Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2001-03-05
2002-10-01
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S235000, C370S419000, C712S034000
Reexamination Certificate
active
06459687
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention relates to wireless communication systems, and more particularly to a method and apparatus for efficiently transmitting and receiving data with a communications system including a Media Access Control coprocessor.
2. Description of the Related Art
As described in the commonly assigned related U.S. Pat. No.: 6,016,311, a wireless communication system facilitates two-way communication between a plurality of subscriber radio stations or subscriber units (fixed and portable) and a fixed network infrastructure. Exemplary communication systems include mobile cellular telephone systems, personal communication systems (“PCS”), and cordless telephones. The key objective of these wireless communication systems is to provide communication channels on demand between the plurality of subscriber units and their respective base stations in order to connect a subscriber unit user with the fixed network infrastructure (usually a wire-line system). In the wireless systems having multiple access schemes a time “frame” is used as the basic information transmission unit. Each frame is sub-divided into a plurality of time slots. Some time slots are used for control purposes and some for information transfer. Subscriber units typically communicate with a selected base station using a “duplexing” scheme thus allowing for the exchange of information in both directions of connection.
Transmissions from the base station to the subscriber unit are commonly referred to as “downlink” transmissions. Transmissions from the subscriber unit to the base station are commonly referred to as “uplink” transmissions. Depending upon the design criteria of a given system, the prior art wireless communication systems have typically used either time division duplexing (“TDD”) or frequency division duplexing (“FDD”) methods to facilitate the exchange of information between the base station and the subscriber units. In a TDD system, data is transmitted and received on a single channel. A typical TDD system will allocate a portion of each data frame to transmitting data and a remaining portion to receiving data. Alternatively, a FDD system transmits and receives data simultaneously. More specifically, a typical FDD system may transmit an entire data frame on a first channel, while simultaneously receiving an entire data frame on a second channel. Both TDD and FDD systems of duplexing are well known in the art.
Recently, wideband or “broadband” wireless communications networks have been proposed for delivery of enhanced broadband services such as voice, data and video. The broadband wireless communication system facilitates two-way communication between a plurality of base stations and a plurality of fixed subscriber stations or Customer Premises Equipment (“CPE”). One exemplary broadband wireless communication system is described in the incorporated U.S. Pat. No.: 6,016,311, and is shown in the block diagram of FIG.
1
. As shown in
FIG. 1
, the exemplary broadband wireless communication system
100
includes a plurality of cells
102
. Each cell
102
contains a base station
106
and an active antenna array
108
. Each cell
102
provides wireless connectivity between the cell's base station
106
and a plurality of CPE's
110
positioned at fixed customer sites
112
throughout the coverage area of cell
102
. In addition, each of the CPE's
110
is coupled to a plurality of end user connections, which may include both residential and business customers. Consequently, the end user connections of the system have different and varying usage and bandwidth requirement needs. Each cell may service several hundred or more residential and business CPE's
110
, and each CPE
110
may service several hundred or more end user connections.
Broad-band wireless communication system
100
provides true “bandwidth-ondemand” to the plurality of CPE's
110
. The CPE's
110
request bandwidth allocations from their respective base stations
104
based upon the type and quality of services requested by the end user connections served by the CPE's
110
. Each CPE
110
may include a plurality of end user connections, each of the connections potentially using a different broadband service. Different broadband services have different bandwidth and latency requirements. The type and quality of services available to the end user connections are variable and selectable. The amount of bandwidth dedicated to a given service is determined by the information rate and the quality of service (“QoS”) required by that service (and also taking into account bandwidth availability and other system parameters). For example, T
1
-type continuous data services typically require a great deal of bandwidth having well controlled delivery latency. Until terminated, these services require constant bandwidth allocation for each frame. In contrast, certain types of data services such as Internet protocol data services (“TCP/IP”) are bursty, often idle (which at any one instant may require zero bandwidth), and are relatively insensitive to delay variations when active.
Prior art communication systems typically include a media access control (“MAC”) which allocates available bandwidth on one or more physical channels on the uplink and the downlink. Within the uplink and downlink sub-frames, the base station MAC allocates the available bandwidth between the various services depending upon the priorities and rules imposed by their quality of service (“QoS”). The MAC transports data between higher layers, such as TCP/IP, and a physical layer, such as a physical channel. According to the prior art, the MAC is software that executes on a processor in the base station. When requests for bandwidth arrive from CPE's
110
, the MAC software must allocate the frame bandwidth among all received requests. If an unexpected high volume of data (bandwidth requests, for example) is received by the MAC, there is a possibility that the software may not be able to respond in real time. If the MAC software cannot respond in real time, data will be lost. For example, MAC software may not be able to process all the incoming data in time to transmit it in the current time frame. This may result in data transfer being delayed, and possibly missed by the receiving CPE
110
. Alternatively, the data may be discarded by the MAC, possibly corrupting large quantities of data. A MAC that can respond in real-time to a high data volume is therefore desirable. In addition, a system that allows a higher data throughput than MAC software is desired.
SUMMARY OF THE INVENTION
The present invention is a novel method and apparatus for efficiently synchronizing, transmitting, and receiving data between a base station and a plurality of CPE's
110
. The method and apparatus achieve these objectives by implementing a MAC coprocessor, which works in conjunction with the MAC, in order to produce a robust, high throughput communication system.
In one embodiment of the present invention, a MAC coprocessor is coupled to the base station MAC. The MAC coprocessor may take a portion of the work load from the MAC, which is software implemented, by performing many of the tasks typically performed by prior art MAC's. These tasks may include, during a downlink, sorting data according to priority, storing a data frame of highest priority data, sorting the data frame according to modulation type, forward error correction (“FEC”) type, end user connection ID, or other criteria, appending a set of CPE settings to the data frame, and appending physical layer information (used by the modem) to the data frame. During an uplink, according to the present invention, the MAC coprocessor receives all data and routes the data either to the MAC or a network backhaul. In both the downlink and uplink processes, having a MAC coprocessor working in conjunction with the MAC may significantly increase the communication system's throughput.
In accordance with the present invention, the present inventive method transmits downlink data
Bourlas Yair
Cohen Lewis N.
Reeves Michael G.
Stanwood Kenneth L.
Ensemble Communications Inc.
Hoang Thai D
Knobbe Martens Olson & Bear LLP
LandOfFree
Method and apparatus for implementing a MAC coprocessor in a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for implementing a MAC coprocessor in a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for implementing a MAC coprocessor in a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3000272