Patent Publication Number: US-11026104-B2

Title: Communications when encountering aggressive communication systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/014,631, filed Jun. 21, 2018, which application is a continuation of U.S. patent application Ser. No. 14/940,850, filed Nov. 13, 2015, the disclosures of which are incorporated in their entirety by reference herein. 
    
    
     BACKGROUND 
     Communication systems exist in a variety of forms operating at numerous frequency ranges. For example, in North America, frequency ranges for Long Term Evolution (LTE) networks operate at 700, 750, 800, 850, 1900, 1700, 2100, 2500 and 2600 MHz. These frequency ranges correspond to government licensed bands of 2, 4, 7, 12, 13, 17, 25, 26, and 41, respectively. In these bands, the Federal Communications Commission (FCC), a government licensing authority, assures that communication networks do not interfere with one another. In other bands, such as the ISM (industrial, scientific and medical) bands, government licensing agencies generally allow communications systems to operate freely because interference between communication systems at these much higher frequency ranges is often limited by distance. However, some communications systems are finding themselves in relatively close proximity with one another at these frequencies, leading to a competition for radio frequency (RF) resources. Accordingly, some of these communication systems, such as WiFi, have developed protocols that ensure each system shares resources fairly. 
     Unfortunately, not all of these communication technologies share the same fairness and resource allocation policies. For example, as the government licensed the bands to LTE networks, there was no need for the technology to adopt any type of spectrum sharing policies because each network had sole use of its frequency band. Accordingly, when LTE communication systems invade other unlicensed spectrums, they tend to occupy all of the frequency resources of the spectrums and interfere with other communication systems. 
     SUMMARY 
     Systems and methods presented herein provide for improving communications when encountering aggressive communication systems. In one embodiment, a communication system includes a wireless access point (WAP) operable to link a first user equipment (UE) to a communication network via a communication protocol. The communication system also includes a communications processor operable with the WAP to detect another communication system operating within a range of the WAP, and to determine that the other communication system is operating via another communication protocol that differs from the communication protocol of the communication network based on one or more UEs in range of the WAP. The UEs are operable to communicate via both communication protocols. The communications processor is further operable to query the UEs in the range of the WAP to determine which of the UEs are communicating with the other communication system via the other communication protocol, and to estimate a rate of successful communication with the first UE via the WAP based on a number of the UEs communicating via the other communication protocol. 
     The various embodiments disclosed herein may be implemented in a variety of ways as a matter of design choice. For example, some embodiments herein are implemented in hardware whereas other embodiments may include processes that are operable to implement and/or operate the hardware. Other exemplary embodiments, including software and firmware, are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Some embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings. 
         FIG. 1  is a block diagram of an exemplary communication system operable when encountering aggressive behavior from other communication systems. 
         FIG. 2  is a flowchart illustrating an exemplary process of the communication system of  FIG. 1 . 
         FIG. 3  is a graph illustrating communication success rates when an LTE network is within range of a WiFi Network. 
         FIG. 4  is a graph illustrating a baseline collision probability when an LTE network is within range of a WiFi Network. 
         FIG. 5  is a block diagram of a WiFi communication system operable when encountering aggressive behavior from an LTE communication system. 
         FIG. 6  is a block diagram illustrating how a WiFi WAP groups UEs for contention free access. 
         FIGS. 7 and 8  are block diagrams of data frames illustrating bits for use in messaging a UE. 
         FIG. 9  is a flowchart illustrating an exemplary process of the communication system of  FIG. 5 . 
         FIG. 10  is a block diagram of an exemplary computing system in which a computer readable medium provides instructions for performing methods herein. 
     
    
    
     DETAILED DESCRIPTION OF THE FIGURES 
     The figures and the following description illustrate specific exemplary embodiments of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within the scope of the invention. Furthermore, any examples described herein are intended to aid in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the invention is not limited to the specific embodiments or examples described below. 
       FIG. 1  is a block diagram of an exemplary communication system operable when encountering aggressive behavior from other communication systems. The communication system includes a communication processor  110  that is coupled to a WAP  104  through a communication network  105 . The communication processor  110  is operable to detect aggressive behavior from the radio access network (RAN) point  102  communicating with one or more the UEs  103 - 1 - 103 -N in the vicinity of the WAP  103 . For example, the UE  103 - 1  may be communicating with the communication network  105  through the WAP  104  under one communication protocol. Other UEs  103  in the area may be communicating with the RAN point  102  via another different communication protocol. Communications from these other UEs  103  with the RAN point  102  may interfere with the communications of UEs  103  trying to communicate through the WAP  104 . The communication processor  110  is operable to detect this aggressive activity and estimate a rate of successful communication with a UE (e.g., UE  103 - 1 ) via the WAP  104  based on some of the UEs  103  (e.g., UEs  103 - 2 - 103 -N, wherein the reference number “N” is merely intended to represent an integer greater than 1 and not necessarily equal to any other “N” references herein) communicating with the RAN point  102  via the other communication protocol. 
     Examples of the UEs  103  include cellular phones, laptop computers, tablet computers, and the like. Generally, the WAP  104  operates on one protocol and the RAN point  102  operates on another different protocol. However, the communication processor  110  may also be operable to detect aggressive activity in an RF band from another communication system using the same communication protocol as the WAP  104 . In any case, the communication processor  110  is operable to detect aggressive activity by another communication system, determine the ability of the UE  103  to communicate through the WAP  104 , and circumvent the aggressive activity of the other communication system. Examples of the communication processor  110  include network elements operable with the communication network  105  (e.g., communication switches, routers, network servers, etc.). Although the communication processor  110  was discussed as being configured external to the WAP  104 , alternative embodiments include the communication processor  110  being configured with the WAP  104 . 
     Examples of the communication system include a WiFi network being interfered with by an LTE network. For example, LTE communications are increasingly moving into unlicensed RF bands where WiFi communications predominately exist (e.g., the ISM band). Accordingly, the embodiments herein may be operable to detect aggressive activity by an LTE network and work to overcome any interference by the LTE network. However, the invention is not intended to be limited to WiFi communications being interfered with by LTE communications. Rather, the embodiments herein are intended to provide an understanding of how one communication system operating under a communication protocol can work to overcome aggressive activity by another communication system operating under a different communication protocol. Other exemplary embodiments are shown and described below. 
       FIG. 2  is a flowchart illustrating an exemplary process  200  of the communication system of  FIG. 1 . In this embodiment, the WAP  104  links a first UE  103  (e.g., UE  103 - 1 ) to the communication network  105  using a first communication protocol, in the process element  201 . From there, the communication processor  110  detects another communication system operating within range of the WAP  104 , in the process element  202 . The communication processor  110  then determines whether the other communication system is operating on the same protocol as that of the WAP  104 , in the process element  203 . 
     For example, if the WAP  104  is part of a WiFi communication network using the 802.11 IEEE protocol and the RAN point  102  is operating under the same WiFi protocol, then the WAP  104  understands how to communicate with the UE  103 - 1  based on contention procedures within the 802.11 IEEE protocol so that both WiFi networks can coexist. However, if the RAN point  102  is part of an LTE network, the LTE network may attempt to acquire as much of the RF band as it needs without regard to any other systems, such as WiFi. And, since the WAP  104  would not understand how to coexist with another communication network, the LTE communications may severely degrade or even destroy any possibility of the WAP  104  communicating with the UE  103 - 1 . 
     Accordingly, if the other communication system is operating in accordance with the protocol signaling of the WAP  104 , then the WAP  104  may implement its “back off” procedures to ensure that the WAP  104  coexists with the RAN  102 , in the process element  206 . From there, the WAP  104  and the communication processor  110  may link another or the same UE  103  to the WAP  104  in the process element  201 . That is, the communication processor  110  may continually evaluate whether communications are likely to be successful for the UEs  103 . But, if the RAN  102  is operating on a different communication protocol than the WAP  104  so as to potentially interfere with the WAP  104 , then the communication processor  110  queries the UEs  103  within range of the WAP  104 , in the process element  204 . From there, the communication processor  110  estimates a successful communication with the first UE  103  (e.g., the UE  103 - 1 ), in the process element  205 , based on the number of UEs  103  communicating via the other communication protocol. 
     To illustrate, LTE-U (also known as Licensed-Assisted Access LTE, or “LAA-LTE”) is a form of LTE communications in the unlicensed band. And, this form of communications is being rapidly implemented so as to provide LTE “hotspots” for subscriber UEs  103 . Although WiFi networks have traditionally been the dominant technology utilizing the unlicensed spectrum, the advent of LTE-U will likely change the manner in which the “free” spectrum is occupied. WiFi traditionally coexists well with other WiFi networks due to the standardized, contention-based MAC (media access control) protocol that is implemented by most WiFi equipment. The DCF (distributed coordinated function) and the EDCA (enhanced distributed channel access) of the MAC ensure that when multiple WiFi networks occupy the same spectrum in the vicinity of each other each network shares the resources fairly. 
     LTE on the other hand is a different Radio Access Technology (RAT) that uses a different channel access algorithm that can aggressively occupy a channel in an RF band, potentially interfering with any neighboring WiFi access points. Using the baseline behavior of DCF/EDCA MAC, WiFi equipment can be configured to detect aggressive behavior of other users of the unlicensed band in the vicinity without any changes to the existing MAC protocol implementations at the WAP  104  and/or in the UEs  103  themselves. Once aggressive behavior is detected, the communication processor  110  can then determine how to ensure the performance of WiFi communications with the UE  103  are not adversely harmed through channel reservation of the LTE network. 
     Consider a WiFi network with one WAP and “N” number of users. The WAP of the WiFi network may detect the presence of another RAN via UEs  103  that are capable of decoding multiple radio access technologies, such as WiFi and LTE. In doing so, the WiFi network (e.g., communication processor  110  and the WAP  104 ) estimates the number of UEs  103  associated with the WiFi network and the number of UEs  103  associated with the LTE network. 
     In one embodiment, the communication processor  110  directs the UEs  103  to turn on their LTE radios to detect a number of their LTE neighbors and report back to the WAP  104 . The UEs  103  may also report the MAC addresses of their LTE neighbors back to the WAP  104 . Based on a union of MAC addresses of LTE neighbors reported by the UEs  103 , the communication processor  110  can estimate the number of LTE users within the range of its WiFi network. Once the number of users for the WiFi network and for the neighboring network(s) has been estimated, the communication processor  110  obtains the statistics of its own successful channel access (e.g., based on a rolling time window of previous channel accesses), and compares it to a baseline/threshold probability of success for communication and/or a communication probability for a particular UE  103 . 
     Generally, the baseline probability of successful channel access is a theoretical probability computed for multiple networks of the same type. For example, graph  230  of  FIG. 3  illustrates when an LTE network is present within the range of a WiFi Network. The curve  231  shows the case when two WiFi networks coexist with each other. In this embodiment, the curve  231  is used as a baseline that WiFi networks coexist fairly well with each other (e.g., by sharing resources equally). The probability of successful channel access is a function of the number of users associated with the WiFi network (e.g., WAP  104 ) and the number of users associated with another network within range of the WiFi network. 
     The baseline curve  231  can be computed for a variety of cases, including multiple networks in the vicinity of the WAP  104  and/or multiple UEs  103  in each network. The baseline  231  may be computed offline by the communication processor  110 , stored in a database, and pushed to the WAP  104  to reduce the computation burden on the WAP  104 . 
     To illustrate, an LAA-LTE network is present within the range of the WiFi Network as shown in  FIG. 3 . A data point on the curve  232  represents actual statistics collected by a WiFi network WAP. The communication processor  110  compares the collected data point to the corresponding baseline on the curve  231  for the same number of UEs  103 , and determines that the actual successful channel access rate is significantly lower than the baseline. Accordingly, the WAP  104 /communication processor  110  of a WiFi Network embodiment determines that the LAA network is behaving aggressively. 
     The graph  240  of  FIG. 4  illustrates baseline collision probability that can be used by the network WAP. For example, instead of or in addition to determining the probability of successful transmission, the WAP  104 /communication processor  110  can determine the probability of a collision when encountering aggressive activity by another network (e.g., the RAN  102 ). The baseline curve  241  illustrates how communication collisions with others can be overcome through standard communications. For example, for data points under the curve  241 , collision probability is relatively low meaning there is no need to change communication strategies. However, data points above the curve  241  mean that collisions are likely to occur and that another network is behaving aggressively. So, the WAP  104  may need to change its communication strategy, as discussed below. 
     Once the communication processor  110  determines that the other network is behaving aggressively, the communication processor  110  can identify ways to overcome the aggressive activity of the other network.  FIG. 5  is a block diagram of a WiFi communication system operable when encountering aggressive behavior from an LTE communication system. In this embodiment, the WAP  104  is a WiFi WAP and the RAN point  102  is an LTE RAN point. However, the invention is not intended to be limited simply to WiFi and LTE as other communication technologies may be used. For example, the inventive aspects herein may be used in any communication systems that do not have contention mechanisms built in when encountering different communication technologies. 
     Existing implementations of WiFi networks follow the contention-based DCF and EDCA MAC protocols when contending with other WiFi networks for RF resources. However, WiFi networks may reserve the medium for the WiFi WAP  104  to override the regular DCF/EDCA back off mechanisms. For example, in response to other aggressive users of unlicensed spectrum, the communication processor  110  may override the backoff mechanisms such that the WiFi WAP  104  remains in “LISTEN” mode if other WiFi WAPs follow the regular 802.11 back off rules. Alternatively or additionally, CSMA (Carrier sense multiple access) contention-based medium access becomes inefficient and channel utilization degrades when a large number of WiFi WAPs contend for a channel due to a high number of collisions. Accordingly, WiFi WAPs can employ a schedule-based access to the medium, which improves the channel utilization. 
     Without changing the baseline DCF/EDCA MAC protocol implementation, the communication processor  110  can enable the WiFi WAP  104  to access the medium according to a schedule and in a contention-free manner. For example, default access to the medium by WiFi WAPs will remain contention-based. When the WiFi WAP  104  perceives that contention-free access to the medium is necessary (e.g., when aggressive behavior from other users of the unlicensed spectrum is detected or when the level of contention is so high that it leads to poor channel utilization if WAPs follow the regular contention-based medium access rules), the WAP triggers the UEs  103 . 
     Consider the WiFi network  105  with one WiFi WAP  104  and “N” UEs  103  associated with the WAP  104 . The WiFi WAP  104  “knows” the identity of its associated UEs  103  through their MAC addresses. The WiFi WAP  104  determines that it needs to grant its associated UEs  103  (or some subset of them, “M”, wherein “M” is also an integer greater than 1 and not necessarily equal to any other “M” reference herein) access to the medium in a contention-free manner. This group is denoted as the “contention-free group”. The WAP  104  may perceive interference from aggressive interference sources on the “M” UEs  103 . Accordingly, the WAP  104  may perceive a high level of contention and low channel utilization as measured through the collision rate. 
     The WAP  104  may send a “trigger frame”, which is a short payload-free packet containing PHY and MAC layer headers destined to the “M” number of UEs  103  of the contention-free group one at a time as illustrated in  FIG. 6 . The WAP  104  may set one of the currently unused bits in the MAC header to indicate to all of its “N” associated UEs  103  that the UE  103  whose MAC address matches the RA (receiver address) field of the MAC header is allowed to over-ride the regular channel sensing and back off mechanism to transmit its packet immediately. In doing so, the WAP  104  may set the length field in the MAC header of the trigger frame equal to a predefined value. 
     The other “N−1” clients (i.e., whose MAC address do not match) will set their network allocation vectors (NAVs) and freeze their back off timers accordingly. Examples of the unused bits in the MPDU (media access control protocol data unit) header that can be used are in the HT capabilities field. For example, the HT capabilities of the MAC provides modulation and coding scheme (MCS) values which are supported by the WiFi WAP  104 . These data rates can be used by both the WAP  104  and a UE  103  to send unicast traffic back and forth. However, some of these bits are unused in the 802.11n HT capabilities field and can be used to indicate to the UE  103  to switch to contention free access. Alternatively or additionally, a reserved bit in the HT capabilities field of 802.11ac can be used. Examples of these are illustrated in  FIGS. 7 and 8 . 
       FIG. 7  illustrates the 802.11n HT capabilities field  350  having unused bits  351  and  352  being capable of employing the messaging used to direct the UEs  103  to employ contention free access.  FIG. 8  illustrates the 802.11ac HT capabilities field  360  with the reserved bit  361  being capable of employing the messaging used to direct the UEs  103  to employ contention free access. 
     Each of the “M” clients in the contention-free group, upon receiving the opportunity to transmit, looks at the packets in its queue and sends a frame whose length plus the ACK (acknowledgment) from the WAP  104  is less than the predefined length value. If the length of all of the available packets is more than this predefined value, then the UE  103  will send an ACK indicating to the WAP  104  that it cannot use this transmission opportunity. The WAP  104  may then provide multiple transmission opportunities for a particular UE  103  by sending multiple trigger frames with the UE  103 &#39;s MAC address in the RA field of MPDU. 
     With these above embodiments in mind, the communication processor  110  and the WAP  104  are operable to implement a process that directs the UEs  103  to operate in a contention free mode.  FIG. 9  is a flowchart illustrating an exemplary process  300  of the communication system of  FIG. 5 . In this embodiment, the WAP  104  establishes a link between a first UE  103  (UE  103 - 1 ) in a typical DCF mode, in the process element  301 . This allows the UEs  103  to contend for access to the WiFi network  105  through the WAP  104  as is normally done. 
     The WAP  104  may then query the first UE  103  (e.g., UE  103 - 1 ) to determine whether any aggressive RF band activity by another communication system is within range of the WAP  104 , in the process element  302 . For example, the UE  103  and others like it may be able to operate using WiFi and LTE communications. If an LTE communication system is operating within range of the WAP  104 , the WAP  104  may begin to experience high collision rates and/or low successful transmission rates with the UE  103 . Accordingly, the WAP  104  may direct the UE  103  to contact neighboring UEs  103  to determine how many UEs  103  are operating with the LTE communication system. 
     When a UE  103  is operating with an LTE network, the LTE RAN  102  reserves spectrum for each of its UEs. Accordingly, each of the UEs  103  communicating with the LTE RAN  102  may know its precise channel under which is communicating. In this regard, the WiFi WAP  104  can transmit a message to the UEs  103  (e.g., the one of the unused bits in the MAC headers) that directs the UEs  103  to report the frequencies which they are occupying. Then, based on the number of UEs  103  reporting back to the WAP  104 , the communication processor  110  can compare the estimated communication success rate and/or the collision rate to the baseline level as mentioned above, in the process element  303 , so as to determine whether the success rate is below a particular threshold level and/or whether the collision rate is above a particular threshold level, in the process element  304 . 
     If the communication success rate is below the threshold level, then the WAP  104  directs its client UEs  103  to switch to the contention free mode, in the process element  305 . This ensures that the UEs communicate with the WAP  104  in a contention free mode. That is, the UEs  103  are directed to operate without regard to other networks in the area, in essence becoming as aggressive as the LTE RAN  102 . Otherwise, the WAP  104  continues to query the UEs  103  within range of the WAP  104  to essentially monitor the activity of any potential LTE networks. Similarly, after the WAP  104  directs the UE  103  to switch to the contention free mode, the WAP  104  continues to monitor the aggressive activity of the LTE networks, in the process element  302 , to switch the UE to the contention based mode once the activity ceases, thereby allowing the WAP  104  to coexist with other WiFi WAPs in the vicinity. 
     Alternatively or additionally, the UEs  103 , when attempting to connect to the WAP  104 , may automatically transfer an indicator that the UEs  103  also have LTE capabilities. For example, an acknowledgment frame to the WiFi WAP  104 , a UE  103  may indicate in an unused bit of a header to show that the UE  103  has the LTE capability. The WAP  104  detects this indicator and determines if the UE  103  is communicating with the LTE network. If so, then the WAP  104  issues a new control frame to the UE  103  that directs the UE  103  to turn the CSMA capability of the UE  103  off. This new WiFi control frame may include the existing PHY and MAC header per WiFi spec as well as a one bit indicator that controls the CSMA capability of the UE  103 . 
     The invention can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In one embodiment, the invention is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc.  FIG. 6  illustrates a computing system  400  in which a computer readable medium  406  may provide instructions for performing any of the methods disclosed herein. 
     Furthermore, the invention can take the form of a computer program product accessible from the computer readable medium  406  providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, the computer readable medium  406  can be any apparatus that can tangibly store the program for use by or in connection with the instruction execution system, apparatus, or device, including the computer system  400 . 
     The medium  406  can be any tangible electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device). Examples of a computer readable medium  406  include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Some examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. 
     The computing system  400 , suitable for storing and/or executing program code, can include one or more processors  402  coupled directly or indirectly to memory  408  through a system bus  410 . The memory  408  can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code is retrieved from bulk storage during execution. Input/output (I/O) devices  404  (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. Network adapters may also be coupled to the system to enable the computing system  400  to become coupled to other data processing systems, such as through host systems interfaces  412 , or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters.