Multi-hop communication setup subject to boundary values

IS 2 296 167 T3

DESCRIPTION

Establishment of multi-hop communication links (multihop) based on limit values.

The present invention relates to a method, a device and a computer program for establishing communication links in a radio communication system with at least one base station and subscriber terminal apparatuses that are configured at least in part as ad nodes. hoc multi-hop capable (multihop). Radio communication systems with multi-hop capable subscriber terminals have long been known from the state of the art.

M. Lott et al. In "Hierarchical Cellular Multihop Networks", EPMCC 2003, March 2003, proposes a combination of a cellular mobile communication system based on a fixedly installed base station infrastructure with an ad hoc WLAN mobile communication system self-organized. The base stations offer access to the core of the network (backbone) that is based on the TCP / IP protocol. The WLAN communication system features permanently installed Internet access points. The scope or spatial coverage (coverage) to establish communication links between an access point and a WLAN mobile network node (mobil node) can be extended by means of fixedly installed or mobile network nodes capable of multi-hop (multihop capable nodes). It is explained there that a multi-hop communication link requires more network capacity than a direct communication link, since the corresponding network resources are required for each partial link to establish the complete multi-hop link.

In G. Cristache et al. "Aspects for the integration of ad hoc and cellular networks", 3. Scandinavian Workshop on Wireless Ad hoc Networks, Stockholm, 6 - 7 May 2003, it is proposed in particular to use a ad hoc network function directly to extend the coverage and to increase the capacity of the cells of a cellular mobile communication system such as UMTS, without then providing access points. Mobile terminal devices of the UMTS network are configured there such that a communication link is established from the base station via a mobile terminal device to another mobile terminal device.

By extending the coverage (coverage extension), the network radius or the cell radius is therefore increased, so that also terminal devices further away from a communications network or from a base station can be powered from this network or from the corresponding base station. However, this has a negative effect on the bandwidth of the entire network.

From EP 1 133 113 A2 a method for the distribution of messages over the entire surface is known. In order to prevent the messages from becoming out of date when they are retransmitted or when they leave the addressed sector, the messages contain information relating to the so-called lifetime or a hop limit (hop-limit). In this way, a terminal device that receives a message such as the one indicated can detect whether it should retransmit it to other terminal devices or not. The corresponding result can alternatively be achieved by prescribing a spatial limitation on the messages, such that a receiving terminal checks whether its current position is still within the range intended for broadcasting the message.

It is the task of the present invention to provide an improved possibility for establishing communication links between a base station and subscriber terminal apparatuses, which are at least partially configured as ad hoc nodes capable of multi-hop (multihop). This task is solved by the particularities of the independent claims. Advantageous developments of the invention can be taken from the dependent claims.

A first object of the invention relates to a method for establishing communication links in a radio communication system with at least one base station and subscriber terminal devices, which are at least partially configured as ad hoc nodes capable of multi-hop. According to the invention, it is provided that for at least part of the communication links, limit values ​​for the multi-hop communication links are set by the radio communication system, current values ​​are calculated for the multi-hop communication links and transmission links are established. Multi-hop communications with subscriber terminal devices only when the actual values ​​do not exceed the set limit values. In a characterizing manner, an exchange of information takes place between base stations on the limit values ​​that have been set for the corresponding base stations.

In this way, it can be ensured in a simple way that the desired requirements in particular as regards the necessary bandwidth are observed within the radio communication system. The limit values ​​can be set once or at regular intervals. They can also be dynamically set event-driven and optimized, for example when there is a change in the current number of active subscriber terminals in the corresponding radio communication system.

Through the exchange according to the invention of information on the limit values, an optimization of the limit values ​​of the base stations also takes place in mutual agreement of the base stations with each other, in order to also achieve the optimum possible operation of the network. in the extension of all base stations. This therefore offers the possibility of an adaptation of the limit values ​​of a base station on the basis of the fixed limit values ​​of neighboring base stations.

IS 2 296 167 T3

It can preferably be provided that individual limit values ​​can be set for each base station. In this way, individual optimization of the corresponding limit values ​​can be carried out for each base station as a function of the local conditions in the area of ​​the respective base station.

The limit values ​​can be set basically in any suitable way and from any suitable instance of the radio communication system. Preferably, however, an evaluation of cell parameters is carried out by a base station of the radio communication system and based on the result of this evaluation, the determination of the limit values ​​for the communication links of this base station is carried out. In this way, the setting of the limit values ​​can be carried out independently and individually by each base station.

In particular, it can be envisaged that the information exchange is based at least partially on a protocol according to IPv6. The protocols according to IPv6 (IP protocol version 6) offer the advantage that functionalities for communication links to and / or to mobile subscriber terminals are already provided within the framework of these protocols. It is then preferably provided that the information exchange is based at least partially on a protocol according to HMIPv6 (Hierarchical Mobility IPv6, ie hierarchical mobility). This protocol is a refinement of IPv6, allowing a scalable IP network infrastructure made up of Mobility Anchor Points (MAP) individual mobility anchor points. This results in special advantages, which affect precisely the radio communication side of the communication links to the subscriber terminals. With the help of MAP, an IP infrastructure with practically any hierarchical stages can be formed, that is, the IP infrastructure is scalable to practically any dimension depending on the need for network coverage and access nodes to the IP infrastructure. In this way, necessary handovers can be carried out on the radio side in particular more quickly, since a handover must only be carried out from the technical point of view of signaling via the locally affected MAPs and not for example via a only common core team, which would slow down the development of the handover.

The limit values ​​can basically be set on the basis of any suitable measurement specifications and / or data. However, it is preferably envisaged that the limit values ​​are set on the basis of ad hoc protocol data. In this way, data existing in connection with the establishment or signaling of ad hoc communication links are used directly for setting the limit values. Hereby an embodiment of the invention is possible with minimal additional cost on the part of the radio communication system.

Another object of the present invention includes a device for establishing communication links in a radio communication system with at least one base station and subscriber terminals, which are at least partially configured as ad hoc nodes capable of multi-hop. According to the invention, the equipment has the following:

equipment for determining limit values ​​for multi-hop communication links, at least for a part of the communication links, equipment for comparing the limit values ​​set with current values ​​for multi-hop communication links, as well as equipment for establishing other communication links multi-hop communications based on the result of the comparison.

The advantages resulting from taking these technical measures have already been described analogously on the basis of the procedure already described above.

A further development of this object of the invention presents equipment for exchanging information on limit values ​​between base stations of the radio communication system. Here too, we refer to the explanations corresponding to the procedure already presented above regarding the importance and advantages of this measure.

In particular, provision can be made for the equipment for the exchange of information to be at least partially designed to process a protocol according to IPv6. It can then preferably be envisaged that the equipment for the exchange of information is designed at least partially to process a protocol according to HPIPv6. The advantages resulting precisely for a radio communication system with mobile subscriber terminals capable of multi-hop have already been described on the basis of the method according to the invention.

A third object of the present invention is a computer program that is preferably configured to carry out a procedure described above. In particular, the computer program can be configured to interact with a device described above, corresponding to the invention.

According to the invention, the computer program is provided with the following:

a first program routine, which for at least a part of the communication links in a radio communication system calculates and sets limit values ​​for multi-hop communication links,

ES 2 296 167 T3 a second program routine for calculating current values ​​for multi-hop communication links and a third program routine that controls a device for establishing multi-hop communication links with subscriber terminal devices, provided that the current values ​​do not exceed the set limit values.

Also the other process steps mentioned above, as well as other process steps, data processing and data transmission steps, and in particular protocols that are described within the framework of the following description of the figures, can basically be carried out in the form of program routines of this computer program or another suitable one.

A special embodiment of the present invention will now be described on the basis of Figures 1 to 11.

Shown in:

Figure 1: schematic representation of a hierarchical communications infrastructure

Figure 2: Schematic representation of an Ad hoc coverage extension without a defined hop radius

Figure 3: Schematic representation of an Ad hoc Coverage Extension with defined jump radii

Figure 4: Schematic representation of an Ad hoc Coverage Extension with optimized hop radius

Figure 5: sequential evolution when the result of the comparison of the hop radius without communication between the base stations is positive

Figure 6: sequential evolution when the result of comparing the hop radius without communication between the base stations is negative

Figure 7: sequential evolution when the result of comparing the hop radius with communication between the base stations is positive

Figure 8: sequential evolution when the result of comparing the hop radius with communication between the base stations is negative

Figure 9: Protocol Stack for Mobile and Ad Hoc IP Connection (AODV)

Figure 10: schematic representation of the essential components according to the invention of a base station

Figure 11: schematic representation of a hierarchical communications infrastructure similar to that of figure 1, but according to HMIPv6.

The execution example presented below refers to a possibility of setting limit values ​​for multi-hop communication links, setting a hop radius (maximum allowable number of hops for each communication link) and / or setting the total number of ad hoc subscriber terminals currently linked with a base station in the ad hoc network. The subscriber terminal apparatuses of the wireless communication network are able to establish, based on the multi-hop capacity of at least a part of the subscriber terminal apparatuses, a link with the base station through an ad hoc network, even when these subscriber terminals are outside the range of the base station. The ad hoc network consequently extends the range of the base station using an ad hoc multi-hop routing protocol. This coverage extension is also called the Coverage Extension. This Coverage Extension is based on the use of subscriber terminal devices in the form of ad hoc nodes, which as routers provide IP links that can be used for the communication path of the corresponding communication link. The wireless communication network can be configured, for example, as a suitable UMTS mobile radio network or else as a WLAN network, which allows a corresponding ad hoc coverage extension, as is basically known from the prior art mentioned above.

The essential components and functions of the object of the invention according to this exemplary embodiment will be briefly described below:

Base station:

The base station is the gateway between the ad hoc subscriber terminals and an IP infrastructure (eg the Internet, see Figure 1 and Figure 11). It offers ad hoc subscriber terminals access to the Internet and thus enables the connection of ad hoc subscriber terminals to very remote communication partners, which are also connected to an IP-based communication infrastructure. The base station is correspondingly configured for the connection of ad hoc subscriber terminals to the Internet and is therefore configured both for the processing of an ad hoc protocol and also an IP-based mobility protocol.

IS 2 296 167 T3

Hop radius (hop):

The hop radius corresponds to the maximum allowable hop length from the base station to the ad hoc subscribers in an ad hoc network. The hop radius is therefore the maximum allowable number of hops (intermediate nodes) between the base station and an ad hoc subscriber terminal. The number of hops is transmitted using the ad hoc protocol to the base station or can be ascertained by the base station on the basis of routing information. If, for example, a link such as the one indicated is composed of three hops, then the base station, an ad hoc subscriber terminal and two other ad hoc nodes are included in this link. If the maximum permissible number of hops increases or the hop radius increases, then the network load increases, since more ad hoc subscribers may also be included in the ad hoc network around the base station. A hop radius can be set by the base station itself. Based on this setting, the ad hoc subscriber terminals whose hop length would be greater than the hop radius are not received in the ad hoc network around the corresponding base station. The network, as well as the network load, thus remains stable.

Number of ad hoc subscribers:

As an alternative or in addition to the aforementioned procedure, the absolute number of ad hoc subscriber terminals within an ad hoc network can be taken into account in calculating the network load and setting the hop radius. As an alternative to setting a hop radius as a limit value, it is also possible to set a maximum number of ad hoc subscriber terminals as a limit value within an ad hoc network. It can then be set, for example, that the hop radius for a certain base station is not reduced as long as a certain number of ad hoc subscriber terminals is not exceeded.

A combination (trade-off) can also be made between hop radius and maximum admissible number of ad hoc subscribers (hybrid procedure):

The above-mentioned procedures for setting the hop radius and the maximum allowable number of ad hoc subscriber terminals can be combined for an optimized calculation of the network load. Here a tradeoff is possible, which as a combination between a hop radio algorithm and an ad hoc subscriber quantity algorithm, enables better planning of the network. The corresponding evaluation parameters are then preferably calculated on the basis of the aforementioned algorithms. This calculation can be done by the base station autonomously and used to set both the hop radius and the maximum allowable number of ad hoc subscribers. In addition, a Coverage Radius can preferably be defined for this method as another limit value. This virtual coverage radius means a value that is determined as a function of the fixed and / or calculated values ​​for the hop radius and the maximum allowable number of ad hoc subscribers. The greater the radius and the number of ad hoc subscribers, the greater the coverage radius. In the simplest case, the Coverage Radius is therefore defined directly proportional to the hop radius and the number of ad hoc subscribers.

Communication between base stations:

A specific communication protocol is used for the exchange of data between various base stations FA-BS1 to FA-BS4 (see figure 1). This communication protocol provides for the exchange of information on limit values, such as the hop radius or the maximum allowable number of ad hoc subscribers between base stations (preferably adjacent) FA-BS1 to FA-BS4. The exchange can be carried out for example via an IP infrastructure represented schematically in figure 1, to which the base stations FABS1 to FA-BS4 are connected. For this, a hierarchical mobile IP structure can be envisaged, which enables higher levels (mobility agents) to coordinate the exchange of information between base stations FA-BS1 to FA-BS4. These are configured in the example in figure 1 as Regional Foreign Agent RFA (foreign regional agent) and / or Gateway Foreign Agent GFA (foreign gateway agent). Figure 11 shows an alternative implementation example based on IPv6. In this regard, an IP structure according to HMIPv6 is shown, where instead of the strictly defined RFAs and GFAs, only Mobility Anchor Points (MAP), basically functionally equivalent mobility anchor points, are provided. Base stations BS1 to BS4 serve as Access Router AR. In this way, the IP infrastructure is practically scalable to any measure. This will be described in detail later.

The mobility agents RFA, GFA according to FIG. 1 are linked in data technology with the base stations FA-BS1 to FA-BS4. In this way, an exchange between the individual base stations FABS1 to FA-BS4 is easily possible. The aforementioned protocol allows this data exchange as part of the autonomous adaptation and optimization of the network planning, based on the hop radius and / or the maximum admissible number of ad hoc subscribers.

By the present invention limit values ​​are set for an ad hoc network around a base station. With this, the extent of the coverage extension or coverage extension around the corresponding base station is also definitively fixed. Smaller hop radii or lower numbers of ad hoc subscribers generally necessarily also lead to a smaller coverage extension, which is achieved by the ad hoc network around a corresponding base station. This fact must be taken into account within the framework of the definition of the aforementioned virtual coverage radius.

IS 2 296 167 T3

The setting of the limit values ​​is necessary so that long IP routes over multiple hops are not established via ad hoc subscriber terminal devices MN0, MN1 too far apart, which in turn would reduce the bandwidth of all the ad hoc network around a base station FA-BS1 to FA-BS4. This will be further clarified below on the basis of Figures 2 to 4. A base station FA-BS1 to FA-BS4 can therefore ultimately influence by setting limit values ​​whether a very remote subscriber terminal MN0, MN1 can be accommodated in its own ad hoc network. For this, an algorithm is required which, based on the already existing number of ad hoc subscribers and the hop lengths, defines a criterion so that the bandwidth can be maintained.

Each base station FA-BS1 to FA-BS4 can further define based on the set limit values ​​and the exchange of information with other base stations FA-BS1 to FA-BS4 and / or with a specific ad hoc subscriber terminal. MN0 if this ad hoc subscriber terminal MN0 is to be hosted in the ad hoc network itself, in particular when this ad hoc subscriber terminal MN0 cannot find out by itself any other link possibility with other base stations FA-BS1 to FA-BS4. In this case, the subscriber terminal MN0 can send the corresponding query to the only reachable base station FA-BS1 to FA-BS4. This is in particular the case when there is only one base station FA-BS1 or when the base stations FA-BS2 to FA-BS4 adjacent to a first base station FA-BS1 are defined in such a way that they cannot modify the radius of hop defined for them so that said subscriber terminal MN0 can be hosted in its ad hoc network.

As already indicated, it is preferably provided that the base stations FA-BS1 to FA-BS4 exchange information about a provisionally fixed hop radius with each other. This information exchange can be carried out as broadcast / multicast (to all users / specific users) and the existing infrastructure, represented in figure 1, based on IP, can be used for this. On the basis of the information received from the neighboring base stations FA-BS1 to FA-BS4, each of the base stations FA-BS1 to FA-BS4 can modify the provisional hop radius in one or more iterative optimization steps. that it is possible to supply as many ad hoc subscriber terminals MN0, MN1 as possible, if necessary taking into account minimum values ​​for the bandwidth of each of the ad hoc networks. This optimization can also be carried out dynamically, for example in case the network load of a certain base station FA-BS1 increases and the hop radius of this base station FA-BS1 has to be reduced accordingly. Here it can be ascertained within the framework of the optimization procedure whether and to what extent other base stations FA-BS2 to FA-BS4 can expand their corresponding hop radius, thus enabling full-area data feed to terminal devices. ad hoc subscriber MN0, MN1, such that each ad hoc subscriber terminal MN0, MN1 can establish a data link with a base station FA-BS1 to FA-BS4. This will be clarified below based on Figures 3 and 4.

Furthermore, within the ad hoc protocol, signaling between base stations FA-BS1 to FA-BS4 and ad hoc subscriber terminals MN0, MN1 can be provided, as well as, if necessary, other signaling within the IP protocol between various stations. of base stations FA-BS1 to FA-BS4, preferably contiguous, which allows a certain base station FA-BS1 to reject an additional ad hoc subscriber terminal MN1 or to assign it to another base station FA-BS2 to FA-BS4 .

As already explained, each ad hoc subscriber terminal MN0, MN1 that wishes to communicate with the Internet requires a base station FA-BS1 to FA-BS4 as a default gateway, so that the routing queries are relayed to the Internet. . An IP-based mobility protocol is used for this, which can relay the queries and responses to the corresponding base station FA-BS1 to FA-BS4. Furthermore, and by using a mobility protocol such as the one indicated (for example mobile IP / HMIP / FMIP) the global mobility of each ad hoc subscriber terminal MN0, MN1 is supported. As a result, roaming (roaming) between disparate ad hoc networks of different base stations FA-BS1 to FA-BS4 and also between various IP infrastructures is possible at any time without damaging existing IP links.

Therefore, according to the present examples, several distributed base stations are housed within the framework of the invention, and the coverage of the base stations can be expanded by using terminal devices capable of multi-hop and ad hoc routing protocol. The range of the base station (Coverage Extension Radius) is then generally expanded with the number of ad hoc nodes connected. Measurements show that this expansion negatively influences the speed of the data flow. By limiting the hop length, ie by fixing the hop radius and / or by limiting the permissible number of ad hoc nodes, the network load can be optimized. With the aid of the present invention, the base stations can autonomously regulate the data rate and the network load such that the effective network load does not exceed a predefined maximum network load. In this way, the data rate required for each ad hoc subscriber terminal can be maintained for ad hoc data links via the corresponding base station.

According to the state of the art, an ad hoc multi-hop protocol has hitherto been designed such that a maximum permissible hop length or a fixed hop radius is not provided for when connecting ad hoc subscriber terminals to existing ad hoc networks. According to the state of the art, rather preference is given to the general acceptance of all subscribers in an existing ad hoc network, regardless of the number of hops. Furthermore, it is currently not envisaged that the base stations inform each other independently of the limit values, as well as, if necessary, their optimization in the protocols, according to the state of the art.

IS 2 296 167 T3

The procedures and process steps described above will be clarified in detail below.

1. Procedure for calculating jump length and setting jump radius:

a) Defining an optimal network load using the base station

b) Determination of the effective network load by the base station

c) comparison of the optimal network load with the maximum allowable network load using the base station

d) setting a jump radius based on the result of step c)

e) transmission of information on the hopping radius set to neighboring base stations through the aforementioned protocol

f) autonomous adaptation of the hop radius on the basis of information received on the hop radios of neighboring base stations, by the base station.

2. Procedure to set the maximum number of ad hoc subscribers (number of nodes):

a) definition of an optimal number of nodes using the base station

b) determination of the effective number of nodes by the base station

c) comparison of the optimal number of nodes with the maximum allowable number of nodes using the base station

d) setting a maximum allowable number of nodes

e) transmission of information on the number of nodes set to neighboring base stations through the aforementioned protocol

f) autonomous adaptation of the number of nodes based on information received relative to the number of nodes from neighboring base stations, by the base station.

3. Procedure for the combined setting of the hop length and the number of ad hoc subscribers (hybrid procedure):

a) setting the optimal network load, consisting of an optimal number of ad hoc nodes and the hop radius by the base station

b) determination of the effective load of the network, composed of the effective number of ad hoc nodes and the effective hop radius, by means of the base station

c) comparison of the effective network load with the optimal network load, using the base station

d) setting the jump radius and the maximum allowable number of nodes

e) transmission of information on the set hop radius and the number of nodes set to neighboring base stations using the aforementioned protocol

f) autonomous adaptation of the hop radius and the number of nodes based on information received about the hop radius and the number of nodes from neighboring base stations, by the base station.

A possible embodiment of the procedure to calculate the jump radius is described below as an example:

An algorithm is used that evaluates the corresponding load and the corresponding status of a base station in relation to the connected ad hoc network. This evaluation is taken as the basis for the calculation of jump density and jump length. The density calculation results from the number of ad hoc subscriber terminals divided by the hop radius. The individual results found at different times of the ad hoc density calculation can also be averaged and used for comparison. When the number of hops increases, then an increasing network density must also be expected. An increase in the density of the network will in turn increase the load on the network. This in turn results in the minimization of the data rate of all ad hoc subscriber terminals. In order for the base station to maintain the calculated data rate for all ad hoc subscriber terminals, the network has to be limited. This can be ascertained by active measurement or by comparative values, whereby an optimum density of the network can be set. The values ​​required for this are known to the corresponding base station.

IS 2 296 167 T3

When establishing an ad hoc network, the base station can compare the current resulting network density based on the currently calculated number of ad hoc subscriber terminals with memorized and / or averaged setpoints and autonomously set the jump radius. By autonomous comparison by the base station between the network density setpoint and the actual density value of the existing ad hoc nodes, the base station can calculate the hop radius and use it to decide whether a new ad hoc subscriber terminal should be accepted. Ad hoc subscriber terminals with a hop length that is less than or equal to the hop radius can be hosted by the base station in the ad hoc network. However, this increases the load on the network. An overflow of a setpoint or maximum value of the network load can be prevented by comparing the number of ad hoc subscribers above at that time with the fixed maximum allowable number of ad hoc subscriber terminals and given the possibly the rejection of the new subscriber terminal, or by recalculating the current network load and possibly reducing the hop radius.

The criteria for an ad hoc node to establish a route to a certain destination node is currently based, according to the state of the art, on a hop metric, which is based on choosing the shortest route and using it as the route of communication. Consequently, an ad hoc node will generally be decided by a base station offering the shortest route. However, this is not permissible according to the invention when the chosen path length exceeds the hop radius of the ad hoc network of the corresponding base station.

In figure 1 the structure of a hierarchical communication infrastructure to carry out the invention is schematically represented. In FIG. 1, four base stations FA-BS1 to FA-BS4 are shown by way of example. These four base stations FA-BS1 to FA-BS4 are configured according to the IP protocol represented in FIG. 1 as Foreign Agents, which are at least regionally connected to each other via Regional Foreign Agents. In IPv6, as represented in Figure 11, this configuration corresponds to a structure composed of Mobility Anchor Points (MAP), mobility anchor points, which carry out the local registration of the ad hoc subscriber terminal devices. Otherwise, figure 1 shows two ad hoc mobile nodes MN0, MN1, which move freely between the four base stations FA-BS1 to FA-BS4.

Figure 2 shows an ad hoc network structure made up of four ad hoc networks, each made up of ad hoc subscriber terminals as well as a base station B. For the hop length between base stations B and ad hoc subscriber terminal sets A, no limit value is defined. This thus results in an undefined network structure around each of the base stations B and an asymmetric distribution of the load in or around the different base stations B, which does not take into account the maximum capacity at all. data transmission from base stations B.

Figure 3 shows a situation according to figure 2, however for the implementation of ad hoc coverage having been set for each base station B a defined hop radius, that is, a maximum allowable number of hops (hop = 1, 1 , 2. 3). By calculating the network load and taking into account the power capacity or transmission capacity of the respective base station (i.e. the maximum theoretical possible network load, here the capacity of the connection is also decisive to the core of the IP network), an optimal individual hop radius can be set by each base station. However, FIG. 3 shows that for a setting only of a hop radius set individually by a base station B the situation may arise that some ad hoc subscriber terminals are not powered by a base station B.

Figure 4 shows the situation of Figure 3, once the individually set hop radius of base stations B has been further optimized by an agreement between base stations B regionally and / or globally in one or more stages iterative optimization, such that all ad hoc subscriber terminals A can be supplied. This results in hop radii (hop = 1, 2, 2, 3). Here too, a dynamic distribution of the network load is possible, which certainly allows each base station B to manage only as many ad hoc subscriber terminals A as it can assume on the basis of its own power capacity, but which Despite this, all subscriber terminals A can be powered. In this way, an increase in network load based on the capacity of each base station B can be avoided, while still ensuring a power supply over the entire area.

Figure 5 shows the sequential evolution of the proposed protocol in the attempt of the subscriber terminal MN (n) to establish a link with the base station BS (n), to obtain through this base station as a gateway (gateway) by default an Internet access. To do this, it sends MN (n) through a terminal device capable of multi-hop MN (n + 1), which is already part of the ad hoc network of the base station BS (n), a Base Station Request BS Req (request to the base station). BS (n) then compares the hop length with the defined hop radius. Since this is true, it welcomes BS (n) to the subscriber terminal MN (n). This then starts the registration process with the Home Agent (HA), local agent, or with the Correspondent Node (CN), interlocutor node, and sends a Binding Update BU, (temporary address update). This is confirmed by the Home Agent (BU ACK). The link is fully established at this time. The subscriber terminal MN (n) is now connected to an IP-based infrastructure (eg the Internet).

Figure 6 shows, analogously to Figure 5, the sequential evolution of the proposed protocol in the attempt of the subscriber terminal MN (n) to establish a link with the base station BS (n), to obtain through this station basic, as a default gateway, an access to the Internet. To do this, it sends MN (n) through a terminal device capable of multi-hop MN (n + 1), which is already part of the ad hoc network of the base station BS (n), a Base Station Request BS Req (request to the base station). BS (n) then compares the jump length to the radius of

ES 2 296 167 T3 defined jump. As a result, however, the base station BS (n) detects in this case that this is not true. Therefore BS (n) sends a negative acknowledgment BS NACK.

The subscriber terminal MN (n) now starts with a new Base Station Request BS Req. Next, another base station BS (n + 1) is announced. This could have already been announced in the first request. The subscriber terminal MN (n) now has no knowledge as to which BS can host it. For this reason, the first BS will not answer in the second request (a memorization of the request can preferably be envisaged). BS (n + 1) is arranged after comparing the hop length with the hop radius to host the new node MN (n) and sends a positive acknowledgment BS ACK.

Subsequently, the subscriber terminal MN (n) starts up by sending the link Update (BU) to the Home Agent (HA). The link is fully established.

Figure 7 shows the sequential evolution in the attempt of the subscriber terminal MN (n) to advertise to the base station BS (n). To do this, MN (n) sends a query again through a multi-hop capable terminal MN (n + 1), which is already part of the ad hoc network of the base station BS (n). The base station BS (n) compares the hop length with a defined hop radius. The comparison leads to the result that the subscriber MN (n) should be rejected. Before the base station BS (n) rejects the new subscriber MN (n), the base station BS (n) starts a query to neighboring base stations BS (n + 1), to detect their hopping radius. To do this, BS (n) sends a HOP Request (HOP Req), jump request. The response of the neighboring station BS (n + 1) results in that BS (n) must nevertheless host the new subscriber MN (n). The link is then fully established. The cause of this may be that the other BS (n + 1) has reached its power limit, which can be indicated by a lower hop radius. BS (n) has the highest hop radius, and can increase it to accommodate the new subscriber terminal MN (n). If BS (n) cannot increase the hop radius because the power limit has been reached, the new subscriber terminal MN (n) is not accepted. This can or must now, by means of a Vertical Handoff, inter-network call management, switch for example to a higher network, for example to a cellular mobile telephone network.

Figure 8 shows the sequential evolution in the attempt of the subscriber terminal MN (n) to announce itself through a multi-hop capable terminal MN (n + 1) to the base station BS (n). The base station BS (n) compares the hop length with a fixed hop radius. The comparison results in the subscriber MN (n) being rejected. Before the base station BS (n) rejects the new subscriber MN (n), the base station BS (n) starts a query to the neighboring base station BS (n + 1), to detect its hopping radius . To do this, BS (n) sends a HOP Request HOP Req. The response from the neighboring base station BS (n + 1) results in that BS (n) does not need to host the new subscriber MN (n). BS (n) thus sends a BS NACK. MN (n) then sends a BS Req, to ​​search for another base station. BS (n + 1) is announced, which has a larger jump radius. This base station BS (n + 1) compares the query with its hop radio and welcomes the new subscriber MN (n). The latter then sends the Binding Update (BU) to the Home Agent (HA). The link is completely established.

Figure 9 shows the protocol row for the integration of mobile IP and AODV (ad hoc On-demand Distance Vector Routing Protocol), which has been used as an example for the protocol described here. The following mobility agents are presented: Correspondent Node (CN) or interlocutor node, Home Agent (HA) or local agent, Gateway Foreign Agent (GFA) or foreign gateway agent, Regional Foreign Agent (RFA) or foreign regional agent and Foreign Agent (FA) or third party agent. In addition, the connection of an ad hoc network is represented, made up of MN (n) and MN (n + 1).

The ad hoc Routing Protocol (here AODV), ad hoc routing protocol, is used for the connection and transmission of IP routing packets. The HMIP protocol stack is used to connect mobile subscriber terminals to the Internet when they switch between IP networks. To do this, the ad hoc subscriber terminals must send the Binding Update (BU) or temporary address update via the base station. The base station here is the FA, which represents the gateway between the ad hoc network and the IP infrastructure.

If the protocol is implemented for HMIPv6, then instead of the Foreign Agent (GFA) and Regional Foreign Agent (RFA) gateway, only Mobility Anchor Points MAP are provided according to figure 11.

Figure 10 schematically shows the essential components according to the invention of a base station BS1 for establishing communication links in a radio communication system with at least several base stations BS1, BS2 and subscriber terminals MN0, MN1. The subscriber terminals MN0, MN1 are configured as ad hoc nodes capable of multi-hop. The subscriber terminal MN0 attempts to establish an ad hoc communication link with the base station BS1 via the subscriber terminal MN1.

The base station BS1 features a Limit Value Definition Unit LVDU, a limit value definition unit, to set the hop radius for multi-hop communication links. This LVDU device is technically data-connected with a Limit Value Comparison Unit LVCU, a limit value comparison unit, to compare the set hop radius with current values ​​for the jump length of the communication link currently in question. This LVCU equipment is in turn technically connected in terms of data with a Multihop Communication Unit MHCU equipment to establish other multi-hop communication links depending on the result of the comparison. Finally is connected at least the LVDU equipment technically as for da

ES 2 296 167 T3 with an Information Exchange Unit IXU, an information exchange unit, for the exchange of information on the hop radius between base station BS1 and one or more neighboring base stations BS2 of the radio communication system .

Figure 11 shows a structure analogous to that of figure 1, which is used to implement HMIPv6 within the framework of the present invention. In this regard, instead of the Gateway Foreign Agent GFA and the Regional Foreign Agents RFA, only Mobility Anchor Points MAP are envisaged, which can basically be arranged in any hierarchy echelon. The base stations BS1 to BS4 serve in this case as Access Router AR, access routers. An IP infrastructure such as the one indicated can be scaled to any dimension, that is to say, MAPs can basically be provided in any quantity in any hierarchical arrangement, to provide a desired network coverage or a desired number of network accesses. The network hierarchy can also be configured differently on different branches of the IP infrastructure, as shown in Figure 11 schematically for the left and right branch of the IP infrastructure. It can thus be seen that for a subscriber terminal MN1 a handover for example from base station BS3 to base station BS4 can generally take place more quickly, since only local MAPs have to be involved in the technical development of handover signals and not a central team like a RFA or a GFA.