Component

Cross-Reference To Related Application

This application makes reference to and claims the benefit of priority of the application for "An Enhanced Dynamic Bandwidth Control MAC Protocol" filed on April 19, 2013, with the Intellectual Property Office of Singapore, and there duly assigned application number 201303001-0. The content of said application filed on April 19, 2013 is incorporated herein by reference for all purposes, including an incorporation of any element or part of the description, claims or drawings not contained herein and referred to in Rule 20.5(a) of the PCT, pursuant to Rule 4.18 of the PCT.

Technical Field

Various embodiments generally relate to the field of performing an operation of a communication network, in particular, Medium Access Control protocols for dynamic bandwidth control for network operations. Background

Recently, there has been an emergence of different wireless technologies all operating within the same unlicensed spectrum bands such as within the 60 GHz, 45 GHz or other frequency bands. With different technologies deployed in the same spectrum bands, co-existence of the different technologies becomes an important issue so as to avoid interference between networks operating under different wireless technology standards. Different standards typically employ different channelization of the spectrum bands with varying centre frequencies and channel bandwidths. For example, numerous technologies have been standardized to work within the 60GHz frequency band, including the IEEE 802.11 ad, the IEEE 802.15.3c and the ECMA-387. Recently, China Wireless Personal Area Network (CWPAN) is working to define a technical specification to operate over the released 60GHz frequency band in China. IEEE 802.11 working group also approved a new task group IEEE 802.1 laj to define the specification amendment over the Chinese mmWave frequency bands. However, the released 60GHz frequency band in China, which is smaller than those in other countries, can only cover 2 channels corresponding to channels 2 and 3 used in IEEE 802.11 ad. In order to support efficient networking, there is a need to support more logic channels. Channelization with smaller channel bandwidth is considered with the provision of keeping the IEEE 802.11 ad channels for interoperability. Interoperability with IEEE 802.11 ad devices provides the attractive incentive of sharing the scarce spectrum resources between the devices of the two different technology standards which advances the proliferation of devices from both standards.

Embodiments of the present invention seek to provide for performing an operation of a communication network which addresses at least one of the above problems and/or needs.

Summary of the Invention

In accordance with a first aspect, there is provided a method of performing an operation of a communication network operating in a channel which overlaps, or resides in, a common channel spectrum band, the method comprising the operating network periodically allocating notification periods (NPs) on the common channel spectrum band in a state in which no other network is operating in another channel which overlaps, or resides in, the common channel spectrum band; and the operating network at least transmitting a notification signal in each periodically allocated NP in the common channel spectrum band.

In accordance with a second aspect, there is provided a method of performing an operation of an intended communication network, comprising the steps of a network component of the intended network scanning the common channel spectrum band for a notification signal of an operating network; the network component determining from the notification signal that the operating network is operating in a first channel that overlaps with, or resides in, the common channel spectrum band; and the network component joining the existing network as a non- PCP/non-AP station (STA).

In accordance with a third aspect, there is provided a network component of a communication network for operating in a first channel which overlaps, or reside in, a common channel spectrum band, the network component comprising an allocator for periodically allocating notification periods (NPs) on the common channel spectrum band in a state in which no other network is operating in another channel which overlaps, or resides in, the common channel spectrum band; and a transmitter for transmitting a notification signal in each periodically allocated NP in the common channel spectrum band.

In accordance with a fourth aspect, there is provided a network component of an intended communication network, the network component comprising a receiver for scanning a common channel spectrum band for a notification signal of an operating network; a determiner for determining from the notification signal that the operating network is operating in a first channel that overlaps with, or resides in, the common channel spectrum band; and wherein the network component is configured to join the existing network as a non-PCP/non-AP station (STA).

Brief Description of the Drawings

The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, various features/elements of the drawings may not be drawn to scale. On the contrary, the dimensions of the various features/elements may be arbitrarily expanded or reduced for clarity. Moreover in the drawings, common numerical references are used to represent like features/elements. Included in the drawings are the following figures:

Figure 1 (Prior Art) shows an example of beacon interval (BI) structure comprised of a beacon time interval (BTI), an association beamforming training time (A-BFT), an announcement transmission interval (ATI), and two contention-based periods (CBAPs) and two service periods (SPs) within data transfer interval (DTI).

Figure 2 (Prior Art) shows conventional dynamic bandwidth control MAC technique. Figure 3a shows an example that PCP/AP 1 operates in a small band and a station (STA) or device (which is later called PCP/AP 2 if it is successful in starting up a new network) joins the PCP/AP 1 's network in the current small band and requests to start up its network in the adjacent unoccupied small band, according to an example embodiment. Figure 3b shows an example of the MAC structure that PCP/AP 2 starts up a new network in the adjacent unoccupied small band after PCP/AP 1 accepts its request and allocates the NPs for it in the large band, according to an example embodiment. Figure 3 c shows an example that PCP/AP 1 ceases its service in a small band while only PCP/AP 2 operates in the adjacent small band, according to an example embodiment.

Figure 3d shows an example how PCP/AP 2 moves its TBTT in the large band after PCP/AP 1 ceases its service in the adjacent small band, according to an example embodiment.

Figure 4 shows AllocationType field values, according to an example embodiment.

Figure 5a and b show respective examples of mixed mode for service compatibility supported by CWPAN or IEEE 802.1 laj to IEEE 802.1 lad, according to example embodiments.

Figure 6a-y show respective possible cases of channel occupancy by CWPAN or IEEE 802.1 laj networks, according to example embodiments.

Figure 10 shows a schematic diagram illustrating a network component of an intended communication network, according to one embodiment

Detailed Description

The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, and logical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

In order that the invention may be readily understood and put into practical effect, particular embodiments will now be described by way of examples and not limitations, and with reference to the figures. The described embodiments relate to dynamic bandwidth control medium access control (MAC) protocols for resolving co-existence of networks operating in overlapping frequency spectrum bands, and providing compatibility solutions for different devices within a common access frequency spectrum band. With the knowledge of existing networks in operation, devices preferably can, depending on their capabilities, employ a multitude of mechanisms to mitigate interferences between networks such as switching operation to other frequency bands, joining the existing networks, using spatial beamforming or deferring transmission. For a device joining an existing network, the device can either join the existing network in the common band or one of the existing networks that operate in a channel band that reside or overlap the common band. This new device can be of the same network type of the existing network(s), or it can be of a different network type from that of the existing network in the band. Furthermore, avoidance of interference from other potential network(s) wanting to start up in a new channel band within a common band where there are already a multitude of existing networks operating in channel bands that overlaps or reside in the common band can preferably be provided in the described embodiments.

Throughout this disclosure, the embodiments are described using the unlicensed 60 GHz frequency bands as an example. However, it should be understood that the invention can be readily extended to other usage models, including to models with similar network operations or to any frequency bands.

In order to facilitate the description of the example embodiments, the following first describes the IEEE 802.1.1 ad MAC beacon interval (BI) and dynamic bandwidth control MAC protocols for an example usage model, as described in the IEEE P802.11ad™-2012 Standard "Part 1 1 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 3: Enhancements for Very High Throughput in the 60 GHz band," December 2012.

IEEE 802.1 l ad MAC Beacon Interval

Figure 1 shows an example of beacon interval (BI) structure 100 comprised of a BTI 102, an A-BFT 104, an ATI 106, and two CBAPs 108, 1 10 and two SPs 112, 1 14 within data transfer interval (DTI) 116 as specified for a directional multi-gigabit (DMG) system in the IEEE P802.11ad/D9.0 Standard "Part 11 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 5: Enhancements for Very High Throughput in the 60 GHz band," December 2012.

- The beacon interval in IEEE 802.11 ad MAC is mainly divided into 4 parts

^■ Beacon transmission interval (BTI) 102

^■ Association beamforming training (A-BFT) 104

^■ Announcement transmission interval (ATI) 106

^■ Data transfer interval (DTI) 116.

The following lists some usage aspects of the respective parts:

- Beacon transmission interval (BTI) 102

Personal basic service set central point (PCP)/ Access point (AP) transmits one or more DMG Beacon frames via different sectors quasi-omni-ly.

DMG Beacon frame carries network management information.

DMG Beacon frame supports network synchronization function.

• DMG Beacon frame is used to as training frame for beamforming between PCP/AP and non-PCP/non-AP stations (ST As).

To join the network, a ST A scans for a beacon, continues with the beam forming process with the PCP/AP in the A-BFT and then associates with the PCP/AP during the AT or CBAP.

- Association beamforming training (A-BFT) (104)

• To perform the initial beamforming training between PCP/AP and non-PCP/non- AP ST As.

It is slotted and allows for multiple non-PCP/non-AP STAs to perform beamforming with PCP/AP concurrently in the same A-BFT.

- Announcement transmission interval (ATI) (106)

• To perform request-response based management access between PCP/AP and non-PCP/non-AP STAs.

• PCP/AP schedules contention-based access period (CBAP) and service period (SP) allocations in the data transfer interval (DTI).

- Data transfer interval (DTI) 116 ^■ Any frame can take place during a CBP and a SP, including application data frame transmission.

^■ Access during CBPs is based on a modified IEEE 802.1 1 EDCA operation that is fine-tuned for directional communications.

■ Access during SPs is scheduled and assigned to specific stations.

Dynamic Bandwidth Control MAC Protocols

The assumption of the occupancy of the channels is based on a first-come- first-serve basis. If a network is operating in a channel, a device from another type of network cannot start its operation in the channel. A mechanism to enable this function is assumed. The network device is also assumed to be able to detect the beacons of an existing network of its own type as well as the beacons of an existing network of another type. Furthermore, it is assumed that at least one type of network device can operate in both a large band (the common channel spectrum band) as well as a smaller band, which reside within the common channel spectrum band, while at least one other type of network device can operate only in the large band as specified in published international patent application WO2012121676 Al and published international patent application WO2012121672 Al. In addition, the network device of the first type can operate in its own type of network as well as in the latter type of network.

When a new network device wants an existing network to be split to a smaller channel from a large channel, it will first join the existing network. This device then sends a command frame to the personal basic service set central point/access point (PCP/AP) of the existing network to request for the channel splitting. A request data frame is used to do channel splitting. If the existing network decides to split its large channel to a smaller channel, it informs all of its devices in the network, including the requesting device, through its beacon time to change its operating channel to a smaller operating channel. A channel switch announcement information element (IE) can be used in the beacon to announce the switching to the new smaller channel. A response data frame can also be sent to the requesting device who wants to start a new network. Then, the existing network suspends its operation in the larger channel after a period of time. Then, the existing network continues its operation as a new network and does the necessary procedures in a new smaller channel when the designated time has arrived. For example, beamforming, association, new schedules for service periods (SPs) and contention-based periods (CBAPs), etc. The requesting device who wants to start up another new network waits for the designated time under the proposed MAC protocols in published international patent application WO2012121676 Al before starting its network operation in its small band. The requesting device needs to listen to the channel switch announcement IE in the beacon of the existing network. The requesting device will start up its operation as a new PCP/AP of the new network in the smaller band. Additionally, both the existing PCP/AP and the new PCP/AP must periodically send the notification signals, e.g., DMG Beacon f ames as described in published international patent application WO2012121676 Al , in the existing large band during the notification periods (NPs). Other devices who want to join this new network in the other smaller channel can do so through standard beamforming and association procedures.

A PCP/AP of a network operating in a smaller channel periodically does channel detection on its adjacent smaller channel which could potentially be used to form a larger channel to improve performance if its network in the adjacent smaller band ceases operation. If a vacant adjacent smaller channel is detected, the PCP/AP can decide if it wants to expand its smaller channel to a larger channel. If the existing network decides to expand its smaller channel to a larger channel, it informs all of its devices in the network through its beacon time to change its operating channel to a larger operating channel. The channel switch announcement information element (IE) can be used in the beacon to announce the channel switching to the new larger channel. Then, the existing network suspends its operation after a period of time. Then, the existing network continues its operation as a new network and does the necessary procedures in the new larger channel, for example, beamforming, association, new schedules for service periods (SPs) and contention-based periods (CBAPs), etc. Co-existence In the context of the above described usage model, example embodiments of the present invention can advantageously ensure the co-existence of different networks while limiting the potential interference between different types of networks through mandating:

1) Negotiations among designated devices of CWPAN or IEEE 802.1 laj networks operating in channel bands overlapping or residing in the common channel band to schedule notification periods of DMG beacon frame transmissions in the common channel band

2) Use of DMG beacon frame transmissions in the common channel band to inform new CWPAN or IEEE 802.1 laj device who wants to start a new network in other channel bands overlapping or residing in the common channel band of the presence of the network.

3) Use of DMG beacon frame transmissions in the common channel band to inform potential new IEEE 802.11 ad device who wants to start a new IEEE 802.1 1 ad network in the common channel band of the occupancy of the common channel band by an existing network.

The details of the co-existence solution in an example embodiment are described below.

Using an example of the band plan 200 described in published international patent application WO2012121672 Al, shown in Figure 2, a CWPAN or IEEE 802.1 1 aj device (termed the upcoming device) is able to operate in large band LI or L2 and is also able to operate in small bands S3, S4, S5 or S6. An IEEE 802.1 lad device (termed the legacy device) can only operate in the large band LI or L2. In such a case, the large band LI or L2 will be the large common channel spectrum band to send the notification signals which in this case is the DMG Beacon frames.

In published international patent application WO2012121676 Al, the co-existence solution is achieved by following the protocols below: · When a CWPAN or IEEE 802.1 laj network is operating in a large band with the designated device PCP/AP 1, the designated device PCP/AP 2 of any other network can easily detect the presence of the existing CWPAN or IEEE 802.1 l aj network by listening to the DMG Beacon frames transmitted in the large band by PCP/AP 1.

· If another CWPAN or IEEE 802.11 aj network with the designated device PCP/AP

2 wants to start another network by splitting the large band into two smaller bands, then PCP/AP 2 will join the existing PCP/AP l 's networks in the large band and then request for the channel split. After a successful channel split procedure, PCPs/APs 1 and 2 will operate in the small band S5 and S6, respectively, and also send their notification signals, e.g., DMG Beacon frames, during NPs 1 and 2, respectively. • When one of the two CWPAN or IEEE 802.1 laj networks ceases its service in either the small band S5 or S6, the other one will expand its bandwidth from its small band to the large band after a successful channel merge procedure.

Thus, in published international patent application WO2012121676 Al, there are only two states of operations. Either the large band is occupied by a single network or two networks will occupy the two small bands that constitute the large band.

In the example embodiment, the MAC protocols are extended to other foreseeable operating scenarios, where CWPAN, IEEE 802.1 laj and IEEE 802.11 ad devices are deployed, with support for interoperability.

In a first scenario, only one CWPAN or IEEE 802.1 laj device starts its network and operates in the small band S5 (or S6) with the designated device PCP/AP 1, leaving the other band S6 (or S5) vacant.

In a second scenario, it is assumed that two CWPAN or IEEE 802.1 laj networks with the designated device PCPs/APs 1 and 2 operate in the small bands S5 and S6 after the channel split. Later, PCP/AP 2 (or PCP/AP 1) ceases its services in the small band S6 (or S5). However, PCP/AP 1 (or PCP/AP 2) continues to operate in the small band S5 (or S6) without channel merge, in contrast to the scenario in published international patent application WO2012121676 Al .

Three possible states of operations will be considered: i) The large band, LI , is occupied by a single network.

ii) The two small bands S5 and S6 are occupied by two different networks.

iii) Either S5 or S6 is occupied by one network with the other being unoccupied.

For iii), PCP/AP 1 can operate in the small band S5 (or S6) with the MAC protocols as described in published international patent application WO2012121676 Al , while the other small band S6 (or S5) is now available for establishing another new network as illustrated in Figure 3 a. In addition, to mitigate the interference with other networks including legacy networks, PCP/AP 1 in an example embodiment periodically sends the notification signals during NPs in the large band LI (see NP 1 in Figure 3a), e.g., DMG Beacon frames, to allow both types of devices to recognize the notification signals. In Figure 3a-d and in Figure 5, NPs that are allocated in the large bands are illustrated as slots extending across the small bands, e.g. NP 1 extends across S5 and S6 in Figure 3a, i.e. is allocated in the large band LI (compare Figure 2).

Either a notification signal as described in published international patent application WO2012121676 Al can be transmitted in an NP in the large band, which basically consists only of the BTI 300 shown in Figure 3a, or an NP in the large band can contain a beacon header interval (BHI) which may include the BTI 300, A-BFT 302, or ATI 304 as defined in the IEEE P802.1 lad™-2012 Standard "Part 1 1 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 3: Enhancements for Very High Throughput in the 60 GHz band," December 2012. In an example embodiment, the first type of NP is denoted as type A NP and the second type of NP as type B NP hereinafter. At least one type B NP is allocated in the example embodiment for every consecutive number, NM _CX _A, of type A NP allocations, where NMO _X _A is determined by the maximum number of Bis after which a A-BFT or ATI is expected as specified in the IEEE P802.1 lad™-2012 Standard "Part 11 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 3: Enhancements for Very High Throughput in the 60 GHz band," December 2012. It is noted that the minimum duration of the BHI is indicated in the example embodiments by a dotl 1 MinBHIDuration parameter which is specified in microseconds.

A first protocol according to an example embodiment, Protocol 1, may be described as: Protocol 1: A network operating in a channel band overlapping, or residing in, a common channel band periodically allocates notification periods (NP) which contain at least a transmission of notification signals in the common spectrum band.

Establishment of a new network

For the i) state of operation described above, the MAC protocols to establish a new network have been described in published international patent application WO2012121676 Al . For the ii) state of operation described above, no new network can be established unless one of the existing networks ceases it operations in either of the small bands. For the iii) state of operation described above, if another new network with the designated device PCP/AP 2 intends to start its network in the vacant adjacent small band S6 as shown in Figure 3a, the devices will follow the detailed procedures designated as Protocol 2 in an example embodiment described below.

Protocol 2:

First, the PCP/AP 2 shall scan in the large band LI before the network initialization. Thus, it can hear the notification signals, e.g., DMG Beacon frames transmitting in the BTI of PCP/AP 1 within the large band LI and can obtain the information that PCP/AP 1 is currently operating in the small band S5 accordingly. Moreover, the PCP/AP 2 may obtain the information that the other small band S6 is now available for occupancy which can be indicated by a channel occupancy element transmitted in the DMG Beacon frames as mentioned above. Note that if such an information element (IE) is not transmitted, the PCP/AP 2 in the example embodiment further scans in the small band S 5 and S6 to know the small band occupancy status. Preferably, PCP/AP 2 need only scan each small band S5, S6 for the duration between two NPs to know the occupancy status. The scanning of the two bands S5, S6 can adyantageously be done concurrently or successively depending on the capability of PCP/AP 2.

Second, if the small band S6 is available, PCP/AP 2 will join the existing PCP/AP l 's network either in the large band Ll or in the small band S5 as a station (or called non- PCP/non-AP, (ST A)) through a bootstrapping procedure.

Third, PCP/AP 2 will send the Request frame to PCP/AP 1 during the ATI or during a scheduled SP or CBAP of DTI within the band where it joins. The Request frame contains the request that PCP/AP 2 intends to start its network in the adjacent small band S6 and other information such as the required length of NP duration, etc. If considering the hidden terminal problem as described in published international patent application WO2012121676 Al, the PCP/AP 1 may reject the PCP/AP 2's request when another new network that has been successfully established or granted to start up in the small band S6. If the PCP/AP 1 grants the request, it shall notify PCP/AP 2 through a Grant frame, DMG Beacon frames or Announce frames. Considering both the hidden terminal problem and the interference mitigation, PCP/AP 1 as well as PCP/AP 2 in the example embodiment periodically send the notification signals during their NPs in the large band LI . Therefore, as shown in Figure 3b, the PCP/AP 1 allocates an SP for the NP of PCP/AP 2, NP 2, within the large band LI through an Extended Schedule Element contained in the DMG Beacon frames or Announce frames that are transmitted within the band LI or S5 in which the PCP/AP 2 joined before. It is noted that in the example embodiment the allocations of NPs (here NP 1 and NP 2) within the large band LI are persistently reserved by both PCPs/APs 1 and 2 unless their networks cease the services later.

The NPs in one cycle allocated for PCPs/APs 1 and 2 are preferably arranged consecutively without interspaces; in which case they will have the same cycle time. Furthermore, without moving the target beacon transmission time (TBTT) of PCP/AP 1 in the small band S5, the NP of PCP/AP 2, e.g., NP 2 is preferably arranged prior to the NP of PCP/AP 1 , e.g., NP 1, which is illustrated in Fig. 3(b). This arrangement advantageously allows PCP/AP 1 and PCP/AP 2 to minimize the bandwidth switch cost between small bands and large band. In the example embodiment, each PCP/AP preferably needs to only switch from its own small band to the large band (i.e. _v the common spectrum band) once to transmit its DMG Beacon frames and subsequently receive the DMG Beacon frame from the other PCP/AP during NP 1 and NP 2 in the large band, shown respectively as 306, 308 and then switch back to its small band in every cycle. It is noted that the switching time between the large band and small band and vice versa depend on the implementation of the RF circuit, with a typical duration of around hundreds of micro-seconds. The NP duration preferably includes the switching time.

Moreover, to advantageously minimize or even eliminate inter-band interference, the synchronization of NPs is maintained in the example embodiment. To counter the time drift due to clock offset between the two PCP/APs, PCP/APs are preferably synchronized periodically during each cycle. This can for example be fulfilled by time synchronization function (TSF) defined in IEEE 802.1 1 with PCP/AP 2 receiving the frame from PCP/AP 1 during PCP/AP 1 's NP, i.e. NP 1 308 in the large band as shown in Figure 3b.

The periodicity of NPs in the example embodiment is determined by both the minimum synchronization period required by PCP/APs operating in the small bands and maximum channel scan time required by PCP/APs operating in the large band. For example, in IEEE 802.1 1 ad, the minimum channel scan time is set equal to the maximum BI duration, i.e., aMinChannelScan = aMaxBIDuration = 1000 time units (TUs). Thus, the cycle time of NP in an example embodiment is not set larger than 1000 TUs. The actual cycle time of NP is preferably determined by PCP/AP 1 before the first NP with the constraints stated above.

Cessation of an existing network

For the i) & iii) state of operation described above, no MAC protocol is required for cessation of an existing network. For the ii) state of operation described above, when one of the networks eventually ceases its network operation, the absence of that PCP/AP's operation in the small band is noted by the other PCP/AP operating in its adjacent small band by it failing to detect any notification signals during NPs in the large band from the other PCP/AP. To guard against the possibility of dropped frames, a PCP/AP in an example embodiment preferably waits for a MaxExpireDuration duration, which is an integer multiple of Bis, starting from when the last frame from the other PCP/AP is received, before making the decision that the other adjacent PCP/AP's network has ceased its network operation.

After the decision that the other adjacent PCP/AP's network has ceased its network operation is made, the remaining PCP/AP can have two options: 1) Expand its bandwidth from the small band to the large band, which has been described in published international patent application WO2012121676 Al . 2) Proceed to operate in the small band S5 without channel merge in an example embodiment, following the MAC protocol designated as Protocol 3 specified below,

Protocol 3: If the PCP/AP 2 is absent from the small band S6, the PCP/AP 1 proceeds its services in the small band S5 but will no longer reserve the SP allocations, i.e., NP 2, in the large band LI for the PCP/AP 2's NPs in the following medium time, which reverts back to operation shown in Figure 3 a.

On the other hand, as illustrated in Figure 3 c, if the PCP/AP 1 is absent from the small band S5, the previous NP 1 will now be vacant. In this case, PCP/AP 2 may extend its NP to cover the whole duration of the previous NP 1 and 2 or schedule the allocations in the small band S6 within this now vacant period (indicated at numeral 310 in Figure 3c). Alternatively, to reduce the channel switch times and improve the channel utilization efficiency, the PCP/AP 2 may select to move its target beacon transmission time (TBTT) for NP 2 within the large band LI prior to the starting of the TBTT for the BHI 312 within the small band S6, as shown in Figure 3d such that NP2 is followed by BHI 312 consecutively without any interspaces in this embodiment.

Interoperability and Backward Compatibility Modes to IEEE 802.11 ad

The example embodiments described above also preferably aim to support the interoperability between different types of network device, which in the context of the example usage model of 60 GHz operation, can also be interpreted as providing backward compatibility with service supports to the legacy network, e.g., CWPAN or IEEE 802.1 1 aj networks providing backward compatibility to IEEE 802.1 lad networks. According to the IEEE 802.11 ad channelization mechanism, the IEEE 802.11 ad devices operate in the large bands only. Therefore, an IEEE 802.1 lad device can start a new network as a PCP/AP or join an existing network as a non-PCP/non-AP STA in a large band. However, the CWPAN or IEEE 802.1 laj devices can operate either in large bands or in small bands, thus they have the ability to start the new networks either in large bands or in small bands.

The IEEE 802.11 ad networks do not support any interoperability to CWPAN or IEEE 802.1 laj networks. Based on first-come first-serve principle, if an IEEE 802.1 1 ad network occupied the large band first, a late coming CWPAN or IEEE 802.11 aj device can only join the IEEE 802.11 ad network as a non-PCP/non-AP STA, become a member PCP/AP when the clustering mechanism is supported by the existing IEEE 802.11 ad network, or search for another available channel to start its network. For all intents and purposes, the new devices act as the legacy devices in this case. Conversely, if a CWPAN or IEEE 802.1 1 aj network occupied a large band first, there are two modes that CWPAN or IEEE 802.1 laj networks can use to provide the backward compatibility an IEEE 802.11 ad device entering the service area, according to example embodiments. Legacy Mode

In the legacy mode, CWPAN or IEEE 802.1 laj networks provide the backward compatibility for legacy devices by operating only in the large band. Thus, the late coming IEEE 802.1 lad device will decided to join the CWPAN or IEEE 802.1 laj network as a non-PCP/non-AP STA, become a member PCP/AP when the clustering mechanism is supported by the existing CWPAN or IEEE 802.1 laj network, or search for another available channel to start its network, by using existing MAC protocols as detailed in the IEEE P802.1 lad™ -2012 Standard "Part 11 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 3: Enhancements for Very High Throughput in the 60 GHz band," December 2012. For all intents and purposes, the CWPAN or IEEE 802.1 laj networks behave as would a legacy networks in this mode.

Mixed Mode The mixed mode supports the backward compatibility for IEEE 802.11 ad devices when CWPAN or IEEE 802.1 laj networks are operating in small bands. It provides the interoperability between CWPAN or IEEE 802.1 laj devices generally operating in the small band and IEEE 802.1 1 ad devices only operating in the large band. The designed MAC protocol according to an example embodiment is detailed as below.

In a first scenario, only one network is in operation in either S5 or S6, and in a second scenario, two networks are in operation in S5 and S6 respectively.

For the first case, without the loss of generality, it is assumed that the only network operates in the small band S5 with the designate device PCP/AP 1 and the other small band S6 is unoccupied, which is shown in Figure 5a. According to the co-existence Protocol 1 described above, PCP/AP 1 not only starts TBTTs in the small band S5, but also sends the notification signals such as DMG Beacon frames during NPs, e.g. NP 1, in the large band LI . The protocols for the legacy device to join and function in the CWPAN or IEEE 802.1 laj network in an example embodiment is designated as Protocol 4 and is described below. Protocol 4: Once a legacy device, e.g., IEEE 802.1 lad device, arrives, it will hear the DMG Beacon frames transmitting during NP 1 within the large band LI and join the PCP/AP l 's network as a non-PCP/non-AP station (STA) through a bootstrapping procedure. Next, this non-PCP/non-AP STA can request for channel time allocation from PCP/AP 1. Since the small band S6 is unoccupied, PCP/AP 1 will allocate SPs or CBAPs 500 to the IEEE 802.11 ad device in the large band following the medium access rules in the IEEE P802.11ad™-2012 Standard "Part 11 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 3: Enhancements for Very High Throughput in the 60 GHz band," December 2012 and notify the scheduling results to the IEEE 802.11 ad device through DMG Beacon frames or Announce frames.

To distinguish the different channel bandwidths, the Bit 5 of the AllocationType field is used to indicate whether an allocation is within the large band or the small band. The possible values are listed in Figure 4, which supports the backward compatibility to IEEE 802.1 lad devices in the example embodiment.

When the scheduled medium time comes, a CWPAN, IEEE 802.1 laj or an IEEE 802.11 ad device that is identified as a source or destination may transmit frames during this period. Particularly, if a CWPAN or IEEE 802.1 l aj non-PCP/non-AP ST As operating in the small band S5 intends to communicate with a CWPAN, IEEE 802.1 laj or IEEE 802.11 ad device operating in the large band LI , it switches its frequency from the small band S5 to the large band LI, after which it switches back and continues to operate in the small band S5.

For the second case, two CWPAN or IEEE 802.1 laj networks have been established in the small band S5 and S6 with the designated devices PCP/AP 1 and PCP/AP2, respectively. The protocols for the legacy device to join and function in the CWPAN or IEEE 802.1 laj networks in an example embodiment is designated as Protocol 5 and is described below.

Protocol 5: When an IEEE 802.1 lad device (named as STA A) arrives and intends to join as a non-PCP/non-AP STA, it will first scan in the large band LI . Considering the hidden terminal problem, STA A may receive the DMG Beacon frames transmitted by either the PCP/AP 1 or PCP/AP 2 or both. Without loss of generality, it is supposed that STA A received the DMG Beacon frames from PCP/AP 1 and intends to join in PCP/AP l 's network.

Since PCPs/APs 1 and 2 are independently operating in their own small bands, the SP or CBAP allocations for STA A preferably abide by the following two constraints:

i) PCP/AP 1 cannot allocate an overlapping duration with the existing allocations, such as the BHIs, SPs or CBAPs either in the large band or in the small bands. ii) PCP/AP 2 should know the updated scheduling information for STA A from PCP/AP 1 and then reserve the same medium time in its following Extended Schedule Element.

With reference to Figure 5b, to satisfy the above constraints, PCP/AP 1 preferably hears the latest DMG Beacon frames or Announce frames of the PCP/AP 2 either in the NP 2 502 in the large band LI or in the BHI 504 in the small band S6 to update its local scheduling information. Alternatively, PCP/AP 1 may directly request for the latest scheduling information from PCP/AP 2 and receive its reply with an Announce frame containing the Extended Schedule Elements during the NP 1. Then, PCP/AP 1 can schedule an allocation for STA A based on the scheduling information of both PCP/AP 1 and 2. After that, PCP/AP 1 will notify the new scheduling results to PCP/AP 2 through an Allocation Request frame, and then PCP/AP 2 may reply with an Allocation Grant frame to grant this schedule or not. If granted or without hearing the reply, PCP/AP 1 sends the schedule results for the SP or CBAP allocations 506 to STA A through Extended Scheduling Element transmitted in DMG Beacon frames or Announce frame within the large band LT . The allocations in the small bands S5 and S6 in the example embodiment also preferably do not overlap with the existing allocations in the large band LI once it is finalized. An example of the medium access allocation is shown in Figure 5b.

If STA A chooses to join PCP/AP 2's network in another example embodiment, the roles of PCP/AP1 and PCP/AP 2 will be switched in the procedures described above, as will be appreciated by a person skilled in the art.

In the following, an overview of practical example operating scenarios based on the protocols in the example embodiment described above is provided to illustrate the ability to ensure the co-existence of networks and to provide the backward capability to legacy devices. In Figure 6, the possible channel occupancy states are listed. For each state, it will be explained how the proposed protocols according to the described embodiment together with existing protocols can ensure the co-existence of networks if a device attempts to start a new network and can ensure backward compatibility by providing interoperability support. It is note that for the purpose of this description, the cases when the channel bands are occupied by CWPAN or IEEE 802.11 aj networks are considered, as the legacy IEEE 802.1 lad networks do not provide the compatibility or co-existence guarantee to the newer CWPAN or IEEE 802.11 aj networks, as will be appreciated by a person skilled in the art.

New network formation

Figure 6a shows the state that both the large bands LI and L2 are vacant and available for new network formation. In this case, an IEEE 802.1 lad device can follow existing protocols to start a new network and a CWPAN or IEEE 802.1 1 aj device can follow the existing protocol to start a new network in LI or L2, or follow the proposed protocols to start a new network in the small band S3, S4, S5 or S6 and follow the example embodiment, Protocol 1, to mitigate the interference with other networks. Figures 6b and c show respective states in which only one large band is occupied by a CWPAN or IEEE 802.1 laj network while the other(s) are available for occupancy. A new IEEE 802.11 ad device can establish a new network within the unoccupied channel using existing protocols. A CWPAN or IEEE 802.1 l aj device can follow the existing protocol to start a new network in the unoccupied large band channel, or follow the protocols to split the occupied large band channel into two smaller band channels, or follow the protocols to start a new network in the two unoccupied small band channels and follows the example embodiment, Protocol 1, to mitigate the interference with other networks.

Figure 6d shows the state that both the large bands LI and L2 are occupied by CWPAN or IEEE 802.1 laj networks. An IEEE 802.1 1 ad device will be duly notified that all available channels are occupied and no new network can be formed except through becoming a member PCP/AP of the cluster either in the large band LI or in the large band L2 through existing protocols. A CWPAN or IEEE 802.1 laj device on the other hand, can follow an existing protocol to split either of the occupied large band channels into two smaller band channels. .

Figure 6e-h show respective states in which only one small band is occupied by CWPAN or IEEE 802.1 laj while others are available for occupancy. An IEEE 802.11 ad device can establish a new network within the unoccupied large band using existing protocols. A CWPAN or IEEE 802.1 laj device can follow an existing protocol to start a new network in the unoccupied large band channel, or follow the example embodiment, Protocol 2, to start a new network in the unoccupied small band channel adjacent to the occupied small band, or follow the protocols to start a new network in the other two unoccupied small band channels and follow the example embodiment, Protocol 1, to mitigate the interference with the other network.

Figure 6i-l show respective states in which one large band and one small band are occupied by CWPAN or IEEE 802.1 laj networks while only one small band is available for occupancy. If an IEEE 802.1 1 ad device arrives, it will be duly notified that all available channels are occupied and no new network can be formed except through becoming a member PCP/AP of the cluster either in the large band LI or in the large band L2 through existing protocols. A CWPAN or IEEE 802.1 laj device on the other hand, can follow the existing protocols to split the occupied large band channels into two smaller band channels, or follow the example embodiment, Protocol 2, to start a new network in the unoccupied small band channel adjacent to the occupied small band.

Figure 6m and n show respective states in which any two small bands within the same large band are occupied by two different CWPAN or IEEE 802.11 aj networks while the other large band is available for occupancy. If an IEEE 802. Had device comes An IEEE 802. Had devices can establish a new network within the unoccupied large band using existing protocols. A CWPAN or IEEE 802.1 laj device can follow the existing protocol to start a new network in the unoccupied large band channel, or follow the protocols to start a new network in the other two unoccupied small band channels and follows Protocol 1 to mitigate the interference with other.

Figure 6o-r show respective states in which any two small bands within the different large bands are occupied by two different CWPAN or IEEE 802.11 aj networks while the other two small bands are available for occupancy. If an IEEE 802.11 ad device arrives, it will be duly notified that all available channels are occupied and no new network can be formed. A CWPAN or IEEE 802.1 laj device on the other hand, can follow the example embodiment, Protocol 2, to start a new network in either of the unoccupied small band channel adjacent to an occupied small band.

Figure 6s and t show respective states in which one large band and the other two small bands are occupied by three different CWPAN or IEEE 802.1 laj networks. If an IEEE 802.1 lad device arrives, it will be duly notified that all available channels are occupied and no new network can be formed except through becoming a member PCP/AP of the cluster either in the occupied large band through existing protocols. A CWPAN or IEEE 802.1 laj device on the other hand, can follow an existing protocol to split the occupied large band channels into two smaller band channels. Figure 6u-x show respective states in which any three small bands are occupied by three different CWPAN or IEEE 802.1 laj networks while only one small band is available for occupancy. If an IEEE 802.1 lad device comes, it will be duly notified that all available channels are occupied and no new network can be formed. A CWPAN or IEEE 802.1 laj device on the other hand, can follow the example embodiment, Protocol 2, to start a new network in the unoccupied small band channel.

Figure 6y shows that all the small bands are occupied by different CWPAN or IEEE 802.1 laj networks. When either an IEEE 802.1 lad device or a CWPAN or IEEE 802.1 laj device comes, it will be duly notified that all available channels are occupied. )

Legacy device joining and functioning in existing network For the state shown in Figure 6a, there is no existing network. For the states shown in Figure 6b-d, the CWPAN or IEEE 802.1 laj networks function in the legacy mode to service IEEE 802.11 ad devices joining the networks. For the states shown in Figures 6e-h, the IEEE 802.11 ad devices and the CWPAN or IEEE 802.1 laj network follow the example embodiment, Protocol 4, to support interoperability.

For the states shown in Figures 6i-l, the CWPAN or IEEE 802.1 laj network in the large band function in the legacy mode to service IEEE 802.1 lad devices joining the network while the CWPAN or IEEE 802.1 laj network in the small band follows the example embodiment, Protocol 4, to provide backward compatibility support for IEEE 802.1 l ad devices.

For the states shown in Figures 6m and n, the IEEE 802.11 ad devices and the CWPAN or IEEE 802.1 laj network follow the example embodiment, Protocol 5, to support interoperability.

For the states shown in Figures 6o-r, the IEEE 802.11 ad devices and the CWPAN or IEEE 802.1 laj networks in both small bands follow the example embodiment, Protocol 4, to support interoperability.

For the states shown in Figures 6s and t, the CWPAN or IEEE 802.1 laj network in the large band function in the legacy mode to service IEEE 802.1 lad devices joining the network while the CWPAN or IEEE 802.1 l aj network in the small band follows the example embodiment, Protocol 5, to provide backward compatibility support for IEEE 802.1 1 ad devices.

For the states shown in Figures 6u-x, the CWPAN or IEEE 802.1 laj network operating in a small band with an adjacent occupied small band follows the example embodiment, Protocol 5, to provide backward compatibility support for IEEE 802.1 l ad devices while the CWPAN or IEEE 802.1 laj network operating in a small band with an adjacent vacant small band follows the example embodiment, Protocol 4, to provide backward compatibility support for IEEE 802.11 ad devices. For the state shown in Figure 6y, the IEEE 802.1 lad devices and the CWPAN or IEEE 802.1 laj network follow the example embodiment, Protocol 5, to support interoperability.

Considerations for dynamic bandwidths operation Possible operating states were described with reference to Figures 6a to y above and described various protocols to ensure networks co-existence and interoperability between devices with different channelization capabilities. There can be a number of different policies that uses the set of proposed protocols according to example embodiments and those in existing protocols to achieve their aims while maintaining networks co-existence and interoperability. Some example policies will be described below as illustrations on how the proposed protocols can be used effectively to achieve their aims.

The first example policy is termed legacy mode where support for legacy devices is prioritized. In this mode, CWPAN or IEEE 802.1 laj network, switch and operate only in the large band to support the backward compatibility to the legacy devices, e.g., IEEE 802.1 lad devices, as the legacy devices appear in the service area. We take one of large bands as an example to describe this mode. Considering the case when one of the small bands is occupied by a CWPAN or an IEEE 802.1 laj network while the other small band within the same large band is idle. If an IEEE 802.11 ad device arrives, it must join in the current CWPAN or IEEE 802.1 1 aj network in the large band first. Then, the CWPAN or IEEE 802.1 laj network proceeds to the channel merge procedure and switches to the large band to support the IEEE 802.1 1 ad device.

In another case, it is assumed that both small bands within the same large band are occupied by two different CWPAN or IEEE 802.1 laj networks. If an IEEE 802.1 lad device arrives, it can join in one of the existing CWPAN or IEEE 802.1 laj networks without any SP or CBAP allocation or be rejected, until one of CWPAN or IEEE 802.1 l aj networks ceases its service and the remaining one finishes the channel merge procedures.

The second policy example can be termed the exclusive mode where support for legacy devices is minimal. If a CWPAN or an IEEE 802.1 laj network operates in one of the small bands within the current large band, it will not do the channel merge procedures to support the late arriving IEEE 802.11 ad devices. Therefore, the IEEE 802.1 1 ad devices are not allowed to join unless the existing or a new CWPAN or IEEE 802.1 laj network operates in the current large band or a large band is available for occupancy. The support for the legacy devices is limited to notify the late arriving IEEE 802.1 l ad devices of the occupancy of the channel and the late arriving IEEE 8021.1 lad devices cannot obtain any service from the CWPAN or IEEE 802.11 aj network.

example embodiments described may exhibit one or more of the following features:

Defining the protocol for a new network starting in a vacant channel band overlapping or residing in the common spectrum band to transmit notification signals in the common channel spectrum band during a notification period.

Using recurrent and intermittent notification signals by a designated device or devices of each operating networks to inform new device wanting to start network operation in a common spectrum band of the existing network(s).

Featuring unique MAC operations of the designated device of each of the operating networks where they switch between transmission in their own channel spectrum band, whilst operating in their native network, and transmission in the common spectrum band for transmitting the notification signals to inform other devices from the same network type or different network type of the presence of the existing networks occupying a part of the common spectrum band.

Coordinating the transmissions of the notification signals through the common channel spectrum band by different designated devices in their respective independent networks operating in the other channel spectrum bands at designated periods of time to avoid any possible collision through communications between devices in different networks either in the common spectrum band or other designated spectrum bands in which the devices can operate.

Providing for the fidelity of the notification signals sent in the common channel spectrum band by establishing notification periods within the networks operating in the other channel spectrum bands where its devices in their respective networks temporarily suspend all transmissions in their respective network's channel spectrum band and synchronizing quiet periods of independent networks when the two or more networks are in operation with synchronization achieved through communications between devices in different networks either in the common spectrum band or other designated spectrum bands in which the devices can operate.

Defining the MAC protocols for negotiating between the existing networks to adjust the location and the duration of the notification periods in the common channel spectrum band to suit the requirements above for the networks operating in channel bands overlapping or residing in the common spectrum band.

Encompassing a set of MAC protocols to coordinate the transmissions of the quasi- omni beacon periods in the common spectrum band by all the designated devices of their networks in a plurality of channel bands that overlap or reside in the common spectrum band and the synchronization of the notification periods within all the networks in the small bands.

Supporting the operation of networks containing different network devices with different channelization capabilities through specifying the MAC protocols for devices to start, to join and to operate within these networks.

Enabling the interoperability of different network devices with different channelization capabilities allowing them to communicate with each other when operating in the same network through defining the MAC protocols for communications.

The above mentioned quasi-omni beacon frames in example embodiments are the basic information and directions for further actions to preferably allow other technologies working in 60 GHz to recognise and make independent decisions without major change in their basic network scanning procedures.

Embodiments of the present invention can, for example:

Enable the co -existence of networks operating in overlapping frequency spectrum bands through sharing the spectrum resources in the common access frequency spectrum band.

Incorporate recurring notifications period which can be used to announce network presence in a common spectrum band and support interoperability between devices with different channelization capabilities

Require no changes to the network start-up scanning procedure for legacy devices which want to access the spectrum resource.

Ensure the fidelity of the notification periods used in the common access band communications by coordinating and synchronizing notification periods of the different operating networks. Provide enormous flexibility in terms of the frequency of announcement and quiet periods to cater to same or different existing wireless technologies. Thus, the method can be easily tailored to suit different operating assumptions and objectives.

Be suited for implementation as a set of MAC protocols which allows efficient coordination and synchronization of independent operating networks to coordinate the notification periods and quiet periods with little overheads and bandwidth wastage as well as minimal channel switching times between different channel bands.

Efficiently implemented as a set of MAC protocols which allows a network to smoothly switch between the common spectrum band (i.e., a large band) and the network channel band (i.e., a small band) whenever the bandwidth is split or expanded

Example embodiments of the present invention can institute and design the protocols for the use of individual notification period allocated within the common channel spectrum band for each network operating in a channel band which overlap or reside in the common channel spectrum band where the notification period are

o Used to transmit notification signals in the common channel spectrum band to notify other devices of the occupancy status of the common channel spectrum band,

o Used to provide for two-way communications link between devices of different channelization capabilities to achieve interoperability between devices,

o Allocated in the common spectrum band periodically,

o Guaranteed fidelity through mandating a period of radio silence in all the channel bands which overlap or reside in the common channel spectrum band, o Synchronized and coordinated so that no notification periods are overlapped with another while one follows another successively,

o Featured in the formation of new networks and maintenance of the networks with devices of different channelization capabilities.

Figure 7 shows a flowchart 700 illustrating a method of performing an operation of a communication network operating in a channel which overlaps, or resides in, a common channel spectrum band, according to one embodiment. At step 702, the operating network periodically allocates notification periods (NPs) on the common channel spectrum band in a state in which no other network is operating in another channel which overlaps, or resides in, the common channel spectrum band. At step 704, the operating network at least transmits a notification signal in each periodically allocated NP in the common channel spectrum band. The operating network may reserve a service period (SP) in the common channel spectrum for the NPs of one or more other networks which start operating in another channel overlapping, or residing in, the common channel spectrum band. If one of the one or more other networks ceases, the operating network may cease to reserve SP allocations to the NPs of said one of the one or more other networks. If one of the one or more other networks ceases, the operating network may extend its NPs to cover the whole duration of its previous NPs and the NPs of said one of the one or more other networks. If one of the one or more other networks ceases, the operating network may move its target beacon transmission time (TBTT) within the common channel spectrum band prior to the starting of its TBTT within its channel.

The method may further comprise synchronizing the NPs between the operating network and the one or more further networks.

A first type of the notification signal may comprise a beacon transmission interval (BTI). A second type of the notification signal may comprise a beacon header interval (BHI). At least one notification signal of the second type may be allocated for every consecutive number, NM _E _A of notification signals of the first type, wherein NM _3X _ _A is determined by the maximum number of beacon intervals (Bis) after which an association beamforming training (A-BFT) or an announcement transmission interval (ATI) is expected.

The method may further comprise a network component of an intended network scanning the common channel spectrum band for a notification signal of the operating network; the network component determining from the notification signal that the operating network is operating in a first channel that overlaps with, or resides in, the common channel spectrum band; and the network component joining the operating network as a non-PCP/non-AP station (STA).

The method may further comprise the STA sending a request to the operating network to start the intended network in a second channel that overlaps with, or resides in, the common channel spectrum band. The method may further comprise the STA receiving a grant from the operating network and starting the intended network in the second channel.

The method may further comprise the STA sending a request for channel time allocation to the operating network, and the operating network allocating SPs or contention-based access periods (CBAPs) to the STA in the common channel spectrum band. The method may comprise indicating whether an allocation is within the first channel or within the common channel spectrum band. The operating network may allocate the SPs or CBAPs based on existing allocations in another network which started operating in another channel that overlaps with, or resides in, the common channel spectrum band. The operating network may scan the common channel spectrum band or the second channel for determining information about the existing allocations in the other network. The operating network may request information about the existing allocations in the other network from the other network. Figure 8 shows a flowchart 800 illustrating a method of performing an operation of an intended communication network according to one embodiment. At step 802, a network component of the intended network scans the common channel spectrum band for a notification signal of an operating network. At step 804, the network component determines from the notification signal that the operating network is operating in a first channel that overlaps with, or resides in, the common channel spectrum band. At step 806, the network component joins the existing network as a non-PCP/non-AP station (STA).

The STA may send a request to the operating network to start the intended network in a second channel that overlaps with, or resides in, the common channel spectrum band. The STA may receive a grant from the operating network and starting the intended network in the second channel, the STA may send a request for channel time allocation to the operating network, and the operating network may allocate SPs or contention-based access periods (CBAPs) to the STA in the common channel spectrum band. The operating network may allocate the SPs or CBAPs based on existing allocations in another operating network operating in another channel that overlaps with, or resides in, the common channel spectrum band. The operating network may scan the common channel spectrum band or the second channel for determining information about the existing allocations in the other operating network. The operating network may request information about the existing allocations in the other operating network from the other operating network. Figure 9 shows a schematic diagram illustrating a network component 900 of a communication network for operating in a first channel which overlaps, or reside in, a common channel spectrum band, according to one embodiment. The network component 900 comprises an allocator 902 for periodically allocating notification periods (NPs) on the common channel spectrum band in a state in which no other network is operating in another channel which overlaps, or resides in, the common channel spectrum band; and a transmitter 904 for transmitting a notification signal in each periodically allocated NP in the common channel spectrum band.

The allocator 902 may be configured to reserve a service period (SP) in the common channel spectrum for the NPs of one or more other networks. If one of the one or more other networks ceases, the allocator 902 may be configured to cease reserving SP allocations to the NPs of said one of the one or more other networks. If one of the one or more other networks ceases, the allocator 902 may be configured to extend its NPs to cover the whole duration of its previous NPs and the NPs of said one of the one or more other networks. If one of the one or more other networks ceases, the allocator 902 may be configured to move its target beacon transmission time (TBTT) within the common channel spectrum band prior to the starting of its TBTT within its channel.

The network component 900 may further comprise a synchronizer 906 for synchronizing the NPS between the respective networks.

A first type of the notification signal may comprise a beacon transmission interval (BTI). A second type of the notification signal may comprise a beacon header interval (BHI). At least one notification signal of the second type may be allocated for every consecutive number, NM _OX _A of notification signals of the first type, wherein NM _3X _A is determined by the maximum number of beacon intervals (Bis) after which an association beamforming training (A-BFT) or an announcement transmission interval (ATI) is expected.

The allocator 902, and/or the transmitter 904, and/or the synchronizer 906 may be implemented in software executed on a computing device and/or in dedicated hardware. Figure 10 shows a schematic diagram illustrating a network component 1000 of an intended communication network, according to one embodiment. The network component 1000 comprises a receiver 1002 for scanning a common channel spectrum band for a notification signal of an operating network, a determiner 1004 for determining from the notification signal that the operating network is operating in a first channel that overlaps with, or resides in, the common channel spectrum band, and wherein the network component 1000 is configured to join the existing network as a non-PCP/non-AP station (STA).

The network component 1000 may further comprise a transmitter 1006 for sending a request to the operating network to start the intended network in a second channel that overlaps with, or resides in, the common channel spectrum band. The receiver 1002 may be configured for receiving a grant from the operating network and the network component is configured for starting the intended network in the second channel. The transmitter 1006 may send a request for channel time allocation to the operating network. The receiver 1002 may be configured to receive information indicating whether an allocation is within the first channel or within the common channel spectrum band.

The receiver 1002, and/or the determiner 1004, and/or the transmitter 1006 may be implemented in software executed on a computing device and/or in dedicated hardware.

The term "substantially" may include "exactly" and a variance of +/- 5% thereof. As an example and not limitation, the phrase "A is substantially the same as B" may encompass embodiments where A is exactly the same as B, or where A may be within a variance of +/- 5%, for example of a value, of B, or vice versa.

While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.