WO2011121485A1

WO2011121485A1 - Network and method for assigning network addresses

Info

Publication number: WO2011121485A1
Application number: PCT/IB2011/051199
Authority: WO
Inventors: Petrus Desiderius Victor Van Der Stok
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2010-03-30
Filing date: 2011-03-22
Publication date: 2011-10-06
Also published as: TW201206133A

Abstract

The method for assigning network addresses in a network that comprises end devices (31) which are arranged in a confined space of a subnet (30) of the network comprises the following steps. The space of the subnet (30) is divided into columns and rows, thereby creating a plurality of subnet cells (SC), each subnet cell (SC) being identified by a column number (c S ) and a row number (r S ), such that each subnet cell (SC) contains none or one end device (31). If a subnet cell (SC) contains an end device (31), a network address (A) that includes the column number (c S ) and the row number (r S ) of the respective subnet cell (SC) is assigned to the end device (31).

Description

NETWORK AND METHOD FOR ASSIGNING NETWORK ADDRESSES

FIELD OF THE INVENTION

The invention relates to a method for assigning network addresses in a network that comprises end devices which are arranged in a confined space of a subnet of the network. The invention further relates to an according network.

BACKGROUND OF THE INVENTION

Building automation in general and lighting control in particular are increasingly based on devices that communicate via a network structure. Especially large lighting systems, for example in factories, offices, stores and green houses, benefit from an automatic control in order to minimize the manual efforts for controlling the lighting settings and to save energy at the same time. But also in the consumer market, network based lighting systems are attractive for their enhanced flexibility compared to a hard- wired switch to device installation.

Devices of a network based control system, such as luminaires, sensors and manual controls (light switches) of a lighting system, can be connected to each other by sending messages over a wired or a wireless medium. Often, a combined system is used, in which a wired backbone provides a couple of routers distributed in a building, each router acting as an access point for a plurality of nearby wireless end devices like sensors and luminaires. Wireless (end-) devices are preferred because they reduce installation costs and make the installation more flexible. The wireless part of the network usually uses an ad-hoc protocol with addresses assigned on the fly. Due to the unreliable nature of the links in such a system, routing algorithms tend to perform poorly because the paths between a given source- destination pair change frequently, thus leading to undesired delays, the need of broadcast requests for address exploitation and, accordingly, to message overhead.

Document US 2009/0177762 Al discloses a method for generating internet protocol (IP) addresses, in which the geographical location of a device is included in the suffix part of an IP-address according to the IPv6 (Internet Protocol version 6) specification. The location can be expressed in GPA- (Global Positioning Address) coordinates, or, in particular for buildings, in a pair of latitude- and longitude- values relative to a reference point within the building. With the location included in the IP-address, routing performance can be improved. Given the close proximity of devices within a building, the location has to be represented in the address with a high spatial resolution. If the resolution is too low, it is not guaranteed that the representation of the geographical location is a unique identifier for a device. An IPv6 address which can be easily matched to a location in the building reduces errors during commissioning and speeds up the commissioning process.

It would therefore be advantageous to achieve a method for assigning addresses to network devices in automation or control systems for example used in buildings and an according network that support the use of direct routing methods thereby minimizing message overhead, wherein it is guaranteed that the network devices are uniquely identified by the address.

SUMMARY OF THE INVENTION

The present application contemplates a method for assigning network addresses in a network that comprises end devices which are arranged in a confined space of a subnet of the network. The method comprises the following steps. The space of the subnet is divided into rows and columns, thereby creating a plurality of subnet cells, such that each subnet cell contains none or one end device. Each subnet cell is identified by a column number and a row number. If a subnet cell contains an end device, network address that includes the column number and the row number of the respective subnet cell is assigned to the end device. The application further contemplates an according network.

The determination method for the row number and the column number provides coordinates that are related to a relative positioning of the end devices compared to each other. This way, the range of values for the coordinates and thus the number of bits of the address used for the position encoding is much smaller compared to coordinate systems, in which the geographic position and the coordinates used in the address are proportional to each other. In the latter case, the high spatial resolution needed to resolve all device positions unambiguously leads to coordinates with more binary digits.

A preferred embodiment of the method is suited for a network, wherein a plurality of subnets is located on a floor of a building and a plurality of routers that form a backbone net is located on the respective floor. In each case, one router is associated with one subnet. The method then comprises the following further steps. The space of the backbone net is divided into columns and rows, thereby creating a plurality of backbone cells, wherein each backbone cell is identified by a column number and a row number, such that each backbone cell contains none or one router. The column number and the row number of the backbone cell that contains the router associated with the subnet, to which the end device belongs, is then further included in the network address assigned to the end device. Encoding the position of an end device within the subnet and the position of the respective router assigned to the subnet in the address of the end devices enhances the routing performance even further.

In further preferred embodiments of the method, the network address is an internet address according to the IPv6-specification with a prefix part and a suffix part. The column number and the row number related to the subnet are included in the suffix part of the address and/or the column number and the row number related to the backbone net are included in the prefix part of the address.

Further advantageous embodiments are provided in the respective dependent claims. Still further advantages and benefits of the present invention will become apparent from and elucidated with reference to the embodiments described hereinafter in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Fig. 1 shows a schematic representation of a floor of a building with an installed lighting control network system;

Fig. 2 shows the same network system as Fig. 1 with focus on its backbone net; and

Fig. 3 shows a schematic representation of a network address.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows the footprint of a floor 10 of a building. The floor comprises rooms 11, separated by walls 12. By way of example, the floor 10 shown is the floor of an office building with three smaller offices on the left end side, an L-shaped floor in the middle part and a larger open-plan office on the right hand side.

The network system installed on the floor 10 comprises a backbone net 20 with routing devices 21, shortly called routers 21. Each router 21 acts as an access point within a subnet 30. In most cases, one router 21 is provided for each room 11, as is the case for the offices on the left hand and the right hand side of Fig. 1. However, a room 11 , can be equipped with two or more routers 21, such that more than one subnet exists in one room 11, as is the case for the L-shaped floor in the example shown. The other case, according to which more than one room 11 is served by a single router 21, is also possible. The rooms 11 of the floor 10 are equipped with a plurality of end devices 31, e.g. luminaires 31a, for example ceiling lamps, and sensors 31b. All end devices 31 within a subnet 30 communicate with the respective router 21 of that subnet 30. While the backbone net 20 is realized as a wired network, for example an Ethernet network, the end devices 31 are preferably wireless devices. However, a wired connection between the end devices 31 and the respective router 21 is also possible.

In the following, a method for assigning addresses to network devices is explained using the example of a network system shown in Figs. 1 and 2.

It is assumed that the routers 21 are connected to external routers that connect the building to the internet. Each external router has an internet prefix IPx, where x denotes the external router's number, i.e. x serves as an index to distinguish the external routers. The internet prefixes IPx are usually assigned by an internet service provider. Prefixes denote a range of addresses: All requests sent to an end device with an address that starts with a certain prefix assigned to a router, are sent to this router.

Each device in the network is then assigned an address A = IPx | T_B | T_s, wherein T_B and Ts denote localization parts related to the backbone net (T_B) and the subnet (T_s), respectively. The pipe symbol | indicates that the address is composed of the given parts, e.g. in such a way that the different parts occupy different blocks of bits of the address A.

The determination of the localization part Ts related to the subnet 30 is now described with respect to Fig. 1, using the larger room 11 on the right hand side of the figure and the associated subnet 30 as an example.

In order to determine the localization part Ts, a grid is applied to the space of the subnet 30 that divides the space into a plurality of rectangular subnet cells SC. In the example shown, the grid has five columns and eight rows. The subnet cells SC can be distinguished from each other by a column number Cs and a row number rs. The grid is constructed such that each cell SC comprises at most one end device 31. The created columns can differ in width among each, and the created rows can differ in height among each other in order to fulfill the target to have at most one end device 31 per subnet cell SC with a minimum number of empty subnet cells SC.

Each end device 31 can now be uniquely identified by the column number Cs and the row number r_s of the subnet cell SC, in which the end device 31 is located. The pair of coordinates (cs, r_s) is then used as the localization part T_s of the internet address A. The localization part TB related to backbone net 20 is then determined in an analogous manner, as described in the following in connection with Fig. 2. The figure shows the same network system on floor 10 as Fig. 1. For simplicity, the end devices 31 are not shown in Fig. 2.

The entire space that is supported by the backbone net 20, i.e. the whole floor

10 shown, is divided into a plurality of rectangular backbone cells BC, such that at most one router 21 is located in one backbone cell BC. In order to achieve this, a grid with three columns and four rows is defined. Again, the columns and the rows might differ in width and height, respectively, in order to achieve the condition to have not more than one router 21 per backbone cell BC, without having too many empty backbone cells BC. The backbone cells are identified by a column number CB and a row number r_B. The pair of coordinates (CB, r_B) is then used as the localization part TB of the internet address A.

Encoding the position of the end devices 31 in their network addresses A by the localization part Ts has the advantage that routing inside the network is simplified, because no paths need to be determined by broadcast requests and packets can be routed directly to their destination. This is even more the case since the localization parts TB related to the backbone net 20 and thus the routers 21 is encoded in the address A as well.

In contrast to methods, in which the position of a device and the representation of the position in the address are proportional to each other (linear mapping), the pairs of coordinates (cs, r_s) and (CB, r_B) are not linearly coupled to the spatial position. The position is not encoded in the address in absolute terms, but only gives the relative positioning of the end devices 31 compared to each other. This way, the range of values for the coordinates and thus the number of bits of the address used up for the position encoding is much smaller compared to the case of a linear mapping with a high spatial resolution needed to resolve all device positions unambiguously.

In the example shown, the columns C and the rows R are constructed with lines parallel to the walls 12 of the building. Depending on the geometrical arrangement of the end devices 31 , columns and rows that are not parallel to the walls 12 of a building can be better suited to divide the backbone network space and the subnet spaces into the respective backbone cells BC and subnet cells SC. Also, the cells itself does not necessarily have to be rectangular in shape, what can also be shaped as parallelograms.

Fig. 3 shows a schematical representation of an internet address A constructed according to the method described above and assigned to an end devices 31 in the network.

The address A is designed according to the Internet Protocol version 6 (IPv6) with a length of 128 bits, divided in a 64 bit prefix part 40 and a 64 bit suffix part 41, also called interface identifier.

The prefix part 40 is composed of three parts (address fields): The internet prefix IPx of the external router and the column and row indices CB and ¾ for identifying the router 21 of the backbone network 20 that is assigned to the subnet 30, the end device 31 belongs to. The column and row indices CB and r_B use blocks of bits according to their value range. If, for example, the column index CB can take values between 0 and CBMAX, the smallest number n of bits that can be used to represent the column index CB is the one that fulfills the criterion 2^n_1 <CBMAx<2ⁿ.

In a similar manner, the suffix part 41 comprises the column and row indices

Cs and r_s in two address fields for identifying the end device 31 within the subnet 30 specified in the prefix part 40. Since the number of bits necessary to decode the values for r_s and Cs will be smaller than the 64 bit length of the suffix par 41, a third address field of the suffix will be either unused or can be used for an additional identifier of the end device 31 , for example its media access address (MAC). It is furthermore possible to include further positioning information in the third address filed, for example an identifier of the floor 10 within the building, e.g. the floor number.

In alternative presentations of the address according to the IPv6-system, the column number CB and the row number ¾ related to the backbone cells BC could also be included in the suffix part 41 of the address A.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A method for assigning network addresses in a network that comprises end devices (31) which are arranged in a confined space of a subnet (30) of the network, the method comprising the steps of:

- dividing the space of the subnet (30) into columns and rows, thereby creating a plurality of subnet cells (SC), each subnet cell (SC) being identified by a column number (cs) and a row number (r_s), such that each subnet cell (SC) contains none or one end device (31); and - if a subnet cell (SC) contains an end device (31), assigning a network address (A) to the end device (31) that includes the column number (cs) and the row number (r_s) of the respective subnet cell (SC).

2. The method according to claim 1, wherein the column number (cs) and the row number (r_s) related to the subnet (20) occupy different blocks of bits of the address (A).

3. The method according to claim 2, wherein the size of the blocks of bits of the address (A) in which the column number (cs) and the row number (r_s) are encoded, is adapted to the maximum values for the column number (cs) and the row number (rs), respectively.

4. The method according to claim 1, wherein the subnet (30) is located on a floor (10) of a building and wherein an identifier of the floor (10) is also encoded in the address (A).

5. The method according to claim 1, wherein the address (A) is an internet address according to the IPv6-specification with a prefix part (40) and a suffix part (41), and wherein the column number (cs) and the row number (rs) related to the subnet (30) are included in the suffix part (41) of the address (A).

6. The method according to claim 1, wherein

- a plurality of subnets (30) is located on a floor (10) of a building; and

- a plurality of routers (21) forming a backbone net (20) is located on the floor (10), in each case, one of the routers (21) being associated with one of the subnets (30); the method comprising the further steps of:

- dividing the space of the backbone net (20) into columns and rows, thereby creating a plurality of backbone cells (BC), each backbone cell (BC) being identified by a column number (CB) and a row number (¾), such that each backbone cell (BC) contains none or one router (21), and

- further including the column number (CB) and the row number (¾) of the backbone cell (BC) that contains the router (21) associated with the subnet (30) to which the end device (31) belongs, in the assigned network address (A).

7. The method according to claim 6, wherein the column number (CB) and the row number (¾) related to the backbone net (20) occupy different blocks of bits of the address (A).

8. The method according to claim 7, wherein the size of the blocks of bits of the address (A) in which the column number (CB) and the row number (r_B) are encoded, is adapted to the maximum values for the column number (CB) and the row number (¾), respectively.

9. The method according to claim 6, wherein the address (A) is an internet address according to the IPv6-specification with a prefix part (40) and a suffix part (41), and wherein the column number (CB) and the row number (¾) related to the backbone net (20) are included in the prefix part (40) of the address (A).

10. A network comprising end devices (31), wherein

- a confined space of a subnet (30) of the network comprises a plurality of subnet cells (SC) arranged in columns and rows, each subnet cell (SC) being identified by a column number (cs) and a row number (rs);

- each subnet cell (SC) contains at most one end device (31); and

- the at most one end device (31) contained in a subnet cell (SC) has a network address (A) that includes the coumn number (cs) and the row number (r_s) of the respective subnet cell

(SC).

11. The network according to claim 10, wherein

- a plurality of subnets (30) is located on a floor (10) of a building; and

- a plurality of routers (21) forming a backbone net (20) is located on the floor (10), in each case, one of the routers (21) being associated with one of the subnets (30);

- the backbone net (20) comprises a plurality of backbone cells (BC) arranged in columns and rows, each backbone cell (BC) being identified by a column number (CB) and a row number

(¾);

- each backbone cell (BC) contains at most one router (21), and

- the network address (A) assigned to the end device (31) further includes the column number (CB) and the row number (¾) of the backbone cell (BC) that contains the router (21) associated with the subnet (30) to which the end device (31) belongs.