1. Field of the Invention
This invention relates to a subscriber wireless access system or other wireless access system or the like that performs wireless communication between fixed base station equipment and fixed customer premises equipment, and particularly to a wireless communications system technology that improves the efficiency of data transmission by implementing wireless band assurance functions based on flow-rate restrictions (shaping) regarding the allocation of data traffic channels, “best effort” type communications functions based on the shared use of data traffic channels, wireless band assurance functions based on scheduling by class and the like.
2. Description of the Prior Art
In wireless access systems, wireless media are used as the media for transmitting signals subject to communication. Typically, wireless media are allocated to each unit of base station equipment (wireless base station equipment), and are shared by a plurality of units of subscriber premises equipment (wireless subscriber premises equipment) present within the service area monitored by each unit of base station equipment.
In the event that the base station equipment and backbone local area network (LAN) or customer premises equipment and customer terminal equipment are connected by an Ethernet® or IEEE 802.3 wired LAN interface, data that is exchanged via wireless media can be broadly divided into data that has a unique address for sending to each customer terminal unit and data that has an address allocated for sending to a plurality of customer terminal units.
Here, packets used for sending the former data that has a unique address for sending to each customer terminal unit are called unicast packets, while packets used for sending the latter data that has an address for sending to a plurality of customer terminal units are called broadcast packets.
In addition, in the base station equipment, in order to achieve efficient utilization of the wireless bandwidth, it is necessary to include functions for controlling the allocation of data traffic channels. For example, the greater the number of units of customer premises equipment covered within the local service area, the larger the amount of traffic (amount of data transmitted) generated is thought to become, so it is not possible to provide adequate data communication services unless a large amount of exclusive wireless bandwidth is secured. Thus, studies have been done on methods of allocating exclusive wireless bandwidth to each unit of customer premises equipment depending on the number of customer terminal units covered by each unit of customer premises equipment and thereby allocating the data traffic channels.
Here follows a description of an overview of subscriber wireless access systems that have been developed in recent years.
In recent years, subscriber wireless access systems that utilize wireless communication called Wireless Local Loop (WLL) or Fixed Wireless Access (FWA) or the like have been developed and put into practical application. In addition, with the popularity of the Internet, the need for high-speed, large-capacity communication over wireless media has heightened.
In the aforementioned subscriber wireless access systems, base station equipment (BSE) connected to a public circuit network or other backbone network is installed in a fixed location on the top of a building or tower or other high place, while a plurality of units of customer premises equipment (CPE) are also installed in a fixed location on the roof of the customer's building or other high place. The customer premises equipment also includes personal computers (PCs) or other communications terminal units and communications terminal units connected via a local area network (LAN) or the like.
Here, the base station equipment and customer premises equipment may each consist of an outdoor unit (ODU) installed in a fixed location on a building roof or tower or other high place and an indoor unit (IDU) installed in a fixed location within a building or the like, and these are connected with a cable. In addition, the outdoor unit of the base station equipment and customer premises equipment is equipped with a wireless processor that performs the processing of wireless communication using an antenna, mainly controlling the processing of wireless communication.
In addition, in the aforementioned subscriber wireless access systems, wireless communication is performed between the base station equipment and customer premises equipment by means of a time-division multiplexing communications protocol using wireless frames. It is thus possible to connect to and perform data communication among the LANs or the like connected to different customer premises equipment covered by the same base station equipment, and also connect to and perform data communication with LANs or the like connected to other customer premises equipment connected to the backbone network connected to the base station equipment.
However, when the allocation of data traffic channels is performed by a method of allocating exclusive wireless bandwidth to each unit of customer premises equipment as indicated in the aforementioned prior art example, the following problems (1)-(3) were present.
(1) For example, when the allocation of data traffic channels is performed in a fixed manner, as described below, there is a problem in that it cannot handle burst traffic. To wit, where burst traffic may occur depending on fluctuations in the usage of customer terminal units covered by customer premises equipment or the number of customer terminal units covered by customer premises equipment, even if such burst traffic occurs, the wireless bandwidth used by a specific unit of customer premises equipment is exclusive, so there is a problem in that the wireless media which are limited in allocation to base station equipment cannot be used efficiently.
(2) In addition, in the opposite case from (1) above, when wireless media are used as shared bandwidth, there is a problem in that when burst traffic is handled it is not possible to assure the wireless bandwidth for the other customer premises equipment. To wit, when a large amount of wireless bandwidth is allocated to a specific unit of customer premises equipment in response to burst traffic on the LAN, there is a problem in that the wireless bandwidth usable by each unit of customer premises equipment may fluctuate so that it is not possible to assure the minimal wireless bandwidth required for data communication.
(3) In addition, in the conventional allocation of data traffic channels, regarding the customer premises equipment covered by the same base station equipment for example, there is a problem in that a portion of the wireless bandwidth is secured for a specific unit of customer premises equipment while the remaining wireless bandwidth cannot be utilized as shared bandwidth.
The present invention is intended to solve the aforementioned problems and has as its object to provide a wireless communications system that is able to perform the allocation of data traffic channels such as to improve the efficiency of data transmission when base station equipment and a plurality of units of customer premises equipment perform wireless data communication using data traffic channels. Note that the present invention specifically provides a wireless communication system that is able to solve any one or two or more of the aforementioned problems (1) through (3).