Patent Application
20070133453
A typical wireless network may include a plurality of access points (“APs”) communicating wireless signals over predefined coverage areas. A mobile unit (“MU”) may gain access to the network by communicating with an AP when the MU is located in the corresponding coverage area thereof. The network is typically configured so that the MU may be within the coverage areas of multiple APs at a single time. However, after selecting a particular AP with which to associate, the MU attempts association until successful. That is, if a first request to associate is denied, the MU may transmit further requests until one is granted.
During operation, a single AP may support wireless connections to the network for a plurality of MUs. This AP may be heavily loaded and deny requests to associate from further MUs. The further MU may be unaware of further APs in the network which are not as heavily loaded as the particular AP. Thus, the further MUs are repeatedly denied access to the network, and the further APs are underutilized.
The present invention relates to a system and method for management of a wireless environment. The system may includes a network management arrangement (“NMA”), a wireless mobile unit (“MU”) and an access point (“AP). The AP receives a request for an association from the MU and transmits the request to the NMA. The NMA determines if the request is to be granted as a function of at least one of a plurality of predetermined factors which may include a data traffic load of the AP. If the request is not granted, the NMA determines a further AP to grant the request instead of the AP and instructs the AP to transmit a response to the MU including identification data of the further AP.
The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are provided with the same reference numerals. The present invention provides a system and a method for management of a wireless environment. During operation, operating conditions of devices in the wireless environment may be evaluated to efficiently allocate resources thereof.
In one embodiment, the NMA 130 provides access to the network 140 for one or more wireless local area networks (“WLANs”) 120. As shown in
The MU 118 may be any mobile computing unit, such as, for example, a laser/image-based scanner, an RFID reader/tag, a cell phone, a laptop, a network interface card, a handheld computer, a PDA, etc. In a preferred embodiment, the MU 118 includes a wireless communications arrangement (e.g., a transceiver) allowing it to wirelessly communicate with the APs 110-114 according to a predetermined wireless communications protocol (e.g., an IEEE 802.1x protocol). In this manner, the MU 118 may transmit/receive RF signals to/from the APs 110-114, thereby allowing the MU 118 to communicate with devices connected to the network 140.
Each AP 110-116 broadcasts a beacon at a predetermined interval which may be heard by MUs within the corresponding coverage areas. A beacon header contains a source address (e.g., a Basic Service Set (“BSS”) identifier or MAC address) identifying the coverage area for the corresponding AP. Each beacon may further include a WLAN identifier (e.g., an Extended Service Set (“ESS”) identifier). Transmission of the beacons synchronizes devices on the WLAN 120. As shown in
The MU 118 may initiate a connection to the network 140 by first performing a scan, or “listening,” for the beacons. Upon receiving the beacons therefrom, the MU 118 may select a particular AP (e.g., AP 112) as a function of data contained in or computed from the beacons. For example, the data may include a Received Signal Strength Indicator (“RSSI”) value for each beacon, a number of MUs already associated with each AP, and a location of the MU 118 relative to each AP. The MU 118 may select the AP 112, because its beacon had a highest RSSI. After selecting the AP 112, the MU 118 transmits a request to associate attempting to gain access to the network 140.
In an exemplary embodiment of the present invention, the AP 112 forwards the request to the NMA 130 which performs a connection admission algorithm (e.g., a call admission control) to determine whether the request should be granted by the AP 112. The NMA 130 may evaluate a network load (e.g., number of MUs associated, type (e.g., voice/data) of MUs associated, aggregate throughput, processor utilized, memory free, etc.) of each AP 110-116 in the network 140. However, in the exemplary embodiment, the NMA 130 may exclude the AP 116 from the connection admission algorithm because a location of the MU 118 is outside of the coverage area of the AP 116
Evaluation of the network load on the AP 112 may reveal that the AP 112 is heavily loaded (e.g., an inadequate amount of bandwidth exists for the AP 112 to establish and/or maintain a reliable connection with the MU 118), or that the AP 112 may support a reliable connection for the MU 118 which will not experience congestions, dropped data packets/VoIP calls, etc. The NMA 130 may further evaluate the network load on at least one additional AP (e.g., the APs 110, 114) which is capable of communicating with the MU 118. When the AP 112 is loaded to capacity or substantially to capacity and would not provide a reliable connection for the MU 118, the NMA 130 determines an AP to grant the request to associate as a function of the network loads on the APs and/or whether the MU 118 is within the corresponding coverage areas thereof. When the AP 112 is unsuitable for any reason, the NMA 130 instructs the AP 112 to deny the request in a response message which includes an instruction to the MU 118 to choose another AP (e.g., the AP 114) when retransmitting the request.
Regarding
If the NMA 130 determines the network load on either of the APs 110, 114 is lighter than the network load of the AP 112 or that it may positively impact the MU 118 and/or the network 140, the NMA 130 selects an AP (e.g., AP 114) which may grant the request to associate when received from the MU 118. For example, the NMA 130 may determine that the AP 114 has a greater amount of bandwidth available to communicate with the MU 118. Thus, NMA 130 instructs the AP 112 to send a response message to the MU 118 denying the request. However, the response message further includes data indicating that the AP 114 may grant the request. Those of skill in the art will understand that the data may include any number of APs which may support the connection of the MU 118 as determined by the evaluation of network loads by the NMA 130.
Although the connection admission algorithm is described as being performed during association of the MU 118 and the AP 112, those of skill in the art will understand that the algorithm may be performed by the AP 112 at run-time. For example, at run-time, the NMA 130 may instruct the AP 112 to refuse the request to associate, and transmit the instruction to redirect the MU 118 to the AP 114.
In another exemplary embodiment of the present invention, the APs 110-116 may share information (e.g., the network load) with one another without use of the NMA 130. For example, if the MU 118 attempts to associate with the AP 112 and it is heavily loaded, the AP 112 may identify the network load(s) of at least one further AP within a predefined range thereof. Preferably, the predetermined range encompasses all of the further APs which may communicate with the MU 118. That is, the AP 112 checks which MUs are in a communicable range of the at least one further AP (e.g., AP 114). The AP 112 compares its network load to the other network loads and grants/denies the request. If the AP 112 denies the request, the response message to the MU 118 may include the instruction to transmit the further request to the AP (e.g., AP 114) with, for example, a lighter network load.
In step 210, the MU 118 receives the beacon(s) from the AP(s). As shown in
In step 230, the MU 118 transmits the request to associate to the AP 112. In step 240, the AP 112 receives the request and forwards it to the NMA 130. Alternatively, the AP 112 may transmit data to the NMA 130 indicating that an MU has requested association therewith and optionally including a current network load on the AP 112. As described above, the network load may include a number and type of each MU associated with the AP 112, a duration of the connection of each MU, aggregate throughput, processor utilized, memory free, etc. Alternatively, the NMA 130 may harvest the data (e.g., the network load, etc.) from the APs at a predetermined interval.
In step 250, the NMA 130 performs an evaluation procedure determining whether the AP 112 may support the connection of the MU 118, or whether another AP may provide a more reliable connection. The NMA 130 may compare the network load of the AP 112 to a predetermined threshold value or the network load(s) of at least one further AP (e.g., the AP 110, 114). The NMA 130 may further identify a number of APs which are in a communicable range of the MU 118, a number/type of connections supported by those APs, etc.
In step 260, the NMA 130 determines whether granting the request to associate would optimize efficiency of the network 140 while providing a reliable connection for the MU 118. In the determination, the NMA 130 may account for the network load at the APs, as well as the other above-mentioned factors. Additionally, the NMA 130 may account for a type of communication initiated by the MU 118. For example, when the MU 118 initiates a VoIP call, the connection provided thereto may provide a quality-of-service factor, whereas transfer of data packets (e.g., emails, web requests) need not be provided the quality-of-service.
In step 270, the NMA 130 determines that the AP 112 granting the request would optimize the efficiency of the network 140 and instructs the AP 112 to grant the request. In this instance, the AP 112 may not be substantially loaded and/or be capable of providing the quality-of-service to the MU 118.
In step 280, the NMA 130 determines which of the APs 110, 114 would provide the reliable connection for the MU 118, because the AP 112 is heavily loaded, at a full capacity and/or any other reason why allowing the MU 118 to connect to the network 140 through the AP 112 would negatively impact efficiency of the network 140. This may be the case if the AP 112 does not have the requisite bandwidth available to establish and maintain a reliable connection with the MU 118. Or, the AP 112 may sustain the connection, but the NMA 130 determines that connection with another AP (e.g., the AP 114) is a more efficient allocation of network resources. For example, the AP 114 may be underutilized supporting substantially less connections than the AP 112.
Thus, in step 290, the NMA 130 instructs the AP 112 to transmit the response message to the MU 118 denying the request to associate. However, the response message includes an instruction to transmit the further request to the AP 114. The MU 118 automatically transmits the further request to the AP 114, or may use the instruction when determining which AP to transmit the further request to. For example, in the latter instance, the MU 118 receives the beacons from the APs and measures the signal strength of each. After the MU 118 makes a preliminary selection based on the signal strength, the MU 118 may take into account the instruction regarding the advice of the NMA 130. That is, while the AP 112 exhibits the highest signal strength, the MU 118 may transmit the further request to the AP 114 for a more reliable connection to the network 140.
Those of skill in the art will understand that the additional attribute may be backward-compatible, because wireless devices which encounter an attribute type that they do not understand merely ignore the attribute. For example, an MU not utilizing the present invention may simply ignore the additional attribute and continue operation.
The present invention has been described with the reference to the above exemplary embodiments. One skilled in the art would understand that the present invention may also be successfully implemented if modified. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings, accordingly, should be regarded in an illustrative rather than restrictive sense.
