wireless applications. The IEEE 802.16e standard is based on an orthogonal frequency-division multiplex access (“OFDMA”) PHY, and is directed to mobile broadband wireless applications.
A problem of implementing with both the IEEE 802.16-2004 standard and the IEEE 802.16e standard is that there is no provision or mechanism in these standards to interoperate with each other. An IEEE 802.16-2004 standard base station typically supports the IEEE 802.16-2004 standard subscriber stations while an IEEE 802.16e standard base station generally supports the IEEE 802.16e standard subscriber stations.
Accordingly, there is a need in the art to provide a mechanism of implementing (or transmitting) information in both IEEE 802.16-2004 standard as well as the IEEE 802.16e standard.
The present invention discloses a multilingual wireless communications network that is capable of supporting multiple wireless communication standards simultaneously. In one embodiment, the communication network provides a mechanism of receiving and/or transmitting an OFDM data stream using IEEE 802.16-2004 standard and an OFDMA data stream using IEEE 802.16e standard at substantially the same time. A timing division duplexing (“TDD”) frame is configured to contain data having different standards. At least a portion of OFDM data is allocated in a portion of the TDD frame while a portion of OFDMA data is allocated in another portion of the TDD frame. The TDD frame is subsequently transmitted to both OFDM subscriber stations and OFDMA subscriber stations.
Additional features and benefits of the present invention will become apparent from the detailed description, figures and claims set forth below.
The present invention will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding only.
A method and system for providing multilingual wireless communications network are disclosed.
Those of ordinary skill in the art will realize that the following detailed description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. It will be apparent to one skilled in the art that these specific details may not be required to practice to present invention. In other instances, well-known circuits and devices are shown in block diagram form to avoid obscuring the present invention. In the following description of the embodiments, substantially the same parts are denoted by the same reference numerals.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
The present invention discloses a multilingual wireless communications system that is capable of supporting multiple air interface wireless communication standards simultaneously. In one embodiment, the communication system provides a mechanism of receiving and/or transmitting an OFDM data stream using IEEE 802.16-2004 standard and an OFDMA data stream using IEEE 802.16e standard at substantially the same time. The OFDM data indicates data formatted in OFDM using IEEE 802.16-2004 standard. The OFDMA data means data formatted in OFDMA using IEEE 802.16e. standard. The present invention includes composing a series of timing division duplexing (“TDD”) frames to contain data formatted different standards. For example, a portion of OFDM data is allocated in a portion of a TDD frame while a portion of OFDMA data is allocated in another portion of the TDD frame. The TDD frame, which includes the OFDM data and the OFDMA data, is subsequently transmitted to both OFDM subscriber stations and OFDMA subscriber stations.
Fixed subscribers stations 106 (“SS”) may be buildings, towers, and/or any other types of fixed structures whereby they are capable of distributing wireless signals from base stations 102-104 to the vicinity and/or surroundings of SS 106. The wireless signals include data, video, real-time videoconference, gaming applications, and/or voice information. In one embodiment, the SS 106 use the IEEE 802.16.2004 air interface standard to transmit and/or receive the signals. Mobile subscribers 108 (“MS”) may be cellular phones, personal digital assistants (“PDAs”), smart phones, laptop computers, et cetera, and are capable of communicating the wireless signals between base stations 102-104 and MS 108. In one embodiment, base station 104 is specifically designated to employ the IEEE 802.16e air interface standard to transmit or receive data or wireless signals to and from MS 108.
The bilingual base stations or multilingual base stations may be implemented as either a single based station or as multiple base stations. If base stations are used as bilingual base stations, one base station, such as base station 104, uses the OFDMA modulation with the IEEE 802.16e standard to communicate with various MS 108, while the other base station, such as base station 102, uses the OFDM modulation with the IEEE 802-2004 standard for communicate with various SS 106. To operate multiple bilingual or multilingual wireless communications, multilingual base stations such as base stations 102-104 need to be synchronized with each other. In one embodiment, a synchronizing device is used to generate timing pulses to sync the base stations. For example, a timing pulse may be used to indicate the start of transmitting the OFDM frame(s). The timing pulses, in one embodiment, are generated by one of the two base stations. Alternatively, the synchronizing device can be an external device (e.g., GPS receiver), which provides wireless data transmission between the base stations.
The IEEE 802.16-2004 standard defines a TDMA-based OFDM point to multipoint system, and the IEEE 802.16e standard defines the use of OFDMA in the point to multipoint system. The standards further define time division duplex (“TDD”) and frequency division duplex (“FDD”) for time or frequency allocations. The media time is organized as a sequence of equal size frames wherein each frame is further divided into a number of subframes with varying sizes. In TDD, each frame includes a downlink portion followed by an uplink portion, wherein the downlink and uplink portions share a single frequency. Each downlink subframe is configured to begin with a preamble, which identifies the start of frame. Similarly, uplink subframes also begin with a preamble. The downlink transmission contains the allocation intervals or subframes for the individual uplink transmissions (from the subscriber station) as well as downlink transmissions (to the subscriber stations). On the other hand, FDD uses one frequency for uplink transmissions and another frequency for downlink transmissions. The base station, in one embodiment, transmits downlink data and uplink data at substantially the same time. It should be noted that frame duration is generally fixed, which could be 2.5, 4, 5, 8, 10, 12.5, or 20 ms as indicated by the IEEE 802.16 standard.
OFDMA subframe 204 includes a downlink portion 230 and an uplink portion 240 wherein downlink portion 230 and uplink portion 240 can be different in length. Downlink portion 230 also includes multiple subframes including an OFDMA preamble 232, a frame control header (“FCH”) 234, and downlink bursts (1 . . . n) 236-238. Also, uplink portion 240 includes multiple pairs of preambles and bursts, such as OFDMA preambles 242-246 with uplink bursts (1 . . . n) 244-248. To implement multilingual capabilities, uplink portion 220 and downlink portion 230, in one embodiment, are swapped as indicated by a dotted line 208. It should be noted that the frame duration 206 can be 2-5, 4, 5, 8, 10, 12.5 or 20 milliseconds (“ms”).
Similarly, uplink frame 304 includes an OFDM uplink portion 330 and an OFDMA uplink portion 340 wherein OFDM uplink portion 330 includes multiple pairs of preambles and bursts such as OFDM preambles 332-336 with uplink bursts (1 . . . n) 334-338. Also, OFDMA uplink portion 340 includes multiple pairs of preambles and bursts such as OFDMA preambles 342-346 with uplink burst (1 . . . n) 344-348. It should be noted that the frame duration 306 is 10 ms.
An advantage of the present invention is to simultaneously support multiple air interface standards for wireless communications, such as the IEEE 802.16-2004 standard and the IEEE 802.16e standard. In one embodiment, a multilingual system transmits the OFDM data together with the OFDMA data in an alternative time interval. To support the multiple standards, the base station allocates a portion of time in the IEEE 802.16-2004 downlink map to the IEEE 802.16e downlink and a portion of time in the IEEE 802.16e downlink map to the IEEE 802.16-2004 downlink. Similarly, in the IEEE 802.16-2004 uplink map, the base station allocates time for the IEEE 802.16e uplink and in the IEEE 802.16e uplink map, the base station allocates time for the IEEE 802.16-2004 uplink.
All base stations, in one aspect, are configured to implement the same frame size and the same offset values, which is used to indicate a portion of a frame. As shown in
In one embodiment, the OFDM base station, such as base station 102 shown in
Since the OFDM data uses the IEEE 802.16-2004 standard and the OFDMA data uses 802.16e standard, both, in one embodiment, require continuous allocations throughout the frame. Each bilingual base station is required to load appropriate downlink maps (FCH+DL-Maps) and uplink maps (UL-Maps) to broadcast the IEEE 802.16e standard allocations to the IEEE 802.16-2004 subscriber stations as well as the IEEE 802.16-2004 standard allocations to the IEEE 802.16e subscriber stations. In this embodiment, the OFDMA of IEEE 802.16e section of the downlink subframe is identified to the OFDM of IEEE 802.16-2004 subscribers as a proprietary extended DIUC in the OFDM map. When DIUC is transmitted, the IEEE 802.16 compliant OFDM subscribers will not recognize this DIUC, and should neither transmit nor receive the DIUC during this interval. Similarly, the OFDM uplink is identified to OFDMA subscriber stations as a proprietary extended DIUC and the OFDMA uplink is identified to OFDM subscribers as a proprietary UIUC. Also, the OFDM downlink is identified to OFDMA subscribers as a proprietary UIUC.
In operation, OFDM subscribers transmit/receive information during intervals 452-454 and ignore the information during intervals 402-404. Similarly, OFDMA subscribers transmit/receive information during intervals 456-458 and ignore the information during intervals 406-408. The OFDMA proprietary DIUC is used to protect the OFDM uplink subframes while OFDMA proprietary UIUC is used to protect OFDM downlink subframes.
It should be noted that a similar implementation may be employed with FDD. In the FDD operation, the uplink and downlink frequencies are individually time-divided between OFDM and OFDMA. Again, proprietary DIUCs and UIUCs may be used to signal proprietary information to subscriber stations.
The present invention includes various processing steps, which will be described below. The steps of the present invention may be embodied in machine or computer executable instructions. The instructions can be used to cause a general purpose or special purpose system, which is programmed with the instructions to perform the steps of the present invention. Alternatively, the steps of the present invention may be performed by specific hardware components that contain hard-wired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. While embodiments of the present invention will be described with reference to wireless communications network, the method and apparatus described herein is equally applicable to other network infrastructures or other data communications environments.
At block 504, the process receives a second data stream formatted in a second AIBWS. In one embodiment, the second AIBWS is the IEEE 802.16e standard. The process then moves to the next block.
At block 506, the process composes a first duplex subframe, which contains downlink information. In one embodiment, the process also composes a second duplex subframe that contains uplink information. The first and second duplex subframes are time division duplexing subframes. In another embodiment, the first and second duplex subframes are frequency division duplexing frames. The process proceeds to the next block.
At block 508, the process allocates a first portion of first duplex subframe to a portion of first data stream with a first multiplexing modulation. In one embodiment, the process loads a portion of a first data stream, which is the OFDM data, in a portion of first duplex subframe using the IEEE 802.16-2004 standard with the OFDM modulation. In another embodiment, the process allocates a portion of second duplex subframe to a portion of OFDM data with the IEEE 802.16-2004 standard with the OFDM modulation. The process, in one aspect, allocates preambles and frame control header in the first duplex subframe. The process proceeds to the next block.
At block 510, the process allocates a second portion of first duplex subframe to a portion of second data stream, which is OFDMA data, with a second multiplexing modulation. In one embodiment, the second multiplexing modulation is the IEEE 802.16e using OFDMA modulation. The process moves to the next block.
At block 512, the process transmits the first duplex subframe to OFDM subscribers, who are capable of receiving and transmitting data with the IEEE 802.16-2004 standard and OFDMA subscribers, who are capable of receiving and transmitting data with the IEEE 802.16e standard. In one embodiment, the process also transmits a second duplex subframe to the IEEE 802.16-2004 subscribers and the IEEE 802.16e subscribers. For example, the process is capable of transmitting duplexing frames, which include the first and second duplex subframes, to a fixed subscriber station using the IEEE 802.16-2004 standard with OFDM modulation and a mobile subscriber using the IEEE 802.16e standard with OFDMA modulation at substantially the same time.
It should be noted that the present application should be applicable to any types of air interface broadband wireless standards including, not limited to, the IEEE 802.16-2004 standard or the IEEE 802.16e standard.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects. Therefore, the appended claims are intended to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention.
