DE102009005352A1 - Radio device/network device, has two different slots or transmission facilities or frequencies with optical colors, used for message, where message is redundantly transferred to slots or transmission facilities or frequencies or colors - Google Patents

Abstract

The radio device/network device has a radio channel designed as a transfer medium, which is used with a communication device. Two different slots or transmission facilities or frequencies with optical colors are used for a message. The message is redundantly transferred to the slots or transmission facilities or frequencies or colors. The communication device uses Code Division Multiple Accessfor the message transmission. A parallel collision-free transmission access to a subcarrier or a group of subcarriers is permitted by the communication device.

Description

Of the Invention is based on the object among several participants on a cable or wireless network access to the common transmission medium or to coordinate the shared radio channel so that On the one hand, transmit the data with the lowest possible latency and on the other hand the fairest possible distribution resources are made among the participants.

One A typical example of this is a point-to-multipoint Radio network in which several subscribers communicate with a base station, for example, to be able to use an Internet access. In Internet use, unlike the telephony hardly predicted which subscriber will have a high data throughput at what time needed.

While in a FDD system in the downlink, the distribution can be made well defined by the base station via scheduler, the problem arises in the uplink that either first airtime from the subscriber modem at the base station must be applied for and allocated, which significantly increases the latency. The same applies to TDD methods with a well-defined division of the time frames into an uplink and downlink portion. Corresponding methods are for. B. in the IEEE standard 802.16 described in different variants.

A another possibility is the use of an ALOHA concept, in which the subscriber modem then sends, if there is no occupation itself of the radio channel (CSMA), in particular to the end A transmission can lead to collisions, if at least two Modems have data to send at the same time and simultaneously access the radio channel. In this case usually leads a detection of the collision to repeat the emissions, wherein to avoid a new collision, a variable waiting time (Backoff) is introduced.

This method also takes into account the hidden station problem (one sender can not detect the occupancy by another sender, but both see the base station) by shifting the potential collision from the actual payload to an RTS / CTS control protocol is used, among others, in the IEEE 802.11 WLAN ,

The Method has the advantage up to a certain channel occupancy small latencies, but these can be at high channel occupancy increase dramatically.

Also known are methods such as Slotted ALOHA, in which well-defined time slots are quasi-random occupied, thereby no longer leads to a segmentation of the radio channel. Also known are ALOHA methods in the frequency / time level, this is based on the Contention Based Focused Bandwidth Requests IEEE 802.16 referenced, which accommodate the collision-prone Bandwidth Requests in a time / frequency matrix. This makes it possible, despite the basic polling and approval-oriented approach of the 802.16 standards Spontaneous at least to send bandwidth requests, the allocation continues to be centrally with appropriate latency.

The patents provide a further overview of the state of the art for ALOHA processes EP 0134057 B1 . EP 1630715 B1 and EP 0177094 B1 , What they all have in common, however, is the disadvantage of a high probability of collision and thus poor predictability of the transmission quality, while the polling-based access methods unfortunately extend the latency considerably.

The The same problem arises with access to a broadband cable with cable modems, again, only one modem at a time occupy a certain proportion of the cable spectrum in the uplink.

task This invention is a method for multiple access to find out what the problem of high collision probability in ALOHA procedures and the problem of high latency at Polling procedure for the control of the multiple access on a Übertrgungsmedium or a radio channel as possible avoids.

The Problem is inventively by the in claim 1 described in general form, its function in the following with reference to an embodiment is explained. In the described in claim 2 This device is for multi-carrier processes specialized variant, closer to the embodiment received, the device described in claim 3 is suitable for CDMA processes.

The Embodiment initially goes from a multi-carrier method which allows multiple radio modems to transmit simultaneously, however, only one sub-carrier at a time by a modem at the same time may be occupied, it should not come to a collision. The Subcarriers can be purely frequency-separated (FDMA, SC-FDMA) or orthogonally interleaved (OFDMA) or hexagonal nested (CIFDM), the entire radio signal is therefore made up of a variety of subcarriers together.

in the Frame of a spatiotemporal multiple access now a radio modem both one or more subcarrier groups, which each particular subcarrier exclusively are assigned, as well as one or more time slots for transmission choose. Which are assigned to a subcarrier group Subcarriers may, but do not have to lie next to each other in the spectrum, a uniformly nested one Distribution may make sense under fading aspects.

One Radio modem, which in the uplink a message - where it directly to user data or to a bandwidth request can act - wants to settle, is now according to the invention in This embodiment at the beginning of a new transmission time slot at least two subcarrier groups random or select pseudorandomly and at the beginning of the time slot transmit the pending message redundantly on both subcarrier groups.

For example could be a modem made up of 8 possible subcarrier groups numbered from 0 to 7 select subcarrier groups 3 and 5 for transmission, another modem occupies groups 5 and 6. This is what happens Although there is a collision on Group 5, the messages are both transmitted without collision and separately on groups 3 and 6, see also picture 1.

Surprisingly In this case, the probability of a complete decrease decreases Collision for two messages considerably, although the Occupancy of the radio channel doubled. In the example, the Collision probability in a single send obviously 1/8, that is, .125, while the probability of both Messaging destructive collision in redundant multicast drops to only 0.036. A partial collision is due to the redundant transmission irrelevant.

image 2 shows a corresponding diagram for 32 subcarrier groups, it turns out that even for stronger channel assignments the inventive method the traditional Solutions is clearly superior.

According to one particularly preferred embodiment of the invention according to dependent claim the modems are now signaled by the base station in the downlink, which subcarrier groups receive properly and which are affected by a local collision. In spite of This local collision is usually the reception of the redundant sent message on another subcarrier group possible. The modem can now be used for follow-up transmissions maintain that subcarrier group on which for the bass station is the best possible reception and the is collision-free. At the same time it signals other modems this subcarrier group until release no longer in to include more random selections.

According to one preferred embodiment, this assignment then as Reservations for follow-up messages are retained For example, timer then controls the release after a predefined one Time if there are no further transmissions.

The Selection of the actually used subcarrier group at no collision based on the reception quality can can also be used, with CIFDM method an equalizer faster to converge. Typically, CIFDM is used as a replacement for the guard interval of the OFDM an equalization of the subcarriers using adaptive equalizer, it also can adjacent subcarriers of the other comb included In particular, the six surrounding sub-symbols are recommended to sequentially order a symbol and then, as if these sub-symbols are sent consecutively on only one subcarrier been fed to an adaptive LMS or RLS filter. there from sub-symbol to sub-symbol may be a phase correction for to execute these neighboring symbols, since the reciprocal of their Frequency spacing not in integer relation to the symbol duration stands.

to Acceleration of convergence can now be done in the multiple access area the radio signal different coefficients in the adaptive filter for typical scenarios, provided both (redundant) Messages can be received by the subcarrier group continue with the better presetting.

Farther It may be appropriate, in addition to the redundant Proportion of the actual message also nonredundant checksums with transfer, for example, the parallel messages to be sent are dotted differently. At the same time Reception of both messages is for example an increased Number of LDPC check bits or an increased proportion at Interleaved vs. Non-interleaved check bits of a turbo encoder to disposal. In a very advanced version of the Invention it would also be possible based on the check bits even the data on a subcarrier group with a To separate collision again.

In a further preferred embodiment of the invention, the number of redundantly transmitted messages is controlled depending on the channel occupancy, if sufficiently many subcarrier groups are occupied or reserved, for example, from a triple Parallelaussendung to a double parallel transmission are switched back, above a further limit then a classical polling or scheduling method is used.

Should a collision take place despite the redundant transmission, so can be based on the known (back-off) procedures for ALOHA access schemes to random or pseudorandom repetition within a time interval, which coincides with the number of failed attempts is exponentially enlarged, resorted to become. Here, in addition to the redundancy and thus the number of parallel transmissions on different Increase subgroup groups in case of repetition, for a higher probability of the correct arrival to receive at least one message.

at The use of the invention are also mixed forms with classic Methods conceivable, for example, modems with large Data volumes to be sent from the general multiple assignment procedure be taken out according to this invention and on completely separate time slots or subcarrier groups be run by scheduler.

The Invention is also suitable for CDMA processes, here Messages can be parallel and redundant on different messages Spread codes are transmitted. With time slots is the Use of the invention then makes sense if a collision on this only be detected and reported with considerable delay can.

Even a usage on passive optical networks when using different Colors or time slots instead of subcarrier groups is possible, would be conceivable here, several on different Colors (light frequencies) to operate tunable lasers in parallel, to randomly select the colors and then the message to transmit in parallel via the lasers. In the case a collision with another participant's signal on one Color can then be the redundant not affected by the collision Message to be used on a different color.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0134057 B1 [0008]
• - EP 1630715 B1 [0008]
• EP 0177094 B1 [0008]

Cited non-patent literature

• - IEEE Standard 802.16 [0003]
• - IEEE 802.11 WLAN [0005]
• - IEEE 802.16 [0007]
• - 802.16 standards [0007]

Claims (10)

Radio device, network device or other communication device or module including integrated circuits of such a device, which accesses a message on a jointly used with other such devices transmission medium, wherein a radio channel is also referred to in this context as a transmission medium, which continues for this access is a This method also includes ALOHA and CSMA access methods, characterized in that the collision probability is reduced by randomly or pseudorandomly paralleling at least two different slots or transmission opportunities or frequencies, including optical colors, on the transmission medium be used for the same message, with their information redundantly transmitted to these slots or transmission opportunities or frequencies or colors wi approx. Radio or other communication device or assembly including integrated circuits Such a device, which is used for message transmission uses a multi-carrier method, in particular FDMA, SC-FDMA, OFDM, DMT or CIFDM, the multi-carrier method having a parallel collision-free transmission access to individual subcarriers or Groups of subcarriers through different devices allowed, an assignment of the same subcarrier or the same group by two different devices however leads to a collision of emissions, characterized in that that the collision probability is reduced by that random or pseudorandom at least two different Subcarriers or groups of subcarriers parallel for the same message to be sent, where whose information is redundant on these subcarriers or Groups of subcarriers is transmitted. Radio or other communication device or assembly including integrated circuits Such a device, which is used for message transmission uses a CDMA (Code Division Multiple Access) method, wherein by different spreading codes a parallel collision-free Transmit access possible through different devices is an assignment of the same spreading code by two different However, equipment leads to a collision of emissions, characterized in that the collision probability thereby is reduced to being random or pseudo-random at least two different spreading codes in parallel for the same message to be sent, with their information is transmitted redundantly with these spreading codes. Device or assembly according to one of the claims 1 to 3 or a combination of these, characterized in that the recipient of the message sends a reply, which signals to the senders which slots, transmission items, subcarriers, Subcarrier groups or spreading codes are decoded correctly could, if necessary, stating the respective reception quality, which gives the broadcasters the opportunity to be affected by collisions Slots, Broadcasting, Subcarriers, Subcarrier Groups or spread codes no longer with follow-up messages to prove or to eliminate the redundancy in the transmission, preferably those slots, transmission matters, subcarriers, Subcarrier groups or spreading codes with the best reception quality to be kept. Device or assembly according to one of the claims 1 to 4 or a combination of these, characterized in that the number of parallel and thus redundant transmissions for a message to the utilization of the transmission medium is adjusted, with the required number of parallel emissions signaled by at least one central unit or base station can be, and in addition at very large Utilization of the transmission medium in whole or in part to a Polling procedure for pending transmissions can be changed. Device or assembly according to one of the claims 1 to 5 or a combination of these, characterized in that Parallel transmissions additionally - not redundant - different Checksums or forward error correction codes for contain the redundantly sent message or the single redundant message Message is encoded differently with each of these, so that in the case of simultaneous receipt of multiple transmissions with redundant Message content without collision improved forward error correction the message is enabled. Device or assembly according to claim 6, characterized characterized in that emissions continue to be non-redundant pieces of information which, if necessary, by use of the contained checksums or error correction codes on slots, transmission items, subcarriers, Subcarrier groups or spreading codes with collision from the receiver again mathematically separated or eliminated. Device or assembly according to claim 2, characterized in that different subcarriers or groups of subcarriers are pre-assigned with different pre-predistorter pre-equalizer or equalizer (equalizer) parameters, wherein In the case of the OFDM and CIFDM adjacent subcarriers can be included in the predistortion or equalization for ICI reduction, in the case of the CIFDM also in the time / frequency diagram adjacent sub-symbols of other transmitting combs or the vorzuverzerrende or to be equalized sub-symbol hexagonal surrounding further sub-symbols can be included. Device or assembly according to one of the claims 1 to 8 or a combination of these, characterized in that in the case of still occurring collisions, the emissions after a break, randomly selected within a time window be repeated, where to reduce the probability of collision for these repetitions, the number of parallel transmissions can be temporarily increased. Device or assembly according to one of the claims 1 to 9 or a combination of these, characterized in that a successful assignment of at least one slot, one transmission opportunity, a subcarrier, a subcarrier group or a spreading code preventive for further transmissions at least a device is retained and the occupancy signaled accordingly or in the absence of further data is held with fill data until a predetermined time (Timeout) has expired, in which no further data for transmission incurred, this slot, this sending opportunity, this Subcarrier, this subcarrier group or this Spread code during its occupancy no longer from others Devices is included in the random selection.